Deck 1: Introduction to Biochemistry

Question 1

A phosphate ester contains a phosphate functional group.

Answer 1

True

Question 2

Which statement about cellulose is false?

A) It is the most abundant polysaccharide in nature.
B) Its monomers are joined by glycosidic bonds.
C) It is present in the stems of flowering plants.
D) The hydroxyl groups of neighboring cellulose molecules interact to form strong, insoluble fibers.
E) It is a branched polymer of glucose.

Answer 2

It is a branched polymer of glucose.

Question 3

Molecules from living cells cannot be synthesized outside of living cells.

Answer 3

False

Question 4

Functional groups describe one or more portions of organic compounds found in living cells.

Question 5

Fermentation in the absence of cells demonstrated that metabolic processes were chemical in nature.

Question 6

Which statement is true about a reaction with an equilibrium constant, K_eq, equal to 1000?

A) The forward rate constant is 1000 times greater than the reverse rate constant.
B) The forward rate constant is 3 times greater than reverse rate constant.
C) The forward rate constant is 1000 times smaller than the reverse rate constant.
D) The forward rate constant is 3 times smaller than the reverse rate constant.
E) There is not enough information given to compare the forward and reverse rate constants.

Question 7

Crick referred to the flow of information from nucleic acid to protein as the Central Dogma.

Question 8

Which cellular component carries out oxidation reactions, some of which produce hydrogen peroxide?

A) peroxisomes
B) mitochondria
C) chloroplasts
D) lysosomes
E) vacuoles

Question 9

Proteins in biological membranes may be

A) porous.
B) attached to the membrane surface.
C) span the membrane.
D) All of the above
E) B and C only

Question 10

The role of DNA as the genetic material was confirmed by transforming Streptococci in experiments performed several years after the famous Watson and Crick description of DNA structure.

Question 11

When K_eq of a reaction = 1, then

A) the forward reaction is faster than the reverse reaction.
B) the reverse reaction is faster than the forward reaction.
C) the forward and reverse reaction rate constants are equal.
D) more products are formed than reactants.
E) fewer products are formed than reactants.

Question 12

Bioinformatics has permitted rapid advances in our understanding of structural macromolecules from living cells.

Question 13

Enzymes are not as efficient as most catalysts used in organic chemistry, since they must function at body temperature.

Question 14

Enzymes are protein catalysts that form an intermediate with a substrate that fits into it.

Question 15

Which elements account for more than 97% of the weight of most organisms?

A) C, H, N, Mg, O, S
B) C, H, N, O, P, S
C) C, H, N
D) Fe, C, H, O, P
E) Ca²⁺, K⁺, Na⁺, Mg²⁺, Cl^-

Question 16

Why is it important that the enzymes in lysosomes are more active at acidic pH than at neutral pH?

A) Since lysosomes are primarily found in the stomach acid of mammals, their pH dependence allows for maximum efficiency for the digestion of foodstuffs.
B) It prevents their diffusion out of the lysosomes.
C) It maximizes the interaction with their substrates which are always bases.
D) It prevents them from accidentally degrading the macromolecules in the cytosol.
E) It allows for regulation of their uptake by the mitochondria.

Question 17

A spontaneous chemical reaction always has a change.

A) positive Gibbʹs free energy
B) negative Gibbʹs free energy
C) positive enthalpy
D) negative enthalpy
E) positive entropy

Question 18

The study of the energy changes during metabolic reactions is called .

A) bioinformatics
B) metabodynamics
C) thermometrics
D) bioenergetics
E) biological heat dynamics

Question 19

Prokaryotes are valuable tools for biochemists because

A) E. coli is well-studied and typical of prokaryotes.
B) they contain as many genes as eukaryotic cells.
C) many of their chromosomes are sequenced.
D) they are not very diverse organisms.
E) All of the above

Question 20

The modified lock-and-key theory of enzyme action proposed by Emil Fischer has been completely replaced by more modern ideas of catalysis.

Question 21

Lipids aggregate to form bilayers because some lipid molecules are hydrophobic and other lipid molecules are hydrophilic.

Question 22

A peptide bond is formed by the condensation of different functional groups from two amino acids.

Question 23

All cells have kept the same general patterns of metabolism, a very similar genetic code and the same monomers or residues.

Question 24

A phosphodiester linkage in DNA contains two phosphorous atoms.

Question 25

Lysozyme is an enzyme with a cleft or depression at its active site.

Question 26

ATP contains both phosphoester and phosphoanhydride linkages.

Question 27

Biochemical reactions are more likely to proceed if the reaction has an increase in enthalpy
(△H and a decrease in entropy △S).

Question 28

Sugars with six carbons are the only ones capable of forming a ring structure as shown in a Haworth projection.

Question 29

The only reason phages are not considered to be cells is because they do not contain a plasma membrane.

Question 30

The absolute molecular mass of macromolecules is given in daltons, where 1 dalton = 1 atomic mass unit.

Question 31

The Haworth projection of the ring form of a monosaccharide always shows a flat plane with one edge projecting out of the page using thicker lines).

Question 32

All prokaryotic cells are about 1/10 the size of an average eukaryotic cell or smaller.

Question 33

Biochemists describing the molecular weight of a protein really mean the atomic weight in grams.

Question 34

The tendency of a metabolic reaction to proceed is due to the free energy of both the reactants and products as well as the change in randomness of that reaction.

Question 35

Eukaryotes include plants, animals and bacteria.

Question 36

Thermodynamics and its laws are obeyed by living cells.

Question 37

The conformation of a protein enzyme determines whether it is functional or not.

Question 38

Removal of water from residues of a macromolecule results in the formation of that macromolecule.

Question 39

M_r is the mass of a molecule relative to 1/12 the mass of an atom of the most common isotope of carbon.

Question 40

Under most biological conditions, acid groups and amino groups are fully protonated.

Question 41

The diffusion of large molecules such as enzymes is significantly slowed by the presence of the cytoskeleton.

Question 42

In an animal cell, DNA can be found only in the nucleus.

Question 43

The endoplasmic reticulum is the major site of RNA synthesis and the site of assembly of ribosomes.

Question 44

Ribosomes on the surface of rough endoplasmic reticulum are the site of ATP synthesis.

Question 45

In eukaryotic cells lysosomes are specialized digestive vesicles with a highly acidic interior.

Question 46

The nuclear envelope is a membrane that surrounds the nucleus and is continuous with the endoplasmic reticulum.

Question 47

The process of cell division that occurs in the tissues is called mitosis.

Question 48

The chemical name for ATP is alanine triphosphate.

Question 49

The mitochondria and Golgi apparatus are two organelles which originated from bacteria and were incorporated into eukaryotic cells via symbiosis.

Question 50

Diffusion is an adequate means of distributing nutrients in prokaryotic cytoplasm because they have more surface area than volume compared to most eukaryotes.

Question 51

Absolute zero is equal to 0 °C.

Question 52

One Angstrom is equal to 1 × 10^-10 meters.

Question 53

The mitotic spindles are formed from microtubule proteins.

Question 54

Chloroplasts are organelles found in plants, algae and some protists and are the site of photosynthesis.

Question 55

Mitochondria are the main sites of energy transduction in aerobic eukaryotic cells.

Question 56

The Golgi apparatus consists of flattened, fluid-filled, membranous sacs and is responsible for chemical modification and sorting of some biomolecules.

Question 57

Photosynthesis involves capturing energy from light that is then used to drive the formation of carbohydrates from carbon dioxide and water.

Question 58

Eukaryotic cells are distinguished from prokaryotes by their usually larger size, a complex cytoskeleton and membrane-bounded organelles.

Question 59

The filament fibers in the cytoskeleton are composed primarily of carbohydrate molecules.

Question 60

Actin has been shown to be one of the most evolutionarily conserved proteins. It is present in all eukaryotic cells and frequently is the most abundant protein in the cell.