Studied by 2 people
Who made the first model of DNA?
Watson and Crick
Who captured the first image of DNA
Rosalind Franklin
What are the building blocks of DNA?
phosphorus base, deoxyribose, and nitrogen bases
What are the 5 nitrogen bases?
Guanine, Thymine, Adenine, Cytosine, and Uracil
What base does Uracil substitute for in RNA?
Thymine
What are purines?
Large and have double rings
Guanine and Adenine
What are pyrimidines?
Small and have 1 ring
Cytosine, Thymine, and Uracil
What does the helicase enzyme do?
it “unzips” the double helix
What enzyme prevents supercooling?
Topoisomerase
What enzyme adds a RNA primer?
RNA primase
What adds DNA base pairs first?
DNA polymerase III in the 5’ to 3’ direction
What is the strand that can be synthesized continuously called?
Leading strand
What is the strand that has to be made in fragments called?
Lagging strand
What are the DNA fragments on the lagging strand called?
Okazaki fragments
What enzyme removes RNA primers?
Exonuclease
What replaces the RNA primers with DNA?
DNA polymerase I
What seals the gaps in-between the fragments of DNA?
DNA ligase
What are telomeres?
They are the ends of the chromosomes
Do telomeres code for genes?
no they don’t code for genes
What are the telomeres job?
They make sure genes don’t get deleted during replication.
What enzyme keeps telomeres long
Telomerase
Who discovered that somatic cells don’t have telomerase?
Elizabeth Blackburn
What is the effect of having no telomerase in somatic cells?
It causes us to age.
What is the process of proofreading?
It is when DNA polymerase checks each base for mistakes before adding the next base.
What is a mismatch repair?
It is when an enzyme recognizes a wrong base combination and corrects it.
What process cuts out and replaces the wrong base?
Nucleotide excision
What are thymine dimers and what are they a result of?
They are covalent bonds between two adjacent thymines
UV light and no repairs of DNA mutations
What are induced mutations
they are a result of external factors
what mutations are a result of natural body reactions
spontaneous mutations
what are silent mutations
They are mutations that aren’t expressed
What are mutations that affect a single base pair called?
Point mutations
What are transition mutation
it is when a purine (or pyrimidine) is replaced by another purine (or pyrimidine)
What mutations involve a purine replacing a pyrimidine or vice versa?
Transversion
what is the central dogma?
Transcription makes pre-mRNA, which makes mRNA, which makes amino acids, which makes proteins
What is a codon
it is a sequence of 3 base pairs that code for a single amino acid
Can multiple codons code for the same amino acid?
They can
it means genetic code is degenerate
How many codons are there
64
Out of the 64 codons how many are stop codons?
3
What is the transcription bubble
it is where the DNA unwinds
what are transcription factors
they help find the RNA polymerase that matches the promoter
Polymerase I
rRNA
Polymerase II
pre-mRNA
Polymerase III
5srRNA, tRNA, and other small RNA
Where does the RNA polymerase bind
TATA box
what positions the DNA in the polymerase active site
preinitiation complex
prokaryotic ribosomes
30s & 50s =70s
eukaryotic ribosomes
40s & 60s =80s
What refills 1 out of the 20 amino acids for tRNA
aminoacyl tRNA sythetase
what is gene expression
it is the process of turning genes on and off
what is the lac operon
it is a catabolic reaction and an inducible control
it is turned on by the presence of lactose
what is the trp operon
it is a repressible control
it is only turned of when there is too much trp in the cell
What proteins stop transcription
Repressor proteins
What proteins increase transcription rates
activator proteins
What does DNA wrap around
histone proteins
What does adding a methyl group do? What is it called?
Tightens DNA around the histone
methylation
What does adding an acetyl group do? What is this called?
it loosens the DNA around the histone
acetylation
What does DNA bending protein do
brings enhancers closer to the transcription factors by bending the DNA
What it is called when transcription factors bind to the promoter upstream of the gene?
Cis- acting element
