Cell bio exam 1 practice exam

Question 1

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also alter the geometry of molecules containing them because they

Answer 1

limit the rotation of the bonded atoms.

Question 2

Prions possess some properties that are unique to them relative to other proteins. Which one is a prion property?

Answer 2

ability to adopt an alternative structure that can convert normally structured proteins to adopt
that structure

Question 3

The Central Dogma provides a framework for thinking about how genetic information is copied and used to produce structural and catalytic components of the cell. From the choices below, select the order of biochemical processes that best correlates with the tenets of the central dogma.

Answer 3

replication, transcription, translation

Question 4

Which is the correct order of bond strength in water environments (>=greater)?

Answer 4

covalent > ionic > hydrogen > van der waals

Question 5

There are 90 naturally occurring elements on the earth, however living cells are 96% composed of four elements. The most abundant of these are carbon, hydrogen, oxygen and a..

Answer 5

Nitrogen

Question 6

An unsaturated phospholipid:

Answer 6

contains one or more C=C double bonds within its hydrocarbon tail

Question 7

Which of the following best matches the biological processes with the model organisms that are best suited or most specifically useful for their study, based on information from your textbook.

Answer 7

development (multicellular): D. melanogaster; photosynthesis: A. thaliana (Arabidopsis)

Question 8

Choose the answer that best fits: Cholesterol is an essential component of biological membranes. Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an __________ molecule, having both hydrophilic and hydrophobic regions.

Answer 8

amphipathic

Question 9

Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment. The specific subset of these reactions that break down nutrients in food can be described as

Answer 9

catabolic

Question 10

ΔG° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable?

Answer 10

glucose → CO2 + H2O ΔG° = −686 kcal/mole

Question 11

The amino acids shown to the right differ only in the structure of part of their side chains (circled). The amino acid shown on the far right contains what type of side chain?

Answer 11

acidic

Question 12

Energy cannot be created or destroyed, but it can be converted into other types of energy. Cells harvest some of the potential energy in the chemical bonds of foodstuffs to generate stored chemical energy in the form of activated carrier molecules, which are often employed to join two molecules together in __________ reactions.

Answer 12

condensation

Question 13

Complete the sentence with the best option provided below. The primary structure of a protein is:

Answer 13

amino acid sequence

Question 14

The potential energy stored in high-energy covalent bonds between monomers in polymers such as DNA or proteins is commonly harnessed when the bonds are split by the addition of __________ in a process called __________. (Hint: this is the reverse of the assembly reaction of the monomers

Answer 14

water; hydrolysis

Question 15

If proteins A and B have complementary surfaces, they may interact to form the dimeric complex AB. Which of the following is the correct way to calculate the equilibrium constant for the association between A and B?

Answer 15

K = [AB]/[A][B]

Question 16

Which of the following statements is TRUE?

Answer 16

Nonpolar amino acids tend to be found in the interior of proteins.

Question 17

Secondary structures within a protein are formed by

Answer 17

interactions between different parts of the polypeptide backbone creating a helices or b sheets

Question 18

The graph below illustrates the relationship between reaction rates and substrate concentration for an enzyme-catalyzed reaction. What does the
Km value correspond to?

Answer 18

the enzyme–substrate binding affinity

Question 19

Disulfide bonds represent covalent linkages between cysteine residues and are essential to the
organization of some proteins such as antibodies.

Answer 19

true

Question 20

The Ras protein is a GTPase that functions in many growth factor–signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gene for Ras are found in many cancers. Of the choices below, which alteration of Ras activity is most likely to contribute to
the uncontrolled growth of cancer cells?

Answer 20

a change that decreases the rate of hydrolysis of GTP by Ras

Question 21

In the p53 protein is given where there are at least 20 different locations on the protein that can be modified through such processes as phosphorylation, ubiquitylation, and acetylation to change the protein’s behavior, its activity or stability, its binding partners, or its location within a cell. This is a good example of:

Answer 21

combinatorial control of a protein

coordinated regulation of transcription due to multiple distinct modifications

Question 22

GTP-binding proteins typically have GTPase activity, and the hydrolysis of GTP transforms them to the “off” conformation.

Answer 22

true

Question 23

The terms “prokaryote” and “bacterium” are synonyms and interchangeable.

Answer 23

false

Question 24

Protein phosphorylation is a way to alter the conformation of an enzyme or protein and can serve either to activate the protein or inactivate its function.

Answer 24

true

Question 25

Which tetrapeptide sequence would you expect to possibly find as a part of a larger protein in which the sequence occurs on the interior of the globular structure of the protein?

Answer 25

alanine-glycine-leucine-alanine

Question 26

Which tetrapeptide sequence when found in a protein would you expect might represent the site of regulation of that protein’s activity state by protein kinases and phosphatases.

Answer 26

serine-threonine-tyrosine-alanine

Question 27

Eukaryotic cells can possess:

Answer 27

no nuclei
a single nucleus
multiple nuclei
nuclei that have different numbers of chromosomes

Question 28

As described at the end of Ch. 1, Hartwell, Nurse and Hunt won the Nobel prize
for their collective work on an important topic in the field of cell biology with Hartwell and Nurse employing genetic approaches in model organisms to study this topic. Which choice describes this area of study?

Answer 28

cell cycle control

Question 29

hydrophobic

Answer 29

is non polar and inside

Question 30

km

Answer 30

the enzyme–substrate binding affinity 

how easily enzymes bind with substrate

Question 31

Vmas

Answer 31

the maximum rate a reaction can go