AP Biology Unit Test

Eukaryote

A cell that contains a nucleus and membrane bound organelles

What are the two categories of movement across the membrane?

Active and passive transport

Which of the following is a characteristic of mitochondria and chloroplasts that supports the endosymbiotic theory?

Both contain DNA molecules.

Important chemical that provides energy for cells to do work (like active transport)

Adenosine triphosphate (ATP)

https://assets.learnosity.com/organisations/537/VH931391.g01.png Which of the following best describes the numbered areas?

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.

Vacuoles

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water.

Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

Embedded in the cell membrane and helps substances move across the membrane

Channel/Transmembrane Proteins, aquaporins

Why do chloroplasts move about in the cytoplasm of plant cells?

Chloroplasts may be moved around with the stream to a position of optimum light absorption for photosynthesis. The rate of motion is usually affected by light exposure, temperature, and pH levels

Make a list of molecules that are incorporated into the phospholipid bilayer and explain their functions.

Cholesterol keeps membrane at the right fluidity and regulates communication between cells. Proteins make sure that the right molecules get in and out of the cell and help fuse two different bilayers. Carbohydrates function as adhesion and address loci for cells and if the temperature drops, they function kind of like spacers between phospholipids keeping them from becoming too packed. They can also function to connect phospholipids to keep them from becoming too fluid in warm temperatures.

The process by which molecules/particles move from a more crowded area to a less crowded area.

Diffusion

How is energy from the sun converted to ATP?

During the process of photosynthesis, light penetrates the cell and passes into the chloroplast. The light energy is intercepted by chlorophyll molecules on the granal stacks. Some of the light energy is converted to chemical energy. During this process, a phosphate is added to a molecule to cause the formation of ATP.

The type of transport using vesicles that moves material INSIDE the cell

Endocytosis

Active Transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

The type of transport using vesicles that moves material OUTSIDE of the cell

Exocytosis

Cisternae

Flattened, membrane-bound compartments that make up the Golgi apparatus.

When the concentration of solution is higher when compared to another solution.

Hypertonic

When the concentration of a solution is lower when compared to another solution

Hypotonic

Matrix

Innermost compartment of the mitochondrion

https://assets.learnosity.com/organisations/537/VH907843.g01.png Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?

Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane.

When two solutions have the same concentration

Isotonic

What are all of the mitochondrial membrane layers made up of?

It is made of a phospholipid bilayer.

Why do mitochondria follow the chloroplasts around?

Mitochondria follow the chloroplasts around because they need energy.

What is so special about mitochondrial DNA?

Mitochondrial DNA is inherited from our mother's side.

Amphipathic

Molecules are said to be this when it has regions that are both hydrophilic and hydrophobic.

Let's recap and describe what particles will be able to move across the membrane in our fruit and vegetable cells.

NaCl can not move across the cell membrane, but water can.

Will salt be able to move across the membrane?

No, because NaCl is ionic

The diffusion of water across a membrane is

Osmosis

Describe passive transport

Particles move from high concentrations to low concentrations; No additional energy is required; Particles move across a membrane

Which one of these two types of movement does not use energy?

Passive transport

The type of molecule that makes up the double layer of the cell membrane

Phospholipid

Why do phospholipids form a bilayer in aqueous environments?

Phospholipids form a bilayer in aqueous environments because when phospholipids are mixed with water, they spontaneously rearrange themselves to form the lowest free-energy configuration. This means that the hydrophobic regions find ways to remove themselves from water, while the hydrophilic regions interact with water.

What is the function of the porins?

Porins act as channels that are specific to different types of molecules and are large enough to allow passive diffusion.

Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?

Rough ER can synthesize and package proteins for export, and smooth ER cannot.

How do scientists believe that mitochondria ended up in eukaryotic cells?

Scientists believe that mitochondria ended up in eukaryotic cells when the mitochondria got ingested by the ancestors of our cells and instead of being engulfed and torn to shreds, they stuck around inside the cell since they helped process glucose and generate energy

What does it mean to be "selectively permeable?"

Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell.

What properties generally describe water molecules?

Small and polar

What kinds of molecules are able to pass through the phospholipid bilayer easily?

Small, uncharged molecules such as oxygen, carbon dioxide, and vitamins.

Briefly explain the Calvin cycle

The Calvin cycle takes place in the thylakoid membrane and occurs as chemical reactions performed by plants to "fix" carbon from CO2 into three-carbon sugars by taking energy and adding carbon dioxide and hydrogen and making high energy molecules such as glucose. Later, plants and animals can turn these three-carbon compounds into amino acids, nucleotides, and more complex sugars such as starches. The three stages of the Calvin cycle are fixation, reduction, and regeneration.

Explain the fluid mosaic model of the cell membrane.

The Fluid mosaic model of the cell membrane consists of phospholipids that pair up tail-to-tail in a two layer sheet that extends all around the cell. The phospholipid heads point in towards the cytoplasm and out towards the watery fluid external to the cell with the lipid tails sandwiched in between. This is a bilayer.

Stroma

The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water. Essential for this because not only does it contain the enzymes necessary for carbon fixation, it also manages the chloroplast response to cellular stresses and signaling between various organelles. It plays an important role in both the light-dependent and light-independent reactions of photosynthesis.

https://assets.learnosity.com/organisations/537/VH904738.g01.png Which statement best explains the orientation of the phospholipid molecules in this model?

The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments.

Why does the inner membrane of the mitochondria have cristae?

The inner membrane of the mitochondria has a cristae as the folding or wrinkling of the cristae on the inner mitochondrial membrane creates a large surface area inside the mitochondria.

What is the main function of the chloroplasts?

The main function of chloroplasts is to convert light energy into relatively stable chemical energy via the photosynthetic process.

What is the main function of mitochondria?

The main function of mitochondria is to produce the energy necessary for the cell's survival and functioning through a series of chemical reactions. Mitochondria break down glucose into an energy molecule known as adenosine triphosphate (ATP), which is used to fuel various other cellular processes. In addition to producing energy, mitochondria store calcium for cell signaling, generate heat, and are involved in cell growth and death.

How is the content of the matrix different from the cytosol and the inter membrane space?

The matrix is different from the cytosol and the inter membrane space as it has a much higher protein concentration.

Water Potential

The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.

Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes. Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions?

They have highly folded membranes.

How do other molecules pass through the membrane?

Transmembrane proteins create channels that allow specific molecules such as sodium and potassium ions pass through the membrane.

Carbon fixation

the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The organic compounds are then used to store energy and as building blocks for other important biomolecules.

Grana

the stacks of thylakoids embedded in the stroma of a chloroplast.

How do scientists think chloroplasts ended up in plant cells?

When the cell engulfed cyanobacteria, instead of breaking it down, they got rid of phagocytes around the outside of the cyanobacteria and it became chloroplasts.

Most cells have aquaporin proteins embedded in the phospholipid membrane. These aquaporins selectively permit water to pass through them. In cell membranes with aquaporins can water move across the membrane?

Yes, water is able to pass across the membrane through the aquaporins.

Prokaryotes

a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles. Prokaryotes include the bacteria and cyanobacteria.

Ribosome

a minute particle consisting of RNA and associated proteins found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins.

Endoplasmic Reticulum

a network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.

Hydrolytic

any chemical reaction in which a molecule of water ruptures one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile

Lysosomes

cell organelle filled with enzymes needed to break down certain materials in the cell

Thylakoids

each of a number of flattened sacs inside a chloroplast, bounded by pigmented membranes on which the light reactions of photosynthesis take place, and arranged in stacks or grana.

Endoplasmic Reticulum (Smooth)

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.

What molecules are generally able to move through the cell membranes of organisms?

non-polar and small

What characteristics describe the solutes in the NaCl solutions

non-polar; small; ionic/charged

Endoplasmic Reticulum (Rough)

produce proteins and is made up of cisternae, tubules and vesicles.

Krebs cycle

second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

Golgi apparatus

stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum