CELL BIO EXAM 1

As the two strands of DNA are unraveled, an enzyme relieves the strain on the two strands. The enzyme is

DNA gyrase

the oxygen utilized in cellular respiration finally shows up as

H2O

DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA?

It contains thymine

By definition, prokaryotic cells do not possess

a nucleus

Which of the following cells rely exclusively on glycolysis to supply them with ATP? a) anaerobically growing yeast b) aerobic bacteria c) skeletal muscle cells d) plant cells

a) anaerobically growing yeast

Which of the following spontaneous lesions in DNA occurs most frequently in a mammalian cell? a) depurination b) cytosine deamination c) guanine oxidation d) guanine alkylation e) depyrimidination

a) depurination

In a folded protein, most of the non polar amino acids are buried inside the protein fold, whereas the polar and charged side chains are exposed to the components in the cytosol. This fold is more stable because of the expulsion of non polar atoms from contact with water, favoring the interaction of non polar atoms with each other. What is this fourth type of non covalent interaction called?

a) hydrophobic interaction

When glucose is being used up and not replaced from food intake, the blood sugar level can be maintained by synthesizing it from smaller molecules such as pyruvate or lactate. This process is called gluconeogenesis. Which organ is principally responsible for supplying glucose to the rest of the body when glucose reserves are low? a) liver b) pancreas c) spleen d) gall bladder

a) liver

Glycolysis is an anaerobic process used to catabolize glucose. What does it mean for this process to be anaerobic?

a) no oxygen is required

biological membranes contain bilayers of which of the following lipids? a) phospholipids b) oils c) prostaglandins d) triglycerides e) sex hormones

a) phospholipids

Two molecules of CO2 are produced after the completion of a single citric acid reaction cycle. Where does the required oxygen come from?

acetyl CoA

Organisms are composed of molecules, which are collections of smaller units, called

atoms

In the final step of the citric acid cycle, oxaloacetate is regenerated through the oxidation of malate and coupled with the production of what other molecule? (a) FADH (b) NADH (c) GTP (d) CO2

b) NADH

Oxidation is the process by which oxygen atoms are added to a target molecule. Generally, the atom that is oxidized will experience which of the following with respect to the electrons in the outer shell?

b) a net loss

eukaryotic chromosomes are composed of a complex of 60% protein and 40% DNA. the name of this chemical complex is a) a histone complex b) chromatin c) a histamine complex d) a chromatid e) a centromere

b) chromatin

The second law of thermodynamics states that the disorder in any system is always increasing. In simple terms, you can think about dropping NaCl crystals into a glass of water. The solvation and diffusion of ions is favored because there is an increase in

b) entropy

Catalysts are molecules that lower the activation energy for a given reaction. Cells produce their own catalysts called

b) enzymes

Which of the following polymer of glucose is used as a vehicle to store energy reserves in animal cells? a) glucagons b) glycogen c) starch d) glycerol

b) glycogen

The phosphorylation of a protein is typically associated with a change in activity, the assembly of a protein complex, or the triggering of a downstream signaling cascade. The addition of ubiquitin, a small polypeptide, is another type of covalent modification that can affect the protein function. Ubiquitylation often results in ______

b) protein degradation

The final metabolite produced by glycolysis is _______.

b) pyruvate

DNA polymerases are processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the growing daughter strand. Which piece of the replication machinery accounts for this characteristic?

b) sliding clamp

which of the following is not a macromolecule? a) carbohydrates b) water c) nucleic acids d) proteins e) lipids

b) water

The potential energy stored in high-energy bonds is commonly harnessed when the bonds are split by the addition of _______ in a process called ______

b) water, hydrolysis

the genetic material of which kind of cells is included in a single, circular molecule of DNA devoid of any histone proteins?

bacteria

Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input)? (a) 6 ATP, 2 NADH (b) 4 ATP, 4 NADH (c) 2 ATP, 2 NADH (d) 4 ATP, 2 NADH

c) 2 ATP, 2 NADH

Which of the following statements is false? a) ATP contains high-energy phosphoanhydride bonds. b) ATP is sometimes called the "universal currency" in the energy economy of cells. c) ATP can be incorporated into DNA. d) ATP can be hydrolyzed to release energy to power hundreds of reactions in cells. e) ATP comprises a sugar, phosphate groups, and a nitrogenous base.

c) ATP can be incorporated into DNA.

Which of the following steps or processes in aerobic respiration include the production of carbon dioxide? a) breakdown of glycogen b) glycolysis c) conversion of pyruvate to acetyl CoA d) oxidative phosphorylation

c) conversion of pyruvate to acetyl CoA

DNA replication is considered semiconservative because __________.

c) each daughter DNA molecule consists of one strand from the parent DNA molecule and new strand

In anaerobic conditions, skeletal muscle produces _____________. a) lactate and CO2 b) ethanol and CO2 c) lactate only d) ethanol only

c) lactate only

In addition to the repair of DNA double-strand breaks, homologous recombination is a mechanism for generating genetic diversity by swapping segments of parental chromosomes. During which process does swapping occur? (a) DNA replication (b) DNA repair (c) meiosis (d) transposition

c) meiosis

Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by __________________.

c) using the energy of ATP hydrolysis to move nucleosomes

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit?

cell

When 2 atoms share a pair of electrons, the bonding is referred to as

covalent

Which of the following sequences can fully base-pair with itself? a) 5'-AAGCCGAA-3' b) 5'-AAGCCGTT-3' c) 5'-AAGCGCAA-3' d) 5'-AAGCGCTT-3'

d) 5'-AAGCGCTT-3'

The octameric histone core is composed of four different histone proteins, assembled in a stepwise manner. Once the core octamer has been formed, DNA wraps around it to form a nucleosome core particle. Which of the following histone proteins does not form part of the octameric core? a) H4 b) H2A c) H3 d) H1

d) H1

an electron carrier that is used in harvesting energy from glucose molecules in a series of gradual steps in the cytoplasm is a) pyruvate b) cyclic AMP c) ATP d) NAD+ e) NADH

d) NAD+

Protein structures have several different levels of organization. The primary structure of a protein is its amino acid sequence. The secondary and tertiary structures are more complicated. Consider the definitions below and select the one that best fits the term "protein domain." a) a small cluster of alpha helices and β sheets b) the tertiary structure of a substrate-binding pocket c) a complex of more than one polypeptide chain d) a protein segment that folds independently

d) a protein segment that folds independently

Which of the following statements about amino acids is true? a) 22 amino acids are commonly found in proteins b) most of the amino acids used in protein biosynthesis have charged side chains. c) amino acids are often linked together to form branched polymers. d) all amino acids contain an NH2 and a COOH group.

d) all amino acids contain an NH2 and a COOH group

Electron transport is coupled to ATP synthesis in mitochondria, in chloroplasts, and in the thermophilic bacterium Methanococcus. Which of the following is likely to affect the coupling of electron transport to ATP synthesis in all of these systems? a) a potent inhibitor of cytochrome oxidase b) the removal of oxygen c) the absence of light d) an ADP analogue that inhibits ATP synthase

d) an ADP analogue that inhibits ATP synthase

In oxidative respiration, energy is harvested from glucose molecules in a sequence of four major pathways. Which one of the following is not one of these four pathways? A. Krebs cycle B. glycolysis C. electron transfer through the transport chain D. beta oxidation E. pyruvate oxidation

d) beta oxidation

The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of

d) chemical bonds

The complete set of information found in a given organism's DNA is called its ______

d) genome

Which of the following repair pathways can accurately repair a double-strand break? a) base excision repair b) nucleotide excision repair c) direct chemical reversal d) homologous recombination e) non homologous end joining

d) homologous recombination (but e also correct :'))

Both DNA and RNA are synthesized by covalently linking a nucleotide triphosphate to the previous nucleotide, constantly adding to a growing chain. In the case of DNA, the new strand becomes part of a stable helix. The two strands are complementary in sequence and antiparallel in directionality. What is the principal force that holds these two strands together?

d) hydrogen bonds

Although all protein structures are unique, there are common structural building blocks that are referred to as regular secondary structures. Some proteins have α helices, some have β sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements?

d) hydrogen bonds along the protein backbone

Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP? a) the digestion of starch to glucose b) glycolysis c) the citric acid cycle d) oxidative phosphorylation

d) oxidative phosphorylation

DNA glycosylases constitute an enzyme family found in all three domains of life. They can a) add sugar moieties to DNA b) remove sugar moieties from DNA c) add a purine or pyrimidine base to DNA d) remove a purine or pyrimidine base from DNA e) remove a nucleotide from DNA

d) remove a purine or pyrimidine base from DNA

The two copies of each chromosome in body cells are called a) chromatids b) homologous chromosomes c) sister chromosomes d) daughter chromosomes e) genes

d) sister chromosomes

Which of the following chemical groups is not used to construct a DNA molecule? a) five-carbon sugar b) phosphate c) nitrogen-containing base d) six-carbon sugar

d) six-carbon sugar

In a DNA double helix, ______ a) the 2 DNA strands are identical b) purines pair with purines c) thymine pairs with cytosine d) the 2 DNA strands run antiparallel

d) the 2 DNA strands run antiparallel

reactions that occur spontaneously and release free energy are called

exergonic reactions

Lipids are the only class of macromolecules that contain

fatty acids

As energy is being reconverted through the many forms, it is continuously lost as

heat

macromolecules are disassembled in

hydrolysis reactions

when atoms gain or lose electrons, they become negatively or positively charged. they are known as

ions

elements that have atoms with the same atomic numbers but different number of neutrons are called

isotopes

membrane-bound organelles that contain powerful enzymes found in cells are known as

lysosomes

nucleolus of the nucleus is the site of

ribosome assembly

Some ribosomes are embedded into

rough endoplasmic reticulum

The method of DNA replication, where each original strand is used as a template to build a new strand, is called the

semiconservative method

Enzymes have specific ________ with which they interact.

substrates

Describe DNA replication in the bacterial system.

DNA replication in a bacterial system is a simple process. Bacteria has a single stranded circular DNA. DNA replication begins with the recognition of the single origin of replication. Specialized initiator proteins recognize the site and form ORC (origin recognition complex). At the origin, DNA primate comes into action and attaches to the strand and synthesizes RNA primer. RNA primer is required to start the process and make the 3' end available for DNA polymerase to bind. DNA polymerase uses the information from the template strand and accordingly adds the nucleotides to form the new strand. The loop of template DNA had opened to a linear strand for the process, after the newly synthesized strand is all ready to detach from the template strand, DNA polymerase detaches and leaves both the strands free.

The nitrogen base not found in DNA is called

Uracil

Which of the following organelles has both an outer and an inner membrane?

mitochondrion

the atomic number of an element is equal to the number of

protons only