Flashcards in DNA replication, transcription, translation Deck (106)
DNA: sugar phosphate backbone and bases
Bond bw. bases
Hydrogen bonds (2 bw. A&T, 3 bw. G&C)
End of the strand
-3´end of the strand: free 3-OH-gr. of D-ribose
-5´end of the strand: free 5-P-gr.
Bond be. sugar and P
DNA. Long polymer of nucleotides as units, w. a backbone of sugar and phosphate.
What part of DNA encodes info.?
Sequence of the 4 bases
What is transcription?
Reading genetic information using genetic code, by copying stretches of DNA into RNA.
What is translation?
Gene expression. The process where mRNA is read and translated into a string of aa.
What is DNA replication?
duplication of chromosomes before the cells divide
chromatin proteins such as histones
conformation of double helix – tertiary structure
Chromosomes in prokaryotes
single circular chromosomal DNA
small circular extrachromosomal DNA
Chromosomes in eukaryotes
many nuclear chromosomes (extrachromosomal DNA: in mitochondria)
Types of proteins in chromosome
histone (alkaline proteins) and non-histone(regulatory and enzyme proteins)
core 2x (H2A, H2B, H3, H4) and (H1) to stabilize the core histone octamer
basic unit of eukaryotic DNA. Regularly repeating unit of chromatin
Primary structure of DNA
sequence (order and nr.) of nucleotides
Secondary structure of DNA
base-pairing (H-bonding bw. bases) and the double helix
Tertiary structure of DNA
conformation of double helix (B, A, Z conformation)
Quaternary structure of DNA
-Prokaryotes: one circular chromosome w. superhelices
-Eukaryotes: nuclear chromosomes, containing regularly repeating units of chromosomal nucleoproteins=nucleosomes.
Define the temp. of which half of the DNA is melted. Melts into ss (single stranded) DNA. Varies on G+C content. If G+C content is more than T+A content, Tm is more. Reverse is A+T rich DNA
Conformation (tertiary structure)
-B form: double helix - turn every 0,34 nm -> 10 base pairs
-A form: structure change, in sol. w. higher salt conc. or alcohol added - 2,3 nm->11 base pairs
-Z form: zigzag - 4,6 nm->12 base pairs
Type of conformation in prokaryotic DNA
Contains superhelix (double double helix). Positive (overtwisting) or negative (untwisting).
Type I topoisomerase
cuts one strand of ds DNA, relax the strand and then reanneal the strands. No ATP is needed.
Type II topoisomerase
cuts both strands of DNA helix, results in undwinding, neg. superhelix. ATP is needed. E.g. DNA gyrase (derived from Escherichia coli, bacterial).