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