Cell Bio Final (Previous Exam Questions)

Select all of the following that are true during the enzymatic transfer of electrons and protons from FADH2 to Fe3+.

- Fe 3+ is reduced to Fe 2+ - FADH2 is oxidized - two protons are released into the medium

From the list below, select all the categories into which plasma membrane receptors can be conveniently classified.

- ion channel receptors - receptors linked to G-proteins - catalytic receptors

From the list below, select all the conversions that generate CO2.

- isocitrate to alpha-ketoglutarate - alpha-ketoglutarate to succinyl coA - pyruvate to acetyl coA

From the list below, select all the processes that generate CO2.

- pyruvate processing - TCA cycle

There are only two ways cells make ATP. From the list below, check those two.

- substrate level phosphorylation - oxidative phosphorylation

Consider a protein inserted into the ER membrane during translation (i.e., co-translational import). A lumenal segment of such a protein may later be found in which of the following places?

- the lumen of a Golgi cisterna - the lumen of a vesicle *there may be more correct answers. idk mane*

On a Hanes-Woolf plot [S]/v is plotted as a function of [S]. On this type of plot the x-intercept represents _______ .

-Km

How much 2 M ethanol would you add to make 100 mL of 02.5 mM ethanol?

0.0125 mL

You spin down 2.0 mL of cell suspension, bring the pellet up in 100 microliters of PBS, then add 10 microliters of trypan blue directly to the smae tube. What is the dilution factor?

0.055

If you dilute 5.0 mL of a citrate solution that is 5 mg/mL to a total volume of 100 mL, what is the citrate concentration of the final solution?

0.25 mg/mL

How many ATP molecules are produced for each "turn" of the TCA cycle?

1

The equation describing the regression line of a LIneweaver Burk plot is y = 0.25x - 0.1. What is the numerical value of Km?

1

How much of a solution that is 7.65 mg urea/mL do you need to have 12 mg of urea?

1.57 mL

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

100%

A linear regression through the data of a standard curve plotting protein concentration as a function of absorbance has a slope of 0.4 absorbance units (AU)/mg protein/mL and a Y-intercept of 0.1 AU. What is the protein concentration of a sample that yields an absorbance of 0.9 AU?

2.0

If there are 20 chromatids in a cell, how many centromeres are there?

20

You have counted your cell culture and found that three "red" squares (1 x 1 x 0.1 mm) gave you counts of 98, 104, and 125 ells, respectively. The dilution factor is 0.25. What is the density of your culture?

272,500 cells/mL

How much protein is contained in 3.78 mL of a solution that is 1 g/L?

3.78 mg

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

32

What is the equilibrium potential for sodium when its concentration inside the cell is 34 mM and outside the cell is 165 mM?

40 mV

After being oxidized completely to H2O and CO2, how many CO2 molecules are produced by one molecule of glucose?

6

How many oxygen molecules (O2) are required each time a molecule of glucose (C6H12O6) is completely oxidized to carbon dioxide and water via aerobic respiration?

6

Which of the following is/are NOT TRUE of ATP?

ATP is found only in mitochondria

How would you make 50 mL of 0.50 mM glutamate (MW = 147.1)?

Add 3.68 mg of glutamate to a 50 mL volumetric flask and bring up to 50 mL?

Phylogenetically, cells are divided into three broad domains, ______.

Bacteria, Archaea, and Eukaria

Codons are three-base sequences that specify the addition of a single amino acid. How do eukaryotic codons and prokaryotic codons compare?

Codons are a nearly universal language among all organisms.

In eukaryotic cells, chromosomes are composed of _____.

DNA and proteins

Which is the correct order of protein movement through the endomembrane system?

ER, golgi, lysosome

The phase of the cell cycle that varies most in duration in various cell types is _____.

G1

Which of the following statements about NAD+ is true?

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle

In addition to ATP, what are the other end products of glycolysis?

NADH and pyruvate

What is the difference between a synthase and a synthetase?

One uses ATP, the other does not

Under normal cellular conditions, pyruvate may be converted into all of the following EXCEPT this one.

PEP

Which of the following is NOT one of the steps of cellular respiration?

RNA processing

The phase of the cell cycle associated with the doubling of the amount of DNA in the cell is _________ phase.

S

Which of the following are true based on what we know today? (about prokaryotes)

Some prokaryotes can have cytoskeletal elements and internal, membrane-bound organelles.

What does it mean to say that a signal is transduced?

The physical form of the signal changes from one form to another.

*True or False?* Ion gradients across the membrane drive numerous cellular functions.

True

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as____.

a cofactor necessary for enzyme activity

The molarity of a solution is___

a measure of solute concentration

What is a nuclear localization signal?

a sequence of amino acids that signals for a protein to enter the nucleus

Different body cells can respond differently to the same peptide hormones because _____.

a target cell's response is determined by the receptors it possesses

Which component(s) of the cytoskeleton is/are polar?

actin and microtubules

Cyclins modulate the progression of cells through the cell cycle by

activating protein kinases that are critical regulators of cell division.

In the article by Hediger, membrane-associated transporters were divided into two categories, _______ and ________.

active, passive

Which enzyme is desginated EC 1.1.1.1?

alcohol dehydrogenase

Which of the following is NOT a tenet of the cell theory?

all cells have a membrane bound nucleus

The nucleus contains

all of the above (DNA, protein, chromatin)

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in ______.

all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

Consider the number of carbon atoms in the molecules listed below. Which one does not belong with the others?

alpha-ketoglutarate

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they _____.

amplifiy the original signal many times

Cyclin-dependent kinase (Cdk) is _____.

an enzyme that attaches phosphate groups to other proteins

____ bind two or more ions or molecules and transport them in opposite directions across a membrane.

antiporters

According to Robinson, the deepest branch of the evolutionary tree is between ______ and _______.

archaea, bacteria

Ribosomes____

are made of RNA and protein and synthesize all the proteins in a cell

Cells are small in part b/c _____.

as they get larger it becomes more difficult to keep the concentrations of reactants relatively high and the surface area is unable to meet the demands of the increased volume

In the term " DG ", the " ' " symbol indicates that the reaction was carried out

at pH = 7.0

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells? The mutant yeast cells wil _____ .

be unable to grow anaerobically

In the equation describing Fick's law, why is it possible to replace term dc/dx with term (Co-Ci) when considering biological systems?

because in biological systems dx is a constant

How might a change of a single amino acid at a site distant from the active site of an enzyme alter an enzyme's substrate specificity?

by changing the conformation of the enzyme

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. The second messenger in this pathway is _____.

cAMP

Cellulose belongs to which of the following groups of macromolecules?

carbohydrates

Of the following molecules, which passes through a lipid bilayer most readily?

carbon dioxide

The simplest structure shared among all living organisms is the___.

cell

Glycosylated proteins and lipids within the plasma membrane are important for

cell recognition and protection

In the cells of some organisms, mitosis occurs without cytokinesis. This results in _____.

cells with more than one nucleus

Cells are _____.

characteristic of prokaryotic and eukaryotic organisms

Which of the following does NOT pass through nuclear pores?

chromosomes

Which of the following chemical bonds is the strongest?

covalent

Kinetochore microtubules assist in the process of splitting centromeres by _____.

creating tension by pulling toward opposite poles

Mitosis separates chromosomes. Cytoplasm is divided between two daughter cells by _____.

cytokinesis

When the size of a cell increases, the surface area/volume ratio ____

decreases

In the equation describing Fick's Law, the variable "D" represents the ______.

diffusion coefficient

The activation of receptor tyrosine kinases is characterized by _____.

dimerization and phosphorylation

Tumor-supressor genese ____.

encode proteins that help prevent uncontrolled cell growth

This organelle is involved in protein synthesis.

endoplasmic reticulum

During normal glycolysis, glucose-6-phosphate is converted into _________.

fructose-6-phosphate

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?

glucose

Which amino acid was produced in Stanley Miller's experiment?

glycine

Which of the following occurs in the cytosol of a eukaryotic cell?

glycolysis and fermentation

In general, an enzyme with a low afifnity

has a high reaction rate

An exothermic reaction______

has a negative DG and proceeds spontaneously

Neurons and some other specialized cells divide infrequently because they _____.

have entered into G0

Which of the following is/are true of Robert Remak?

he was one of the first to postulate that all cells arise from preexisting cells

What is the difference between a biphosphate and a diphosphate?

in a diphosphate, the phosphates are directly attached to one another

In the cell cycle, a mitotic Cdk is present during _________ phase.

in all phases on this list

The product of the p53 gene _____.

inhibits the cell cycle

During ATP synthesis by the F0F1 ATPase, protons flow from the __________ into the ________.

intermembrane space, matrix

In a cell of a kelp plant the concentration of K+ is much greater inside the cell that outside the cell. The equilibrium voltage for K+ is -73 mV. You measure Vm and get a reading of -90 mV. In this situation, in which direction will K+ tend to flow?

into the cell

Metabolism ____________.

is the total of all the reactions occurring within a cell

Gramicidin is an antibiotic that increases the permeability of bacterial cell walls to inorganic ions. What is the most likely mode of action of gramicidin?

it forms a channel in the membrane

Rough ER is called "rough" because_____

it is covered with ribosomes

Which of the following is true of the genetic code?

it is redundant

Why is the Lineweaver-Burke plot important in enzyme kinetics?

it makes it easier to determine Vmax

Which of the following is/are NOT TRUE of facilitated passive diffusion?

it requires ATP

Why can glycolysis be described as having an energy investment phase and an energy payoff phase?

it uses stored ATP and then forms a net increase in ATP

Microtubules often perform their role in movement in association with the motor protein ______ .

kinesin

Consider the equation y=(ax)/(x+k). A graph of 1/y as a function of 1/x will be _______ .

linear

Glycolysis is active when cellular energy levels are ____; the regulatory enzyme, phosphofructokinase, is _____ by ATP.

low; inhibited

Translation requires _____.

mRNA, tRNA, and rRNA

At the most fundamental level, what do enzymes do?

make and break chemical bonds

What is the common name for Callithrix jacchus?

marmoset

The F0 unit of the F0F1 ATPase resides in the inner mitochondrial membrane and the F1 unit resides in the ___________.

matrix

Which of the fundamental properties of life do viruses NOT possess?

metabolism & irritability

The major structural elements of the cytoskeleton are

microtubules, microfilaments, and intermediate filaments

In post-translational import a "transit sequence" targets proteins to which of the following organelle(s)?

mitochondria & cholorplasts

Energy released by the electron transport chain is used to translocate H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

The first gap in the cell cycle (G1) corresponds to _____.

normal growth and cell function

Which of the following structures are involved in ribosome synthesis?

nucleolus

This organelle has a double membrane system.

nucleus

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

What kind of molecules serve as electron acceptors in cellular respiration?

oxidized molecules with low potential energy

Which of the following processes includes all others?

passive transport

Which of the following is the major lipid found in membranes?

phospholipids

Which of the following is not a "logical" reason for cells to phosphorylate glucose?

phosphorylated glucose is a competitive inhibitor of glyceraldehyde-3-phosphoate dehydrogenase

mRNAs are smaller than the length of the DNA that codes for them because _____.

post-transcriptional modification removes the introns

The primary function of an enzyme or any biological catalyst is to ____.

reduce the energy of activation and increase the rate of a reaction

Which of the following is NOT a function of cell membranes?

regulate the transfer of genetic information in the form of DNA and RNA

A gap junction is a channel that connects adjacent cells. Which one of the following CANNOT pass through a gap junction?

ribosomes

All form of life on Earth possess these structures at some point in their lives.

ribosomes

Biological membranes___

separate "inside" from "outside" and allow eukaryotes to compartmentalize

A primary objective of cell fractionation (including differential centrifugation) is to ____.

separate the major organelles

A cell with an extensive are of smooth endoplasmic reticulum is specialized to _____.

synthesize large quantities of lipids

In the NCBI database, the file designated "M10098.1" is the sequence for __________.

the Human 18S RNA gene

In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____.

the attachment of microtubules to kinetochores

Enzyme and product do not reform the ES complex b/c

the enzyme does not recognize the product

What is the equilibrium potential for a given ion in a given chemical environment?

the membrane voltage at which the net flux of the ion is 0

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

the organism ultimately must obtain all of the necessary energy for life from its environment

Ions diffuse across membranes through specific ion channels down ___

their electrochemical gradient

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because _____.

their normal products participate in repair of DNA damage

Which of the following is/are true of the signal recognition particle?

they are composed of both protein and RNA and they bind to a sequence of amino acids in proteins

Which of the following is/are true of enzymes?

they can convert endothermic reactions into an exothermic reaction

Which of the following statements is TRUE of membrane phospholipids?

they freely move laterally within the membrane

Why are fermentation reactions important for anaerobic cells?

they regenerate NAD+ so that glycolysis can continue to operate

In glycolysis, for each molecule of glucose oxidized to pyruvate _____.

two molecules of ATP are used and four molecules of ATP are produced

Which of the following is the correct form of the Michaelis-Menton equation?

v0 = Vmax[S] / Km + [S]

Which organelle often takes up much of the volume of a plant cell?

vacuole

Chemiosmotic theory was originally termed ______ by its proposer.

vectorial metabolism

In the Week 5 Action Set you plotted the equation y = (ax)/(x+k) where a and k are constants. What is the simplest form of the equation when x=k?

y = a/2