dddna Flashcards
what is a histone
the protein that dna is wrapped around
do prokaryotic cells have histone complexes
no
when dna is wrapped a histone what is formed
chromosome
what is an allele
different versions of the same gene
what is the strcuture of dna
a double helix with strands bonded by hydrogen bonds between nirogenous bases and phosphodiester bonds between nucleotides
define genome
the complete set of genes in a cell including those in mitochondria and chloroplasts
define proteome
the full range of proteins produced by the genome
what is mRNA
a long strand that is arranged into a single helix
what is the function of mRNA
acts as a template for DNA in protein synthesis
what is a codon
three bases that are complementary to a triplet in DNA
what will a sequence of codon do
determine the amino acid sequence of a specific polypeptide that will be made
what is tRNA’s structure
a single stranded chain folded into a clover leaf shape, with one end of the chain extending over the other - at this part of the molecule is where the AA can easily attach
where is an anticodon located
opposite end of a tRNA molecule
define degenerate code
several codons that code for one amino acid
what is an anticodon
three more nitrogenous bases that are complementary to the codon
what is non-overlapping code
each codon only codes for one amino acid
what is universal code
genetic code is the same inall living organisms
derscribe the stages of transcription
DNA helicase attaches and breaks the hydrogen bonds to expose the bases.
- RNA polymerase attaches
- RNA polymerase works in the 5’3 direction
- rna polymerase will bind complementary base pairs together until a stop codon si reached - this creates pre - mrna
it needs to be spliced to remove introns
DNA polymerase will join adjacent bases behind it.
mrna can now leave the nucleus
why do prokaryotes not need ;to be spliced
they dont have introns
describe translation
a ribosome becomes attached to the start codon
- the trna molecule that is complementary to the codon brings an amino acid with its anticodon
-two amino acids are able to fit at any one time - they will join by a peptide bond
this repeats until stop codon is reached and a primary protein is acheieve
