genetic diversity and adaptations Flashcards
how does genetic diversity happen
change in quantity and structure of DNA (mutation)
recombining DNA of two individuals after meisosis or binary fission
what is the concequence of a mutation on a protien
a mutation in a dna base sequence would lead to different triplet codons made in transcription
this means the complementary base pairs of MRNA codons will be differnet
in translation amino acids will be inserteded into the primary strucure wrong so the tertiary structure will be different
which two mutations cause frame shift
addition
deletion
why dont silent substitutions change anything
the primary structure of the protein wont change because of the degenerate coding
or
the substitution could be in the codon
what is a chromosomal mutation
chnage to the structure of the whole chromosome
how do changes in a whole set of chromosmes happen
when organisums have 3 or more sets of chromsomes rather than 2
because homologous pairs fail to seperate during meiosis (its called non disjunction)
what is a haploid cell
cell containing one complete set of chromosmes
what is a diploid cell
cell containing homologous pairs of chromosmes
what is crossing over and how does it work in meiosis
homologous pairs come together and the chromatids of of each pairs wrap around each other ( they are called bivalent )
parts of the chromotids break off and exchange between the homologous pairs
what is independant segrigation and how does it work
homologous chromosomes line up at the equator of the cell
maternal and paternal chromosmes reshuffle and are then pulled apart of that one chromotid from each pair is in the new daughter cell randomly
what are the stages of meiosis 1
prophase 1
chromosomes condense , homologous chromosmes do crossing over , nuclear memebrane breaks down , spindle fibres form
metaphase 1
homologous chromosomes line up at the equator
anaphase 1
spindle fibres shortern , homologous chromsomes move to opposite poles
telophase 1
nuclear membranes reform ,chromosomes uncoil into chromotins , cytokinesis into haploid cells
what are the stages of meiosis 2
prophase 2
chromosomes condense , nuclear memebrane breaks down , spindal fibres form
metaphase 2
chromsomes line up at equator
anapahse 2
centromere divides , chromatids are pulled to the poles
telophase 2
nuclear membrane reforms , chrosomes become chromotin , cytokinesis
what is genetic diversity
the total number of differnet alles in a population
how do alleles affect reproductive success
species have gene pools with different alleles
random mutations mean some alleles survive better than others because they can get more resources and reproduce passing on the good alleles
what is directional selection
change in population from one phenotype to another
what is stabalising selection
reduction of variation about an optimum model
