BIO 102 Test 1
The LAC operon of E.Coli consists of
1. A segment of DNA 2. A promoter 3. An operator 4. Three structural genes
When can gene expression be regulated?
1. Before transcription 2. During transcription and before translation 3. During translation 4. After translation
A prokaryotic cell can control the amount of enzymes it produces by
1. Blocking transcription 2. Hydrolyzing the mRNA after its made 3. Preventing translation of mRNA 4. Hydrolyzing the protein after translation
The genetic information of viruses can be
1. DNA 2. RNA 3. Single Stranded 2.Double Stranded
Alternative splicing helps to explain
1. The great variety in proteins 2. The differences in complexity among organisms 3. Why there are more mRNAs than human genes 4. The small number of genes in the human genome
Prokaryotes and Eukaryotes differ in transcription in that
1. There are 3 RNA polymerase in eukaryotes 2. Initiation of transcription is simpler in prokaryotes 3. Structural genes for a pathway are more likely to be clustered in operons in prokaryotes 4. Eukaryotic promoters may bind to several transcription factors
A point mutation is
A change in a single nucleotide of DNA
The type of mutation that stops translation of a protein results in a shortened protein because translation does not proceed beyond the mutation. This type of point mutation is
A nonsense mutation
An Operon is a what?
A promoter, operator, and a group of linked structural genes
Which of the following is a transcription factor?
A regulatory protein
Viruses are
Acellular
Which of the following mechanisms of post transcriptional regulation of gene expression can produce several different proteins from a single gene ?
Alternative splicing
The Anticodon is
Always present on a tRNA and is located in the middle
Mutations
Can arise from errors in DNA replication
Epigenetic changes
Can involve DNA methylation
The CRP-cAMP complex binds to the ____ of the operon
Close to the RNA polymerase binding site
A promoter is the region of ?
DNA that binds RNA polymerase
The Central dogma of molecular biology states that ________ is transcribed into ______ is translated into _______
DNA: RNA; Protein
In Eukaryotes, a DNA sequence, which can be distant from the gene, stimulates transcription when bound by an activator protein. This sequence is called a what?
Enhancer
Research on E.Coli indicates that
Glucose is the preferred energy source
Mutations are
Heritable changes in the nucleotide sequence of DNA that are passed on from one organism to another
How are inducible and repressible systems similar?
In both systems, the regulator molecules function by binding to the operator
When the operator is unbound by the repressor by its biding to the inducer, the binding of the CRP-cAMP complex _____ the binding of RNA polymerase at the promoter
Increases
In DNA, 5-methylcytosine
Is related to transcriptional silencing of genes
What effect does the presence of ample glucose have on the amount of lac operon transcription ?
It decreases the rate of transcription
In sickle-cell disease, one amino acid is substituted for another. This type of mutation is referred to as a _______ mutation
Missense
DNA is _____ charged due to the presence of a ______ group
Negatively; phosphate
What is the name of the type of mutation that results in a stop codon
Nonsense mutation
Bacteriophages are composed of what?
Nucleic acids and proteins
DNA is wound around histones to form structures that block both the invitation and the elongation steps of transcription. These structures are
Nucleosomes
The region of DNA in prokaryotes to which RNA polymerase binds to most tightly is the
Promoter
The genes that encode repressor proteins are
Regulatory genes
What structure of molecules brings tRNA and mRNA together?
Ribosomes
The most efficient means of regulating protein synthesis is by
Selective blocking of transcription
When an enhancer (a DNA consensus sequence) is bound, it
Stimulates transcription of a specific gene
The lytic life cycle of a phages results in
The bursting of a bacterium by a bacteriophage
In gel electrophoresis of DNA fragments
The fragments are separated on the basis of their sizes due to their differential ability to sieve through the pores of the gel
Which of the following statements about the lytic cycle is true
The host cell lysis
Ubiquitin forms a complex with proteins and then binds with ______, forming a sort of "molecular chamber of doom," where proteins are digested into small peptides and amino acids
The proteasome
A mutation of a sigma factor in a bacterium would most likely affect what?
The rate at which transcription is initiated
What happens during lysogengy?
The viral genome is integrated into the host's genome creating a prophage
Which of the following is the truth of both positive and negative gene regulation?
They involve regulatory proteins binding to DNA
RNA polymerase II by itself cannot bind to the chromosome and initiate transcription. It can bind to the chromosome and initiate transcription. It can bind and act only after regulator proteins called _______ factors have been assembled
Transcription
The process by which some phages may transfer DNA fragments from on bacterium to another is called what?
Transduction
Exons are
Translated
Why are most genetic disease rare?
Two parents probably do not carry the same recessive alleles
Damage to DNA can be caused by _________ absorbed by the thymine in DNA, causing interpose covalent bonds
Ultraviolet radiation in sunlight
Frame-shift mutations occur
With all insertions and deletions whose sizes are not multiples of three nucleotides
Nucleosomes disaggregate to allow transcription and then reaggregate
by the acetylation and deacetylation
To be activated, the CRP, an allosteric protein must first bind to what?
cAMP
The expression of the LAC structural gene is ____ when lactose is absent from the culture medium and is_____ when lactose is added because lactose binds to the ____ and inactivates it
low; high; lac repressor
Transcription factors are
proteins that bind to the DNA promoter sequence
The promoter in the LAC operon is
the region that binds to RNA polymerase
