BIOL 1406 EXAM 2 (CH 5-7)

What is the process by which monomers are linked together to form polymers?

Dehydration reaction

In a hydrolysis reaction, __________, and in this process, water is __________.

a polymer is broken up into its constituent monomers; consumed

In what polysaccharide form do plants store glucose to be available later as an energy source?

Starch

Which of the following molecules is a monosaccharide?

C₆H₁₂O₆

The polysaccharide that you are most likely to have eaten recently is __________.

starch

Carbohydrates can function in which of the following ways?

Structural support and energy storage

Amylase is an enzyme that breaks down starch. Why can the same enzyme not break down cellulose?

The monosaccharide monomers in cellulose are bonded together differently than those in starch.

Which of the following components of a tossed salad will pass through the human digestive tract and be digested the least?

Cellulose (in the lettuce)

Lipids differ from other large biological molecules in that they __________.

are not truly polymers

If a small droplet of triacylglycerol molecules is suspended in water, the fat molecules form a "ball of spaghetti" with no particular orientation. But if a droplet of phospholipid molecules is put in water, all the molecules point outward, toward the water. Phospholipids are forced into this orientation because phospholipids have __________.

a charged or polar end and an uncharged or nonpolar end

Which of the following is a true statement comparing phospholipids and triacylglycerols (fats and oils)?

Phospholipid molecules have a distinctly polar "head" and a distinctly nonpolar "tail," whereas triacylglycerols are predominantly nonpolar.

High cholesterol levels are considered a major risk factor for heart disease. If it is so bad for humans, why does the body make cholesterol in the first place?

Cholesterol is the precursor for many important molecules such as sex hormones.

Some lipids are formed when fatty acids are linked to glycerol. These subunits are linked together by __________.

ester linkages

The fatty acid tails of a phospholipid are __________ because they __________.

hydrophobic; have no charges to which water molecules can adhere

The overall three-dimensional shape of a single polypeptide is called its __________.

tertiary structure

Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the shape of an enzymatic protein?

Denaturing the protein

A change in salt concentrations or pH

Heating the protein

Treating the protein with a chemical that breaks hydrogen bonds

The α helix and β pleated sheet represent which level of protein structure?

Secondary structure

The peptide bond is __________.

a covalent bond joining amino acids together to form a polypeptide

The "primary structure" of a protein refers to __________.

the sequence of amino acids along a polypeptide chain

What do Alzheimer's, Parkinson's, and mad cow disease have in common?

All are associated with the buildup of misfolded proteins in cells.

A glucose molecule is to starch as __________.

a nucleotide is to a nucleic acid

Which of the following are pyrimidines found in the nucleic acid DNA?

Thymine and cytosine

Which of the following describes a difference between DNA and RNA?

RNA molecules generally consist of a single polynucleotide chain, whereas DNA molecules generally consist of two polynucleotide chains organized into a double helix.

Both molecules contain adenine, guanine, and cytosine, but DNA also contains thymine and RNA also contains uracil.

They contain different sugars.

In a dehydration synthesis reaction, __________ is always formed as a by-product of the reaction.

Water

Which is the term for compounds that do not mix with water?

Hydrophobic

When comparing saturated and naturally occurring unsaturated fats, the unsaturated fats have __________ and are __________ at room temperature.

cis double bonds; liquids

Carbohydrates are used in our bodies mainly for __________.

energy storage and release

In living organisms, DNA exists as a __________ with the strand(s) __________.

double helix; running antiparallel

Sugars are molecules that have __________ C:H:O and are called __________.

a 1:2:1 ratio of; carbohydrates

The subunits (monomers) in cellulose are linked together by __________.

glycosidic linkages

The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond.

Covalent

The lipids that form the main structural component of cell membranes are __________.

phospholipids

Which of the following is a polymer?

Cellulose, a plant cell wall component

Sugars have a(n) __________ group that interacts with a _________ group that forms ring structures when the dry molecule is placed in water.

carbonyl (-C=O); hydroxyl (-OH)

Nitrogenous bases are classified as either purines or pyrimidines. Examples of purines are __________.

adenine and guanine

The proper three-dimensional shape and folding of a protein is assisted by _________.

molecules called chaperonins

The secondary structure of a peptide backbone is stabilized by __________ forming either a(n) __________ or a(n) __________.

hydrogen bonds; α helix; β pleated sheet

Macromolecules, the molecules of life, include all of the following except __________.

trace elements

Protein molecules are polymers (chains) of __________.

amino acid molecules

The components of nucleic acids are __________.

a nitrogenous base, a pentose sugar, and a phosphate

At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________.

Chitin

The tertiary structure of a protein includes all of the following interactions except _________ bonds.

peptide

A polysaccharide that is used for storing energy in human muscle and liver cells is __________.

Glycogen

The molecule with four fused rings that is found in animal membranes and is the precursor of vertebrate sex hormones is __________.

cholesterol

__________ is always involved in hydrolysis reactions.

Water

One characteristic shared by sucrose, lactose, and maltose is that __________.

they are all disaccharides

The fluid mosaic model describes the plasma membrane as consisting of

diverse proteins embedded in a phospholipid bilayer.

The lipids in a cell membrane are arranged

_____.

so that the nonpolar parts of two lipids point toward each other

The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called

_____.

Diffusion

The diffusion of water across a selectively permeable membrane is called __________.

osmosis

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration

gradient.

transport proteins; down

Aquaporins are proteins that facilitate the transport of __________ across the

membrane.

water

Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form?

Chaperonins

Which of the following is the simplest collection of matter that can live?

Cell

A researcher wants to film the movement of chromosomes during cell division. Which type of microscope should she choose and why is it the best choice?

light microscope, because the specimen is alive

Which of the following statements is true about cell fractionation?

Cell fractionation separates cells into their component parts

Consider two cells with the same volume but with very different surface areas due to differences in their shapes. The cell with the larger surface area is likely to __________.

be involved in the rapid uptake of compounds from the cell's environment

Which of the following is/are likely to limit the maximum size of a cell?

1. the time it takes a molecule to diffuse across a cell

2. the cell's surface-to-volume ratio

3. the shape of the cell

Which of the following structures is found in eukaryotic but NOT prokaryotic cells?

Mitochondria

A substance moving from outside the cell into the cytoplasm must pass through __________.

the plasma membrane

In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?

Eukaryotic cells are compartmentalized, which allows for specialization.

Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell, they __________.

have no membrane-bounded organelles in their cytoplasm

Which of the following features do prokaryotes and eukaryotes have in common?

ribosomes, plasma membrane, and cytoplasm

What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?

Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.

Which of the following is FALSE in respect to eukaryotic chromosomes?

Chromosomes appear only as a cell is about to divide (false)

Which of the following groups is primarily involved in synthesizing molecules needed by the cell?

ribosome, rough endoplasmic reticulum, smooth endoplasmic reticulum

Which of the following categories best describes the function of the rough endoplasmic reticulum?

manufacturing

You would expect a cell with an extensive Golgi apparatus to __________.

secrete large amounts of protein

Consider a protein that is made in the rough endoplasmic reticulum. You observe that when the synthesis of the protein is completed, the protein is located in the ER membrane. Where else in the cell might this protein be found?

embedded in the plasma membrane, functioning in the transport of molecules into the cell

Which of the following sequences represents the order in which a protein made in the rough endoplasmic reticulum might move through the endomembrane system?

Golgi apparatus → lysosome

A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.

in the rough endoplasmic reticulum

Which of the following five membranes is most likely to have a lipid composition that is distinct from those of the other four?

mitochondrial outer membrane

Which of the following statements about chloroplasts and mitochondria is true?

Chloroplasts and mitochondria synthesize some of their own proteins.

Which of the following organelles might be found inside other organelles?

Ribosomes

Microtubules and microfilaments commonly work with which of the following to perform many of their functions?

Golgi apparatus

Which statement about the cytoskeleton is true?

Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm.

Cilia and flagella move due to the interaction of the cytoskeleton with which of the following?

motor proteins

Basal bodies are most closely associated with which of the following cell components?

Cilia

Dye injected into a plant cell might be able to enter an adjacent cell through __________.

Plasmodesmata

Your intestine is lined with individual cells. No fluids leak between these cells from the gut into your body. Why?

The intestinal cells are bound together by tight junctions.

Which of the following statements correctly describes a common characteristic of a plant cell wall and an animal cell extracellular matrix?

Both are permeable to water and small solutes.

The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________.

in the rough endoplasmic reticulum and in the Golgi apparatus

The function of the rough endoplasmic reticulum (RER) is __________.

to synthesize proteins that are secreted as glycoproteins

Which of the following is present in a prokaryotic cell?

Ribosomes

The network of fibers that organizes structures and activities in a cell __________.

is the cytoskeleton

The region of a bacterial cell that contains the genetic material is called the __________.

nucleoid

Cell junctions in plant cells are called __________, and communicating junctions in animal cells are called __________.

plasmodesmata; gap junctions

Cells are small because __________.

of the geometric relationships between surface and volume

Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton __________.

with motor proteins

The endoplasmic reticulum is part of the endomembrane system, which also includes the __________.

nuclear envelope, the Golgi apparatus, lysosomes, and vesicles

Microfilaments function in cell motility including __________.

muscle contraction, amoeboid movement, and cytoplasmic streaming in plants

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?

Phospholipids form a selectively permeable structure.

The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true?

The fluid aspect of the membrane is due to the mobility of phospholipids, and embedded proteins account for the mosaic aspect.

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found?

In the interior of the membrane

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?

Membrane carbohydrates function primarily in cell-cell recognition.

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the membrane would carbohydrates most likely be found?

On the outside (external) surface of the membrane

Which statement about the sidedness of the plasma membrane is correct?

1. The asymmetrical distribution of membrane proteins, lipids, and carbohydrates across the plasma membrane is determined as the membrane is being constructed.

2. The two lipid layers may differ in specific lipid composition.

3. Every integral membrane protein has a specific orientation in the plasma membrane.

4. Parts of proteins that are exposed on the cytoplasmic side of the endoplasmic reticulum are also exposed on the cytoplasmic side of the plasma membrane.

Which of the following molecules is most likely to passively diffuse across the plasma membrane?

Carbon dioxide

Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?

A large, polar molecule

Which of the following statements about passive transport is correct?

Passive transport permits the solute to move in either direction, but the net movement of solute molecules occurs down the concentration gradient of the molecule.