STEM Summative (copy)

alleles

different forms of genes for a single trait

dominant trait

one whose trait always shows up in the organism when the allele is present; always expressed

recessive trait

one whose trait is hidden whenever the dominant alleles is present; only expressed in the homozygous state

heterozygous

genotypes made of two different alleles

homozygous

genotypes made of the same alleles

genetics

the scientific study of heredity

trait

each specific characteristic, such as stem height or seed

gene

used to describe the factors that control a trait

purebread

the offspring of many generations that have the same form of a trait

heredity

the passing of physical characteristics from parents to offspring

hybrid

an organism that has two different alleles for a trait

fertilization

a process in which new organism begins to form when egg and sperm cells join together

genotype

an organism’s genetic makeup, or allelles

phenotype

an organism’s physical appearance, or visible traits; how a trait looks or is expressed

Punnett square

a chart that shows all of the possible ways that alleles can combine in a genetic cross

probability

a number that describes how likely it is that an event will occur

incomplete dominance

occurs when one allele is only partially dominant

codominance

occurs when both alleles for a gene are expressed equally

mutations

Any change in the DNA of a gene or chromosome. Therefore, the organisms trait may be different from what it normally would be. If mutations occur in a body cell, it will not be passed on to the offspring, if occurs in a sex cell, it can be passed onto an offspring, and affect it’s traits.

nitrogen bases

molecules that contain nitrogen and other elements;

Adenine

Thymine

Guanine

Cytosine

how nitrogen bases mix

A goes with T; C goes with G