Unit 2 - DNA replication Flashcards
what are the purines?
2 carbon-nitrogen rings
adenine/ guanine
what are the pyrimidines?
1 ring
cytosine/ thymine/ uracil
what does each nucleotide contain?
- five carbon sugar
- nitrogenous base
- phosphate group
what are the four nucleotides found in DNA?
dAMP - deoxyadenosine monophosphate
dCMP - deoxycytidine
dGMP - deoxyguanosine
dTMP - deoxythymidine
what are the four nucleotides found in RNA?
AMP - adenosine monophosphate
CMP - cytidine
GMP - guanosine
UMP - uridine
what is the bond linking nucleotides between C3 and C5?
phosphodiester bonds
what are primers and what are they needed for?
short piece of nucleic acid base-paired template
starting point for DNA replication - requires 3’ - OH group
describe the DNA polymerase reaction
DNA partially unwound and RNA primers synthesised attach to the ends
DNA polymerase adds nucleotides to 3’ end
as the strand is further unwound the leading strand is synthesised continously but lagging strand synthesised as okazaki fragments
primers removed by nucleases and replaced with DNA
what is the role of telomerase in DNA replication?
extends the ends of chromosomes so prevents shortening of chromosomes
- found in germ-line cells
what attaches to the promoter region of gene?
RNA polymerase
how is gene expression controlled? - explain any components involved
- controlling availability of regulatory proteins (transcription factors) that bind to promoters&enhancers
(enhancers= DNA sequence in eukaryotes which varies in position and boosts transcription in nearby gene) - controlling strength of interaction between DNA & histones (euchromatin/ heterochromatin)
- splicing
what are the initiation and termination codons?
initiation: AUG
termination codons: UGA, UAG, UAA
What are ribosomes composed of and what are its three tRNA binding sites?
protein/ ribosomal RNA
EPA - exit site/ peptidyl site/ aminoacyl site
what are the three main repeated cycle within translation?
binding of aminoacyl-tRNA (requires GTP)
peptidyl-transferase reaction (formation of peptide bonds)
translocation (movement of ribosome one codon along mRNA) - also requires GTP
which antibiotics inhibit peptidyl transferase reaction and translocation?
erythromycin/ clarithromycin
chloramphenicol