POM 16 - Introduction to medical genetics and mendelian inheritance Flashcards
what is RNA
single strand molecule that is transcribed from DNA and translated into proteins by ribosomes
what are the 4 categories of genetically determined diseases
single gene disorders
chromosomal disorders
multifactorial disorders
somatic cell disorders
what are mutations
permanent heritable change in the sequence of genomic DNA
change in DNA from its natural state which may be disease causing or benign normal variant
what is polymorphism
occurrence of 2+ alternative genotypes which each at a frequency greater than that which would be maintained by recurrent mutations alone
natural variations in genomic DNA sequence which have no obvious adverse effects on individual and occur with high frequency
why are polymorphisms important
evolutionary advantage to have variety
what are the 6 types of mutations
silent
missense
nonsense
frameshift
splice donor/acceptor
InDel
what is a silent mutation
single base change in protein coding part of DNA that does not result in an amino acid change
what is a missense mutation
single base change that does result in amino acid change but may not cause an abnormal phenotype
what is a nonsense mutation
single base change that changes an amino acid to a STOP codon and truncates the protein that is made
what is a frameshift mutation
insertion/deletion of bases in anything other than a multiple of 3 and changes the reading frame
what is a splice donor/acceptor mutation
alteration of sequences for accurate splicing of introns
what is an InDel mutation
a frame shift mutation
insertion/deletion of one or more bases - if its not a multiple of 3 bases then will shfit reading frame
what are the 2 strands of DNA called
RNA is a transcribed version that is complementary to what strand of DNA
sense and antisense strands
RNA is complementary to the sense strand - looks like the antisense strand of DNA
what eventually happens in a frameshift mutation
eventually introduces a stop codon by random chance in frameshift mutation
what is nonsense mediated decay
if peptide produced is going to be nonsense then the RNA encoding it is often broken down/decayed
what is a somatic genetic mutation and who can it affect
if a new mutation occurs in the non gamete forming cells
consequences of mutation are limited to the person in whom the changes occurred
what is a germline genetic mutation and who can it affect
new mutation occurs in cells that form gametes
change my be transmitted to and inherited by subsequent generations
how many pairs of chromosomes do humans have and which are sex chromosome
23 pairs
one pair of sex chromosomes and 22 pairs of autosomes
where do genes occupy
specific loci/positions on chromosomes
what does it mean to say genes are paired
one paternal one maternal
what are alleles
alternate forms of genes
what does homozygous and heterozygous mean
if the maternal and paternal alleles are identical = homozygous
if the maternal and paternal alleles differ = heterozygous
what are the 2 phenotypic consequences of mutations
gain of function mutations
loss of function mutations
what is a gain of function mutation
produces either increased amount/activity of the encoded protein/gene product