Bio 172: Exam 1 Review

When polymerizing nucleic acids, new nucleotides are always added to the:

3' hydroxyl group of the molecule

In polymerization of nucleic acids, the next incoming incoming nucleotide is added to the ... of the previous nucleotide

3'; OH

Which of the following best describes a theory in the scientific methhod?

A broad explanation that incorporates facts, laws, inferences, and tested hypotheses

You have just discovered a new extremophile whose plasma membrane consists largely of unsaturated fatty acids. From which type of environment was this organism most probably isolated?

A cold environment

Which of the following molecules can easily cross an artificial liposome?

A long-chain fatty acid

Cholesterol can function as:

A stabilizing component of membranes

Where does the energy come from to power secondary active transport?

An electrochemical gradient

Why are rRNA sequences good for studying probable evolutionary relationships of all life on the planet?

Because all organisms on the planet have rRNA

Which of the following represents the order that molecules cross a synthetic membrane liposome from LEAST (not permeable) ot MOST (permeable)?

Chloride ion, Alanine, H2O, O2

Which best describes how water crosses a cellular membrane:

Facilitated diffusion using aquaporins

Which of the following is not a classification of amino acids?

Globular (acidic, hydrophilic, hydrophobic)

Extremophiles live in harsh environments. Which statement about extremophiles is true?

Halophiles adapt to life in salty environments by maintaining high solute concentrations in their cytosol

What type of bond holds a T-A pair together in a DNA molecule?

Hydrogen

Which statement is correct about a micelle?

Hydrophobic tails will interact with each other to avoid the hydrophilic environment.

Where is the chemical energy in carbohydrates stored?

In both the C-C and C-H bonds

You are studying a metabolic enzyme that is found in organisms living at extremely high temperatures and an acidic environment. You carry out your reactions on your lab bench at room temperature in water and find that the reaction is quite slow, even though you are able to reach a Vmax. Which of the following is not a good way to increase the rate of reaction?

Increase substrate concentration

Halophiles need enzymes that can work under high salt conditions. Which types of interactions do you think would be the least abundant in a halophilic enzyme?

Ionic bonds

Which of the following is false regarding the Na+/K+ ATPase

It causes the Na+ ion concentration to be high inside the cell

At room temperature, how does cholesterol affect the plasma membrane?

It reduces the mobility of phospholipids

Which of the following would you expect to be true of a catalase enzyme isolated from an Archaea living in an acidic pool?

It would have a lower Km at pH 4 than catalase enzyme isolated from a soil dwelling bacteria

Which of the following does not influence the Vmax of an enzyme catalyzed reaction?

Km

Which of the following is true regarding phospholipid membranes?

Membranes that have cholesterol tend to be more rigid at body temperatures than membranes that do not have cholesterol.

You are studying onion root cell division under a microscope. You add a drug called colchicine to your root cells. Colchicine inhibits spindle fiber formation and prevents chromosome movement during cell division. What is colchicine inhibiting?

Microtubules

Which of the following represents the order that molecules cross a synthetic membrane liposome from most easily (permeable) to least easily (not permeable)?

O2, H2O, glucose, Na+

Which functional group is not found in proteins?

Phosphate

Which of the following correctly describes secondary active transport of protons and sugar across a membrane into a cell?

Protons move down their concentration gradient while sugar moves against its concentration gradient

Which of the following is not a monosaccharide?

Starch (glucose, fructose, deoxyribose)

You are given two chemical bonds to examine, a C-H bond and a C-O bond. Which of the following statements is true?

The C-H bonds have more potential energy than C-O bonds

Which of the following is true of an enzyme catalyzed reaction?

The Km of the reaction would change with the addition of a competitive inhibitor

You have some cells that you have cultured in the lab that are growing in a solution that contains 200 mM NaCl. One Friday afternoon you accidently replace this salty solution with pure water. What might happen to your cells?

The cell will burst because the inside of the cell is hypertonic (higher salt) relative to pure water

Which of the following statements is not true about the similarities in the synthesis of triglycerides and the synthesis of proteins?

The final product for both is one long chain of connected monomeric building blocks.

Which of the following is true regarding the molecular structure of DNA?

The helix has a uniform diameter because purines pair with pyrimidines

A common delivery method for getting drugs into cells is to surround the drug with a lipid bilayer called a liposome. How do you think this allows the drugs to enter the cell?

The liposome fuses with the phospholipid bilayer of cells that results in the drug being delivered into the cell

An enzyme called phospholipase can cleave the polar head group off of a phospholipid molecule. consider a cell where the plasma membrane has a monolayer of phospholipids facing the interior of the cell (Phospholipid A) and aa layer facing the exterior of the cell (Phospholipid B). If you added phospholipase to the outside of the cell, what would you expect to find in the fluid surrounding the cell?

The phosphate head group from phospholipid B only

If most chemical reactions are reversible, what is one way to ensure that the biochemical reactions in humans proceed in a forward direction?

The products of the reactions are quickly consumed by the next reaction.

Which of the following is true regarding the Na+/K+ ATP-dependent transporter?

The transporter accepts a phosphate group when ATP is hydrolyzed, causing a conformational change of the pump

When the temperature is lower than optimal for a particular enzyme, why does enzyme activity decrease? Choose the most complete answer.

There are fewer collisions between enzyme and reactants, and the enzymes' active site is no longer is flexible enough to allow the reaction to proceed.

Which of the following is NOT a reasonable adaptation characteristic of the extremophiles?

Thermophile; a higher proportion of T-A base pairs in the DNA (Acidophile: proton pumps in their plasma membranes; Halophiles: high internal solute concentration; Acidophile: protonated amino acid R groups)

Which of the following is true of phospholipids?

They are part of the cell membrane of bacteria

Which of the following is not part of mitochondria?

Thylakoid membrane

Which of the following is false regarding the Na+/K+ pump?

Transport of Na+ and K+ is driven by the electrochemical gradient across the plasma membrane

Which of the following is the most reasonable explanation for why unsaturated fatty acids help keep membranes more fluid at lower temperatures?

Unsaturated fatty acids tend to have bent and rigid hydrophobic tails that prevent adjacent lipid molecules from making strong interactions

Which of the following is the most reasonable explanation for why unsaturated fatty acids help keep membranes more fluid at lower temperatures?

Unsaturated fatty acids tend to have bent and rigid hydrophobic tails that prevent adjacent lipid molecules from making strong interactions.

If the external solution is hypertonic relative to the inside of the cell, what type of water movement will occur?

Water will move out of the cell via osmosis

Which of the following makes a biological membrane more fluid and flexible?

a higher proportion of unsaturated fatty acids

A general explanation of the world supported by a large body of experiments and observations is called...

a theory

Bacteria need ATP for growth and to provide energy for cellular activities. Where do bacteria synthesize the ATP necessary for such activities?

across the plasma membrane

Chaperones...

allow proteins to assume their proper three dimensional state

Insulin, a protein that is synthesized in cells of the pancreas, gets secreted or exported from the pancreas after it is made. Targets of insulin include muscle and liver cells. Which of the following would not be involved in insulin synthesis?

cytosolic ribosomes

Which of the following statements about protein folding is true?

high salt concentrations can affect the folded state of a protein

An acidic solution has a ... concentration of protons and a ... concentration of hydroxide ions.

high; low

The alpha helix in proteins is due to...

hydrogen bonds that form between each amino acid carbonyl group and the amide group of another residue

Which of the following would be most likely to destroy the primary structure of a protein?

hydrolysis

You are studying enzyme "X" whose active site consists of 5 amino acids; 2 acidic amino acids and 3 amino acids with R-groups containing only nonpolar covalent bonds. What chemical properties would you expect the substrate for enzyme "X" to have?

hydrophobic and basic properties

You are running an enzyme catalyzed reaction in the presence of a competitive inhibitor. All of the following are true except...

inhibition is not affected by increasing substrate concentration

What determines the primary structure of a polypeptide?

its sequence of amino acids

The entire set of chemical reactions that convert molecules into other molecules and transfer energy is called...

metabolism

If a cell suddenly developed a mutation in its tubulin gene and could no longer make microtubules, what would that cell be unable to do?

move vesicles from the ER to the Golgi

The molecule below might participate in Van der Waals interactions, which are the same as what type of chemical bond?

none of the answers are correct

Animals cells do not have chloroplasts. But they do have ... instead, which fulfills a similar function for the cell.

none of these are correct

Which of the following is never found in bacterial cells

nucleus

The second law of thermodynamics states that...

one usable form of energy cannot be completely converted into another usable form

Gibb's free energy represents

the energy available to do work

In Pasteur's experiment testing the idea of spontaneous generation,...

the observation of cells growing in the straight necked flask supports both spontaneous generation and cells from pre-existing cells

Which types of amino acids would be most soluble in water?

those having polar or charged side chains

Which of the following is NOT, or does NOT contain a monosaccharide?

triglycerides

We place human red blood cells into a hypotonic solution. This means...

water will enter the cell, causing it to swell and potentially bursts