Coding Life: Patterns of Inheritence Flashcards
patterns of inheritance
how genes are passed down from one generation to the next.
molecular level of genetics
for instance genes that control certain traits
transmission level
how a gene is passed from one generation to the next
population level
advantages of traits in different environments
trait
characteristic of an organism eg. Seed colour
phenotype
appearance of an organism eg. Yellow seed
genotype
genetic composition of an individual eg. YY, Yy or yy
gene
unit of heredity (region of DNA) that influences a trait eg. Gene for seed colour
allele
alternate version of the same gene eg. Y or y
locus
specific place on a chromosome occupied by a gene
homozygote
an organism with two of the same alleles at a locus
heterozygote
an organism with two different alleles at a locus.
modern transmission genetics - Mendel and his discoveries
Mendel observed how traits passed down in peas
Chose traits he was interested in - seed colour, shape (round or wrinkled)
All happened to be controlled by single genes (fortunate)
Had two true breeding strains (always give yellow or always give green) and crossed them to produce F1 generation and observe the phenotype
Found that all were yellow!
Yellow is dominant and green is recessive (do not blend)
reciprocal cross
involve swapping the phenotypes of male and female parents
Same result in F1 offspring
Gender of parent does not matter in this case
F2 generation
Cross F1 together and look at phenotypes
Found that 3:1 yellow to green
7 different traits that all end up about 3:1 (Law of Segregation)
law of segregation
Cross AA and aa
F1 are all Aa
Half gametes are A and the other half are a
From a punnet square, AA, Aa, Aa and aa form
3 out of 4 are yellow
3:1 ratio for all 7 traits
segregation and test crosses
Test cross: a cross with a homozygous recessive individual that reveals the genotype of the other parent.
Can work out if AA or Aa
segregation of alleles in meiosis
One chromosome for AA and the other for aa (cell is heterozygous) in meiosis 1
Segregate to get 2 A gametes and 2 a gametes (haploid)
product rule
probability of independent events occurring together is the product of the probabilities of the individual events (can be multiplied).