Biology Exam 2
a substrate
"Induced fit" refers to the fact that an enzyme typically changes its shape when ___ binds to it.
the activation energy barrier for this reaction cannot be surmounted
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because...
an accumulation of B and no production of C
A---> B In the metabolic pathway indicated above, a mutation results in a defective enzyme B. Which of the following would be a consequence of that mutation?
a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive.
Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?
add more substrate
Consider a situation in which an enzyme is operating at optimum temperature and pH, and has not been saturated with substrate. What is your best option for increasing the rate of the reaction?
The lagging strands contain more short DNA segments than the leading strand, and these short segments are joined together by DNA ligase.
During DNA replication, DNA ligase is most active on the lagging strand. This is because:
lagging, opposite, discontinuous
During DNA replication, the ___ strand is assembled in the ____ direction that the DNA double helix unwinds and is produced by____ replication.
5'-3', N-C
During the process of translation, mRNA is read in the ____ direction and a polypeptide is built in the ____ direction.
gaps left at the 5' end of the lagging strand because of the need for a 3' onto which nucleotides can attach.
Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?
packed nucleosomes (30 nm fiber)
Histone H1 interacts with linker DNA to form the...
cells use catabolic pathways to provide the energy to make ATP.
How do cells typically get the ATP that they need?
Bacteria were centrifuged to form the pellet, and they had incorporated radioactive DNA.
In the Hershey and Chase experiment, the pellet was radioactive after bacteria had been infected with 32P-labeled viruses and centrifuged. Why?
(Only A and C are correct) A. proteins have a greater variety of 3D forms than does DNA. C. proteins are made of 20 different amino acids while DNA is made of only 4 different nucleotides.
In the early 1900s biologists knew the nucleus contained DNA and proteins. The prevailing opinion. then was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. This is because...
The various domains of the polypeptide product
In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?
As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
E
Meselson and Stahl found evidence supporting the theory that DNA replication is semiconservative when they grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure above matches the results that they found after two rounds of DNA replication in the presence of N14?
cytoplasm, cytoplasm
Prokaryotes perform transcription in the ____ and translation in the ____ .
3' to 5', 3'
RNA polymerase moves along the template strand of DNA in the ____ direction of the template strand, and adds nucleotides to the ___ end of the growing transcript.
net change in free energy
Refer to figure 06-2. The line on the graph labeled C represents the...
DNA ligase
Refer to the representation of DNA replication in Figure 16-1 above. The structure labeled "A" is....
DNA polymerase
Refer to the representation of DNA replication in Figure 16-1 above. The structure labeled "B" is....
single-strand DNA binding protein
Refer to the representation of DNA replication in Figure 16-1 above. The structure labeled "D" is....
tyrosine
See the genetic code table and the statement below it. The second codon (counting the start codon as the first codon) directs incorporation of which amino acid in the polypeptide?
valine
See the genetic code table and the statement below it. The third codon (counting the start codon as the first codon) directs incorporation of which amino acid in the polypeptide?
36,14
The DNA of an organism is studied and found to contain 36% cytosine. This organism should have ___% guanine and ____% adenine in its DNA.
a competitive inhibitor
The conversion of citrate to isocitrate is catalyzed by a specific enzyme. When oxaloacetate is introduced to a solution containing the enzyme and a saturating concentration of citrate the rate of the reaction decreases. Adding more citrate can mostly overcome the effect of oxaloacetate on the reaction rate. Further studies reveal that oxaloacetate binds to the enzyme reversibly, allowing the enzyme to be fully functional if oxaloacetate is removed from the solution. In this situation oxaloacetate is acting as...
nucleosomes, DNA
The electron micrograph above shows chromatin organized like "beads on a string." At this level of DNA compaction the "beads" are ____ and the "string" is ____.
NADPH, NADP+
The molecule ___ is reduced relative to ___.
two of the above
The polypeptide SJK has 68 amino acids. The mutated version of SJK polypeptide only has the first 32 amino acids. What kind of mutation could have caused this?
an aminoacyl-tRNA synthase
The process of adding the correct amino acid onto a tRNA molecule is catalyzed by ____.
DNA, an RNA strand
The process of transcription refers to the direct use of information encoded in ____ to make ___.
the rules for base pairing between that third base of a codon and tRNA are flexible
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that...
rRNA
This type of RNA forms the main structural and catalytic elements of ribosomes...
A; termination factor
Translation ends when a stop codon is at the ___ site, allowing a/an ___ to enter there and then cause the translation machinery to fall apart and release the new polypeptide.
a cofactor
When Zn+2 is introduced to a solution containing a specific enzyme the rate of the reaction catalyzed by that enzyme dramatically increases. Further studies reveal that the enzyme does not function as a catalyst at all if Zn+2 is absent, and that Zn+2 associates with the enzyme in the active site. In this situation Zn+2 is acting as...
no energy is conversion is 100% efficient
When living systems couple exergonic with endergonic reactions, the overall reaction has a net exergonic nature because...
nucleosome, 30-nm chromatin fiber, looped domain
Which of the following represents the order of increasingly higher levels of organization of chromatin?
an allosteric inhibitor
a series of enzymes catalyze the reaction X->Y->Z->A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. In this scenario, substance A functions as...
lyase
an enzyme that catalyzes the cleavage of a bond by means other than hydrolysis and oxidation would be considered a/an:
an ATP concentration typically around 10 times greater than their ADP concentration.
cells maintain...
alternative splicing
human cells produce perhaps as many as 100,000 different proteins, and yet the human genome has only 25,000 genes. This is best explained by...
differences in gene expression
muscle cells and nerve cells in one species of animal owe their differences in the structure to...
generation of a poly-A tail.
stopping transcription in eukaryotes requires:
required for binding to a ribosome in eukaryotes
the cap on an mRNA is...
DNA á RNA á protein
the central dogma describes the flow of information of gene expression as ...
active site
the site where substrate(s) bind to an enzyme is called a/an...
transcription factors to help it bind to a promoter
to start transcription in eukaryotic cells, RNA polymerase needs...
it introduces a stop codon into the mRNA.
what is the effect of a nonsense mutation in a gene?
primase
which of the following act in DNA replication to begin new strands?
providing a net input of energy to the reactants.
which of the following is NOT considered one of the primary ways that enzymes reduce activation energy requirements?
3' - CCATGA - 5'
which of the following nucleotide sequences represents the complementary sequence that would bind to the DNA strand 3' - TCATGG - 5'?
Endergonic reactions are not spontaneous and have a net requirement for energy, while exergonic reactions are spontaneous and have a net release of energy.
which statement below is true?
catabolism
which term most precisely describes the cellular processes that break down larger molecules into smaller molecules?
