14.3: Recessive and Dominant Mutations

diploids

organisms with two sets of chromosomes, one from each parent

homozygous

having two identical alleles for a specific gene. (bb/BB)

heterozygous

having two different alleles for a specific gene (Bb).

dominant traits

Alleles that mask the expression of other alleles when present. They determine the phenotype even when only one copy is present.

recessive trait

An allele that is only expressed in the phenotype when two copies are present (bb) and is masked by dominant alleles.

incomplete dominance

neither allele is completely dominant over the other, resulting in a blended phenotype in heterozygotes.

red and white flower = pink flower

codominance

both alleles in a heterozygote are fully expressed, resulting in a phenotype that displays both traits distinctly. For example, a red and white flower may produce a flower with both red and white patches.

Mendel’s experiment

pea plant crossbreeding revealed patterns of inheritance including dominant and recessive traits in offspring.

sickle cell disease

a genetic disorder caused by a recessive missense mutation in the hemoglobin gene = sickle shaped red blood cells = impaired ability to carry oxygen = various health complications.

how do mutations cause cancer

Mutations can lead to cancer by disrupting normal cell growth and division processes. These genetic changes can result in uncontrolled cell proliferation, evasion of apoptosis, and increased ability to invade nearby tissues.

apoptosis

is the process of programmed cell death that helps maintain cellular health by eliminating damaged or unneeded cells.