DNA replication Flashcards
what makes up a nucleotide
phosphate sugar and base
where are UTRs located
5’ ends and 3’ ends
where does splicing occur
nucleus
how is DNA condensed in prokaryotes
by a set of polyamines and proteins in back and forth loops
how is DNA condesned in eukarytes
into nucleosomes -> chromatin -> solenoids ->superosolenoids -> chromosomes
what makes up a nucleosome
200 BP and histones
how long is the average gene and what does it contian
27,000 BP long and contains 9 exons and a coding sequence of about 1340 BP
how big is the human genome
3.2 billion base pairs
what is the difference between siblings in genes
1.2 million BP
what is the difference between unrelated humans in genes
6 million BP
what does DNA polymerase do
catalyzes the stepwise addition of a deoxyribonucleotide triphosphate to the 3’ OH end of a polynucleotide chain
what is addition of bases driven by
free energy change caused by the release of pyrophosphate and its subsequent hydrolysis to molecules of inorganic phosphate
what is RNA primer sythesis
reactino catalyzed by DNA primase- the enzyme that synthesizes short RNA primers made on the lagging strand using DNA as a template
where do okazaki fragments occur
lagging strand
how does DNA primase start a new polynucleotide chain
joining 2 nucleoside triphophates together
how long is the RNA primer
10 nucleotides
what does DNA ligase do
seals okazaki fragments
what does the sliding clamp do
at replication fork the clamp loader remains close to the lagging strand polymerase ready to assemble a new clamp at the start of each okazaki fragment
what is werner syndrome and what does it affect
- premature aging disease
- mutation in RECL2 gene which encodes helicase
- cells divide more slowly or stop dividing earlier
