storing and using genetic information week 8 Flashcards
what is primary structure
sequence of amino acids
what is secondary structure
- alpha helix
- beta sheets
- hydrogen bonding
what is tertiary structure
final structure of the protein that gives it its functionality
what does a nucleotide contain
sugar
base
phosphate group
what is a structural feature of the double helix
it has a major groove and a minor groove
usually the major groove that is the site DNA interacts with things e.g. transcription factors
- on major groove roughly 6 base pairs visible
what bases are purine
adenine and guanine
- purine has two cyclic rings
what bases are pyrimidine
thymine and guanine
what type of bonding is between bases
hydrogen
what takes place in the nucleus
- replication of DNA
- transcription and so formation of RNA
how many chromosomes do humans normally have
46
how are chromatins made more accessible for transcription and replication
- histones can be enzymatically modified (groups added to modify their charge so looser grip on DNA)
- histones can be displaced by chromatin remodelling complexes
(reversible processes)
what do they mean when they say DNA replication is semi-conservative
one half of each DNA molecule is old the other half is new
what unzips the helix
helicase (breaks hydrogen bonds)
what direction does replication occur
5’ to 3’
what stage of mitosis is most ordered
metaphase
what are exons
coding regions
what are introns
non-coding regions
what is alternative splicing
a set of processes that will alternate the introns or exons that are removed and then how the exons are stitched back together again
what is a codon
set of three bases which codes for a particular amino acid
how many amino acids are found in proteins
20
how many codons can be made from the bases
64 (4^4)
what is redundancy of the genetic code
- with the exception of two amino acids all others have more than one codon which encodes them
- so this means you can have slight changes in the DNA sequence and you will still get the same amino acid (redundancy)
what are point mutations
change of a nucleotide to another
what is mRNA
- messenger RNA
- the actual sequence that codes for protein
steps of protein synthesis
in nucleus:
DNA is transcribed to mRNA then alternative splicing occurs
processed RNA leaves nucleus and goes to ribosome in RER or just free floating in cytoplasm and with the help of tRNA and rRNA protein is formed
post translational modifications can them occur
what does tRNA do
- major role is to translate mRNA sequence into amino acid sequence
- acts as an adaptor molecule between coded amino acid and mRNA
- so anticodon on tRNA recognises codon
what is rRNA
- component of ribosomes
- produced in the nucleus
- transported to cytoplasm where they combine with proteins to form a ribosome
