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Variation and inheritance - Coggle Diagram
Variation and inheritance
Varation
Differences between members or species
Sexual reproduction increases genetic varation
-during fertlisation, different forms of genes (
Alleles
) combine to form off spring
Continuous
A characteristic shows a range of values e.g height, weight, show size
The characteristic is
polygenic
which means influenced by many genes
Caused by genes and the environment
Genes + Alleles
Alleles: different forms of gene this means it gives different versions of the same characteristic e.g blue or brown eyes
Organisms possess two Allies for each characteristic
Gene: a section of DNA that carries information to create a particular characteristic
Discrete
Characteristics that fall into distinct groups or categories e.g tongue rolling, blood group, eye colour
Characteristics is controlled by a single gene
the environment has little to no effect
some exceptions are hair colour
Recessive Alleles
Represented by lower case letters and are usually hidden
however, if the organism has inherited one for from each parent the recessive allele will be shown (aa)
Dominant Alleles
Represented by capital letters and they always show
(AA or Aa)
Genotype
Identifies the alleles of a gene the organism possesses e.g GG, Gg, gg for eye colour in flies
Phenotype
An organisms appearance resulting from genetic information e.g wing type - wild type, weak, strong
eye colour - green, blue, brown
flower colour - red, white, purple
Monohybrid Cross + Predicted vs observed ratios.
Phenotype ratio - 3 tall : 1 dwarf
Genotype ratio - 1 TT : 2Tt :1tt
The predicted and oberved rations can differ due to the fact that
FERTILISATION IS A RANDOM PROCESS
Heterozygous
An organism that has inherited two different alleles of a gene (Aa)
Homozygous
An organism that has two copies of the same alleles (AA) aka true breading
