Deck 1: The Foundations of Biochemistry

Question 1

Which is a list of organelles?

A)Mitochondria,chromatin,endoplasmic reticulum
B)Peroxisomes,lysosomes,plasma membrane
C)Proteasomes,peroxisomes,lysosomes
D)Mitochondria,endoplasmic reticulum,peroxisomes
E)All of the above

Answer 1

Mitochondria,endoplasmic reticulum,peroxisomes

Question 2

Which one of the following has the cellular components arranged in order of increasing size?

A)Amino acid < protein < mitochondrion < ribosome
B)Amino acid < protein < ribosome < mitochondrion
C)Amino acid < ribosome < protein < mitochondrion
D)Protein < amino acid < mitochondrion < ribosome
E)Protein < ribosome < mitochondrion < amino acid

Answer 2

Amino acid < protein < ribosome < mitochondrion

Question 3

The enzyme fumarase catalyzes the reversible hydration of fumaric acid to l-malate,but it will not catalyze the hydration of maleic acid,the cis isomer of fumaric acid.This is an example of:

A)biological activity.
B)chiral activity.
C)racemization.
D)stereoisomerization.
E)stereospecificity.

Answer 3

stereospecificity.

Question 4

If heat energy is absorbed by the system during a chemical reaction,the reaction is said to be:

A)at equilibrium.
B)endergonic.
C)endothermic.
D)exergonic.
E)exothermic.

Question 5

The catalog of all proteins functioning in a cell is the:

A)metabolome.
B)proteasome.
C)lysosome.
D)proteome.
E)genome.

Question 6

The dimensions of living cells are limited,on the lower end by the minimum number of biomolecules necessary for function,and on the upper end by the rate of diffusion of solutes such as oxygen.Except for highly elongated cells,they usually have lengths and diameters in the range of:

A)0)1 $\mu$ m to 10 $\mu$ m.
B)0)3 $\mu$ m to 30 $\mu$ m.
C)0)3 $\mu$ m to 100 $\mu$ m.
D)1 $\mu$ m to 100 $\mu$ m.
E)1 $\mu$ m to 300 $\mu$ m.

Question 7

In a bacterial cell,the DNA is in the:

A)cell envelope.
B)cell membrane.
C)nucleoid.
D)nucleus.
E)ribosomes.

Question 8

The macromolecules that serve in the storage and transmission of genetic information are:

A)carbohydrates.
B)lipids.
C)membranes.
D)nucleic acids.
E)proteins.

Question 9

Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it.This is an example of a(n):

A)dynamic steady state.
B)equilibrium state.
C)exergonic change.
D)free-energy change.
E)waste of energy.

Question 10

A major change occurring in the evolution of eukaryotes from prokaryotes was the development of:

A)DNA.
B)photosynthetic capability.
C)plasma membranes.
D)ribosomes.
E)the nucleus.

Question 11

Use the terms a)chemoautotrophs,b)chemoheterotrophs,c)photoautotrophs,and d)photoheterotrophs and identify the answer that correctly finishes the statement:
Carnivores are and herbivores are .

A)b,c
B)b,d
C)b,b
D)a,b
E)a,a

Question 12

The three-dimensional structure of macromolecules is formed and maintained primarily through noncovalent interactions.Which one of the following is not considered a noncovalent interaction?

A)Carbon-carbon bonds
B)Hydrogen bonds
C)Hydrophobic interactions
D)Ionic interactions
E)van der Waals interactions

Question 13

Which one of the following is not among the four most abundant elements in living organisms?

A)Carbon
B)Hydrogen
C)Nitrogen
D)Oxygen
E)Phosphorus

Question 14

The bacterium E.coli requires simple organic molecules for growth and energy-it is therefore a:

A)chemoautotroph.
B)chemoheterotroph.
C)lithotroph.
D)photoautotroph.
E)photoheterotroph.

Question 15

If the free energy change $\Delta$ G for a reaction is -46.11 kJ/mol,the reaction is:

A)at equilibrium.
B)endergonic.
C)endothermic.
D)exergonic.
E)exothermic.

Question 16

The four covalent bonds in methane (CH₄)are arranged around carbon to give which one of the following geometries?

A)Linear
B)Tetrahedral
C)Trigonal bipyramidal
D)Trigonal planar
E)Trigonal pyramidal

Question 17

Which group of single-celled microorganisms has many members found growing in extreme environments?

A)Bacteria
B)Archaea
C)Eukaryotes
D)Heterotrophs
E)None of the above

Question 18

Stereoisomers that are nonsuperimposable mirror images of each other are known as:

A)anomers.
B)cis-trans isomers.
C)diastereoisomers.
D)enantiomers.
E)geometric isomers.

Question 19

In eukaryotes,the nucleus is enclosed by a double membrane called the:

A)cell membrane.
B)nuclear envelope.
C)nucleolus.
D)nucleoplasm.
E)nucleosome.

Question 20

What functional groups are present on this molecule?

A)Ether and aldehyde
B)Hydroxyl and aldehyde
C)Hydroxyl and carboxylic acid
D)Hydroxyl and ester
E)Hydroxyl and ketone

Question 21

What is the difference,if any,between cytosol and cytoplasm?

Question 22

According to Oparin's theory for the origin of life,the prebiotic atmosphere:

A)already contained some primitive RNA molecules.
B)basically was very similar to the atmosphere of today.
C)contained many amino acids.
D)had an abundance of methane,ammonia,and water.
E)was rich in oxygen.

Question 23

All cells are surrounded by a plasma membrane composed of lipid and protein molecules.What is the function of the plasma membrane?

Question 24

When a region of DNA must be repaired by removing and replacing some of the nucleotides,what ensures that the new nucleotides are in the correct sequence?

A)DNA cannot be repaired and this explains why mutations occur.
B)Specific enzymes bind the correct nucleotides.
C)The new nucleotides base pair accurately with those on the complementary strand.
D)The repair enzyme recognizes the removed nucleotide and brings in an identical one to replace it.
E)The three-dimensional structure determines the order of nucleotides.

Question 25

E.coli is known as a gram-negative bacterial species.
(a)How is this determined?
(b)How do gram-negative bacteria differ structurally from gram-positive bacteria?

Question 26

Name two functions of (a)proteins, (b)nucleic acids, (c)polysaccharides, (d)lipids.

Question 27

What is the underlying,organizing biochemical principle that results in the chemical similarity of virtually all living things? Given this biochemical similarity,how is the structural and functional diversity of living things possible?

Question 28

Explain the difference,if any,between a proteome and a proteasome.

Question 29

Differentiate between configuration and conformation.

Question 30

Most cells of higher plants have a cell wall outside the plasma membrane.What is the function of the cell wall?

Question 31

Why is an asymmetric carbon atom called a chiral center?

Question 32

The three-dimensional structure of a protein is determined primarily by:

A)electrostatic guidance from nucleic acid structure.
B)how many amino acids are in the protein.
C)hydrophobic interaction with lipids that provide a folding framework.
D)modification during interactions with ribosomes.
E)the sequence of amino acids in the protein.

Question 33

Hereditary information (with the exception of some viruses)is preserved in:

A)deoxyribonucleic acid.
B)membrane structures.
C)nuclei.
D)polysaccharides.
E)ribonucleic acid.

Question 34

Enzymes are biological catalysts that enhance the rate of a reaction by:

A)decreasing the activation energy.
B)decreasing the amount of free energy released.
C)increasing the activation energy.
D)increasing the amount of free energy released.
E)increasing the energy of the transition state.

Question 35

What six characteristics distinguish living organisms from inanimate objects?

Question 36

Provide a brief explanation for the observation that macromolecules diffuse at a slower rate in the cytosol than they do in dilute solution.

Question 37

Energy requiring metabolic pathways that yield complex molecules from simpler precursors are:

A)amphibolic.
B)anabolic.
C)autotrophic.
D)catabolic.
E)heterotrophic.

Question 38

Draw the structures of the following functional groups in their un-ionized forms:
(a)hydroxyl.
(b)carboxyl.
(c)amino.
(d)phosphoryl.

Question 39

(a)List the types of noncovalent interactions that are important in providing stability to the three-dimensional structures of macromolecules.
(b)Why is it important that these interactions be noncovalent,rather than covalent,bonds?

Question 40

The major carrier of chemical energy in all cells is:

A)acetyl triphosphate.
B)adenosine monophosphate.
C)adenosine triphosphate.
D)cytosine tetraphosphate.
E)uridine diphosphate.

Question 41

How is the genetic information encoded in DNA and how is a new copy of DNA synthesized?

Question 42

What is meant by feedback inhibition and why is it important in a living organism?

Question 43

Explain why living organisms are able to produce particular chiral forms of different biomolceules while laboratory chemical synthesis usually produces a racemic mixture.

Question 44

Describe the "RNA world" hypothesis.

Question 45

Instant cold packs get cold when the contents,usually solid urea and liquid water,are mixed,producing an aqueous solution of urea.Although this process is clearly spontaneous,the products are colder than the reactants.Explain how this is possible in terms of the difference between $\Delta$ G and $\Delta$ H.

Question 46

(a)What is optical activity?
(b)How did Louis Pasteur arrive at an explanation for the phenomenon of optical activity?

Question 47

Hereditary transmission of genetic information can be viewed as a balance between stability and change.Explain.

Question 48

The free-energy change for the formation of a protein from the individual amino acids is positive and is thus an endergonic reaction.How,then,do cells accomplish this process?

Question 49

Describe Stanley Miller's experiment (1953)and its relevance.

Question 50

What is meant by endosymbiotic association? How can this concept explain the evolution of eukaryotic cells that are capable of carrying out photosynthesis and/or aerobic metabolism?

Question 51

A chemist working in a pharmaceutical lab synthesized a new drug as a racemic mixture.Why is it important that she separate the two enantiomers and test each for its biological activity?

Question 52

Proteins are constantly being synthesized in a living cell.Why doesn't the number of protein molecules become too great for the cell to contain,leading to cell destruction?

Question 53

Describe the relationship between a living organism and its surroundings in terms of both matter and energy.

Question 54

(a)On the reaction coordinate diagram shown below,label the transition state and the overall free-energy change ( $\Delta$ G)for the uncatalyzed reaction A $\rightarrow$ B.
(b)Is this an exergonic or endergonic reaction?
(c)Draw a second curve showing the energetics of the reaction if it were enzyme-catalyzed.

Question 55

Describe how the rise of O₂-producing bacteria might have led to the eventual predominance of aerobic organisms on earth.

Question 56

Discuss how a mutation in DNA could be harmful or beneficial to an organism.