module 6 Flashcards
(30 cards)
what is a gene mutation
change on sequence of base pairs in a DNA molecule which alters the polypeptide, continous and spontaenous, in DNA replication, increases with presence of facotrs/mutagens such as ionising radiation whihc breaks dna strands, deaminating chemcials which alter chemcial structure of bases and adding methyl or ethyl gorups as they cause incorrect base pairing as virus as they add viral dna
why arent mutations very effective
alter polypeptide slightly if not at all, genetic code is degenerate and mutations occur ion the non coding strand
types of gene mutation
insertion-nucleotide is randomly inserted which changes amino acid of original base triplets.
deletion-nucleotide randomly deleted from dna sequence which changes amino acid of triplet
substitution-base in dna is swapped and only changes of triplet without affecting the rest of the triplets
what is insertion
nucleotide is randomly inserted which changes amino acid of original base triplets. creates new and different triplet which as knock on effect on triplets further on, frameshift, changes amino acid sequence and ability of polypeptide to function
what is deletion
nucleotide randomly deleted from dna sequence which changes amino acid of triplet, knock on effect on triplets further on, frameshift, changes amino acid sequence and ability of polypeptide to function
what is substitution and what are the 3 types
base in dna is swapped and only changes of triplet without affecting the rest of the triplets,
silent-no alternation of amino acids as genetic code is degenerate
missense=alters single amino acid in polypeptide eg sicle cell anaemia
nonsense=crerates premature stop codon leading to incomplete polypeptide that affects final protein structure and function eg cystic fibrosis
types of mutation
point-substitution-missense, non sense, silent
indel-insertion-frameshift,
chromosome-deletion, duplication, translocation, inversion
what is a conservative mutation
new amino acid has similar properties and functions so change is less severe
what is non conservative mutation
new amino acid has different properties, more severe
sickle cell mutation
single base change leads to miss sense and non conservative mutation, valine instead og glutamic acid causes different properties, valine is hydrophobic gluatmic acid is hydrophilic meaning valine binds to the hydrophobic region on haemoglobin makes it distorted and die sooner, homozygous is worse than heterozygous
what does when frameshift not have an effect
number of bases are a multiple of 3 meaning that following triplets are unaffected, indel mutation occurs on a few bases so it cancels out meaning it is 3 consecutive rather than 1 indel
what is deletion
section breaks off or lost in cell
what is duplication
section of chromosome duplicated
what is inversion
section of chromosome breaks off reversed then rejoins
translocation
broken ends of non homologous chromosomes joined together
what is gene control
makes sure genes are expressed in correct cell by regulatory mechanisms and regulatory genes
what are the three types of regulatory mechanisms
post translational, post transcriptional and transcriptional
what are the types of genes involved in regulatory mechanisms
structural and regulatory
what is structural genes
codes for protein that has a function within a cell
what are regulatory genes
codes for a protein that control expression of structural genes
what are introns
non coding region, non expressive
what are exons
coding region, expressive,
splice
cut and separate the exons from mrna
spliceosome
structure removing the intron (splicing)
