bio genetics until 11

gene

A sequence of DNA that codes for a protein that determines a trait

**Allele**

a form of a gene

**Dominant**

The trait that is always exhibited when the allele is present

**Recessive**

The trait that is only exhibited when the dominant allele is NOT present

**Gamete**

A reproductive cell→ sperm and eggs(haploid)

**Haploid**

* A cell with one copy of each chromosome

**Diploid**

* A cell with two copies of each chromosome

**Homologous Chromosome**

Maternal and paternal copy of the same chromosome → only in diploid cells

**Sister Chromatid**

Identical copies of the same chromosome in duplicated chromosomes

**Zygote**

Diploid cell created when sperm and egg combine→ blueprint for the new organism

genotype

the set of genes in a trait (hh)

phenotype

the physical trait

homozygous

2 sets of the same allele

heterozygous

2 different alleles

pure bred

same gene pairs ( only homozygous)

hybrid

different gene pairs ( heterozygous)

monohybrid

simple punnet square

di-hybrid

mega punnet square

In-complete dominance

when two different phenotypes combine into one ( red + white = pink)

Co-dominance

when both phenotypes from parent are present ( red + blue = blue and red stripes)

sex-linked

characteristics o traits that are criied on sex chromosomes (X)

karyotype

picture of chromosomes in body

monosomy

1 copies of each chromosome;  a person is missing one chromosome in the pair

trisomy

3 copies of each chromosomes (xxy or xxx)

down syndrome

trisomy in chromosome 21, normally has a low IQ, shorter flattened face, small hands and feet

Klinefelter’s

Extra X chromosome in males (xxy), harder to spot in children, devlop breast, less facial and body hair, cannot have children.

Meta-female

trisomy in X chromosome, some people never realise they have it, taller than average, learning disability, behavioral issues, delayed speech development, seizures, weakened muscle tone.

mendel’s law of dominance

when a allele is heterozygous the dominant allele will show instead of both ( dominant always overpowers)

mendel’s low of segregation

When gametes are formed, each allele of one parent segregates randomly into the gametes, 

mendel’s law of independent assortment

the alleles of two (or more) different genes get sorted into gametes randomly (shown in di-hybrid crosses)

polygenic traits

traits controlled by multiple genes (hair color, eye color)

multiple alleles

When three or more alleles control a trait (blood type)

difference between polygenic traits and multiple alleles

Multiple alleles refer to a series of three or more alternative forms of a gene and A polygenic trait is a trait controlled by a group of non-allelic genes.

what is a pedigree

A diagram of family history that uses standardized symbols. 

rules of autosomal dominant

* doesn’t skip a generation
* if one offspring has a trait one parents must have it
* males and female affected equally
* unaffected parents wont have affected kids

autosomal recessive

* traits can skip a generation
* unaffected parents can have affected child
* two affected parents always have affected child
* males and females are affected equally

sex-linked dominant

* females are more affected than males
* does not skip a generation
* affected male must have affected mother
* affected males must pass traits on to daughter
* affected daughter must have affected parents
* carried on x chromosome

sex- linked recessive

* more males affected than females
* traits can skip a generation
* affected sons typically have unaffected mother
* daughters have trait only if father is affected
* trait cannot go from father to son

how is meiosis different from mitosis

Mitosis produces two genetically identical “daughter” cells from a single “parent” cell, whereas meiosis produces cells that are genetically unique from the parent and contain only half as much DNA.

What happens in meiosis 1

one parent cell divides into two daughter cells

What happens in meiosis 2

the sister chromatids separate forming four new haploid gametes, each with one copy of each chromosome.

What is the point of going through meiosis?

**to produce gametes, or sex cells**

What types of organisms go through meiosis?

multicellular plants and animals