Cell Biology Exam 2
Each chromosome is a single molecule of 1)______ whose extraordinarily long length is most highly compacted during 2)_________. This is accomplished by the DNA binding to 3)_______ that package the DNA. 4)________ are the basic unit structure of eukaryotic chromatin. Genes that are being transcribed are packaged in a 5)_______ condensed type of chromatin.
1)DNA 2)Mitosis 3)Histones 4)Nucleosomes 5)Less
How many nucleotides are necessary to specify a single amino acid?
3
What is the total number of chromosomes found in each of the somatic cells in your body?
46
Which of the following molecules of RNA would you predict to be the most likely to fold into a specific structure as a result of intramolecular base pairing?
5'-CCCUAAAAAAAAAAAAUUUUUUUUUUUUAGGG-3'
When a gene regulatory protein binds to DNA, its most important interaction occurs with which parts of the DNA?
Base pairs
Why do two complementary strands of DNA hybridize?
Base-pairing
__________ puts a short strip of strip of RNA to initiate DNA replication.
DNA polymerase.
In the 1940's, proteins were thought to be the most likely candidate for genetic material. What is the primary reason that DNA was not the prime candidate?
DNA was found to contain only four chemical building blocks.
Which of the following questions would not be answered by using karyotyping?
Do any chromosomes contain point mutations?
The MyoD transcriptional regulator induces transcription of genes that produce muscle-specific proteins. Expression of MyoD in nonmuscle cell type A causes cells to produce proteins only seen in muscles. However, MyoD does not induce expression of muscle specific genes in nonmuscle cell type B. Which of the following is the best explanation of why MyoD causes cell type A to produce muscle specific proteins, but not cell type B?
During their developmental history, cell A has accumulated some transcriptional regulators in common with differentiations muscle cells.
Eukaryotic gene activation proteins stimulate transcription initiation by recruiting a DNA polymerase to the promoter. T/F
False
Stop codons are recognized by one tRNA. T/F
False
Feedback inhibition is defined as a mechanism of down-regulating enzyme activity by the accumulation of a product earlier in the pathway. T/F
False.
Which statement is true about the tight association of histones and DNA?
Histones proteins have a high proportion of positively charged amino acids, which attract the negatively charged phosphate group on DNA.
What is the correct of order of techniques to use to identify an unknown protein from an extract?
IEF, SDS-PAGE, mass spectroscopy
A pregnant mouse was exposed to high levels of chemicals. The mice in the litter are deformed, when interbred, the offspring are normal. Explain.
In deformed mice, somatic cells were mutated.
Separates proteins based on the pH at which the protein has no charge
Isoelectric focusing
Which of the following is false concerning the N-terminus "tail" of histones?
It binds to DNA in a sequence specific manner.
How does an allosteric inhibitor affect the activity of an enzyme?
It binds to a second site, causing a conformational change in the enzyme that makes the active site less able to bind the substrate.
Adds phosphate groups to molecules
Kinase
Joins two ends of DNA together
Ligase
__________ seals a nick in the newly replicated strand.
Ligase
The classic beads on a string structure is the most decondensed chromatin structure possible. Which chromatin components are not retained when this structure is generated?
Linker histones
Which amino acid would you expect a tRNA with anticodon 5'-CUU-3' to carry?
Lysine
In eukaryotes, the initiator tRNA always carries which amino acid?
Methionine
What are the first three amino acids of protein encoded by mRNA?
Methionine, Serine, Alanine
Hydrolyzes bonds between nucleotides
Nuclease
Transcription is similar to DNA replication in that:
Nucleotide polymerization occurs in the 5'-to-3' direction.
Which of these is false of transcription?
Only one strand of a DNA helix per chromosome serves as a template
Removes a phosphate group from a molecule
Phosphatase
Catalyzes the synthesis of DNA
Polymerase
RNA processing does not include:
Post-translation modification
Initiation site for transcription
Promoter
Which of the following is not the general mechanism that cells use to maintain stable patterns of gene expression as cells divide?
Proper segregation of housekeeper proteins when cells divide.
Introns are removed by
RNA splicing in the nucleus
Replication origins consist of a small stretch of DNA that is relatively easy to open. Which of the following is true?
Replication origins are rich in A and T nucleotides.
Separates proteins based on their molecular weight
SDS-Polyacrylamide gel electrophoresis
What is false about codons in mRNA?
Some codons code for more than one amino acid
Which of the following correctly explains the meaning for DNA replication to bidirectional?
The replication forks formed at any given origin move in opposite directions.
Which of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon?
The transcription of a eukaryotic gene can be influenced by proteins that brin far from the promoter.
The modular nature of the Eve gene's regulatory region means that:
There are seven regulatory elements and each element is sufficient for driving expression in a single strip.
Which statement is false about replication?
There is only one DNA polymerase
Which of the following is false about differences between liver cells and kidney cells in the same organism?
They contain different genes.
Gene expression includes
Transcription and translation
Some antibiotics disrupt bacterial, but not eukaryotic, protein synthesis. T/F
True
Some genes do not encode proteins, but instead encode functional RNA. T/F
True
The effect of a single gene regulatory protein can be decisive in switching any particular gene on or off. T/F
True
In RNA, which base pairs with the base A?
U
Proteasomes act primarily on proteins that have been marked for destruction by the covalent attachment of which small protein?
Ubiquitin
Although chromatin structure is very compact, DNA-binding proteins and protein complexes must be able to gain access to DNA. Chromatin-remodeling complexes provide this access by:
Using the energy of ATP hydrolysis to move nucleosomes.
Reveals proteins 3D structure
X-ray crystallography
Amino acids are attached to their tRNA molecules by:
aminoacyl-tRNA synthetase
Which of the following about iPS cells is false?
iPS cells created from mouse cells differentiate into almost any human cell type.
DNA synthesis proceeds:
in the 5' to the 3' direction
What part of the DNA replication process would be directly affected if a cell lacked primase?
initiation of DNA synthesis
Two types of noncoding regulatory RNAs are:
small interfering RNAs and microRNAs
Which of the following pairs of codons might you expect to be read by the same tRNA as a result of a wobble?
CAC and CAU
The ribosome is important for catalyzing the formation of peptide bonds. Which of the following statements is true?
Catalytic site for peptide bond formation is formed primarily from an rRNA.
Which of the following is not a mechanism to maintain cell memory?
Cell division
The complex of DNA and protein in chromosomes is called
Chromatin
Repetitive DNA at the ends of chromosomes are called:
Telomeres
The process of DNA replication requires each of the parental DNA strands used as a _____ to produce a duplicate of the opposing strand.
Template
Copying errors not caught by replication machinery can be corrected by:
The DNA Mismatch Repair System
Which part of a protein is synthesized by a ribosome first?
The N-terminus
The assembly of general transcription factors to a eukaryotic promoter begins at what site in a promoter?
The TATA box
How does phosphorylation control protein activity?
The addition of a phosphate group can induce major conformational changes in a protein.
You are a virologist interested in studying the evolution of viral genomes. You isolate a virus whose genome is 25% A, 55% G, 20%, and 10% T. You report that you have isolated a virus with a single stranded DNA genome. Conclusion?
The double stranded DNA has equal amounts of A and T.
Which is not an example of epigenetic inheritance?
The inheritance of a single nucleotide mutation in a gene.
Which of the following is false regarding the replication of telomeric sequences?
The leading strand
What is the fate of mRNA targeted by microRNA based on their complementary nucleotide sequences?
The mRNA will be destroyed by a nuclease
Alternative splicing allows:
one gene to code for multiple proteins
