Biology - Inheritance and Meiosis

Gene

Section of DNA that carries a code to make a protein

Genome

The complete set of DNA contained within an organisms chromosomes

Alleles

Alternative form of a gene

Chromosomes

Each molecule of DNA is coiled tightly around histone proteins and packaged into thread-like structures

Homologous chromosomes

Each set of 23 chromosomes within a human nucleus

Karyotype

Visual representation of individuals entire genome organised into pairs

Aneuploidy

Incorrect number of total chromosomes caused by addition or loss of an individual chromosome

Polyploidy

Chromosomal abnormality, organism has more than two sets of each chromosome

Dominant alleles

written as a capital letter

Recessive alleles

written as a lowercase letter

Homozygous

Having the same alleles for same genes

Heterozygous

Having different alleles for the same gene

Genotype

Genetic composition of organism

Phenotype

Observable physical traits, result of gene expression

Complete dominance

Only the dominant allele is expressed

Codominance

Both alleles are fully expressed

Incomplete dominance

Neither allele is fully expressed (allele is blended)

Proportionate heritability

phenotype variance that can be explained by genes in population

Epigenetics

Molecular interactions with DNA that modify expression of genes

DNA methylation

Methyl groups attach to certain nucleotides and alter level of gene expression, reducing transcription

Histone modification

Histone modifying enzymes modify how tightly a DNA molecule is wrapped around the histone

Importance of Epigenetics

Help control cell differentiation and provide organism mechanism to respond