Bio 1000 Exam 2

The products of the light reactions of photosynthesis are ________.

ATP and NADPH

Which of the following are sometimes referred to as rough or smooth, depending on the structure?

endoplasmic reticulum

A protist that contains contractile vacuoles most likely lives ________.

in fresh water

Vacuoles are ________.

membranous sacs

If a cell's lysosomes burst, the cell would ________.

digest itself

Prokaryotic cells do NOT have

membrane-bound nuclei.

Energy is transferred from ATP to other molecules by transferring a(n) ________.

phosphate group

Compare the structures and functions of a plant cell wall with the extracellular matrix of an animal cell.

plant cells have a cell wall surrounding the plasma membrane. Unlike prokaryotic cell walls, the rigid cell walls of plants are made from cellulose fibers embedded in a matrix of other molecules. The walls protect the cells, maintain cell shape, and keep cells from absorbing so much water that they burst. Animal cells lack a cell wall, most of them secrete a sticky coat called the extracellular matrix this layer holds cells together in tissues, and it can also have protective and supportive functions.

Explain how the genetic information in the nucleus is used to direct the production of proteins in the cytoplasm.

1.) DNA programs protein production in the cytoplasm by transferring its coded information to mRNA. The mRNA carries the order to "build this type of protein" from the nucleus to the cytoplasm 2.) The mRNA exits through the pores in the nuclear envelope and goes to the cytoplasm, where it then binds to ribosomes 3.) The ribosome moves along the mRNA, translating the genetic message into a protein with a specific amino acid sequence

Which of the following is a measure of randomness in a system?

Entropy

Explain how inhibitors and poisons can affect enzyme activity

Enzyme inhibitors and poisons can prevent metabolic reactions by binding to the enzyme's active site or binding near the active site which changes the active site's shape. In both cases, the enzyme can no longer accept the substrate.

When a person cries, tears are exported from cells through the process of ________.

Exocytosis

flagella

Flagellum, plural flagella, hairlike structure that acts primarily as an organelle of locomotion in the cells of many living organisms. Flagella, characteristic of the protozoan group Mastigophora, also occur on the gametes of algae, fungi, mosses, slime molds, and animals. Flagellar motion causes water currents necessary for respiration and circulation in sponges and coelenterates. Most motile bacteria move by means of flagella.

Lactic acid build up in muscles is a sign that ________.

insufficient oxygen is reaching the muscles

endomembrane system

The endomembrane system (endo- = "within") is a group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins. It includes a variety of organelles, such as the nuclear envelope and lysosomes, which you may already know, and the endoplasmic reticulum and Golgi apparatus, which we will cover shortly. Important note: the endomembrane system does not include mitochondria, chloroplasts, or peroxisomes.

Describe the evidence that suggests that mitochondria and chloroplasts evolved by endosymbiosis.

When one organism actually lives inside the other it's called endosymbiosis. The endosymbiotic theory describes how a large host cell and ingested bacteria could easily become dependent on one another for survival, resulting in a permanent relationship. Over millions of years of evolution, mitochondria and chloroplasts have become more specialized and today they cannot live outside the cell.

The phospholipid molecules of most membranes have

a hydrophilic head and two hydrophobic tails.

Which of the following is the CORRECT sequence of stages in cellular respiration?

glycolysis, citric acid cycle, electron transport

When mixed with water, phospholipids spontaneously form membranes because they ________.

have hydrophilic phosphate groups that are attracted to water and hydrophobic fatty acid tails that avoid water

An object at rest has no ________ energy, but it may have ________ energy resulting from its location or structure.

kinetic... potential

conservation of energy

principle stating that energy cannot be created or destroyed, but can be altered from one form to another.

Diffusion ________.

proceeds until equilibrium is reached

Photosynthetic organisms are ________.

producers that make all their own organic matter from inorganic molecules

cytoskeleton

The cytoskeleton is a network of filaments and tubules that extends throughout a cell, through the cytoplasm, which is all of the material within a cell except for the nucleus. It is found in all cells, though the proteins that it is made of vary between organisms. The cytoskeleton supports the cell, gives it shape, organizes and tethers the organelles, and has roles in molecule transport, cell division and cell signaling.

Which of the following equations best summarizes photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

In eukaryotic cells, what name is given to the region between the nucleus and the plasma membrane?

Cytoplasm

cytosol

Cytosol is the intra-cellular fluid that is present inside the cells. Once the process of eukaryotes starts, the fluid is separated by the cell membrane from the organelles (mitochondrial matrix) and the other contents that float about in the cytosol. Cytosol is the part of the cytoplasm that is not held by any of the organelles in the cell.

Active transport

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

Concentration gradient

the process of particles moving through a solution from an area of higher number of particles to an area of lower number of particles. The areas are typically separated by a membrane.

Compare the amount of energy in a calorie, kilocalorie, and Calorie. Which is most commonly used on food labels?

A calorie is the amount of energy that can raise the temperature of 1 gram of water by 1 degree Celsius. Calories are kilocalories, equal to 1,000 calories, which are used on food labels.

Calorie

A calorie is a unit of measurement, specifically: energy. It is the amount of energy needed to increase the temperature of 1 gram of water by 1°C.

Compare the structures and functions of the following components of the endomem-brane system: nuclear envelope, rough endoplasmic reticulum, smooth endoplasmic re-ticulum, Golgi apparatus, lysosomes, and vacuoles.

A nuclear membrane, also known as the nuclear envelope, is the lipid bilayer membrane which surrounds the genetic material and nucleolus in eukaryotic cells. The nuclear membrane consists of two lipid bilayers—the inner nuclear membrane, and the outer nuclear membrane. Endoplasmic Reticulum—factors can affect the amount of ER that a cell has, certain cells with have more than the other or less and etc. ROUGH ER: rough refers to the ribosomes that stud the outside of the membrane; makes more membrane; function of the rough endoplasmic reticulum is intimately bound to the production and transport of proteins in the cell; during protein synthesis, the ribosomes on the rough ER are the site where messenger ribonucleic acid builds proteins according to the specific code it carries; as the protein is produced, it is moves into the interior of the organelle, where it awaits transport; once the protein is complete, a bit of the rough ER membrane breaks off to form a vesicle around the protein SMOOTH ER: smooth ER is devoted almost exclusively to the manufacture of lipids and in some cases to the metabolism of them and associated products; smooth ER is also involved in the production of steroid hormones in the adrenal cortex and endocrine glands; smooth ER also plays a large part in detoxifying a number of organic chemicals converting them to safer water-soluble products GOLGI APPARATUS: works with the ER; it receives, refines, stores, and distributes chemical products of the cell— 1.) one side of a Golgi stack serves as a receiving dock for vesicles from the ER 2.) proteins within a vesicle are usually modified by enzymes during their transit from the receiving to the shipping side of the Golgi apparatus 3.) the shipping side of a Golgi stack is a depot from which finished products can be carried in transport vesicles to other organelles or to the plasma membrane—vesicles that bind to the plasma membrane transfer proteins to it or secret finished products to the outside of the cell LYSOSOMES: membrane enclosed sac of digestive enzymes found in animal cells, not in plant cells; develop from the membrane of the Golgi apparatus; enzymes within can break down large molecules (proteins, polysaccharides, fats, and nucleic acids); lysosomes fuse with food vacuole to expose the food to digestive enzymes (can kill bacteria and damaged organelles) VACUOLES: large sacs of membrane they bud from the ER, Golgi apparatus, or plasma membrane; plants have a huge central vacuole; contractile vacuoles escort excess water out of the cell

Phospholipids

A phospholipid is a type of lipid molecule that is the main component of the cell membrane. Lipids are molecules that include fats, waxes, and some vitamins, among others. Each phospholipid is made up of two fatty acids, a phosphate group, and a glycerol molecule. When many phospholipids line up, they form a double layer that is characteristic of all cell membranes.

Explain how ATP powers cellular work and how ATP is recycled

ATP generated by the chemical energy of cellular respiration acts like an energy shuttle by storing energy from food and releasing it to perform work. ATP energizes other molecules by transferring phosphate groups powering mechanical (muscle), transport (proteins), and chemical (reactions) work. Once the phosphate group of ATP is transferred to another molecule, what remains is ADP and 1 lone phosphate group. ATP is recycled from ADP by re-adding a phosphate group from food obtained through cellular respiration. • A working muscle cell spends and recycles up to 10 million ATP molecules per second.

Activation energy

Activation energy, in chemistry, the minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport. In transition-state theory, the activation energy is the difference in energy content between atoms or molecules in an activated or transition-state configuration and the corresponding atoms and molecules in their initial configuration. The activation energy is usually represented by the symbol Ea in mathematical expressions for such quantities as the reaction rate constant, k = Aexp(−Ea/RT), and the diffusion coefficient, D = Doexp(−Ea/RT).

ATP

Adenosine triphosphate, or ATP for short, is the energy currency of life. ATP is a high-energy molecule found in every cell. Its job is to store and supply the cell with needed energy.

Compare the structure and function of chloroplasts and mitochondria, and explain what structures in chloroplasts and mitochondria result in adaptive advantages.

Both organelles work as cellular power stations and have their own DNA; it is believed that the mitochondrion and chloroplast evolved from free-living prokaryotes in the distant past CHLOROPLASTS: unique to the photosynthetic cells of plants and algae—perform photosynthesis. The STROMA is the thick fluid within the second compartment. The GRANA are disks occurring in interlocking stacks—they are the structures that capture light energy and convert it to chemical energy MITOCHONDRIA: the organelles of cellular respiration in nearly all cells, harvesting energy from sugars and other food molecules and using it to produce ATP—adenosine triphosphate. Mitochondria are found in almost all eukaryotic cells. Cells use ATP as the direct energy source. Tick fluid called the MATRIX is contained within two membranes. The inner membrane has many foldings called CRISTAE. The folding increases surface area—thus cristae maximizes more ATP

Describe the functions of the cytoskeleton and compare the structures and functions of cilia and flagella.

CYTOSKELETON: infrastructure of the cell, a network of fibers extending throughout the cytoplasm; gives mechanical support to the cell and maintain its shape. Crucial for animal cells that lack a cell wall. Cytoskeleton is made of different fibers—microtubules are straight, hollow tubes composed of proteins. The others—intermediate filaments and micro filaments are thinner and solid. Cytoskeleton supports organelles in fixed positions and is dynamic; it can quickly dismantle itself and reform in a new location. Cilia and flagella are created by some eukaryotic cells that arrange their microtubules into these motile appendages to aid in movement Almost never found on plant cells Propel various protists through water FLAGELLA: propel cells through their undulating, whip-like motion CILIA: shorter and more numerous; promote movement by a coordinated back-and-forth motion, like the rhythmic oars of a crew team Some cilia extend from nonmoving cells that are part of a tissue layer, such as the cilia in your lungs

Compare the processes by which a car and a human use "fuel" to perform work.

Cars Humans, like all other organisms, use cellular respiration, which is the energy-releasing chemical breakdown of fuel molecules and storage of that energy as chemical energy in the form of ATP.

cell theory

Cell Theory is one of the basic principles of biology. Credit for the formulation of this theory is given to German scientists Theodor Schwann, Matthias Schleiden, and Rudolph Virchow. The Cell Theory states: 1 All living organisms are composed of cells. 2 They may be unicellular or multicellular. 3 The cell is the basic unit of life. 4 Cells arise from pre-existing cells. (They are not derived from spontaneous generation.) The modern version of the Cell Theory includes the ideas that: 1 Energy flow occurs within cells. 2 Heredity information (DNA) is passed on from cell to cell. 3 All cells have the same basic chemical composition.

chemical energy

Chemical energy, Energy stored in the bonds of chemical compounds. Chemical energy may be released during a chemical reaction, often in the form of heat; such reactions are called exothermic. Reactions that require an input of heat to proceed may store some of that energy as chemical energy in newly formed bonds. The chemical energy in food is converted by the body into mechanical energy and heat. The chemical energy in coal is converted into electrical energy at a power plant. The chemical energy in a battery can also supply electrical power by means of electrolysis

Which plant organelle is responsible for photosynthesis?

Chloroplast

chloroplasts

Chloroplasts are a type of plastid—a round, oval, or disk-shaped body that is involved in the synthesis and storage of foodstuffs. Chloroplasts are distinguished from other types of plastids by their green colour, which results from the presence of two pigments, chlorophyll a and chlorophyll b. A function of those pigments is to absorb light energy. In plants, chloroplasts occur in all green tissues, though they are concentrated particularly in the parenchyma cells of the leaf mesophyll.

Chromatin

Chromatin is comprised of histones and DNA: 147 base pairs of DNA wraps around the 8 core histones to form the basic chromatin unit, the nucleosome. The function of chromatin is to efficiently package DNA into a small volume to fit into the nucleus of a cell and protect the DNA structure and sequence. Packaging DNA into chromatin allows for mitosis and meiosis, prevents chromosome breakage and controls gene expression and DNA replication.

Cilia

Cilia are slender, microscopic, hair-like structures or organelles that extend from the surface of nearly all mammalian cells (multiple or single). They are primordial. The ciliary apparatus is connected to cell cycle progression and proliferation, and cilia play a vital part in human and animal development and in everyday life.

Define and distinguish between the following pairs of terms: diffusion versus osmosis, passive transport versus active transport, hypertonic versus hypotonic, and endocytosis versus exocytosis.

Diffusion is the movement of solute molecules across a membrane that they spread out evenly into the available space (equilibrium), whereas osmosis is the movement of water molecules via transport proteins, which also diffuse down its concentration gradient. Passive transport requires no energy input since substances diffuse down their concentration gradient, whereas active transport requires ATP to pump a substance up its concentration gradient via a transport protein. A hypertonic solution is a solution with a higher concentration of solute with a lower concentration of water, whereas a hypotonic solution is a solution with a lower concentration of solute with a higher concentration of water. Endocytosis takes material in via vesicles that bud inward from the plasma membrane, whereas exocytosis is the secretion of large molecules within transport vesicles. Phagocytosis is when a cell engulfs a particle and packages it within a food vacuole ("cell-eating"), whereas pinocytosis is when a cell takes in droplets of fluid through vesicles ("cell drinking").

Diffusion

Diffusion is the net passive movement of particles (atoms, ions or molecules) from a region in which they are in higher concentration to regions of lower concentration. It continues until the concentration of substances is uniform throughout.

Rough ER

Endoplasmic reticulum (ER), in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins . All eukaryotic cells contain an endoplasmic reticulum (ER). In animal cells, the ER usually constitutes more than half of the membranous content of the cell. Differences in certain physical and functional characteristics distinguish the two types of ER, known as rough ER and smooth ER.

Define the terms energy, kinetic energy, potential energy, and the principle of conservation of energy.

Energy is the capacity to cause change. Kinetic energy is the energy of motion. Potential energy is stored energy that an object has because of its location (rock on a cliff) or structure (atomic arrangement = chemical energy). Conservation of energy states that energy cannot be created nor destroyed, only converted from one form to another.

eukaryotic cells

Eukaryotic cells contain membrane-bound organelles, including a nucleus. Eukaryotes can be single-celled or multi-celled, such as you, me, plants, fungi, and insects. Bacteria are an example of prokaryotes.

Explain how and why antibiotic-resistant bacteria have evolved.

Evolution easily takes over; within a population of bacteria, random genetic changes can occur resulting in slightly different proteins being produced in different bacteria—potentially creating a protein that reduces the effectiveness of an antibiotic.

Golgi apparatus

Golgi apparatus, also called Golgi complex or Golgi body, membrane-bound organelle of eukaryotic cells (cells with clearly defined nuclei) that is made up of a series of flattened, stacked pouches called cisternae. The Golgi apparatus is responsible for transporting, modifying, and packaging proteins and lipids into vesicles for delivery to targeted destinations. It is located in the cytoplasm next to the endoplasmic reticulum and near the cell nucleus. While many types of cells contain only one or several Golgi apparatus, plant cells can contain hundreds.

Which of the following are primarily structures for the packaging of cellular secretions for export from the cell?

Golgi bodies

Explain the relationship between heat and entropy.

Heat is a randomized type of kinetic energy and a product of all energy conversions. Since entropy is the measure of disorder/randomness in a system, ALL energy conversions increase the entropy.

transport vesicles

In a very general sense a transport vesicle could be any vesicle that transports material around the cell. More specifically, transport vesicles are usually refered to those vesicles that transport material from the Endoplasmic Reticulum to the Golgi apparatus or from one part of the Golgi to another.

organelles

In cell biology, an organelle is one of several structures with specialized functions, suspended in the cytoplasm of a eukaryotic cell.

extracellular matrix

In other words, the extracellular matrix largely determines how a tissue looks and functions. The extracellular matrix is made up of proteoglycans, water, minerals, and fibrous proteins.

Chromosomes

In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure. Chromosomes are not visible in the cell's nucleus—not even under a microscope—when the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope. Most of what researchers know about chromosomes was learned by observing chromosomes during cell division.

Based on its function in detoxifying drugs, you would expect to find a large amount of smooth ER in ________ cells.

Liver

lysosome

Lysosome, subcellular organelle that is found in nearly all types of eukaryotic cells (cells with a clearly defined nucleus) and that is responsible for the digestion of macromolecules, old cell parts, and microorganisms. Each lysosome is surrounded by a membrane that maintains an acidic environment within the interior via a proton pump. Lysosomes contain a wide variety of hydrolytic enzymes (acid hydrolases) that break down macromolecules such as nucleic acids, proteins, and polysaccharides. These enzymes are active only in the lysosome's acidic interior; their acid-dependent activity protects the cell from self-degradation in case of lysosomal leakage or rupture, since the pH of the cell is neutral to slightly alkaline. Lysosomes were discovered by the Belgian cytologist Christian René de Duve in the 1950s. (De Duve was awarded a share of the 1974 Nobel Prize for Physiology or Medicine for his discovery of lysosomes and other organelles known as peroxisomes.)

microtubules

Microtubules are usually discussed with microfilaments. Although they are both proteins that help define cell structure and movement, they are very different molecules. While microfilaments are thin, microtubules are thick, strong spirals of thousands of subunits. Those subunits are made of the protein called tubulin.

mitochondria

Mitochondrion, membrane-bound organelle found in the cytoplasm of almost all eukaryotic cells (cells with clearly defined nuclei), the primary function of which is to generate large quantities of energy in the form of adenosine triphosphate (ATP). Mitochondria are typically round to oval in shape and range in size from 0.5 to 10 μm. In addition to producing energy, mitochondria store calcium for cell signaling activities, generate heat, and mediate cell growth and death. The number of mitochondria per cell varies widely; for example, in humans, erythrocytes (red blood cells) do not contain any mitochondria, whereas liver cells and muscle cells may contain hundreds or even thousands. The only eukaryotic organism known to lack mitochondria is the oxymonad Monocercomonoides species. Mitochondria are unlike other cellular organelles in that they have two distinct membranes and a unique genome and reproduce by binary fission; these features indicate that mitochondria share an evolutionary past with prokaryotes (single-celled organisms).

Explain how antibiotics specifically target bacteria while minimally harming the human host.

Most antibiotics kill bacteria while minimally harming the human host by binding to structures found only on bacterial cells such as the bacterial ribosome or bacterial enzymes.

Explain why enzymes are needed in living organisms and how they speed up specific chemical reactions

Most metabolic AKA biochemical reactions require the assistance of enzymes which are proteins that speed up specific chemical reactions which allow organisms to function.

nucleus

Nucleus, in biology, a specialized structure occurring in most cells (except bacteria and blue-green algae) and separated from the rest of the cell by a double layer, the nuclear membrane. This membrane seems to be continuous with the endoplasmic reticulum (a membranous network) of the cell and has pores, which probably permit the entrance of large molecules. The nucleus controls and regulates the activities of the cell (e.g., growth and metabolism) and carries the genes, structures that contain the hereditary information. Nucleoli are small bodies often seen within the nucleus; they play an important part in the synthesis of ribonucleic acid (RNA) and protein. The gel-like matrix in which the nuclear components are suspended is the nucleoplasm.

Explain why phospholipids were probably some of the first organic compounds to form as life emerged on Earth.

Phospholipids were probably among the first organic compounds that formed from chemical reactions on Earth since phospholipids spontaneously self-assemble into simple bilayer membranes.

A rock on the top of a mountain contains ________ energy.

Potential

Prokaryotic cells

Prokaryotic cells are cells without a nucleus. The DNA in prokaryotic cells is in the cytoplasm rather than enclosed within a nuclear membrane. Prokaryotic cells are found in single-celled organisms, such as bacteria, like the one shown in Figure below. Organisms with prokaryotic cells are called prokaryotes. They were the first type of organisms to evolve and are still the most common organisms today.

Compare the following pairs of terms, noting similarities and differences: (1) prokary-otic cells versus eukaryotic cells and (2) plant cells versus animal cells.

Prokaryotic cells- smaller, simpler, most do not have organelles, found in bacteria and archaea. Eukaryotic Cells- Larger, More complex, have organelles, found in protists, planet, fungi, and animals. Animal and Plant cells- presence of chloroplasts in plant cells but not in animal cells. Plant cells have a protective cell wall outside the plasma membrane, animal cell-lysosome,flagellum,centriole.

Ribosomes

Ribosome, particle that is present in large numbers in all living cells and serves as the site of protein synthesis. Ribosomes occur both as free particles in prokaryotic and eukaryotic cells and as particles attached to the membranes of the endoplasmic reticulum in eukaryotic cells. The small particles that came to be known as ribosomes were first described in 1955 by Romanian-born American cell biologist George E. Palade, who found them to be frequently associated with the endoplasmic reticulum in eukaryotic cells.

The rough endoplasmic reticulum is so called because __________ stud the surface of that organelle.

Ribosomes

Through what structure(s) do plants obtain most of their water?

Roots

Explain how nanotechnology might be used to power microscopic robots.

Scientists can power nanotechnology by mimicking the functions of working cellular structures such as energy, enzymes, and the plasma membrane. For example, three glycolysis enzymes were attached to a computer chip to produce energy from sugar.

An enzyme's function is most dependent on its ________.

Shape

ADP

Short for adenosine diphosphate. An organic compound that is composed of adenosine and two phosphate groups. With the addition of another phosphate group, it is converted to ATP for the storage of energy during cell metabolism.

Which component of the following reaction is the substrate? sucrose + sucrose + water → sucrose + glucose + fructose

Sucrose

central vacuole

The central vacuole is a cellular organelle found in plant cells. It is often the largest organelle in the cell. It is surrounded by a membrane and functions to hold materials and wastes. It also functions to maintain the proper pressure within the plant cells to provide structure and support for the growing plant.

endoplasmic reticulum (ER)

The endoplasmic reticulum (ER) plays a key role in the modification of proteins and the synthesis of lipids. It consists of a network of membranous tubules and flattened sacs. The discs and tubules of the ER are hollow, and the space inside is called the lumen.

Active site

The enzyme's active site is the site at which the enzyme binds to the substrates and increases their chances of reacting.

Cytoplasm

The jelly-like fluid that fills a cell is called cytoplasm. It is made up of mostly water and salt. Cytoplasm is present within the cell membrane of all cell types and contains all organelles and cell parts. Cytoplasm has various functions in the cell. Most of the important activities of the cell occur in the cytoplasm. Cytoplasm contains molecules such as enzymes which are responsible for breaking down waste and also aid in metabolic activity. Cytoplasm is responsible for giving a cell its shape. It helps to fill out the cell and keeps organelles in their place. Without cytoplasm, the cell would be deflated and materials would not be able to pass easily from one organelle to another. Cytosol is the part of the cytoplasm that does not contain organelles. Instead, cytosol is confined by the boundaries of a matrix which fills the part of the cell that does not contain organelles.

nuclear envelope

The nuclear membrane, sometimes referred to as the nuclear envelope, is the membrane that encloses the nucleus. This bilayer membrane is made of lipids, and encases the genetic material in eukaryotic cells.

nucleoid

The nucleoid (meaning nucleus-like) is an irregularly shaped region within the cell of a prokaryote that contains all or most of the genetic material, called genophore. In contrast to the nucleus of a eukaryotic cell, it is not surrounded by a nuclear membrane.

nucleolus

The nucleus of many eukaryotic cells contains a structure called a nucleolus. As the nucleus is the "brain" of the cell, the nucleolus could loosely be thought of as the brain of the nucleus. The nucleolus takes up around 25% of the volume of the nucleus. This structure is made up of proteins and ribonucleic acids (RNA). Its main function is to rewrite ribosomal RNA (rRNA) and combine it with proteins. This results in the formation of incomplete ribosomes. There is an uninterrupted chain between the nucleoplasm and the interior parts of the nucleolus, whichoccurs through a system of nucleolarpassages. These passages allow macromolecules with a molecular weight up to 2,000 kDato be easily circulated throughout the nucleolus. Because of its close relationship to the chromosomal matter of the cell and its important role in producing ribosomes, the nucleolus is thought to be the cause of a variety of different human diseases.

Describe the structure of cell membranes, and explain why the plasma membrane is called a fluid mosaic.

The plasma membrane and other membranes of the cell are composed mostly of lipids and proteins. Phospholipid-dietary fats but have only two fatty acid tails instead of three. Phospholipid biplayer-two layered membrane material. Fluid mosaic-fluid because the molecules can move freely past one another and a mosaic because of the diversity of proteins.

plasma membrane

The plasma membrane is the boundary between the cell and its environment. It regulates what enters and exits the cell. Cells must maintain an appropriate amount of molecules to function inside them. They must also have a way to keep things out or to allow things to enter. This is the job of the plasma membrane. The plasma membrane is like the guard at a gated community. The guard must inspect those who enter and those who leave to make sure that only the people and things needed in the community are there.

Smooth ER

The smooth endoplasmic reticulum (smooth ER) is a membranous organelle found in most eukaryotic cells. It is a subset of the endomembrane system of the endoplasmic reticulum. Its main functions are the synthesis of lipids, steroid hormones, the detoxification of harmful metabolic byproducts and the storage and metabolism of calcium ions within the cell. The smooth ER is distinguished from the other parts of the endoplasmic reticulum by the absence of membrane-bound ribosomes. This organelle is also morphologically distinct, often made of tubular structures called cisternae.

A balloon permeable to water but not to glucose contains a 10% glucose solution. A beaker contains a 5% glucose solution. Which of the following is TRUE?

The solution in the balloon is hypertonic relative to the solution in the beaker.

balloon permeable to water but not to glucose contains a 10% glucose solution. A beaker contains a 5% glucose solution. What will happen when the balloon is submerged in the beaker?

The volume of water in the beaker will decrease.

T/F Cellular respiration can produce around 32 ATP molecules for each glucose molecule consumed.

True

T/F Many cancer drugs inhibit enzymes that promote cell division.

True

T/F The initial incorporation of carbon from the atmosphere into organic compounds is called carbon fixation.

True

T/F The waste products of cellular respiration are CO2 and H2O, the very same ingredients used for photosynthesis.

True

phospholipid bilayer

a two-layered arrangement of phosphate and lipid molecules that form a cell membrane, the hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward

One portion of the cell theory states that

all living organisms are made up of cells.

A hormone that will be secreted from a cell is manufactured by ribosomes ________.

attached to the endoplasmic reticulum

Plant cells, unlike animal cells, are characterized by the presence of a ________.

cell wall and a central vacuole

Which part of cellular respiration produces the most NADH?

citric acid cycle

Cells in the thyroid gland produce and secrete thyroid hormone (a polymer of amino acids) that helps to regulate metabolism. What organelle is most likely abundant in cells of the thyroid gland?

rough endoplasmic reticulum

Similar to the nucleus, chloroplasts and mitochondria are ________.

surrounded by two membranes

Photosynthesis contributes to plant growth by ________.

taking in carbon dioxide and making sugars (carbohydrates)