maintaining the genome Flashcards
which protein does DNA combined with and what does this form
histones
nucleosomes
what is the basic building block of DNA
nucleotide
what do nucleotides consist of
sugar
phosphate
base
what part of the nucleotide makes up the backbone of the double helix
sugar and phosphate
what is the sugar present in DNA? how many carbons?
2-deoxyribose, 5 carbons
4 bases? 2 different types?
cytosine and thymine - pyrimidines
adenine and guanine - purines
which bases pair
cytosine and guanine
thymine and adenine
what is the name for just the sugar and the base
nucleoside (not nucleotide)
which prime end is the start of the chain? which is the end?
5’ is start
3’ is end
what is DNA and its associated histones called
chromatin
how many histone proteins are present in a nucleosome? what are their names?
8 proteins in a nucleosome, 2 of each:
H2A
H2B
H3
H4
what extends out from a nucleosome and what is their significance
long amino acid tails from each histone.
subject to reactions that control chromatin structure
number of chromosomes in humans
23 pairs (22 pairs of autosomes, 1 pair of sex chromosomes)
where does DNA synthesis start
DNA origin
what seperates DNA strands
initiator proteins
what synthesizes new strands of DNA
DNA polymerase
2 different strands in DNA replication
leading strand and lagging strand
what occurs in the lagging strand
short fragments of DNA strands are created (okazaki fragments) and are joined by DNA ligase
what does DNA polymerase bind to to start a strand
primase (an RNA polymerase)
what is primase removed by
nuclease activity
what helps unwind the double helix
DNA helicase
DNA mismatch repair?
newly synthesised DNA removed, DNA polymerase bind to 3’ end of new strand and replaces section
what can cause DNA damage
replication errors
UV light
chemicals
radiation
cellular metabolism
differences between mitochondrial and nuclear DNA
circular not linear
inheritance is only maternal
