MUTATION + GENE POOLS Flashcards
Evolution
gradual change in characteristics of a species over time/multiple generations
permanent change in population’s gene pool from one generation to next
Phenotype
observable characteristics due to genotype
Genotypes
combination of alleles for a gene
Population
group of organisms of same species living together in particular place at particular time
Gene pool
sum of all alleles in a given population
Allele (gene) frequencies
how often an allele of a gene occurs in the gene pool for that population
Mutation
permanent change in a gene/chromosome of a cell leads to organism’s new characteristics
can affect body cells + reproductive cells
effects occur during DNA replication
beneficial, neutral, deleterious
Types of mutations
Gene
Chromosomal
Gene mutations
changes in single gene which codes for a particular protein, so that its traits are changed/destroyed
cause frameshift mutations
usually advantageous
eg: albinism
Chromosomal mutation
all/part of chromosome affected
change in structure of a chromosome/ total no. chromosomes
miscarriages in early pregnancy
usually disadvantageous
eg: Down syndrome- trisomy 21
Species
basic unit of biological classification
group of individuals that share many characteristics + able to interbreed under natural conditions to produce fertile offspring
Ways gene frequencies alter as result of mechanisms of evolution
mutations
differing selection pressures
random genetic drift- founder effect
change in gene flow between adjoining groups
Types of chromosome mutations
deletion
duplication
inversion
translocation
non-disjunction
Somatic mutation
mutation in body cells
only affect characteristics of individual who has the mutation- not passed to future generations
Germline mutations
affect germline cells
change in sperm/ova hereditary material
can be passed to offspring
don’t affect the individual who carries it
if advantageous variation in structure produced, mutation will be incorporated into DNA of every cell in offspring’s body
Archromatopsia
total colour blindness
inherited form
Albinism
inability to produce pigment in hair/skin/eyes
inherited
Anaemia
reduced amount of haemoglobin in blood/
reduced no. RBC’s
Aneuploidy
change in chromosome no.
result of non-disjunction
Bottleneck effect
extreme genetic drift effect
when size of population severely reduced due to sudden event
allele frequency of survivors may not reflect that of original population
Cri-du-chat syndrome
rare genetic disorder
missing part of chromosome 5
Cystic fibrosis
disorder controlled by recessive allele carried on autosome
incurable
detected during foetal development
Down syndrome
AKA trisomy 21
genetic disorder
extra copy of chromosome 21
Duchenne muscular dystrophy
genetic disease
wasting of leg muscles + then arms, shoulders + chest
Frameshift
caused by gene mutation
base insertion/deletion/duplication that results in change in way that sequence is read
Gene flow
transfer of alleles from one population to another through migration of individual
Geographical barrier
feature of landscape
prevents populations from interbreeding
eg: oceans, mountain ranges, large lake systems, deserts, + expansive ice sheets
Heterozygote advantage
where heterozygous genotype has higher chance of survival than either homozygous genotype
Induced mutation
caused by mutagenic agent
Klinefelter syndrome
genetic disorder
results from inheritance of 2 X chromosomes + 1 Y chromosome
XX + Y
Lethal recessive
homozygous recessive allele that results in death of embryo/foetus/child
eg: Tay-Sachs disease
Migration
movement of people from one area to another with intention of settling permanently