QUIZ 5 BIOCHEM Flashcards
3 stages of interphase
G1 (growth and metabolism)
S (DNA Replication)
G2 (Preparation for cell division)
Mitosis
short phase following interphase
DNA replication
the process of making a copy of DNA, chain will split and put matching nucleotides in
Epigenetics
as DNA is replicated, tags are copied too (ex. methyl coping enzymes place methyl tags on newly synthesized strand)
Bacterial Replication
circular DNA, DNA replication begins at the origin in both directions
Eukaryotic Replication
multiple origins, replication bubbles arise and synthesis proceeds along a fork in each direction
in order to replicate DNA …
the double helix must be unwound and opened
Helicase
will open the helix, untwisting the double helix
single strand binding proteins
keep DNA from re-annealing
Topoisomerase
enzyme that breaks and rejoins strands to relieve tension from twisting
what bonds will topoisomerase cut allowing for the helix to relax and spin freely?
phosphodiester bonds
DNA synthesis in what direction
5’ to 3’
bonds easy to break during DNA synthesis
the hydrogen bonds between nucleotides
Direction of reading DNA
3’ to 5’
exonuclease
cuts incorrect bases and replaces with the correct base
RNA primers
synthesized to start replication
primase
enzyme that adds the RNA bases in a 5’ - 3’ direction, coping from the template strand
leading strand
continuous synthesis of DNA replication, DNA polymerase synthesizing 5’ to 3’
lagging strand
opposite from the leading strand, made out of Okazaki fragments, discontinuous
Okazaki fragments
synthesized, RNA primers used to start each and is replaced by DNA
Ligase
enzyme that joins Okazaki fragments together
telomeres
caps at the end of each chromosome that ensure coding regions aren’t lost when chromosomes shorten during replication
telomerase
RNA-dependent DNA polymerase, lengthens the ends of chromosomes
reverse transcriptase
in telomerase, a single strand of RNA is reverse transcribed to single-stranded DNA and complementary DNA, RNA is removed and DNA is made double-stranded
mutations
a random error in gene replication that leads to a change, repair mechanisms in place
4 steps of DNA repair
- Damaged DNA recognized
- Enzymes break phosphodiester bond and remove damaged area
- DNA polymerase designed to repair, rebuilds the damaged area
- DNA ligase seals the nicks
Transcription
RNA synthesis from a DNA template
Polymerase
joins nucleotides to form a single stand
RNA Polymerase
able to initiate synthesis, primer not needed, lack of exonuclease
Changes in RNA bases
A will change places with T and U will replace T’s place
RNA polymerase in prokaryotes
One RNA transcribes all RNA in the cell
RNA polymerase in eukaryotes
an individual RNA polymerase for each rRNA, mRNA, tRNA
RNA polymerase I
transcribes rRNA
RNA polymerase II
transcribes mRNA
RNA polymerase III
transcribes tRNA
promoter region
site of attachment for the RNA polymerases and identify thee start point for transcription
operons
a number of genes all under the control of a single promoter in RNA
TATA box
many A and T at the start point of transcription, with only 2 bonds, easier to separate
polycistronic transcript
produced by an operon, translates several proteins
what cells contain introns and axons?
eukaryotic
Bacterial Transcription
- Initiation
- Elongation
- Termination
Sigma factor
controls the binding of RNA polymerase to the promoter, allows for bacterial transcription to occur
5’ capping
Addition of methyl guanosine to the 5’ end of a eukaryotic mRNA during processing.
what methylates guanosine? how is it regenerated?
S-adenosylmethionine (SAM) regenerated by folate and vitamin B12
Poly A polymerase
catalyzes the addition of adenines from ATP after transcription is finished
Poly (A) tails
post transcriptional modification, is a protein binding site that protects mRNA transcript from being degraded in the cytosol
removal of introns
a sequence signals the borders of the intron, spliceosomes attach and cut the introns out between the borders
a-Amanitin
poisonous mushroom, binds to RNA polymerase II, halting transcription and translation so the cells die