Meiosis

Interphase

DNA Replicates,

Prophaes 1

Chromatin shortens and thickens, each chromosome pairs with corresponding homologous chromosome to form a tetrad

Metaphase 1

Tetrads line up at the center of the cell

Anaphase 1

Tetrads break apart, pairs move to opposite sides of the cell

Telophase 1

Cell seperates into 2 cells, each cell a haploid(1N) daughter cell

Prophase 2

Sister Chromatids start to move to line up at the center

Metaphase 2

Sister chromatids line up at the center

Anaphase 2

Pairs of Sister Chromatids move to opposite poles

Telophase 2

Each of the 2 cells are divided again, final process results in 4 haploid(1N) daughter cells

Genetic diversity in meiosis is caused by:

Independent Assortment in metaphase and crossing over during prophase 1

Trait

Specific Characteristics passed on from one parent to another offspring. Example: hair or eye color

Heredity

process of passing a trait from one generation to the other

Genetics

Study of heredity

mono hybrid cross

A cross between 2 individauls differing in one characteristic

Di-hybrid cross

a cross between 2 individuals differing in 2 characteristics

Allele

Alternative from of a gene

Genotype

Genetic make-up of an individual. Example: TT, Tt

Phenotype

Out-ward Expression of genotype. Example: how tall a plant is

True breeding plants will always:

self pollinate

Cross breeding plants will

produces hybrids

Law of Dominance

When contrasting traits are crossed, the dominant trait will show in the next generation and cover up the recessive trait

Law of Segregation

During gamete production, a pair of alleles are separated and each gamete gets only one allele

Law of Independent Assortment

Traits are inherited independently. Example: a mom with straight hair and freckles and a dad with curly hair can have an offspring with freckles AND curly hair

Non-mendalian Genetics

when genetics dont follow Mendel’s laws. Usually caused by a mistake during reproduction

Incomplete Dominance

Neither allele is completely dominant. Example: red flower and white flower produce a pink flower

Co-dominance

Both parental traits appear together. For example: a white cow wtih black spots

Polygenic traits

Inherited traits that are controlled by more than 2 genes

Example: eye color

Sex-linked inheritance

Traits whose alleles are located on sex chromsomes

multiple alleles

Genes that have multiple alleles

example: blood type

Female chromosmes

xx

male chromosmes

xy

x-linked traits

traits carried on the x chromosome

y-linked traits

traits carried on the y chromsome

Sex-linked disorder

majority of males are affected

autosomal disorder

50/50 ratio of affected men and women

Autosomal Dominant

if a person inherits one dominant allele, they will have the trait: examples: huntington’s disease or widow’s peak

Autosomal Recessive

requires 2 copies of a mutated gene to inherit the disease. Example: Cystic Fibrosis or Sickle cell amenia

X-linked dominant

a single mutation on the x chromsome causes the disease. Examples: Rett syndrome or VItamin d resistant/rickets

x-linked recessive

In males, the single x chromsome would have to be mutated. In females, both x chromosomes would have to be mutated. X-linked traits can not be passed male to male(dad to son). Example: haemophilia

y-linked

can only be passed male to male(dad to son). Example: hairy ears