DNA + RNA Flashcards
What does DNA & RNA stand for?
Deoxyribonucleic acid
Ribonucleic acid
What is the structure of DNA and RNA?
How many strands in each?
Deoxyribose sugar, phosphate group, base (A,T,C,G)
Double helix
Ribose sugar, phosphate group, base (A,U,C,G)
Single stranded
What are the functions of DNA and RNA?
DNA= stores genetic info RNA= transfers genetic info
What are 3 bases called in DNA & RNA?
Triplet code
Codon
Where can DNA be found?
How is it arranged? (Coiled?)
Nucleus and mitochondria
DNA coils around proteins (histones) and forms nucleosomes, then supercoils, then chromosomes
What is DNA replication called? And why is it called that?
Semi conservative replication
Retains one strand of original DNA
Which enzymes are involved in DNA replication?
Topoisomerase
DNA helicase
DNA polymerase
DNA ligase
What does topoisomerase do?
Unwinds the supercoil
What does DNA helicase do?
Separates DNA strands by breaking H bonds between bases, exposing nucleotides
What happens after DNA helicase?
Free nucleotides bind to complimentary exposed template bases on DNA strands
What does SSB stand for and what does it do?
Single strand binding protein
Bind to exposed bases, keeps two strands apart whilst synthesis of new DNA occurs, prevent annealing to other strand
*What does DNA polymerase do?
Prime ends=‘
Reads 3’ to 5’ and synthesises DNA on daughter strand 5’ to 3’
Forms phosphodiester bonds between free nucleotides
Why is DNA synthesised 5’ to 3’?
Runs antiparallel
What does DNA ligase do?
Join short DNA pieces (Okazaki fragments) together into one continuous strand
Where does transcription occur?
What initiates it? What enzymes and what do they do?
Nucleus
Topoisomerase- unwinds supercoil and double helix
DNA helicase- separates DNA strands by breaking H bonds and exposing nucleotides
SSB- coat DNA to prevent reannealing
What happens In transcription after SSBs are attached?
Free mRNA nucleotides bind to complimentary bases on template strand of DNA, initiated by TATA box sequence (promoter region)
AUG = start codon methionine
RNA polymerase goes from 5’ to 3’ from Promoter to stop codon
Pre mRNA released
What happens after transcription?
Where does it occur?
Where does it exit?
Splicing
Pre mRNA removes introns (non coding parts of DNA) to leave just exons
Now translatable
Nucleus
Nuclear pore
Where does translation occur?
Cytoplasm
What are the 3 types of RNA?
mRNA
rRNA
tRNA
What does tRNA carry and have on it?
mRNA
Amino acids
Binds to mRNA codon with complimentary anticodon (temp H bonds)
What happens in translation?
Ribosome moves along mRNA, once ‘read’, tRNA detaches and leaves AA behind, another tRNA arrives
Adjacent AA form peptide bonds
Polypeptide chain released at mRNA stop codon
Sent to Golgi apparatus for modification
