BMB Exam 4

Where is the oxygen produced during photosynthesis?

In the thylakoid

Where is the chlorophyll located in a plant?

Thylakoid membrane

What is the function of Rubisco

Carbon fixation

Atrazine is a chemical that blocks the electron from leaving photosystem II. What would be the immediate effect on the plant?

Prevents ATP synthesis

Name this molecule which is the 1st product of photosynthesis?

3-phosphoglycerate

Name the substrate for the 1st step in photosynthesis. 

Ribulose-1,5-biphosphate

For every three molecules of CO2 that enter the cycle, how many molecules of Glyceraldehyde-3-phosphate (G3P) actually exit to be used for sugar synthesis?

1

During the reduction phase, what molecules provided by the light reactions are used to convert 3-PGA into G3P?

ATP and NADPH

Why is the membrane considered 'semi-permeable' rather than 'permeable'?

It regulates the passage based on size, charge and solubility

Which of the following best describes the movement of molecules during facilitated diffusion?

Molecules move down their gradient through a transport protein

If a cell is placed in a hypertonic solution, what will be the net movement of water?

water moves out of the cell causing it to shrivel

Which of the following is an example of exocytosis in a physiological context?

The release of neurotransmitters into a synapse

What happens to the surface area of the plasma membrane during heavy endocytosis?

It decreases as membrane sections are internalized via vesicle formation

How does the cell balance the change in surface area of plasma membrane due to endocytosis?

Cells often use exocytosis to rapidly replenish the membrane surface, maintaining a dynamic equilibrium

In the Na+/K+ pump cycle, what is the primary role of ATP phosphorylation?

To induce conformational change that releases sodium ions to the extracellular space

Name this molecule

3-phosphoglycerate

Name this molecule

serine

Pyrimidines are ___-membered rings

6

True or False: Purines are 6-membered rings fused to a 5-membered ring.

true

Identify pyrimidines in the list provided

thymine, cytosine, uracil

Identify the following nitrogenous base:

Adenine

Identify the following nitrogenous base:

Uracil

Which of the following is/are differences between DNA and RNA

Both C and D are correct

Which of the following describes the flow of genetic information as stated in the central dogma of molecular biology?

DNA —> RNA—> Protein

The DNA "backbone" is composed of

A phosphodiester bond between 3^! and 5^! hydroxyl groups of adjacent deoxyribose residues

There are approximately _________ human genes.

20,000

Where do the enzymatic reactions of the Calvin cycle take place?

stroma of the chloroplast

What is the primary function of the Calvin cycle?

synthesize simple sugars from carbon dioxide

The reactions that produce molecular oxygen (O₂) take place in

the light reactions alone.

Which of the events listed below occurs in the light reactions of photosynthesis?

Light is absorbed and funneled to reaction-center chlorophyll a.

Which of the following are directly associated with photosystem I?

receiving electrons from the thylakoid membrane electron transport chain

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

ATP and NADPH

Water passes quickly through cell membranes because

it moves through aquaporins in the membrane.

What kinds of molecules pass through a cell membrane most easily?

small and hydrophobic

Which of the following factors would tend to increase membrane fluidity?

a greater proportion of unsaturated phospholipids

Which of the following is a characteristic feature of a carrier protein in a plasma membrane?

It exhibits a specificity for a particular type of molecule.

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

The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

Which of the following membrane activities require energy from ATP hydrolysis?

Na⁺ ions moving out of a mammalian cell bathed in physiological saline

Which of the following statements is correct about diffusion?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO₂

Which of these are not embedded / inserted within in the hydrophobic portion of the lipid bilayer?

peripheral proteins

White blood cells engulf bacteria through what process?

endocytosis

Why are lipids and proteins free to move laterally in membranes?

There are only weak hydrophobic interactions in the interior of the membrane.

A membrane's fluidity is largely determined by the percentage of

Unsaturated fatty acids

Sodium and potassium are necessary electrolytes. As a result, the human body uses a great deal of energy keeping these electrolytes in balance. Explain why the body needs to use energy for this process.

ATP is required to move sodium ions against their concentration gradient outside the cell.

What will happen to the opening of the sodium-potassium pump if no ATP is present in a cell?

It will remain facing the cytoplasm, with sodium ions bound.

The sodium-potassium pump is called an electrogenic pump because it

contributes to the membrane potential.

The double bonds in naturally occurring fatty acids are usually _______ isomers.

Cis

The functions of fat include

all of the above

Which of the following molecules are lipids?

fatty acids, steroids, waxes, triacylglyderois

Decomposers convert organic nitrogen to ________.

all of the above

The ammonia that is incorporated into urea molecules is produced in reactions catalyzed by all of the following enzymes except

Serine hydroxymethyltransferase

Amino acids whose degradation yields α-ketoglutarate include all of the following except _________.

Leucine

Amino acids whose degradation yields succinyl-CoA includes all of the following except ________.

Histidine

The end product of uracil degradation is ________.

β-Alanine

In general, catabolism of amino acids begins with

Removal of the amino group

Urea is synthesized in which organ?

Liver

What are the seven metabolic products produced by the degradation of amino acids?

acetoacetyl-CoA, acetyl-CoA, oxaloacetate, fumarate, succinyl-CoA, α-ketoglutarate, Ammonia

In humans the purine ring cannot be degraded. How is it excreted?

Uric acid

The glutamate family of amino acids includes all of the following except

Lysine

The bonds that link the base pairs in the DNA double helix are ________.

hydrogen bonds

True or False: Adenine is a purine

true

True or False: A nucleotide consists of only a base and a sugar.

false

True or False: One of the differences between DNA and RNA is the sugar it contains.

true

Which of the following is not a component of nucleic acid?

Glucose

Which of the following statements describes the eukaryotic chromosome?

It consists of a linear molecule of double-stranded DNA plus proteins.

Why do histones bind tightly to DNA?

Histones are composed predominantly of positively charged amino acids , and DNA is negatively charged.

Which of the following is/are differences between DNA and RNA

RNA is single stranded and RNA contains uracil

The DNA "backbone" is composed of

A phosphodiester bond between 3^! and 5^! hydroxyl groups of adjacent deoxyribose residues

Nucleosomes are composed of all of the following except ________.

H5

Protein synthesis, using the mRNA template is called _____. 

Translation

In nucleosome structure the histone ________ aids in stabilizing the wrapping of DNA around the protein octomer.

H1

True or False: The melting point of a DNA molecule increases as the GC content increases. 

true

True or False: Chargaff's rule apply to DNA but not RNA. 

true

The Z-form of DNA

tends to occur in alternating purine-pyrimidine sequences.

Which of the following sequences of DNA is most likely to form Z-DNA?

5'-GCGCGCGCGCGCCGCGCGCG-3'
3'-CGCGCGCGCGCGCGCGCGCG-5'

Topoisomerases are associated with

supercoiling of DNA.

The T_m for melting the double helix is:

The midpoint of the range over which the helix denatures.

The hydrogen bonding interactions in a Watson-Crick AT base-pair involve what units in the adenine base?

N-1 and the amino group on C-6

Which of the following statements describes the eukaryotic chromosome?

It consists of a single linear molecule of double-stranded DNA plus proteins.

Which of the following statements is true of histones?

Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

What is the function of topoisomerase?

relieving strain in the DNA ahead of the replication fork

A genome is

All the DNA in an organism

In nucleosome structure the histone ________ aids in stabilizing the wrapping of DNA around the protein octomer.

H1

Name the substrates and products in this reaction.

Glutamate, Oxaloacetate, alpha-ketoglutarate, aspartate

The NADPH required for the Calvin cycle comes from

reactions initiated in photosystem I.

The light reactions of photosynthesis supply the Calvin cycle with

ATP and NADPH.

The pH of the inner thylakoid space has been measured, as have the pH of the stroma of a particular plant cell. Which, if any, relationship would you expect to find?

The pH within the thylakoid is less than that of the stroma.

The reactions that produce molecular oxygen (O₂) take place in

the light reactions alone.

Which molecule(s) of the Calvin cycle is (are) also found in glycolysis?

B, C, D, and 3-phosphoglycerate only

Oxygen released as a result of photosynthesis is a direct by-product of 

splitting water molecules.

Where are the molecules of the electron transport chain found in plant cells?

thylakoid membranes of chloroplasts

Where do the enzymatic reactions of the Calvin cycle take place?

stroma of the chloroplast

Which of the events listed below occurs in the light reactions of photosynthesis?

Light is absorbed and funneled to reaction-center chlorophyll a.

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

ATP and NADPH

Which of the following does not occur during the Calvin cycle?

release of oxygen

What does the chemiosmotic process in chloroplasts involve?

establishment of a proton gradient across the thylakoid membrane

What is the primary function of the Calvin cycle?

synthesize simple sugars from carbon dioxide

Ribulose–1,5-bisphosphate carboxylase catalyzes the carboxylation of ribulose-1,5-bisphosphate to form

Two molecules of 3-phosphoglycerate