biology unit 2 aos 1 - inheritence

Karyotype

A visual representation of the chromosomes from a cell nucleus of any individual, therefore a full set of the species chromosomes

Autosome

Refers to the 22 chromosome pairs in humans that determine body traits such as height,

Sex chromosomes

Whilst humans have 1 pair of sex chromosomes called X and Y, determining if someone is male or female

Epigenetic factors

Changes in gene expression caused by modification of DNA without changing the sequence

DNA methylation

The process of adding methyl group to C bases of DNA

Histone modification

The addition of chemical groups to histone proteins which affects the spacing between nucleosomes

Genotype vs phenotype

The particular genetic makeup and allele for each gene, whilst phenotype is the visible expression of each gene

Test cross

With a homozygous recessive phenotype to determine the genotype of the dominant individual

Co dominance

Two traits are equally dominant, a heterozygous displays both traits

Incomplete dominance

Heterozygous displays an intermediate phenotype that is a combination of both alleles

DNA

deoxyribonucleic acid, a double stranded helix structure made of nucleotide monomers

Monomer

a single unit of molecule that can react with other monomers to combine

Polymer

A large molecule or chain made up of many single monomers bonded together

Genes

A section of DNA that has a functional purpose; coding for proteins

Alleles

an alternative form of a gene

Genome

The complete set of genetic material in a cell of an organism

Homologous chromosomes

Are the same size and structure, they carry the same genes at the same locus, the position of the gene

Diploid

Two complete sets of chromosomes, represented as 2n, one from mother, one from father, all somatic cells are diploid cells

Haploid

Contains half the number of chromosomes of a diploid cell, represented as n, sex cells are haploid cells

Aneuploidy

A genetic abnormality in which an individual has an abnormal number of chromosomes. Missing or an extra chromosome can result in a number of genetic disorders

Trisomy

An individual has an extra copy of one of the chromosomes, eg. Down syndrome, this is an extra of the number 21 chromosome

Monosomy

An individual is missing one chromosome from a homologous pair