Clicker Review Flashcards
Let’s follow a triplet of DNA nucleotides.
The TEMPLATE strand of DNA: 3’ C T A 5’
What is the NON-TEMPLATE DNA sequence?
5’ G A T 3’
Let’s follow a triplet of DNA nucleotides.
The TEMPLATE strand of DNA: 3’ C T A 5’
What is the mRNA codon sequence?
5’ G A U 3’
Let’s follow a triplet of DNA nucleotides.
The TEMPLATE strand of DNA: 3’ C T A 5’
What is the ANTICODON sequence?
3’ C U A 5’
Let’s follow a single triplet of DNA nucleotides.
The TEMPLATE strand of DNA: 3’ C T A 5’
3’ C T A 5’ DNA Template
5’ G A T 3’DNA Non-template
5’ G A U 3’mRNA codon
3’ C U A 5’anticodon
The most important part of DNA’s structure, that allows it to easily make copies of itself is:
The base pair rules of A=T and C=G
Without Chargaff’s Rules, even with two strands, one strand of DNA as a template would not have any reliable guide to the order of bases on the other strand.
The accepted model of DNA replication used today is the:
Semi-conservative method
In this method, the new strands of DNA are each made of one strand of “old” DNA and one strand of “new” DNA nucleotides.
New DNA nucleotides are added to the _______ of the growing daughter strand.
3’ end
Therefore, the new strand grows in the 5’ to 3’ direction.
The role of single stranded binding proteins in DNA replication is to
Keep the 2 strands apart during DNA replication
The role of single stranded binding proteins in DNA replication is to
Add DNA nucleotides to the growing strand.
DNA polymerase
Untwist the DNA double helix and separate the strands.
Helicase
Keep the 2 strands apart during DNA replication
Single strand binding proteins
Keep the DNA strand from overwinding ahead of replication: Topoisomerase
Seal Okasaki fragments together: DNA Ligase
Other Enzyme Helpers
Nuclease: Cuts segments of DNA for repair
Primase: Makes RNA primer which begins DNA replication
Telomerase: Extends telomere segments in germ line cells to prevent chromosomes from shortening during DNA replication in gametes
The region of chromosomes where DNA is less tightly condensed so gene expression can take place is the __________.
Euchromatin
DNA in these regions is less tightly wound around the histone proteins. Heterochromatin is much more condensed and can be found in the telomere and centromere regions where little to no gene expression occurs.
Which type of RNA has an anticodon?
tRNA
The site on the ribosome that docks the tRNA that is empty and ready to go get a another amino acid is the ________.
E site
Which of the following is not DIRECTLY used during translation?
RNA polymerase
RNA polymerase plays its role during transcription of DNA nucleotides into RNA nucleotides to make mRNA.
True or False: Inducible operons use inducers and not repressors.
False
Inducible operons will use BOTH inducers and repressors. Repressors will block RNA polymerase from binding unless an inducer makes the repressor inactive. In the lac operon, the inducer allolactose binds with the repressor so that transcription can occur.
Which of the following in NOT a way eukaryotes control gene expression?
- Degradation of mRNA
- Chromatin modification
- RNA processing
- Operons
- Post translation protein modification
Operons
The operon model of gene expression control is in prokaryotes, not eukaryotes.
If there is no glucose and plenty of lactose in the environment, you would expect the lac operon to be
On and transcribing lacZ, lacY & lacA
E. coli would need the genes of the lac operon to be transcribed in order to import and break down lactose properly so we would expect the operon to be on if lactose is present (by way of allolactose acting as an inducer which blocks the repressor).
Which of the following genes codes for b-galactosidase, the enzyme that breaks down lactose into glucose and galactose?
lacZ: b-galactosidase
lacA: transacetylase
lacY permease
lacI: regulatory gene = repressor
Over an organism’s lifetime, is it possible for them to acquire traits that are then passed on to their offspring?
Yes! Sort of.
While the actual genes (DNA sequences) and what traits they encode are what is traditionally thought of as “inherited”, it turns out the control of those genes can be altered throughout an organism’s lifetime AND those control changes can be passed on to offspring.
An anabolic pathway is one that ______.
builds bigger molecules from smaller molecules = anabolic
If an operon is described as REPRESSIBLE, it is usually _______.
On
The operon genes are therefore making their gene products unless something makes the repressor active and shuts the operon off (represses).
Let’s say a mutation occurs in the regulatory gene lacI so that it can NOT make a functional repressor protein for the lac operon. What effect would you expect?
It won’t matter if lactose is present or not: The lac operon will be on all the time.
If the repressor is never made, it can therefore never block RNA polymerase from binding to the operator so the lac operon will stay on, lactose or not.
What is an operon?
A mechanism for coordinated control of several genes involved in a biochemical pathway
A mechanism for allowing gene expression to be controlled by environmental cues
The operon model is a method of gene expression control in _________.
prokaryotes only
Prokaryotes have the operon model of one operator controlling the expression of multiple genes. While eukaryotes do not have operons, they have many other mechanisms for gene expression control that prokaryotes do not such as alternative mRNA editing.
