Genetic Variation (Mutation (point (chromosomal) mutation (Substitution,…
point (chromosomal) mutation
Occurs at only one point on chromosome.
can not be inherited
occurs in all body cells (apart from gametes)
can be inherited
occurs in gametes
produced in ovaries
determines if offspring are xx (female) or xy (male)
produced in testes
caused by mutagens
mutagens: chemicals, ultraviolet light, radiation
Block (gene) mutation
genes are removed from the original chromosome and lost
the genes are rearranged/inverted
rearranges the genetic information
relocation of genes from one chromosome to another
the new genes are not coded for
genes are copied and added on to the chromosome
extra genes are not coded for
Changes DNA transcription to messenger MRNA which translates to a protein.
Organisms such as bugs can become immune to pesticides
affects an organisms ability to survive
e.g. lack of tumour suppressing genes
enhance an organisms ability to survive
e.g. resistance to pesticide
do not have any visible affects to an organism
no change to the amino acids produced
substitution point mutation
A complete range of measurements from one extreme to another.
Characteristics that fall into a number of distinct classes/categories.
helps a species to survive in changing environments
Differences within the same species.
clones species/no variation
therefore the species cannot adapt to changes in environment
if the species cannot survive in changed environment they will become extinct
does not need to find a mate
Fast & efficient
an organism with sperm and an organism with ova
variation in a species
helps species to survive changes in environment
has to find a mate
may alter the expression of genotype
Food and nutrient availability, competition, light intensity
Modification of expected phenotype.
Special type of cell division.
Homologous chromosomes split so each gamete receives one allele for each pair. Resulting in all daughter cells being unique.
four daughter cells are produced from parent cell
Male gamete and female gamete join, forms Zygote
Homologous chromosomes can swap part of chromosomes breaking gene combinations. Increasing variation between gametes.
point that chromatids cross over : chiasma
Homologous pairs of chromosomes randomly line up during Meiosis. This meaning random combination of alleles end up in a gamete
cell division that forms gametes
23 chromosomes each
Occurs in testes and ovaries