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Module 5 Study Guide

Terms in this set (67)

Feedback Inhibition Differs from operon repression because feedback inhibition
Stops the action of preexisting enzymes
The 3' end of DNA
Refers to the end that has the hydroxyl group attached to the number 3 carbon on the ribose; forms a phosphodiester bond with the 5' phosphate group of the incoming nucleotide
The genetic code used during translation is based on a 3-nucleotide sequence found on the
Codons of mRNA molecules
Eukaryotic RNA processing
Introns are cut out before mRNA leaves the nucleus; Nucleotides may be added at both ends of RNA; A primary transcript is often much longer than the final RNA molecules that leaves the nucleus
Statements regarding the induction of the lac operon
A form if lactose serves as an inducer; the inducer acts by turning off the repressor; induction of the operon ceases when lactose is absent from the system
Catabolite repression by glucose is a phenomena seen in
The lactose operon
In DNA synthesis, the enzyme that erases the primer and fills the gaps with DNA is called
DNA polymerase I
In which of the following actions does RNA polymerase differ from DNA polymerase?
RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis
In operon systems, _________ binds to the promoter region
RNA polymerase
In transcription as the ribosome translocates along an mRNA molecule by one codon which
The tRNA that was in the A site moves into the P site
When glucose levels are high cAMP levels are ________ low: CAP _________ bind the CAP-binding site, and RNA polymerase ________ bind the lac promoter
Low, does not, does not
A eukaryotic gene that is 3,000 nucleotides long may use 900 nucleotides to make mRNA coding for a protein consisting of approximately 300 amino acids. This is the best explained by the fact that:
Introns are present in primary mRNA
Excess tryptophan turns off the trp operon
True
In the trp operon, tryptophan plus repressor
Binds the the operator and blocks transcription
The lac operon is induced by the __________ of lactose and the _________ of glucose
Presence; absence
Which is/ are repressible operons systems?
The tryptophan operon
An enzyme that makes the final covalent bonds between the nucleotide sequences of Ozaki fragments during DNA synthesis is
DNA Ligase
Whats true about protein synthesis in bacteria
Translation can begin while transcription is still in progress
In the lac operon, the lac genes are transcribed in when:
Lactose binds to the repressor protein and removes it from the operator
At the beginning of transcription, the enzyme responsible for transcription binds to a site on the DNA (in front if the gene) called the
Promoter
Genetic elements found in an operon
Operator, Structural genes, Promoter
A nucleotide is
A five carbon sugar, a phosphate group and a nitrogen-containing base
RNA polymerase does not..
Make molecules of RBA from an RNA template
Excess lactose turns OFF the lac operon
False
How is mRNA modified prior to translation? Is this in prokaryotes or eukaryotes?
This is in eukaryotes
5' cap, 3' poly A tail
introns removed, exons spliced together
Explain ribosomal translocation
Whatever is in the A site moves to the P site and then he E site
What is a point mutation? What other mutations are caused by these
change in a single base
missense: change of amino acid
nonsense: changed to stop codon
silent mutation: no change
Where does the central dogma take place in prokaryotes?
DNA Replication: Nucleoid
Transcription: Cytoplasm
Translation: Cytoplasm
Where does the central dogma take place in eukaryotes?
DNA Replication: Nucleus
Transcription: Nucleus
Translation: Cytoplasm > On the ribosome
The genetic code is ________
degenerate
What is the name of the RNA polymerase in prokaryotes and what is it made of?
RNA holoenzyme > made up of sigma subunit and core polymerase
What is chargaff's rule?
A=T & C=G
A+C = G+T
The carbons on the 5 carbon sugar of a nucleotide are read which way?
Counter clockwise
What is on each carbon of the sugar of a nucleotide?
1 ' - Base
2' - OH or H
3' - Hydroxyl Group
4' - Not important
5' - Phosphate Group
How was the structure of DNA found
Rosalind Franklin used X-ray diffraction to discover the DNA double helix
What did Watson and Clark
That the strands have to be anti-parallel for it to work
What is the central dogma?
DNA -> RNA -> Protein
What is mRNA used for
Translation
What is tRNA used for
Carry amino acids
What is rRNA used for
Part of the ribosome
What direction is the leading strand?
What direction is the lagging strand?
5' > 3'
3' > 5'
Why is replication semi discontinuous?
Only can synthesize DNA 5' > 3'
so there's a lagging strand since strands are antiparallel
What is the result of trying to replicate the lagging strand?
Osaki Fragments
What is a codon?
A codon is on mRNA
What is an anticodon?
Its on tRNA w/ amino acid
What is the most common and efficient level of control of gene expression?
Transcriptional: control RNA polymerase/ which genes get transcribed
What systems are indurable?
catabolic systems (lac operon)
What systems are repressible?
Anabolic systems (trp operon)
What are the functions of the parts of the holoenzyme?
Sigma subunit: identifies promoter sequence
core polymerase: transcribes mRNA
What is the hair pin loop, how is it formed?
The end of prokaryotic transcription;
Complementary bases fold on themselves and form a loop
What type of model is DNA Replication?
A semi-conservative model
What enzyme is responsible for DNA nucleotide synthesis in replication?
DNA polymerase III
What is the difference between DNA polymerase I and DNA polymerase III?
DNA polymerase I replaces RNA primers, DNA polymerase III does the main DNA synthesis
What end does translation begin?
5' end
What is a mutagen?
Any agent that causes DNA damage
Ex: UV Radiation, X-ray radiation
What are the two type of repair?
Exasion repair: general
photo repair: thymine dimers, plants
Name + structure of nucleic acid monomer
nucleotide: 5 carbon sugar, phosphate group, nitrogenous base
Why is the C-G bond more stable than the A-T bond?
C-G has 3 hydrogen bonds. making it more stable
In what direction does DNA polymerase read the template?
In what direction does it make the new strand?
reads 3' > 5'
makes 5' > 3'
In transcription, Which strand is coding which is template?
The one not being transcribed is coding the one that is is template
DNA polymerase III function
Replace primers
DNA Ligase function
make links b/w okasaki fragments
Primase function
Makes A primer for DNA
DNA Helicase function
Unwinds DNA
DNA Gyrase function
Reduces super-coiling strain
DNA polymerase I function
DNA synthesis
Single-stranded binding protein function
Holds Replication Fork in place
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