Genetic Inheritance - Chp 16

What is a somatic cell?

all body cells that are not reproductive cells

Genetics

the study of inheritance

What scientist is known as ‘The Father of Genetics’?

Mendel

Species 

a group of organisms that can interbreed to produce fertile offspring

Inheritance/Heredity

passing on of traits from one generation to the next

Traits

physical/chemical characteristics that an orgnaism pocesses

Gene

a piece of DNA that contains the instructions to make a protein

Locus

the location of a gene on a chromosome

Allele

different forms of the same gene

Homozygous chromosomes

2 alleles are the same

Heterozygous chromosomes

2 alleles are different

Genotype

the genetic make-up of an organism

Phenotype

an organisms physical, visible traits

Dominant

only 1 allele needs to be present for the gene to be expressed

Recessive

a gene that is not expressed in the presence of a dominant allele, 2 recessive alleles are needed in order to be expressed

F1 Progeny

the first generation of offspring

Monohybrid cross

a cross between organisms involving 1 pair of traits

Dihybrid cross

a cross between 2 organisms that involve 2 traits

Incomplete dominance

neither allele is dominant or recessive over the other allele

Linked Cross

genes are located on the same chromosome

Sex Linked Cross

traits controlled by genes located on sex chromosomes

Mendel’s 1st Law: The Law of Segregation

states that at gamete formation pairs of alleles separate from each other, resulting in an allele in each gamete

Mendel’s 2nd Law: The Law of Independent Assortment

states that each allele separates at gamete formation and each allele is equally likely to combine with either member of another pair of alleles

Why are recessive phenotypes expressed more frequently in males in a sex linked cross?

• the Y chromosomes is shorter than the X genes, and contains less genes

• if the X chromosome carries a recessive gene, there is no corresponding allele on the Y chromoeome that could preventi it from being expressed

• as a result there is a ½ chance instead of a 1/3 chance of the male having the recessive phenotype

What is non-nuclear inheritance?

• the inheritance of DNA via the mitochondria (and chloroplasts in plants)

• this is always inherited meternally via the egg cell, as it is the cell that carry the cell organelles

What is a human disorder associated with non-nuclear inheritance:

Lack of ATP production - effects muscular and nervous system