mendelian genetics (M.B+G)

lecture 1

father of modern genetics and type of experiments used

Gregor Mendel. Used cross fertilisation

patterns of trait inheritance

laws of Mendelian inheritance

basis of understanding how genes pass on information to offspring

how many traits did Mendel choose to observe

7. all were easily observable and independently inherited

state Mendel’s laws of inheritance

law of segregation

law of independent assortment

why choice of peas?

• easy to cultivated quickly

• * controlled fertilisation to ensure parentage is identifiable

• *many pea plant varieties avaliable

homozygous

identical allele for particular gene on the two chromosomes

heterzygous

different allele for particular gene on the two chromosomes

dominant

allele if present is always expressed (in homozygous or heterozygous pairings)

recessive

allele if present is not always expressed (only in homozygous pairings, not in heterozygous pairings)

diploid

a cell containg teo copies of homologous chromosomes (autosomal case)

haploid

cell containing one copy of each chromosome (think abt sex chromosomes)

alleles

specific forms  of a gene that differ by one or a few bases and occupy the same physical location on a chromosome

gene

heritable factor that controls a specific characteristic or function

behaviours mendel observed

F1 generation (cross- fertilisation) → law of dominance (but still 50/50 heterzygous/homozygous split)

F2 generation (self- fertilisation) → ratio 3:1

law of segregation

two alleles for each gene separate when gametes are formed; each gamete receives one allele for each trait (diploid 2n → haploid n). diploid state i is restored at fertilisation.

law of independent segregation

alleles of different genes segregate independently during gamete formation. 9:3:3:1 ratio.