BIO EXAM 2

ADP

(Adenosine Diphosphate) The compound that remains when a phosphate group is removed from ATP, releasing energy this is how ATP functions like a rechargeable battery

TAKE HOME MESSAGE 4.3

TAKE HOME MESSAGE 4.3 » Eukaryotes are single-celled or multicellular organisms consisting of cells with a nucleus that contains linear strands of genetic material. Most eukaryotic cells also have organelles throughout their cytoplasm; these organelles may have originated evolutionarily through endosymbiosis or invagination, or both.

What is cellulae?

What Hook first discovered in a microscope as what he thought the magnified views of a very thin piece of cork resembled a mass of small, empty rooms.

TAKE HOME MESSAGE 5.1

» The sun is the source of the energy that powers most living organisms and other "machines." The energy from sunlight is stored in the chemical bonds of molecules. When these bonds are broken, energy is released, regardless of whether the bond is in a molecule of food, of a fossil fuel, or of a biofuel such as the oil in which french fries are cooked.

How many basic structural features do prokaryotes have?

1. A plasma membrane encompasses the cell (and sometimes is simply called the "cell membrane"). Anything inside the plasma membrane is referred to as "intracellular," and everything outside the plasma membrane is "extracellular." 2. The cytoplasm refers to the cell's contents contained within the plasma membrane. This includes the jelly-like fluid, called the cytosol, and the cell's genetic material. 3. Ribosomes are little granular bodies where proteins are made; thousands of them are scattered throughout the cytoplasm. 4. Each prokaryote has one or more circular loops or linear strands of DNA. *Some prokaryotes have additional structures. For example, many have a rigid cell wall that protects and gives shape to the cell.

How many different enzymes are needed for lysosomes to function?

50

What is a prokaryotic cell?

A cell bound by a plasma membrane enclosing the cell contents (DNA is in cytoplasm, and ribosomes); the cell has no nucleus or other organelles.

Phospholipids

A group of lipids that are the major components of the plasma membrane. Phospholipids are structurally similar to fats, but contain a phosphorus atom and have two, not three, fatty acid chains. **appear to be a head and two long tails. The head consists of a molecule of glycerol linked to a molecule containing phosphorus **The chemical structure of phospholipids gives them a sort of split personality: their polar, hydrophilic ("water-loving") head region mixes easily with water, while their nonpolar, hydrophobic ("water-fearing") tail region does not mix with water.

central vacuole

A large vacuole that rests at the center of most plant cells and is filled with a solution that contains a high concentration of solutes.

Chlorophyll

A light-absorbing pigment molecule in chloroplasts.

chlorophyll b

A photosynthetic pigment similar in structure to chlorophyll a. Chlorophyll b absorbs blue and red-orange wavelengths and reflects yellow-green wavelengths.

What are receptor proteins?

A protein in the plasma membrane that binds to specific chemicals in the cell's external environment to regulate processes within the cell; for example, cells in the heart have receptor proteins that bind adrenaline.

What are surface proteins?

A protein that resides primarily on the inner or outer surface of the phospholipid bilayer that constitutes a cell's plasma membrane. Also called peripheral proteins.

light energy

A type of kinetic energy made up of energy packets called photons, which are organized into waves.

chemical energy

A type of potential energy in which energy is stored in chemical bonds between atoms or molecules.

Which of the following is correct? Energy cannot be created. Energy and matter can be transformed into one another. Energy cannot be destroyed. All of the above

ALL OF THE ABOVE

primary active transport

Active transport using energy released directly from ATP.

Which of the following statements is TRUE? Many reactions that release energy and linked to reactions that requires energy. Glucose breakdown is almost 100% efficient in cells. Entropy increases in the universe with every chemical reaction. All of the Above A and C

BOTH A AND C

two groups of prokaryotes

Bacteria and Archaea - all other organisms are eukaryotes

How do beta-blocker drugs work on a cellular level? Please choose the correct answer from the following choices, and then select the submit answer button. Beta-blocker drugs are pumped into the cell while adrenaline is pumped out of the cell. Beta-blocker drugs break down adrenaline molecules, preventing them from having an effect on the cell. Beta-blocker drugs diffuse between phospholipids in the plasma membrane, entering the cell and blocking the effects of adrenaline. Beta-blocker drugs bind to a receptor protein to block the binding and effect of adrenaline on the cell. Beta-blocker drugs bind to adrenaline molecules, thereby preventing them from attaching to adrenaline receptors.

Beta-blocker drugs bind to a receptor protein to block the binding and effect of adrenaline on the cell. Beta-blocker drugs bind to beta-receptor proteins on the cell membrane, blocking adrenaline from binding to the receptors, and thereby inhibiting its effect on the cell.

Which of the following statements about the cell theory is correct? All living organisms are made up of one or more cells. All cells arise from other, preexisting cells. All eukaryotic cells contain symbiotic prokaryotes. All prokaryotic cells contain symbiotic eukaryotes. Both a) and b) are correct.

Both A and B are correct

Microtubules are: part of the cytoskeleton part of the endoplasmic reticulum part of the transportation system in the cell Both A and C

Both A and C

hypertonic

Describes one of two solutions that has the higher concentration of solutes

hypotonic

Describes one of two solutions that has the lower concentration of solutes.

CAM ("crassulacean acid metabolism")

Energetically expensive photosynthesis in which the stomata are open only at night to admit CO2, which is bound to a holding molecule and released to enter the Calvin cycle to make sugar during the day. In this type of photosynthesis, found in many fleshy, juicy plants of hot, dry areas, water loss is reduced because the stomata are closed during the day.

All of the following are examples of endocytosis EXCEPT Pinocytosis Exocytosis Phagocytosis Receptor- mediated endocytosis Both (A) and (C)

Exocytosis

tonicity

For a cell in solution, a measure of the concentration of solutes outside the cell relative to that inside the cell.

biofuel

Fuels produced from plant and animal products.

Glycolysis

Glycolysis means the splitting (lysis) of sugar (glyco-), and it is the first step that all organisms on the planet take to capture energy from the breakdown of food molecules; for many single-celled organisms, this one step is sufficient to provide all of the energy they need 10 chemical reactions

Which of the following is FALSE? The exchange of gases in plants occurs through the stomata Glucose is broken down to pyruvate in glycolysis Glycolysis requires Oxygen Glycolysis yields ATP

Glycolysis requires Oxygen

Which of the following facts supports the claim that mitochondria developed from bacteria that, long ago, were incorporated into eukaryotic cells by the process of phagocytosis? Mitochondria have flagella for motion. Mitochondria have proteins for the synthesis of ATP. Mitochondria are the "powerhouses" of the cell. Mitochondria are small and easily transported across cell membranes. Mitochondria have their own DNA.

Mitochondria have their own DNA.

Which of the following is not a correct statement about passive transport across the cell membrane? Please choose the correct answer from the following choices, and then select the submit answer button. Passive transport decreases free energy. Passive transport may involve chemical energy in the form of ATP. Passive transport increases entropy in a system. Facilitated diffusion by transport proteins is one form of passive transport. Diffusion across an electrochemical gradient is one form of passive transport.

Passive transport may involve chemical energy in the form of ATP. Passive transport does not involve the use of ATP.

carotenoids

Pigments that absorb blue-violet and blue-green wavelengths of light and reflect yellow, orange, and red wavelengths of light.

ATP is most similar to: glucose RNA cellulose sodium

RNA

What happens to the rest of the energy not captured by organisms?

Some (probably less than 1%) is captured by organisms and transformed into usable chemical energy through photosynthesis. The rest is reflected back into space (probably about 30%) or is absorbed by land, the oceans, and the atmosphere (about 70%) and mostly transformed into heat.

What are organelles?

Specialized structures in the cytoplasm of eukaryotic cells, with specific functions; include, among others, the rough and smooth endoplasmic reticulum, Golgi apparatus, and mitochondria.

TAKE HOME 4.11

TAKE HOME MESSAGE 4.11 » When materials cannot get into a cell by diffusion or through a pump (for example, when the molecules are too big), cells can engulf the molecules or particles with their plasma membrane in a process called endocytosis. Similarly, molecules can be moved out of a cell by exocytosis. In endocytosis, the plasma membrane moves to surround the molecules or particles and forms a little vesicle that is pinched off inside the cell; in exocytosis, a vesicle inside the cell fuses with the plasma membrane and dumps its contents outside the cell.

TAKE HOME 4.12

TAKE HOME MESSAGE 4.12 » In multicellular organisms, most cells are connected to other cells. The connections can form a water-tight seal between the cells (tight junctions), can hold sheets of cells together while allowing fluid to pass between neighboring cells (desmosomes), or can function like passageways, allowing the movement of cytoplasm, molecules, and other signals between cells (gap junctions).

TAKE HOME MESSAGE 4.9

TAKE HOME MESSAGE 4.9 » The diffusion of water across a membrane is a special type of passive transport called osmosis. Water moves from an area with a lower concentration of solutes to an area with a higher concentration of solutes. Water molecules move across the plasma membrane until the concentration of water inside and outside the cell is equalized.

common genetic disorder where a child inherits an inability to produce a critical lipid-digesting enzyme

Tay Sachs disease

energy

The capacity to do work, which is the moving of matter against an opposing force.

Which of the following statements about cell theory is true? Please choose the correct answer from the following choices, and then select the submit answer button. All living organisms are made up of one or more cells. All cells arise from other, preexisting cells. All eukaryotic cells contain symbiotic prokaryotes. All prokaryotic cells contain symbiotic eukaryotes. Both the first and second answer choices are true.

The first two choices

What is ivagination?

The folding in of a membrane or layer of tissue so that an outer surface becomes an inner surface.

What is solvent?

The gas or liquid in which a substance is dissolved; for example, in a solution of water and sugar, water is the solvent.

electron transport chain

The path of high-energy electrons moving from one molecule within a membrane to another, coupled to the pumping of protons across the membrane, creating a concentration gradient that is used to make ATP; occurs in mitochondria and chloroplasts.

Which of the following is FALSE about chloroplasts? Their presence in green plants is consistent with endosymbiosis They contain DNA They are found in animal cells They contain ribosomes They are the location of photosynthesis

They are found in animal cells

_______ are found in all metabolically active cells and are involved primarily in transporting materials within, into, and out of cells. Please choose the correct answer from the following choices, and then select the submit answer button. Vesicles Peroxisomes Mitochondria Lysosomes Vacuoles

Vesicles Vesicles are in all metabolically active cells and are involved in transport of materials.

final products of the "photo" of photosynthesis

With the electrons' passage through the second photosystem and arrival in NADPH, we now have the final products of the "photo" part of photosynthesis (which is also called the "light-dependent reactions"): we've captured light energy from the sun and converted it to the chemical energy of ATP and the high-energy electron carrier NADPH

What is a eukaryotic cell?

a cell with a membrane-surrounded nucleus that contains DNA, membrane-surrounded organelles, and internal structures organized into compartments.

It's important to note that the direction of osmosis is determined only by:

a difference in the total concentration of all the molecules dissolved in the water: it does not matter what the solutes are, only how many molecules of solutes there are. **To determine which way the water molecules will move, you need to determine the total amount of "dissolved stuff" on either side of the membrane. The water will move toward the side with the greater concentration of solute.

What is a vesicle?

a little pocket-like sac

What is a nucleus?

a membrane-enclosed structure that contains linear strands of DNA. The central and most massive part of an atom, usually made up of two types of particles, protons and neutrons, which move about the nucleus.

Every living cell has: A. A nucleus B. Mitochondria C. A plasma membrane D. ALL OF THE ABOVE

a plasma membrane

Intermediate filaments

a second type of cytoskeleton fiber, are durable, rope-like systems of numerous different overlapping proteins. They give cells great strength. One of three types of protein fibers (the others are microtubules and microfilaments) that make up the eukaryotic cytoskeleton, providing it with structure and shape; a durable, rope-like system of numerous different overlapping proteins.

Which of the following is not considered to be a prokaryote? Please choose the correct answer from the following choices, and then select the submit answer button. an E. coli cell a bacterium a virus an S. pyogenes cell an archaean

a virus Viruses are non-living; therefore, they are neither eukaryotes nor prokaryotes.

Humans: In the absence of oxygen, _______ accepts the electrons released from NADH, allowing glycolysis to resume.

acetaldehyde

An electron transport chain is Involved in photosynthesis Involved in cellular respiration Uses electron carriers All of the above

all of the above

Which answer below is a product of the Krebs cycle? ATP NADH FADH2 CO2 All of the above.

all of the above

Glycolysis has two distinct phases:

an "uphill" preparatory phase and a "downhill" payoff phase.

To help break down food into more digestible bits, the cells lining your stomach create:

an acidic environment by pumping large numbers of H+ ions (also called protons) into the stomach contents, against their concentration gradient

microfilaments

are the thinnest elements in the cytoskeleton. Long, solid, rod-like fibers, microfilaments help generate forces, including those important in cell contraction and cell division. One of three types of protein fibers (the others are intermediate filaments and microtubules) that make up the eukaryotic cytoskeleton, providing it with structure and shape, These are the thinnest elements in the cytoskeleton. The long, solid, rod-like fibers help generate forces, including those important in cell contraction and cell division.

Hypotonic solutions will cause red blood cells to: Divide Burst Shrivel None of the above

burst

What is the most basic unit of any organism?

cell

They contain chains of carbon and hydrogen atoms bound together, and breaking these bonds and forming new, lower-energy bonds releases large amounts of

energy (and water and CO2)

When ndividuals have the misfortune of inheriting genes that code for faulty liver cell membranes that have few LDL receptors.

familial hypercholesterolemia.

Tight junctions

form continuous, water-tight seals around cells and anchor cells in place EX: Much like the caulking around a tub or sink that keeps water from leaking into the surrounding walls, tight junctions prevent fluid flow between cells. Tight junctions are particularly important in the small intestine. A continuous, water-tight connection between adjacent animal cells. Tight junctions are particularly important in the small intestine, where digestion occurs, to ensure that nutrients do not leak between cells into the body cavity and so become lost as a source of energy.

The cytoskeleton: Please choose the correct answer from the following choices, and then select the submit answer button. gives animal cells shape and support. gives plant cells shape and support. controls the extracellular traffic flow. produces no force and is unrelated to cell movement. All of the above are correct.

gives animal cells shape and support. It also enables cellular movement.

The cytoskeleton: is a viscous fluid found in all cells. fills a cell's nucleus but not the other organelles. gives an animal cell shape and support, but cannot control movement. helps to coordinate intracellular movement of organelles and molecules. All of the above are correct.

helps to coordinate intracellular movement of organelles and molecules.

Energy is released from ATP by: osmosis hydrolysis exocytosis photosynthesis

hydrolysis

If the concentration of solutes outside the cell is higher than the concentration inside the cell, the outside solution

hypertonic In this situation, if the cell membrane is not permeable to the solutes, the concentrated solutes outside the cell will crowd and bump the water molecules and slow their entry into the cell membrane. More water will move out of the cell than into it. The cell will shrivel.

If the concentration of solutes outside the cell is lower than the concentration inside the cell, the outside solution is:

hypotonic In this situation, if the cell membrane is not permeable to the solutes, more water molecules will move into the cell than out of it. The cell will swell.

What is a peculiar feature of chloroplasts?

is that they resemble photosynthetic bacteria, particularly with their circular DNA (which contains many of the genes essential for photosynthesis).

If the solution surrounding a cell contains the same amount of solute as the cytoplasm, the osmotic condition is said to be _________.

isotonic

The garbage disposal within a cell is called the: golgi apparatus lysosome ribosome nucleolus

lysosome

Which organelle will digest a bacteria that has been phagocytized by a white blood cell? Lysosome Rough endoplasmic reticulum Golgi apparatus Smooth endoplasmic reticulum

lysosome

The cellular structure responsible for converting fuel to energy are called: smooth endoplasmic reticulum mitochondria ribosomes A and C

mitochondria

What is is the largest and most prominent organelle in most eukaryotic cells?

nucelus --nucleus is generally larger than any prokaryotic cell.

The ______ membrane surrounds the nucleus and separates it from the cytoplasm.

nuclear

Ribosomes are assembled in the: rough endoplasmic reticulum nucleolus golgi apparatus lysosomes

nucleolus

Which of the following is NOT found in all living cells? Ribosomes Plasma membrane A nucleus All of the above

nucleus

What is the cell's genetic control center?

nucleus --directing most cellular activities by controlling which molecules are produced and in what quantity, and is the storehouse for hereditary information

What are the three types of endocytosis? Please choose the correct answer from the following choices, and then select the submit answer button. plasmocytosis, pinocytosis, and exocytosis phagocytosis, pinocytosis, and exocytosis vesicles, LDL particles, and HDL particles vesicles, LDL particles, and receptors phagocytosis, pinocytosis, and receptor-mediated endocytosis

phagocytosis, pinocytosis, and receptor-mediated endocytosis All three types of endocytosis involve cells engulfing molecules or particles that are too large to enter the cell by either passive or active transport.

An organism can use energy from the sun only if it can convert the light energy of the sun into the chemical energy of the bonds between atoms. The most important molecule in this conversion is the :

pigment chlorophyll

Two types of active transport

primary and secondary differ only in the source of the fuel that keeps the revolving doors spinning

Plasma membrane functions include all of the following EXCEPT: controls the flow of molecules in and out of cell allows cell to take in water receiving signals via embedded proteins producing energy build and export material from the cell

producing energy

Which of following is not a critical function of the plasma membrane of a cell? Please choose the correct answer from the following choices, and then select the submit answer button. enables food and nutrient intake and waste export enables the cell to construct and export molecules needed elsewhere in the body provides structural support communicates with the external environment and other cells controls what goes into and out of the cell

provides structural support Providing structural support is a function of the cell wall, especially in plant cells.

Protein functions include all of the following EXCEPT: receptors for signaling molecules cell recognition storing genetic information enzymatic activity

storing genetic information

The second step of cellular respiration:

the citric acid cycle extracts energy from sugar.

Chloroplast

the organelle in plant and eukaryotic algae cells in which photosynthesis occurs.

chlorophyll a

the primary photosynthetic pigment. Chlorophyll a absorbs blue-violet and red light; because it cannot absorb green light and instead reflects those wavelengths, we perceive the reflected light as the color green.

cellular respiration

the process by which all living organisms extract energy stored in the chemical bonds of molecules and use it for fuel for their life processes.

photsynthesis

the process by which some organisms, including plants and some protists and bacteria, are able to capture energy from the sun and store it in the chemical bonds of sugars and other molecules

What are archaea?

these microorganisms inhabit some of the harshest environments on earth, thriving in extremes of temperature, salinity, and pH.

Cystic fibrosis is the result of what type of faulty plasma membrane molecule? Please choose the correct answer from the following choices, and then select the submit answer button. receptor protein cholesterol recognition proteins membrane enzymes transport protein

transport protein Transport proteins move molecules into the cell that are not able to diffuse through the membrane. Cystic fibrosis occurs when an individual inherits incorrect genetic instructions for producing a transport protein that controls the flow of chloride ions into and out of cells found primarily in the lungs and digestive tract.

HIV

uses molecular fingerprints to infect an individual's cells. These molecular markers belong to a group of identifying markers called "clusters of differentiation." Abbreviated as "CD markers" and having names such as CD1, CD2, and CD3, these marker molecules are proteins embedded in the plasma membrane. They enable the cell to bind to outside molecules and, sometimes, transport them into the cell. One CD marker, called the CD4 marker, is found only on cells deep within the body and in the bloodstream, such as immune system cells and some nerve cells.

TAKE HOME MESSAGE 5.11

» C4 and CAM photosynthesis are evolutionary adaptations at the biochemical level that, although more energetically expensive than regular (C3) photosynthesis, allow plants in hot, dry climates to partly or fully close their stomata and conserve water without shutting down photosynthesis.

TAKE HOME MESSAGE 5.4

» Cells temporarily store energy in the bonds of ATP molecules. This potential energy can be converted to kinetic energy and used to fuel life-sustaining chemical reactions. In other reactions, inputs of kinetic energy are converted to the potential energy of the energy-rich but unstable bonds of ATP molecules.

TAKE HOME MESSAGE 5.3

» Energy is neither created nor destroyed but can change form. Each conversion of energy is inefficient, and some of the usable energy is converted to heat, a less useful form of energy.

TAKE HOME MESSAGE 5.2

» Energy, the capacity to do work, comes in two forms. Kinetic energy is the energy of moving objects, while potential energy, such as chemical energy, is stored energy that results from the location, position, or composition of an object.

TAKE HOME MESSAGE 5.13

» Glycolysis is the initial phase in the process by which all living organisms harness energy from food molecules. Glycolysis occurs in a cell's cytoplasm and uses the energy released from breaking chemical bonds in food molecules to produce high-energy molecules, ATP and NADH.

TAKE HOME MESSAGE 5.6

» In plants, photosynthesis occurs in chloroplasts, green organelles packed in cells near the plants' surfaces, especially in the leaves.

TAKE HOME MESSAGE 4.21

» In plants, vacuoles can occupy most of the interior space of the cell. Vacuoles, usually less prominent, are also present in some other eukaryotic species. In plants, they function as storage spaces and play roles in nutrition, waste management, predator deterrence, reproduction, and physical support.

TAKE HOME MESSAGE 5.12

» Living organisms extract energy through a process called cellular respiration, in which the high-energy bonds of sugars and other energy-rich molecules are broken, releasing the energy that went into creating them. The cell captures the food molecules' stored energy in the bonds of ATP molecules. This process requires fuel molecules and oxygen, and it yields ATP molecules, water, and carbon dioxide.

TAKE HOME MESSAGE 4.17

» Lysosomes are round, membrane-enclosed, acid-filled organelles that function as a cell's garbage disposals. They are filled with about 50 different digestive enzymes and enable a cell to dismantle macromolecules, including disease-causing bacteria.

TAKE HOME MESSAGE 5.17

» Oxygen deficiency limits the breakdown of fuel because the electron transport chain requires oxygen as the final acceptor of electrons during the chemical reactions of glycolysis and the citric acid cycle. When oxygen is unavailable, yeast cells resort to fermentation, in which they use a different electron acceptor, acetaldehyde, and in the process generate ethanol, the alcohol in beer, wine, and spirits.

TAKE HOME MESSAGE 4.19

» The Golgi apparatus—another organelle within the endomembrane system—processes molecules synthesized in the cell and packages those that are destined for use elsewhere in the body.

TAKE HOME MESSAGE 4.20

» The cell wall is an organelle found in plants (and in some other non-animal organisms). It is made primarily from the carbohydrate cellulose, and it surrounds the cell's plasma membrane. The cell wall confers tremendous structural strength on plant cells, gives plants increased resistance to water loss, and provides some protection from insects and other animals that might eat the plant. Plasmodesmata connect the plant cells and enable communication and transport between them.

TAKE HOME MESSAGE 4.22

» The chloroplast is the organelle of plants and algae that is the site of photosynthesis—the conversion of light energy into chemical energy, with oxygen as a by-product. Chloroplasts may originally have been bacteria that were engulfed by a predatory cell by endosymbiosis.

TAKE HOME MESSAGE 4.18

» The production and modification of biological molecules in eukaryotic cells occurs in a system of organelles called the endomembrane system, which includes, among other organelles, the rough and smooth endoplasmic reticulum. In rough ER, proteins that will be shipped elsewhere in the body are folded and packaged. In the smooth ER, lipids and carbohydrates are synthesized and alcohol, antibiotics, and other drugs are detoxified.

Polar

Having an electrical charge.

intermembrane space

In a mitochondrion, the region between the inner and outer membranes.

To generate energy, fuels such as glucose and other carbohydrates, as well as proteins and lipids (after some preliminary modifications), are broken down in three steps:

(1) glycolysis, (2) the citric acid cycle, and (3) the electron transport chain.

Three primary types of connections between animal cells

(1) tight junctions, (2) desmosomes, and (3) gap junctions

The "synthesis" part of photosynthesis takes place in a series of chemical reactions called :

Calvin Cycle

Where can you find cells that are and are not metabolically active?

Cells that are not very metabolically active, such as some fat storage cells in humans, have very few mitochondria. Cells that have large energy requirements, such as muscle, liver, and sperm cells in animals and fast-growing root cells in plants, are packed densely with mitochondria

__________________ are the plant cell's solar power plant.

Chloroplasts

nonpolar

Electrically uncharged.

Eukaryotic vs. Prokaryotic

Eukaryotic cells are about 10,000 times larger than prokaryotic cells in volume.

fossil fuel

Fuels produced from the decayed remains of ancient plants and animals; include oil, natural gas, and coal.

Which of the following statements about prokaryotes is incorrect? Prokaryotes appeared on earth before eukaryotes. Prokaryotes have circular pieces of DNA within their nuclei. Prokaryotes contain cytoplasm. Prokaryotes contain ribosomes. Some prokaryotes can conduct photosynthesis.

Prokaryotes have circular pieces of DNA within their nuclei.

isotonic

Refers to solutions with equal concentrations of solutes.

pyruvate

The end product of glycolysis.

Which of the following statements is true about a plasma membrane? The molecules making up the plasma membrane are locked in place. It is a rigid structure that protects the cell like a shell. It is composed of a single layer of phospholipids. The molecules that make up the membrane are phospholipids. The molecules that make up most of the plasma membrane are polar at their heads and tails.

The molecules that make up the membrane are phospholipids. The plasma membrane is made up of a bilayer of phospholipids, which prevent fluids from leaking out of the cell.

What is the primary function of the Rough ER?

The primary function of the rough ER is to fold and package proteins for shipment to other locations in the endomembrane system, to the cell surface, or to the outside of the cell.

fermentation

The process by which glycolysis occurs in the absence of oxygen; the electron acceptor is pyruvate (in animals) or acetaldehyde (in yeast) rather than oxygen.

What is a cell?

The smallest unit of life that can function independently; a three-dimensional structure, surrounded by a membrane and, in prokaryotes and most plants, by a cell wall, in which many of the essential chemical reactions of the life of an organism take place.

mitochondriol matrix

The space enclosed by the inner mitochondrial membrane, where the carriers NADH and FADH2 begin the electron transport chain by carrying high-energy electrons to molecules embedded in the inner membrane.

What is the function of rubisco in the Calvin Cycle?

To remove CO2 from the air and transfer to G3P

A drug that alters membrane function and serves to reduce anxiety is called: Please choose the correct answer from the following choices, and then select the submit answer button. a beta-receptor. adrenaline. caffeine. alcohol. a beta-blocker.

a beta-blocker. By binding to beta-adrenergic receptors (or beta-receptors) and thereby blocking adrenaline from binding, beta-blocker drugs reduce anxiety.

What is the largest group of prokaryotes?

bacteria

Where do cells build proteins and lipids and disarm toxins?

endoplasmic reticulum

The first step of cellular respiration:

glycolysis is the universal energy-releasing pathway.

mitochondrion

the organelle in plant and animal cells (as well as in protists and fungi) that converts the energy stored in food into a form usable by the cell

What are aquaporins?

"water channels", which are transmembrane proteins with hydrophilic channels through which water molecules pass in single file.

For every 50-100 phospholipids in the membrane, there is ____ protein molecule(s).

1

What is the critical responsibility of the ER?

A critical responsibility of the smooth ER—particularly in human liver cells—is to help protect us from the many dangerous molecules that get into our bodies.

chromatin

A mass of long, thin fibers consisting of DNA and proteins in the nucleus of the cell.

What are transmembrane proteins?

A membrane protein that penetrates the phospholipid bilayer of a cell's plasma membrane.

Kinetic versus potential energy

A concentration gradient also has potential energy: if molecules in an area of high concentration move toward an area of lower concentration, the potential energy of the gradient is converted to the kinetic energy of molecular movement, and this kinetic energy can do work.

Prokaryotes: Please choose the correct answer from the following choices, and then select the submit answer button. lack a plasma membrane. evolved after eukaryotes. are multicellular. lack a nucleus. are more complex than eukaryotes.

lack a nucleus. Prokaryotes lack a nucleus. They do, however, contain genetic material.

the most important form of kinetic energy on earth

light because it comes from the movement of high-energy particles,

3 inputs to the process of photosynthesis

light energy (from the sun), carbon dioxide (from the atmosphere), and water (from the environment). From these three inputs, the plant produces sugar and oxygen.

First part of photosynthesis

light reaction In the first part of photosynthesis, the "photo" part, sunlight hits the chloroplasts of a plant's leaves, and some of the energy in this sunlight is captured and stored in ATP and in another molecule, called NADPH, which stores energy by accepting high-energy electrons (FIGURE 5-17). After these transformations, the captured energy is ready to be used to make sugar molecules in the "synthesis" part of photosynthesis.

The electron transport chain is located in the cytosol located in the inner mitochondrial membrane located in the nucleus located on ribosomes

located in the inner mitochondrial membrane

__________ are the cell's garbage disposal

lysosomes

C4 photosynthesis

method (along with C3 and CAM photosynthesis) by which plants fix carbon dioxide, using the carbon to build sugar. It serves as a more effective method than C3 photosynthesis for binding carbon dioxide under low CO2 conditions, such as when plants in warmer climates close their stomata to reduce water loss.

vacuole

A membrane-enclosed, fluid-filled, multipurpose organelle prominent in most plant cells (but also present in some protists, fungi, and animals). Its functions vary but can include storing nutrients, retaining and degrading waste products, accumulating poisonous materials, containing pigments, and providing physical support.

first law of thermodynamics

A physical law stating that energy cannot be created or destroyed; it can only change from one form to another.

second law of thermodynamics

A physical law stating that every conversion of energy is not perfectly efficient and invariably includes the transformation of some energy into heat.

If the concentration of solutes outside the cell is equal to the concentration inside the cell, the outside solution:

it's isotonic Water still moves between the solution and the cell, but because it moves at the same rate in both directions, there is no net change in the amount of water inside versus outside the cell.

Energy has two forms:

kinetic and potential.

Endomembrane system at work

1) Transport vesicle buds from the smooth or rough ER. 2) Transport vesicle fuses with Golgi apparatus, dumping contents inside. 3) Golgi apparatus modifies the molecules as they move through its successive chambers. 4) Modified molecules bud off from the Golgi apparatus as a transport vesicle. 5) Vesicle may fuse with the plasma membrane, dumping contents outside the cell for delivery elsewhere in the organism.

Nearly all life depends on capturing energy from the sun and converting it into forms that living organisms can use. This energy capture and conversion occurs in two important processes that mirror each other:

1) photosynthesis, the process by which plants capture energy from the sun and store it in the chemical bonds of sugars, and (2) cellular respiration, the process by which all living organisms release the energy stored in the chemical bonds of food molecules and use it to fuel their lives

The idea of the role of endosymbiosis in the evolution of eukaryotes is supported by several observations:

1. Chloroplasts and mitochondria are similar in size to prokaryotic cells and divide by splitting (fission), just like prokaryotes. 2. Chloroplasts and mitochondria have ribosomes, similar to those found in bacteria, that allow them to synthesize some of their own proteins; this ability is not found in other organelles, which rely on proteins made by the cell's cytoplasmic ribosomes. 3. Chloroplasts and mitochondria have small amounts of circular DNA, similar to the circular DNA in prokaryotes and in contrast to the linear DNA strands found in a eukaryote's nucleus. 4. Analysis of chloroplast and mitochondrial DNA has revealed that it is highly related to bacterial DNA, much more closely than it is related to eukaryotic DNA. The best current theory about the origin of the other organelles in eukaryotes is a process called invagination.

the central vacuole can play an important role in five different areas of plant life:

1. Nutrient storage. The vacuole stores hundreds of dissolved substances, including amino acids, sugars, and ions. 2. Waste management. The vacuole retains waste products and degrades them with digestive enzymes, much like the lysosome in animal cells. 3. Predator deterrence. The poisonous, nasty-tasting materials that accumulate inside the vacuoles of some plants make a powerful deterrent to animals that might try to eat parts of the plant. 4. Sexual reproduction. The vacuole may contain pigments that give some flowers the colors that attract pollinators—birds and insects that help the plant reproduce by transferring pollen. 5. Physical support. High concentrations of dissolved substances in the vacuole can cause water to rush into the cells via osmosis. The increased fluid pressure inside the vacuole can cause the cell to enlarge and push against the cell wall. This process is responsible for the pressure (called turgor pressure) that allows stems, flowers, and other plant parts to stand upright. The ability of non-woody plants to stand upright is due primarily to turgor pressure. Wilting is the result of a loss of turgor pressure.

Primary Types of Membrane Proteins and their Functions

1. Receptor proteins are surface or transmembrane proteins that bind to chemicals in the cell's external environment. In doing so, receptor proteins can attach a cell to the extracellular matrix or convey information from the outside to the inside of the cell. Cells in the heart, for example, have receptor proteins within their membrane that bind to adrenaline, a chemical released into the bloodstream in times of extreme stress or fright. When adrenaline binds to these heart cells, the cells increase the heart's rate of contraction to pump blood through the body more quickly. You have experienced this reaction if you've ever been startled and felt your heart start to pound. 2.Recognition proteins are surface or transmembrane proteins that give each cell a "fingerprint" that makes it possible for the body's immune system (which fights off infections) to distinguish body cells from invaders. Carbohydrates also play a role in recognition. On the outside of the cell membrane, short glycoproteins (proteins with one or more attached sugars) serve as part of the membrane's fingerprint. Like receptor proteins, recognition proteins can also help cells bind or adhere to other cells or molecules within the extracellular matrix. 3.Transport proteins are transmembrane proteins that help polar or charged substances pass through the plasma membrane. 4.Membrane enzymes are surface or transmembrane proteins that accelerate chemical reactions on the plasma membrane's surface. In addition, the lipid cholesterol can also be incorporated in a cell's plasma membrane. Cholesterol helps the membrane maintain its flexibility, preventing the membrane from becoming too fluid or floppy at moderate temperatures and acting as a sort of antifreeze, preventing the membrane from becoming too rigid at freezing temperatures. The membranes of some cells are about 25% cholesterol; other plasma membranes, such as those of most bacteria and plants, have no cholesterol.

Plasma membranes must perform several critical functions:

1. The membrane enables the cell to take in food and nutrients and dispose of waste products. It allows the cell to build and export molecules needed elsewhere in the body. 2. It mediates communications with the external environment and with other cells, and adhesion to other cells or surfaces. 3. Like a border control checkpoint, it controls the flow of molecules (including water) into and out of the cell. **The foundation of all plasma membranes is a layer of tightly packed lipid molecules, called phospholipids.

Calvin Cycle Step 3

3. Regeneration. Not all of the G3P molecules are used to produce sugars. In the third and final phase of the Calvin cycle, some G3P molecules are rearranged to regenerate the original five-carbon molecule. The rearrangement of G3P requires energy from ATP produced in the "photo" reactions of photosynthesis. Once the five-carbon molecule is regenerated, the Calvin cycle can continue to fix carbon and produce molecules of G3P. The three "turns" of the Calvin cycle required to synthesize one molecule of G3P from carbon in the atmosphere consume nine molecules of ATP and six molecules of NADPH generated in the "photo" reactions of photosynthesis.

What evidence supports endosymbiosis as the origin for mitochondria? Presence of two lipid bilayers Maternal inheritance Mitochondria have their own DNA Both (A) and (C)

A and C

Which of the following is TRUE? Prokaryotic cells do not have a nucleus The plasma membrane is mainly composed of protein Mitochondria have their own DNA All of the above Both (A) and (C)

A and C

endocytosis

A cellular process in which large particles, solid or dissolved, outside the cell are surrounded by a fold of the plasma membrane, which pinches off to form a vesicle, and the enclosed particle moves into the cell. The three types of endocytosis are phagocytosis, pinocytosis, and receptor-mediated endocytosis. EX: bacterial invaders engulfed by cells in plasma membrane

exocytosis

A cellular process in which particles within the cell, solid or dissolved, are enclosed in a vesicle and transported to the plasma membrane, where the membrane of the vesicle merges with the plasma membrane and the material in the vesicle is expelled to the extracellular fluid for use throughout the body. EX: To export large particles, such as digestive enzymes manufactured for use elsewhere in the body,

What is plasma membrane?

A complex, thin, two-layered membrane that encloses the cytoplasm of the cell, holding the contents in place and regulating what enters and leaves the cell; also called the cell membrane.

cell wall

A rigid structure, outside the cell membrane, that protects and gives shape to the cell; found in many prokaryotes and plants. it is porous, allowing water and solutes to reach the plasma membrane The plant cell wall is made largely from long fibers of a polysaccharide called cellulose. Animal cells do not have cell walls, but some non-plants such as archaea, bacteria, protists, and fungi do. Their cell walls are made of polysaccharides other than cellulose.

What is solute?

A substance that is dissolved in a gas or liquid; for example, in a solution of water and sugar, sugar is the solute

What is fluid mosaic?

A term that describes the structure of the plasma membrane, which is made up of several different types of molecules, many of which are not fixed in place but float, held in their proper orientation by hydrophilic and hydrophobic forces.

Endosymbiosis is: An expalnation as to why eukaryotic cells have ribosomes A theory as to how ancestral eukayotic cells acquired a nucleus A theory as to how ancestral eukaryotic cells acquired mitochondria All of the above None of the above

A theory as to how ancestral eukaryotic cells acquired mitochondria

What is osmosis?

A type of passive transport in which water molecules move across a membrane, such as the plasma membrane of a cell. The direction of osmosis is determined by the relative concentrations of all solutes on either side of the membrane.

TAKE HOME 4.15

AKE HOME MESSAGE 4.15 » In mitochondria, which are found in nearly all eukaryotic cells, the energy contained in the chemical bonds of carbohydrate, fat, and protein molecules is converted into carbon dioxide, water, and ATP, the energy source for all cellular functions and activities. Mitochondria may have evolutionary origins as symbiotic bacteria living inside other cells.

Endosymbiosis: A. is a theory that explains how organelles first appeared in eukaryotic cells B. Explains why mitochondria are similar in size to prokaryotic bacteria C. Explains why chloroplasts have ribosomes D. Explains why chloroplasts and mitochondria have their own DNA E. ALL OF THE ABOVE

ALL OF THE ABOVE

The third step of cellular respiration:

ATP is built in the electron transport chain.

secondary active transport

Active transport in which there is no direct involvement of ATP (adenosine triphosphate). The transport protein simultaneously moves one molecule against its concentration gradient while letting another flow down its concentration gradient. EXAMPLE: The process is like using energy to pump water to the top of a high water tower. Later, the water can be allowed to run out of the tower over a water wheel, which can, in turn, power a process such as grinding wheat into flour. Our bodies frequently use the energy from one reaction that occurs spontaneously to fuel another reaction that requires energy.

nucleolus

An area near the center of the nucleus where subunits of the ribosomes are assembled - a critical part of the cellular machinery EX: Ribosomes are like little factories in which the information stored in the DNA is used to construct proteins. The ribosomes are built in the nucleolus but pass through the nuclear pores and into the cytosol before starting their protein-production work.

What are eukaryotes?

An organism composed of eukaryotic cells. Eukaryotas are cells that have a nucleus, and organelles that have different functions(like the mitochondria, which produces energy). Eukaryotas can include simple organisms like protozoa. Human cells are Eukaryotas!

What is a prokaryote?

An organism consisting of a prokaryotic cell (all prokaryotes are one-celled organisms invisible to the naked eye).

Which of the following statements is TRUE? A. Eukaryotic cells have a nucleus and prokaryotic cells do not. B. Eukaryotic cells have ribosomes and prokaryotic cells do not. C. Eukaryotic cells have mitochondria and proakroptic cells do not. D. ALL OF THE ABOVE E. BOTH A and C

BOTH A and C

Why is conversion of energy from one form to another inefficient? Because it is impossible to harvest 100% of the sun's energy Because it is impossible to release all the stored energy in a chemical bond Because forming chemical bonds is a poor way to store energy Because some energy is always transformed into heat

Because some energy is always transformed into heat

Osmosis is: An example of passive transport An example of active transport The passage of water across a membrane All of the above Both A and C

Both A and C

In plant cells, chloroplasts: serve the same purpose that mitochondria serve in animal cells. are the site of conversion of light energy into chemical energy. play an important role in the breakdown of plant toxins. have their own linear strands of DNA. Both b) and d) are correct.

Both b) and d) are correct.

Which process is similar between cellular respiration and photosynthesis Both break down sugar to form ATP and electron carriers Both use oxygen as a final electron acceptor Both produce a proton gradient for ATP production Both use light to produce ATP and electron carriers

Both produce a proton gradient for ATP production

Which statement is true? Please choose the correct answer from the following choices, and then select the submit answer button. Correct: Both prokaryotic and eukaryotic cells arose from preexisting living cells. Both prokaryotic and eukaryotic cells arose from preexisting living cells. Cell theory only applies to eukaryotic cells. Only eukaryotic cells arose from preexisting living cells. Only prokaryotic cells arose from preexisting cells. Cell theory only applies to prokaryotic cells.

Both prokaryotic and eukaryotic cells arose from preexisting living cells. Both prokaryotic and eukaryotic cells apply to cell theory.

stroma

In the leaf of a green plant, the fluid in the inner compartment of a chloroplast, which contains DNA and protein-making machinery. With a simple light microscope, little spots of green are visible within the chloroplasts.

Which of the following is FALSE about the carbon cycle It requires ATP It requires NADPH It produces sugars It only occurs in the dark None of the above

It only occurs in the dark

Most cholesterol that circulates in the bloodstream is in the form of particles is called

LDL - low density lipoproteins Each molecule of LDL is a cholesterol globule coated by phospholipids

Which of the following statements about the endoplasmic reticulum and the Golgi apparatus is true? Please choose the correct answer from the following choices, and then select the submit answer button. Incorrect: The Golgi apparatus is a site of processing and packaging only; the endoplasmic reticulum is responsible for synthesizing compounds such as carbohydrates. The Golgi apparatus is a site of processing and packaging only; the endoplasmic reticulum is responsible for synthesizing compounds such as carbohydrates. The Golgi apparatus is connected to the endoplasmic reticulum via tight junctions. Not all eukaryotic cells contain an endomembrane system; only those involved in transporting materials possess this system. Incorrect: Both the Golgi apparatus and the endoplasmic reticulum work together to form the endocytotic and exocytotic cycles of the cell. Both the Golgi apparatus and the endoplasmic reticulum work together to form the endocytotic and exocytotic cycles of the cell. Correct: Both the Golgi apparatus and the endoplasmic reticulum work together to form the endomembrane system. Both the Golgi apparatus and the endoplasmic reticulum work together to form the endomembrane system.

Both the Golgi apparatus and the endoplasmic reticulum work together to form the endomembrane system. The Golgi apparatus, rough ER, and smooth ER all work together to produce and modify molecules for transport to other parts of the organism, as well as break down toxins and cellular by-products.

What role does Smooth ER play in increasing our tolerance to drugs (from antibiotics to heroin)?

Chronic exposure to many drugs (from antibiotics to heroin) can induce a proliferation of smooth ER and detoxification enzymes, particularly in the liver. This proliferation increases tolerance to the drugs, necessitating higher doses to achieve the same effect.

Which function is specific to chloroplast? Garbage disposal of the cells Convert light into chemical energy. Converts chemical energy into ATP. Used to maintain turgor pressure.

Convert light into chemical energy.

______ and the ________ form the cell's internal environment, provide support, and can generate motion.

Cytoplasm and the cytoskeleton

Mitochondria contain circular strands of ____, similar to that found in many prokaryotes.

DNA Like many prokaryotes, including bacteria, mitochondria contain a circular strand of DNA.

Cell types contain...

DNA (deoxyribonucleic acid)

What is facilitated diffusion?

Diffusion of molecules through the phospholipid bilayer of a plasma membrane that takes place through a transport protein (a "carrier molecule") embedded in the membrane. Molecules that require the assistance of a carrier molecule are those that are too big to cross the membrane directly or are electrically charged and would be repelled by the middle layer of the membrane. **a transport protein spans the membrane and functions like a revolving door, allowing movement of molecules in either direction, depending on their concentration gradient.

What are the 3 chief purposes of a cytoskeleton?

First, it gives animal cells shape and support—making red blood cells look like little round doughnuts (without the hole in the middle) and giving neurons their very long, thread-like appearance. Second, the cytoskeleton controls the intracellular traffic, serving as a series of tracks on which a variety of organelles and molecules are guided across and around the inside of the cell. And third, because the elaborate scaffolding of the cytoskeleton is dynamic and can generate force, it gives all cells some ability to control their movement.

Calvin Cycle Step 1

Fixation. First, using an enzyme called rubisco, plants pluck carbon from the air, where it occurs in the form of carbon dioxide (which has one carbon), and attach, or "fix," it to an organic molecule (which has five carbon atoms) within the chloroplast. Not surprisingly, given its role as the critical chemical that enables plants to build food molecules, rubisco is the most abundant protein on earth.

If a cell lacks the CD4 marker, what does this mean for HIV? Please choose the correct answer from the following choices, and then select the submit answer button. HIV (but no other viruses) will be able to infect the cell. HIV will not be able to infect the cell. HIV will utilize a CD2 marker on the cell instead. HIV will not be able to infect the cell; however, AIDS will. HIV will be able to diffuse into the cell, where it will lie dormant.

HIV will not be able to infect the cell. HIV specifically targets the CD4 marker. If the virus locates a cell with this marker, it can infect the cell.

According to the endosymbiotic theory, which of the following inferences can be made? Please choose the correct answer from the following choices, and then select the submit answer button. The simplicity of prokaryotes is in part due to eukaryotic engulfment. An ancestral prokaryote engulfed a eukaryote, therefore eukaryotes and prokaryotes are not as different as they seem. Chloroplasts and mitochondria are originally eukaryotes but prokaryotic engulfment caused them to convert to prokaryotes. Human beings may have been part bacteria and have an ancestry arising in prokaryotes. The plasma membrane is capable of folding on itself.

Human beings may have been part bacteria and have an ancestry arising in prokaryotes. It is believed that organelles, such as the mitochondria, were once free-living prokaryotes, and the ancestors of eukaryotic cells engulfed them. This enabled these cells to then use oxygen as an electron acceptor since oxygen was becoming an abundant component of the earth's atmosphere.

What is simple diffusion?

In cells, molecules such as oxygen (O2) and carbon dioxide (CO2) that are small and carry no charge can pass directly through the phospholipid bilayer of the membrane without the assistance of any other molecules EXAMPLE: Each time you take a breath, for example, there is a higher concentration of O2 molecules in the air you pull into your lungs than in the blood in your lungs. And so O2 diffuses across the plasma membranes of the lung cells and into your bloodstream, where red blood cells pick it up and deliver it to where it is needed. Similarly, because CO2 in your bloodstream is at a higher concentration than in the air in your lungs, it diffuses from your blood into the cells of your lungs and is released to the atmosphere when you exhale

primary electron acceptor

In photosynthesis, a molecule that accepts excited, high-energy electrons from chlorophyll a, beginning the series of electron handoffs known as an electron transport chain.

plasmodesmata

In plants, microscopic tube-like channels connecting the cells and enabling communication and transport between them.

"photo" part of photosynthesis

Like the first photosystem, the second photosystem has numerous pigments that harness photons from the sun and pass the light energy to another special chlorophyll a molecule. The special chlorophyll a molecule at the center of this second photosystem has electron vacancies because, as in the first photosystem, as its electrons are boosted to an excited state, they are whisked away from the chlorophyll molecule by another primary electron acceptor. The electrons must be replaced, but rather than being supplied by the splitting of water, the electrons in the second photosystem are passed from the first photosystem.

The electron transport is: located in the cytosol Located in the inner mitochondrial membrane Located in the nucleus Located on ribosomes

Located in the inner mitochondrial membrane

_____________ are the cell's energy converters.

Mitochondria

First, the pyruvate molecules move from the cytoplasm into the mitochondria, where they undergo THREE quick modifications that prepare them to be broken down in the citric acid cycle:

Modification 1. Each pyruvate molecule passes a pair of its high-energy electrons (and a proton) to the electron-carrier molecule NAD+, building two molecules of NADH. Modification 2. Next, a carbon atom and two oxygen atoms are removed from each pyruvate molecule and released as carbon dioxide. The CO2 molecules diffuse out of the cell and, eventually, out of the organism. In humans, for example, these CO2 molecules pass into the bloodstream and are transported to the lungs, from which they are eventually exhaled. Modification 3. In the final step in the preparation for the citric acid cycle, a giant compound known as coenzyme A attaches itself to the remains of each pyruvate molecule, producing two molecules called acetyl-CoA. Each acetyl-CoA molecule is now ready to enter the citric acid cycle.

What is passive transport?

Molecular movement that occurs spontaneously, without the input of energy. The two types of passive transport are diffusion and osmosis.

Which of the following statements about mitochondria is correct? Mitochondria are found in both eukaryotes and prokaryotes. There tend to be more mitochondria in fat cells than in liver cells. Most plant cells contain mitochondria. Mitochondria may have originated evolutionarily as photosynthetic bacteria. All of the above are correct.

Most plant cells contain mitochondria.

pinocytosis

One of the three types of endocytosis, in which dissolved particles and liquids are engulfed by the plasma membrane, a vesicle is formed, and the material is moved into the cell. The vesicles formed in pinocytosis are generally much smaller than those formed in phagocytosis.

phagocytosis

One of the three types of endocytosis, in which relatively large solid particles are engulfed by the plasma membrane, a vesicle is formed, and the particle is moved into the cell. EX: Amoebas and other unicellular protists, as well as white blood cells, use phagocytosis to consume entire organisms for defense or food.

3 general outcomes in citric acid cycle

Outcome 1. A new molecule is formed. Acetyl-CoA adds its two-carbon acetyl group to the starting material of the citric acid cycle, a four-carbon chemical called oxaloacetate, creating a six-carbon molecule (called citrate). Outcome 2. High-energy electron carriers (NADH) are made and carbon dioxide is exhaled. The six-carbon molecule then gives electrons to NAD+ to make the high-energy electron carrier NADH. (Don't forget that the main purpose of the citric acid cycle is the capture of energy.) The six-carbon molecule also releases two carbon atoms along with four oxygen atoms to form two carbon dioxide molecules. In mammals (including humans), this CO2 is carried by the bloodstream to the lungs. Outcome 3. The starting material of the citric acid cycle is re-formed, ATP is generated, and more high-energy electron carriers are formed. After the CO2 is released, the remaining four-carbon molecule is modified and rearranged to once again form oxaloacetate, the starting material of the citric acid cycle. In the process of this reorganization, one ATP molecule is generated, and more electrons are passed to NAD+ and a molecule called FAD to form NADH and FADH2, both of which are high-energy electron carriers. The formation of these high-energy electron carriers increases the energy yield of the citric acid cycle. One oxaloacetate is re-formed, and the cycle is ready to break down the second molecule of acetyl-CoA. Two turns of the cycle are necessary to completely dismantle our original molecule of glucose.

Which of the following describes simple diffusion? Please choose the correct answer from the following choices, and then select the submit answer button. Hydrogen ions are pumped out of stomach lining cells with the use of ATP. Oxygen moves through the cell membrane from an area of high concentration outside the cell into an area of lower concentration inside the cell. Glucose is transported into the cell via a transport protein. Sodium is transported out of the cell to an area of lower concentration with the use of ATP. The salts in a laxative cause water to move from surrounding cells into the intestines.

Oxygen moves through the cell membrane from an area of high concentration outside the cell into an area of lower concentration inside the cell. Simple diffusion involves particles moving from an area of high concentration to an area of lower concentration without the use of energy or helper membrane proteins.

What is diffusion?

Passive transport in which a particle (the solute) is dissolved in a gas or liquid (the solvent) and moves from an area of higher solute concentration to an area of lower solute concentration

"synthesis" of photosynthesis

Plants carry out these reactions using the energy stored in the ATP and NADPH molecules that are built in the "photo" portion of photosynthesis. This dependency links the light-gathering ("photo") reactions with the sugar-building ("synthesis") reactions

What were the first cells on Earth?

Prokaryotes

Which of the following statements about prokaryotes and eukaryotes is false? Please choose the correct answer from the following choices, and then select the submit answer button. Eukaryotic cells are about 10,000 times larger than prokaryotic cells in volume. Eukaryotic cells can be distinguished easily from prokaryotic cells under a microscope. Organelles are the primary reason why eukaryotic cells can do many things that a prokaryotic cell cannot. Genetic material in prokaryotes resides in the cytoplasm, whereas genetic material in eukaryotes resides in a membrane-enclosed structure. Prokaryotic cells are about 10 times larger than eukaryotes.

Prokaryotic cells are about 10 times larger than eukaryotes. Although eukaryotic cells can vary greatly in size, they are generally much larger than prokaryotic cells.

Protein sequence A shows a string of leucines (hydrophobic amino acids) at one end, and a string of arginine (hydrophilic amino acids) at the opposite end. Protein sequence B contains purely hydrophilic amino acids. It is known that both proteins are membrane proteins. Which of the following statements best classifies Protein A and Protein B? Please choose the correct answer from the following choices, and then select the submit answer button. Protein A is a transmembrane protein; Protein B is a peripheral membrane protein that can only be situated on the inner side of the membrane. Protein A is a transmembrane protein; Protein B is a peripheral membrane protein. Protein A is a transmembrane protein; Protein B is also a transmembrane protein. Protein A is a surface protein; Protein B is a transmembrane protein. Protein A is a transmembrane protein; Protein B is a peripheral membrane protein that can only be situated on the outer side of the membrane.

Protein A is a transmembrane protein; Protein B is a peripheral membrane protein. Transmembrane proteins tend to have a string of hydrophobic amino acids due to membrane insertion, whereas surface membrane proteins usually contain all hydrophilic amino acids.

Energy is required for: Diffusion Osmosis Pumping H+ ions across membranes None of the above

Pumping H+ ions across membranes

Who first used the term "cell"?

Robert Hooke

Ribosomes can be attached: smooth Endoplasmic Reticulum Golgi apparatus Rough Endoplasmic reticulum Lysosomes

Rough Endoplasmic reticulum

stomata

Small pores, usually on the undersides of leaves, that are the primary sites for gas exchange in plants. Carbon dioxide (for photosynthesis) enters and oxygen (a by-product of photosynthesis) exits through the stomata. Closing their stomata solves one problem for plants (too much water evaporation) but creates another: with the stomata shut, oxygen from the "photo" reactions of photosynthesis cannot be released from the chloroplasts, and carbon dioxide cannot enter. And without carbon dioxide molecules for sugar production, the Calvin cycle cannot proceed. Plant growth comes to a standstill and crops fail.

active transport

Sometimes the transport of molecules into and out of cells needs energy Molecular movement that depends on the input of energy, which is necessary when the molecules (or ions) to be moved are large or are being moved against their concentration gradient. proteins embedded in the membrane act like motorized revolving doors, pushing molecules across cell membranes regardless of the concentration of those molecules on either side of the membrane.

potential energy

Stored energy; the capacity to do work that results from an object's location, position, or composition, as in the case of water held behind a dam. does not have to be moving EX: Water behind a dam, for example, has potential energy. If a hole is opened in the dam, the water can flow through, and perhaps spin a waterwheel or turbine.

Calvin Cycle Step 2

Sugar creation. The newly built molecule immediately splits in two, and each half is chemically modified. First a phosphate from ATP is added, and then each of the two molecules receives some high-energy electrons from NADPH. The result is two molecules of a three-carbon sugar called glyceraldehyde 3-phosphate (G3P). For the net synthesis of one molecule of G3P from carbon in the atmosphere, three "turns" of the Calvin cycle are required to fix three molecules of carbon dioxide. Some of the G3P molecules are combined to make the six-carbon sugars glucose and fructose. These sugars can be used as fuel by the plant, enabling it to grow. They can also be used as fuel by animals that eat the plant.

TAKE HOME MESSAGE 4.10

TAKE HOME MESSAGE 4.10 » In active transport, movement of molecules across a membrane requires energy. Active transport is necessary if the molecules to be moved are very large or if they are being moved against their concentration gradient. Proteins embedded in the plasma membrane act like motorized revolving doors to actively transport (pump) the molecules.

TAKE HOME 4.13

TAKE HOME MESSAGE 4.13 » The nucleus is usually the largest and most prominent organelle in the eukaryotic cell. It directs most cellular activities by controlling which molecules are produced and in what quantity. The nucleus is the storehouse for hereditary information.

TAKE HOME 4.14

TAKE HOME MESSAGE 4.14 » The inner scaffolding of the cell, which is made from proteins, is the cytoskeleton. Consisting of three types of protein fibers—microtubules, intermediate filaments, and microfilaments—the cytoskeleton gives animal cells their shape and support, gives cells some ability to control their movement, and serves as a series of tracks on which organelles and molecules are guided across and around the inside of the cell.

TAKE HOME 4.16

TAKE HOME MESSAGE 4.16 » Form follows function in an organism's cells and reflects their environment. When cells must perform intensive heat production, for example, they significantly increase the number and size of their mitochondria. They also increase the blood supply to the tissue and make use of existing stores of energy.

TAKE HOME MESSAGE 4.4

TAKE HOME MESSAGE 4.4 » Every cell of every living organism is enclosed by a plasma membrane, a two-layered membrane that holds the contents of a cell in place and regulates what enters and leaves the cell.

TAKE HOME MESSAGE 4.5

TAKE HOME MESSAGE 4.5 » The plasma membrane is a fluid mosaic of proteins, lipids, and carbohydrates. Proteins in the membrane enable it to carry out most of its gatekeeping functions. In conjunction with carbohydrates, some plasma membrane proteins identify the cell to other cells. And, in addition to the phospholipids that make up most of the plasma membrane, the membrane lipid cholesterol influences fluidity.

TAKE HOME MESSAGE 4.6

TAKE HOME MESSAGE 4.6 » Normal cell functioning can be disrupted when cell membranes—particularly the proteins embedded in them—do not function properly. Such malfunctions can cause health problems, such as cystic fibrosis. But intentional disruption of normal cell membrane function can have beneficial, therapeutic effects, such as in the treatment of high blood pressure and anxiety.

TAKE HOME MESSAGE 4.7

TAKE HOME MESSAGE 4.7 » Every cell in your body has a "fingerprint" made from a variety of molecules on the outside-facing surface of the cell membrane. This molecular fingerprint is key to the function of your immune system.

Proteins: are embedded in the plasma membrane can have lipids added to them can have carbohydrates added to them all of the above

all of the above

TAKE HOME MESSAGE 4.8

TAKE HOME MESSAGE 4.8 » For proper functioning, cells must acquire food molecules and/or other necessary materials from outside the cell. Similarly, metabolic waste molecules and molecules produced for use elsewhere in the body must move out of the cell. In passive transport—which includes simple and facilitated diffusion and osmosis—the molecular movement occurs spontaneously, without the input of energy. This generally takes place as molecules move down their concentration gradient.

What is a cell?

The cell is the smallest unit of life that can perform all of the necessary activities of life. All living organisms are made up of one or more cells, and all cells arise from other, preexisting cells. Prokaryotes are a metabolically diverse group of single-celled organisms, with no nucleus. They include the bacteria and archaea. Eukaryotes are single-celled or multicellular organisms consisting of cells with a nucleus that contains linear strands of genetic material, and most eukaryotic cells have organelles.

photons

The elementary particle that carries the energy of electromagnetic radiation of all wavelengths. Photons can do work as they bombard surfaces such as your face (heating it) or a leaf (enabling it to build sugar from carbon dioxide and water). the shorter the wavelength, the more energy the photon carries.

endomembrane system

The endomembrane system occupies as much as one-fifth of the cell's volume and is responsible for many of the fundamental functions of the cell. A system of organelles (rough endoplasmic reticulum, smooth endoplasmic reticulum, and Golgi apparatus) that surrounds the nucleus. It produces and modifies necessary molecules, breaks down toxic chemicals and cellular by-products, and is thus responsible for many of the fundamental functions of the cell.

Which of the following statements about the nucleus is false? Please choose the correct answer from the following choices, and then select the submit answer button. The nucleus contains pores that only open in response to DNA entering or exiting the cell. The nucleus consists of two bilayers, layered one on top of the other. Ribosomes are assembled inside of the nucleus. The nucleus acts as the genetic control center of the cell, directs all cellular activity, and stores hereditary information. The nucleus contains three important structural components: the nuclear membrane, chromatin, and the nucleolus.

The nucleus contains pores that only open in response to DNA entering or exiting the cell. The pores enable a variety of large molecules to pass from the nucleus to the cytosol and from the cytosol to the nucleus.

Nine important landmarks distinguish eukaryotic cells.

The nucleus is the genetic control center of eukaryotic cells. It directs protein production and is the storehouse for hereditary information. The cytoskeleton is the inner scaffolding of a cell. Made from three types of protein fibers—microtubules, intermediate filaments, and microfilaments—it gives the cell shape and support and serves as a series of tracks on which organelles and molecules are guided. Mitochondria are found in virtually all eukaryotic cells and act as all-purpose energy converters, harvesting energy to be used for cellular functions. Lysosomes are acid- and enzyme-filled organelles that function as cellular garbage disposals. The production and modification of biological molecules in eukaryotic cells occurs in a system of organelles called the endomembrane system, which includes the rough and smooth endoplasmic reticulum. The Golgi apparatus—an organelle within the endomembrane system—processes molecules synthesized in the cell and packages those that are destined for use elsewhere in the body. The cell wall of plant cells is made primarily from cellulose and provides structural strength, increases resistance to water loss, and provides some protection from animals that might eat plant parts. Vacuoles are storage spaces found in several types of eukaryotes, and especially prominent in plants, that play a role in nutrition, waste management, predator deterrence, reproduction, and physical support. The chloroplast is the organelle in plants and algae that is the site of photosynthesis—the conversion of light energy into chemical energy, with oxygen as a by-product.

chloroplast

The organelle in plant cells in which photosynthesis occurs. most chloroplasts are located within the cells of leaves.

chloroplasts

The sac-shaped organelle is filled with a fluid called the stroma. Floating in the stroma is an elaborate system of interconnected membranous structures called thylakoids, which often look like stacks of pancakes. And embedded within the thylakoid membranes are many light-catching pigments organized into structures called photosystems. The chloroplast is where photosynthesis takes place in a plant. Inside the chloroplast, there are two distinct places: in the stroma or inside the thylakoids. The conversion of light energy to chemical energy—the "photo" part of photosynthesis—occurs on the surface of and inside the thylakoids. The production of sugars—the "synthesis" part of photosynthesis—occurs within the stroma.

Citric Acid Cycle (Krebs Cycle)

The second step of cellular respiration, in which energy is extracted from sugar molecules as additional molecules of ATP and NADH are formed; also called the Krebs cycle

Which of the following statements about chloroplasts is true? Please choose the correct answer from the following choices, and then select the submit answer button. Chloroplasts are found in eukaryotic cells, therefore they contain linear DNA. The DNA of the chloroplast is found within the thylakoid sacs. The chloroplast has one single membrane layer due to its small size. The stacks of interconnected sacs within the chloroplast are known as thylakoids; the light-collecting for photosynthesis occurs here. The stacks of interconnected sacs within the chloroplast are known as stroma; this is where the light-collecting for photosynthesis occurs.

The stacks of interconnected sacs within the chloroplast are known as thylakoids; the light-collecting for photosynthesis occurs here. It is on the membranes of the thylakoids that the light-collecting for photosynthesis occurs.

thermodynamics

The study of the transformation of energy from one type to another, such as from potential energy to kinetic energy.

What is the difference between pinocytosis and phagocytosis?

The two processes are largely the same, except that the vesicles formed during pinocytosis are generally much smaller than those formed during phagocytosis.

Cilia: Please choose the correct answer from the following choices, and then select the submit answer button. are microtubule-based structures. are short projections. help the cell move through its environment. when they are present, occur in large numbers on a single cell. All of the above.

all of the above

What feature of chloroplasts suggests that they are derived from photosynthetic bacteria? Please choose the correct answer from the following choices, and then select the submit answer button. They contain thylakoids. They are filled with stroma. They contain circular DNA. They have a nucleus. They contain a central vacuole.

They contain circular DNA. Chloroplasts contain loops of DNA. They also have a dual membrane, which suggests that a predatory cell engulfed a photosynthetic bacterium via endocytosis, enveloping the photosynthetic bacterium with its plasma membrane.

Specific exocytosis process

To shuttle molecules out of the cell, particles within the cell are first enclosed in a vesicle. The vesicle then moves through the cytoplasm to the plasma membrane, where the membrane of the vesicle merges with the plasma membrane, and the material in the vesicle is expelled from the cell. The hormone insulin, for example, is transported out of pancreatic cells in this way

Mitochondrion structure

To visualize the structure of a mitochondrion, imagine a plastic sandwich bag. Now take another, bigger plastic bag and stuff it inside the sandwich bag. There is a smooth outer membrane and a scrunched-up inner membrane. This construction forms two separate compartments within the mitochondrion: a region outside the inner bag (called the intermembrane space) and another region, called the mitochondrial matrix, inside the inner bag. This bag-within-a-bag structure has important implications for energy conversion

In chemistry class we learn the rule "like dissolves like" when studying why polar substances dissolve in each other (like sucrose in water) and why nonpolar substances dissolve in each other (like fats in oil). Which of the following statements illustrates this rule? Please choose the correct answer from the following choices, and then select the submit answer button. Transmembrane proteins remain in the plasma membrane even though they are not attached to anything. Prokaryotes lack a nuclear membrane while eukaryotes have one. More prokaryotic cells could fit inside a 1 cm cube than eukaryotic cells could. Ribosomes are found inside of prokaryotic cells rather than outside. Chemical messengers or hormones bind tightly to their receptor proteins on the outside of a cell.

Transmembrane proteins remain in the plasma membrane even though they are not attached to anything. Transmembrane proteins remain associated with the membrane because hydrophobic and hydrophilic forces keep them properly oriented.

Which of the following properly describes the role of vacuoles? Please choose the correct answer from the following choices, and then select the submit answer button. Vacuoles function as storage spaces and also play a role in plant nutrition, waste management, predator deterrence, reproduction, and physical support. Vacuoles help provide physical support to plants, allowing stems, flowers, and other plant parts to stand upright. Vacuoles function to connect cells and enable communication and transport between them. Vacuoles are empty sacs within a plant cell that simply provide structure. Vacuoles are involved in nutrient storage as well as waste management for plants.

Vacuoles function as storage spaces and also play a role in plant nutrition, waste management, predator deterrence, reproduction, and physical support. Vacuoles, which are found in plants and some protists, fungi, and animals, may appear to be empty sacs, but they play a role in all of these aspects of plant life.

What happens when a cell consumes a particle of food?

When a cell consumes a particle of food or even an invading bacterium via phagocytosis, the cell directs the material to lysosomes for dismantling. After this dismantling, the cell releases most of the component parts of molecules, such as the amino acids from proteins, into its cytoplasm, where they can be used by the cell as raw materials.

Adenosine Triphosphate (ATP)

a free-floating molecule found in cells that acts like a rechargeable battery, temporarily storing energy that can then be used for cellular work in plants, animals, and all other organisms on earth. The use of ATP solves an important timing and coordination problem for living cells: a supply of ATP guarantees that the energy required for energy-consuming reactions will be available when it's needed. A molecule that temporarily stores energy for cellular activity in all living organisms. ATP is composed of adenine, a sugar molecule, and a chain of three negatively charged phosphate groups. PG 130

Rough ER (Rough Endoplasmic Reticulum)

a large series of interconnected, flattened sacs that look like a stack of pancakes. These sacs are connected directly to the nuclear envelope. In most eukaryotic cells, the rough ER almost completely surrounds the nucleus an organelle, part of the endomembrane system, structurally like a series of interconnected, flattened sacs connected to the nuclear envelope; called "rough" because its surface is studded with ribosomes. Its "rough" surface is studded with ribosomes, the cell's protein-making machines.

Which of the following describes receptor-mediated endocytosis? Please choose the correct answer from the following choices, and then select the submit answer button. chloride entering a trachea cell via a transport protein sodium and potassium ions being pumped across a cell membrane a liver cell recognizing and engulfing an LDL molecule the ends of neural cells releasing neurotransmitters white blood cells engulfing an invading bacterium

a liver cell recognizing and engulfing an LDL molecule LDL receptor proteins in the plasma membrane of liver cells recognize and bind to LDL molecules. The plasma membrane forms a vesicle, engulfing the LDL, and ultimately LDL is broken down and used to make other molecules, including hormones.

What is as flagellum?

a long, thin, rotating, whip-like projection of the plasma membrane that moves the cell through the medium in which it lives. In prokaryotes, a projection of the plasma membrane that aids in the cell's movement through the medium in which it lives. In eukaryotes, a microtubule-based projection; in animals, the only cell with a flagellum is the sperm cell. PLURAL - FLAGELLA

In an experiment, you measure the concentration of a polar molecule inside and outside a cell. You find that the concentration is high and gradually increasing inside the cell. You also measure the ATP concentration inside the cell and find that it is dropping. What is your best hypothesis for the process you are observing? Please choose the correct answer from the following choices, and then select the submit answer button. facilitated diffusion passive transport simple diffusion active transport exocytosis

active transport Active transport is the only form of transport associated with ATP usage.

Cholesterol enters a cell: as a LDL particle by receptor mediated endocytosis using energy all of the above

all of the above

The theory of endosymbiosis is supported by which of the following observations? Please choose the correct answer from the following choices, and then select the submit answer button. Chloroplasts and mitochondria are similar in size to prokaryotic cells. Chloroplasts and mitochondria have small amounts of circular DNA, similar to the circular DNA in prokaryotes and in contrast to the linear DNA strands found in a eukaryote's nucleus. Chloroplasts and mitochondria divide by splitting (fission), just like prokaryotes. Chloroplasts and mitochondria have ribosomes, similar to those found in bacteria, which allow them to synthesize their own proteins. All of the above.

all of the above

Which of the following is TRUE about cholesterol ? It is the precursor for making testosterone It circulates in the plassma as low-density lipoproteins (LDL) The LDL particles bind to receptors and then undergo endocytosis All of the above Both (A) and (C)

all of the above

Which of the following is TRUE? Proton are important in photosynthesis Protons are important in cellular respiration Protons power ATP synthase All of the above

all of the above

Which of the following is correct? Energy cannot be created. Energy and matter can be transformed into another Energy cannot be destroyed all of the above

all of the above

chloroplast

an organelle found in all plants and eukaryotic algae, is the site of photosynthesis—the conversion of light energy into the chemical energy of food molecules, with oxygen as a by-product

Mitochondria

are all-purpose energy converters that are present in nearly all plant cells, animal cells, and every other eukaryotic cell Our mitochondria convert the energy contained in the chemical bonds of carbohydrates, fats, and proteins into carbon dioxide, water, and ATP. Because this energy conversion requires a significant amount of oxygen, mitochondria consume most of the oxygen used by each cell. In humans, for example, our mitochondria consume as much as 80% of the oxygen we breathe. Mitochondria give a significant return on this investment by producing about 90% of the energy our cells need to function. The organelle in eukaryotic cells that converts the energy stored in food, in the chemical bonds of carbohydrate, fat, and protein molecules, into a form usable by the cell for its functions and activities.

desmosomes

are like spot welds or rivets that fasten cells together into strong sheets. Irregularly spaced connections between adjacent animal cells that, much like Velcro, hold the cells together by multiple attachments but are not water-tight. They provide mechanical strength and are found in muscle tissue and in much of the tissue that lines the cavities of animal bodies. EX: They occur at irregular intervals and function like fastened Velcro: they hold cells together but are not water-tight, allowing fluid to pass around them. Desmosomes and similar junctions are found in much of the tissue that lines the cavities of animals' bodies. They also are found in muscle tissue, holding fibers together.

Cell walls: occur only in plant cells. are not completely solid, having many small pores. confer less structural support than the plasma membrane. dissolve when a plant dies. are made primarily from phospholipids.

are not completely solid, having many small pores.

gap junctions

are pores surrounded by special proteins that form open channels between two cells A junction between adjacent animal cells in the form of a pore in each of the plasma membranes that is surrounded by a protein, linking the two cells and acting like a channel between them, thus allowing materials to pass between the cells. EX: Functioning like secret passageways, these junctions are an important mechanism for cell-to-cell communication. In the heart, for example, the electrical signal telling muscle cells to contract is passed from cell to cell through gap junctions.

Lysosomes

are round, membrane-enclosed, acid-filled vesicles that dispose of garbage. They are filled with about 50 different digestive enzymes and a super-acidic fluid, a corrosive broth so powerful that a burst lysosome would rapidly kill the cell by digesting many of its component parts. A round, membrane-enclosed, enzyme- and acid-filled vesicle in the cell that digests and recycles cellular waste products and consumed material.

cilia (cilium)

are short projections often found in large numbers on a single cell hort projections from the cell surface, often occurring in large numbers on a single cell, that beat against the extracellular fluid to move the fluid past the cell. EX: Cilia beat swiftly, often in unison and in ways that resemble blades of grass in a field, blowing in the wind. Cilia can move fluid along and past a cell. This movement can accomplish many important tasks, including sweeping the airways to our lungs to clear them of debris (such as dust).

symbiotic

become more and more dependent on each other, until neither cell could live without the other

Cellular "fingerprints": are exposed on the cytoplasmic side of the membrane. are made from cholesterol. are "erased" by HIV. can help the immune system distinguish "self" from "non-self." All of the above are correct.

can help the immune system distinguish "self" from "non-self."

Which of the following membrane molecules is correctly matched to its function? Please choose the correct answer from the following choices, and then select the submit answer button. cholesterol: binds to external chemicals in order to regulate processes within the cell receptor protein: helps the plasma membrane retain flexibility transport proteins: catalyze intra- and extracellular reactions on the plasma membrane recognition protein: provides a passageway that allows polar or charged substances to pass through the plasma membrane carbohydrate chains: provide a "fingerprint" for the cell so it can be identified by other cells

carbohydrate chains: provide a "fingerprint" for the cell so it can be identified by other cells This is the function of carbohydrate chains in the plasma membrane.

primary photosynthetic pigment

chlorophyll a

The cell organelles most analogous to mitochondria are: Please choose the correct answer from the following choices, and then select the submit answer button. ribosomes. peroxisomes. lysosomes. chloroplasts. the Golgi apparatus.

chloroplasts. Chloroplasts are analogous to mitochondria; they also have a double membrane and contain DNA.

The cell organelles most analogous to mitochondria are: Please choose the correct answer from the following choices, and then select the submit answer button. ribosomes. peroxisomes. lysosomes. chloroplasts. the Golgi apparatus.

chloroplasts. Chloroplasts are analogous to mitochondria; they also have a double membrane and contain DNA.

What does the most important example of receptor-mediated endocytosis involve?

cholesterol

What is it when there is a difference in the concentration of solutes in two areas?

concentration gradient ** the larger the difference in the concentration of the solutes in the two areas, the greater the concentration gradient.

What is the most common inherited disease in the US?

cystic fibrosis

What is DNA?

deoxyribonucleic acid, a molecule that contains the information that directs the formation of various cellular products within the cell, the chemical reactions in the cell, and the cell's ability to reproduce itself

When vesicles merge with a membrane in order to release chemicals stored in them the process is called: pinocytosis endocytosis exocytosis none of the above

exocytosis

Insulin is made by pancreatic cells, packaged in small vesicles, and then released into the bloodstream. This describes what sort of cell transport? Please choose the correct answer from the following choices, and then select the submit answer button. endocytosis pinocytosis exocytosis receptor-mediated endocytosis osmosis

exocytosis Exocytosis is a transport mechanism used for bulk transport of particles. Particles are packaged within a vesicle and shuttled through the cytoplasm. Then, the vesicle fuses with the plasma membrane, and particles in the vesicle are expelled out of the cell.

The transport of large molecules out of the cell, across the membrane, is accomplished via: Please choose the correct answer from the following choices, and then select the submit answer button. facilitated diffusion. exocytosis. active transport. endocytosis. passive transport.

exocytosis. Cells use exocytosis to export particles out of the cell, such as molecules of insulin, that are too big to exit the cell by passive or active transport for use elsewhere in the body.

Polar molecules and many charged molecules like water, ions, amino acids, and sugars pass across the membrane via: Please choose the correct answer from the following choices, and then select the submit answer button. membrane transport. facilitated diffusion. protein-mediated exchange. exocytosis. endocytosis.

facilitated diffusion. The transport of these molecules require channel proteins in order to cross the membrane.

Calvin Cycle

in photosynthesis, a series of chemical reactions in the stroma of chloroplasts in which sugar molecules are assembled. All the Calvin cycle reactions occur in the stroma of the leaves' chloroplasts, outside the thylakoids.

pigment

in photosynthesis, molecules that are able to absorb the energy of light of specific wavelengths, raising electrons to an excited state in the process. When plants use sunlight's energy to make sugar during photosynthesis, they also use the visible portion of the electromagnetic spectrum. Unlike the pigments in our eyes, however, plant pigments (the energy-capturing parts of a plant) absorb and use only a portion of the visible light wavelengths. Chlorophyll is the main pigment molecule in plants that absorbs light energy from the sun.

stroma

in the leaf of a green plant, the fluid in the inner compartment of a chloroplast, which contains DNA and protein-making machinery. sac-shaped organelle is filled with a fluid

cytoskeleton

inner scaffolding of the cell, which is made from proteins A network of protein structures in the cytoplasm of eukaryotes (and, to a lesser extent, prokaryotes) that serves as scaffolding, adding support and, in some cases, giving animal cells of different types their characteristic shapes. The cytoskeleton serves as a system of tracks guiding intracellular traffic flow and, because it is flexible and can generate force, gives cells some ability to control their movement.

thylakoids

interconnected membranous structures in the stroma of a chloroplast, where light energy is collected and converted to chemical energy in photosynthesis. The light-collecting process for photosynthesis occurs on the membranes of the thylakoids.

Golgi apparatus

is a flattened stack of membranes (each of which is called a Golgi body), which are not connected to the endoplasmic reticulum. The job of the Golgi apparatus is to process molecules synthesized in the cell—primarily proteins and lipids—and to package those that are destined for use elsewhere in the body. An organelle, part of the endomembrane system, structurally like a flattened stack of unconnected membranes, each known as a Golgi body. The Golgi apparatus processes molecules synthesized in the cell and packages those molecules that are destined for use elsewhere in the body.

Proliferation of the smooth ER is likely in an individual who: Please choose the correct answer from the following choices, and then select the submit answer button. works outdoors in a cold temperatures. is addicted to prescription painkillers. lacks rough ER in their cells. has just started lifting weights. is training to run a marathon.

is addicted to prescription painkillers. The smooth ER detoxifies molecules such as alcohol and drugs. Chronic exposure to a prescription drug can cause the smooth ER to proliferate, especially in the liver. The proliferation of smooth ER increases the individual's tolerance to the drug. Consequently, the individual must take more and more of the drug to achieve the same effect.

Smooth Endoplasmic Reticulum (Smooth ER)

is part of the endomembrane network that is smooth, because it has no ribosomes bound to it An organelle, part of the endomembrane system, structurally like a series of branched tubes; called "smooth" because its surface has no ribosomes. Smooth ER synthesizes lipids such as fatty acids, phospholipids, and steroids. The smooth ER is not extensively involved in folding or packaging proteins. Instead, it takes part in the synthesis of lipids such as fatty acids, phospholipids, and steroids, as well as carbohydrates. An organelle, part of the endomembrane system, structurally like a series of branched tubes; called "smooth" because its surface has no ribosomes. Smooth ER synthesizes lipids such as fatty acids, phospholipids, and steroids.

What are the three types of protein fibers that make up the cytoskeleton? Please choose the correct answer from the following choices, and then select the submit answer button. microtubules, intermediate filaments, and microfilaments cilia, intermediate filaments, and microfilaments large, intermediate, and small microfilaments tubules, filaments, and flagella There are actually four types of protein fibers that make up the cytoskeleton.

microtubules, intermediate filaments, and microfilaments Microtubules are thick, hollow tubes; intermediate filaments are rope-like systems of overlapping proteins; and microfilaments are long, solid rod-like fibers.

Three types of protein fibers make up the cytoskeleton

microtubules, intermediate filaments, microfilaments

Which of the following organelles contains a small circular loop of DNA? Please choose the correct answer from the following choices, and then select the submit answer button. lysosomes smooth endoplasmic reticulum Golgi apparatus mitochondria nucleus

mitochondria This is explained by the endosymbiotic theory, which postulates that an ancient eukaryote engulfed an ancient prokaryote, which contained its own DNA, and the prokaryote eventually evolved into an organelle, such as a mitochondrion.

In passive transport: Please choose the correct answer from the following choices, and then select the submit answer button. molecules move spontaneously from an area of high concentration to an area of low concentration. a transport protein moves one molecule against the concentration gradient, while another molecule moves down its gradient. ATP is required to move molecules against the concentration gradient. ATP is required to move especially large molecules or ions across a cell membrane. molecules move from an area of low concentration to an area of high concentration.

molecules move spontaneously from an area of high concentration to an area of low concentration. During passive transport, energy is not required to move molecules across a cell's membrane. The molecules simply move from an area of high solute concentration to an area of low concentration.

Which of the following would be performed by a transport protein in the cell membrane? Please choose the correct answer from the following choices, and then select the submit answer button. maintaining the flexibility of the cell membrane initiation of an immune system response upon identifying a foreign cell moving testosterone produced within a testicular cell into the bloodstream recognizing and ingesting a cold virus binding to adrenaline on heart cells, thereby increasing the heart's rate of contraction

moving testosterone produced within a testicular cell into the bloodstream Transport proteins provide a passageway for molecules through the cell. A transport protein would allow a molecule of testosterone produced in a testicular cell to move out of the cell and into the bloodstream.

flagella

much longer than cilia A long, thin, whip-like projection from a cell that aids in cell movement. In prokaryotes, a projection of the plasma membrane that aids in the cell's movement through the medium in which it lives. In eukaryotes, a microtubule-based projection; in animals, the only cell with a flagellum is the sperm cell. **IMPORTANT: While many algae and plants have cells with one or more flagella, in animals, cells with one or more flagella are very rare. **one of these cell types, however, has a critical role in every animal species: sperm cells. With a flagellum for a tail, sperm are among the most mobile of all animal cells.

receptor-mediated endocytosis

much more specific than pinocytosis and phagocytosis; One of the three types of endocytosis, in which receptors on the surface of a cell bind to specific molecules; the plasma membrane then engulfs both molecule and receptor and draws them into the cell. EX: Receptor molecules on the surface of a cell recognize and bind one specific type of molecule. For one receptor it might be insulin, for another it might be cholesterol. When the appropriate molecule binds to each of the receptor proteins, the membrane begins to fold inward, first forming a little pit and then completely engulfing the molecules, which are still attached to their receptors.

What is pili?

much thinner, hair-like projections that help prokaryotes attach to surfaces and can serve as "tubes" through which they exchange DNA.

What are three important structural components that stand out in the nucleus?

nuclear membrane, chromatin, nucleolus

What are the two types of passive transport?

osmosis and diffusion

The transport of water across a membrane from a solution of lower solute concentration to a solution of higher solute concentration is best described as: Please choose the correct answer from the following choices, and then select the submit answer button. active transport. secondary active transport. facilitated diffusion. osmosis. receptor-mediated transport.

osmosis. Water itself moves from high water concentration to low water concentration.

The movement of molecules across a membrane from an area of high concentration to one of low concentration is best described as: active transport. inactivated transport. passive transport. channel-mediated diffusion. electron transport.

passive transport.

What are the three types of endocytosis?

phagocytosis, pinocytosis, and receptor-mediated endocytosis In all three types of endocytosis, the plasma membrane oozes around an object outside the cell—surrounding the object—and forms a little pocket-like sac called a vesicle.

What makes phospholipid molecules good membrane material? Please choose the correct answer from the following choices, and then select the submit answer button. Phospholipid molecules do not let any substance pass through. Phospholipid molecules dissolve easily in water. Phospholipid molecules are able to break down large molecules as they cross the membrane. Phospholipids are able to communicate with their extracellular environment. Phospholipid molecules inhibit extracellular and intracellular fluid to leak across the membrane.

phospholipid molecules inhibit extracellular and intracellular fluid to leak across the membrane. The center of the bilayer membrane is made up of hydrophobic lipids; therefore, the intracellular or extracellular fluids cannot leak across.

Photosynthesis process

photosynthesis is best understood as two separate events: a "photo" segment, during which light is captured, and a "synthesis" segment, during which sugar is built. In the "photo" reactions, light energy is captured and temporarily saved in energy-storage molecules. During this process, water molecules split and produce oxygen. In the "synthesis" reactions, the energy in the energy-storage molecules is used to assemble sugar molecules from carbon dioxide from the atmosphere.

Which of the following cell connections is incorrectly matched with its location in living organisms? Please choose the correct answer from the following choices, and then select the submit answer button. tight junctions: small intestines gap junctions: cardiac tissue plasmodesmata: nerve cells desmosomes: muscle tissue plasmodesmata: plant cells

plasmodesmata: nerve cells Plasmodesmata are cell connections between plant cells; they have nothing to do with animal nerve cells.

What is endosymbiosis theory?

provides the best explanation for the presence of two types of organelles in eukaryotes: chloroplasts in plants and algae, and mitochondria in plants and animals. *theory of the origin of eukaryotes. *For photosynthetic eukaryotes, the theory holds that, in the past, two different types of prokaryotes engaged in a close partnership and eventually one, capable of performing photosynthesis, was subsumed into the other, larger prokaryote. The smaller prokaryote made some of its photosynthetic energy available to the host and, over time, the two became symbiotic and eventually became a single, more complex organism in which the smaller prokaryote had evolved into the chloroplast of the new organism. A similar scenario can be developed for the evolution of mitochondria. **For example, some small prokaryotes capable of performing photosynthesis (the process by which plant cells capture light energy from the sun and transform it into the chemical energy stored in food molecules) may have come to live inside a larger "host" prokaryote. The photosynthetic "boarder" may have made some of the energy that it captured in photo-synthesis available for use by the host.

Which of the following is found in both prokaryotic and eukaryotic cells? Please choose the correct answer from the following choices, and then select the submit answer button. ribosome lysosome centriole nucleolus peroxisome

ribosome Ribosomes are present in all living cells.

What is a cell wall?

rigid structure, outside the cell membrane, that protects and gives shape to the cell; found in many prokaryotes and plants. *Some have a sticky, sugary capsule as their outermost layer. This sticky outer coat provides protection and enhances prokaryotes' ability to anchor in place when necessary.

cellular respiration

s a bit like photosynthesis in reverse. In photosynthesis, the energy of the sun is captured and used to build molecules of sugars, such as glucose. In cellular respiration, plants and animals break down the chemical bonds of sugars and other energy-rich food molecules (such as fats and proteins) to release the energy that went into creating them.

NADPH

second important product of the "photo" portion of photosynthesis. A molecule (nicotinamide adenine dinucleotide phosphate) that is a high-energy electron carrier involved in photosynthesis, which stores energy by accepting high-energy protons. It is formed when the electrons released from the splitting of water are passed to NADP +.

Given that a cell's structure reflects its function, what function would you predict for a cell with a large Golgi apparatus? movement secretion of digestive enzymes transport of chemical signals rapid replication of genetic material and coordination of cell division attachment to bone tissue

secretion of digestive enzymes

What is glycerol?

small molecule that forms the head region of a triglyceride fat molecule. This head region is said to be polar, because the electrons are not shared equally among the atoms, leading to regions of partial positive and partial negative charge. The two tails of the phospholipid are long chains of carbon and hydrogen atoms. Because the electrons in these bonds are shared equally, the carbon-hydrogen chains are nonpolar. It makes them good membrane material.

nuclear membrane

sometimes called the nuclear envelope, which surrounds the nucleus and separates it from other parts of the cytoplasm. membrane enclosing the nucleus of a cell, separating it from the cytoplasm. It consists of two bilayers and is perforated by pores, enclosed in embedded proteins, that allow the passage of large molecules between the nucleus and the cytoplasm. Also called the nuclear envelope. EX: Unlike most plasma membranes, however, the nuclear membrane consists of two bilayers, one on top of the other, much like the double-bagging of groceries at the market. The nuclear membrane is a very leaky bag, though. It is perforated, covered with tiny pores that enable large molecules to pass between the nucleus and the cytosol. Made from multiple proteins embedded in the phospholipid membranes and spanning both bilayers, these pores also permit free diffusion of small molecules, such as water, sugars, and ions.

All of the following are important functions of proteins EXCEPT Enzymatic activity Recognition of self v non-self cells Storage of the genetic code Transport of materials e.g. oxygen None of the above

storage of genetic code

Photosynthesis

the conversion of light energy into the chemical energy of food molecules, with oxygen as a by-product Because all photosynthesis in plants and algae takes place in chloroplasts, these organelles are directly or indirectly responsible for everything we eat and for the oxygen we breathe.

ethanol

the end product of fermentation of yeast; the alcohol in beer, wine, and spirits.

kinetic energy

the energy of moving objects, such as legs pushing the pedals of a bicycle or wings beating against the air.

electromagnetic spectrum

the range of wavelengths that produce electromagnetic radiation, extending (in order of decreasing energy) from high-energy, short-wave, gamma rays and X rays, through ultraviolet light, visible light, and infrared light, to very long, low-energy, radio waves.

phospholipid bilayer

the structure of the plasma membrane; two layers of phospholipids, arranged tail to tail (the tails are hydrophobic and so avoid contact with water), with the hydrophilic head regions facing the watery extracellular and intracellular fluids. **another way to describe the plasma membrane structure *are not locked in place; they just float around their side of the bilayer. avoid coming in contact with water molecules

microtubules

the thickest, are linear fibers made from repeating units of protein, and look like rigid, hollow tubes. Like intracellular conveyor belts, they are the tracks to which molecules and organelles within the cell can become attached and moved along. Microtubules also help to pull chromosomes apart during cell division. Continuously built, disassembled, and rebuilt, microtubules rarely last more than about 10 minutes in a cell. One of three types of protein fibers (the others are intermediate filaments and microfilaments) that make up the eukaryotic cytoskeleton, providing it with structure and shape. These are the thickest elements in the cytoskeleton. They resemble rigid, hollow tubes, functioning as tracks to which molecules and organelles within the cell may attach and be moved along; also help pull chromosomes apart during cell division.

Cystic fibrosis is to "faulty chloride ion transport," as anxiety and high blood pressure are to: Please choose the correct answer from the following choices, and then select the submit answer button. beta-blockers. the inability of immune cells to recognize the proteins on a cell's surface. too much mucus accumulating in the lungs. too much cholesterol in the membrane. too much adrenaline binding to membrane beta-receptors.

too much adrenaline binding to membrane beta-receptors. The more adrenaline binding to beta-receptors will cause the heart to beat more frequently and with greater force, raising blood pressure.

photosystems

two arrangements of light-absorbing pigments, including chlorophyll, within the chloroplast that capture energy from the sun and transform it first into the energy of excited electrons and ultimately into ATP and high-energy electron carriers such as NADPH.

photosystem

two arrangements of light-absorbing pigments, including chlorophyll, within the chloroplast that capture energy from the sun and transform it first into the energy of excited electrons and ultimately into ATP and high-energy electron carriers such as NADPH. The chlorophyll a molecule at the center of the photosystems is special, differing from the other pigment molecules in one key feature. When its electrons are boosted to an excited state, they do not return to their resting, unexcited state. Instead, a nearby molecule, called the primary electron acceptor, acts like an electron vacuum, grabbing the excited electrons and leaving electron vacancies. This is where the electron journey begins.

Primary active transport is to secondary active transport as ______________ is to ______________. Please choose the correct answer from the following choices, and then select the submit answer button. winding a clock by hand; having the clock run on the stored energy from winding walking; running a molecule moving alone across a membrane; a molecule moving together with another across a membrane oxygen moving across a membrane; carbon dioxide moving across a membrane molecules moving down their concentration gradient directly across a phospholipid bilayer; molecules moving down their concentration gradient through a membrane transport protein

winding a clock by hand; having the clock run on the stored energy from winding Primary active transport is unique because it requires the input of energy to move molecules across the plasma membrane. In secondary active transport, a transport protein simultaneously moves one molecule against its concentration gradient while letting another flow down its concentration gradient, so there is no ATP used directly in this reaction.

TAKE HOME MESSAGE 5.14

» Much additional energy can be harvested by cells after glycolysis. First, pyruvate is chemically modified. Then, in the citric acid cycle, the modified pyruvate is broken down. This breakdown releases carbon into the atmosphere (as CO2) as bonds are broken and captures some of the released energy in two ATP molecules and many high-energy electron carriers for every glucose molecule.

TAKE HOME MESSAGE 5.7

» Photosynthesis is powered by light energy, a type of kinetic energy made of energy packets called photons. Photons hit chlorophyll and other light-absorbing molecules in the chloroplasts of cells near the green surfaces of plants. These molecules capture some of the light energy and harness it to build sugar from carbon dioxide and water.

TAKE HOME MESSAGE 5.10

» The "synthesis" part of photosynthesis is the Calvin cycle. During this phase, carbon from CO2 in the atmosphere is attached to molecules in the stroma of chloroplasts, sugars are built, and molecules are regenerated to be used again in the Calvin cycle. The fixation, building, and regeneration processes consume energy from ATP and NADPH (the products of the "photo" part of photosynthesis).

TAKE HOME MESSAGE 5.9

» There are two parts to photosynthesis. The first is the "photo" part, in which light energy is transformed into chemical energy, while splitting water molecules and producing oxygen. The energy of sunlight is first captured when an electron in a chlorophyll molecule is excited. As this electron is passed from one molecule to another, energy is released at each transfer, some of which is used to build the energy-storage molecules ATP and NADPH.

TAKE HOME MESSAGE 5.5

» Through photosynthesis, plants use water, the energy of sunlight, and carbon dioxide gas from the atmosphere to produce sugars and other organic materials. In the process, photosynthesizing organisms also produce oxygen, which makes all animal life possible.

TAKE HOME MESSAGE 5.8

» When chlorophyll is hit by photons, the light energy excites an electron in the chlorophyll molecule, increasing the chlorophyll's potential energy. The excited electrons can be passed to other molecules, moving the potential energy through the cell.