Biology gentics

allele

a version of a gene; a person inherits two alleles for each gene

chromatid

one side of the X-shaped chromosome that contains a double helix of DNA

chromosome

the form of DNA that is tightly wound around proteins before replication

co-dominant

two different alleles that can both appear in the phenotype at the same time; both can appear with a single allele

complementary base

a nucleotide base that pairs with its partner nucleotide on the alternative DNA strand; adenine pairs with thymine

cytokinesis

the splitting of a replicating cell into two cells

deoxyribonucleic acid (DNA)

a molecule that contains all the instructions for every job performed by the cell; this information can be passed from one generation to the next

diploid

containing two complete sets of chromosomes

dominant trait

a characteristic that needs only one copy of an allele to appear in the physical appearance of an organism

genetically modified organism (GMO)

an organism that has had its DNA changed in a laboratory

genetic code

the sequence of nucleotides in DNA

genotype

the combination of alleles for a particular trait

haploid

containing one complete set of chromosomes in each cell; an example is gametes

heterozygous

having two different alleles for a particular trait; a carrier for a recessive trait

homozygous

having two identical alleles for a particular trait

interphase

a phase of cell life where normal functioning occurs

karyotype

a way of representing a complete set of chromosomes

meiosis

the process that results in the formation of gametes with half the genetic material of the parent cell

mitosis

the process of cell division that results in genetically identical daughter cells; allows growth and repair

mutation

a permanent change in the sequence or amount of DNA

nucleotide

a subunit of a DNA molecule

pedigree

a chart showing the phenotypes for an individual and their ancestors

phenotype

the physical characteristics that result from an interaction between the genotype and the environment

Punnett square

a diagram used to predict the outcome of breeding organisms

recessive trait

a characteristic that is only expressed in the phenotype when two identical alleles are inherited

sex chromosome

a chromosome that determines the sex of an organism

somatic cells

the body cells except gametes (egg and sperm)