Inheritence

inheritance

the transmission of traits from one generation to the next

genetics

scientific study of heredity + inheritance

Gregor Mendel

a man who worked in the 1800s and was the first person to analyze patterns of inheritance and come up with the fundamental principles of genetics

Gregor Mendel's famous experiment

studied pea plants to understand how traits are inherited, discovering dominant and recessive traits through crossbreeding. His work established the basic rules of genetics.

alleles

Two or more versions of a gene.

How many alleles does each organism inherit for each trait?

At least 2 alleles, one from each parent.

dominant

when alleles for a trait are different, the dominant allele will be expressed

recessive

allele that is masked when a dominant allele is present

When is the only time recessive alleles are expressed?

when 2 recessive alleles are present

punnett square

a table used to predict genetic probability

homozygous

an organism that has two identical alleles for a trait

heterozygous

an organism that has two different alleles for a trait

Gregor Mendel's first hypothesis

alternative versions of genes are called alleles

Gregor Mendel's second hypothesis

for each inherited character, an organism inherits two alleles, one from each parent

Gregor Mendel's third hypothesis

if two alleles of an inherited pair differ, the dominant allele determines the organism's appearance, and the recessive allele has no effect on the organism's appearance

Gregor Mendel's fourth hypothesis

gametes carry only one allele for each inherited character

geneotype

an organism's genetic makeup

phenotype

an organism's physical appearance

test cross

the mating of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

sex-linked traits

traits controlled by genes located on the sex chromosomes, frequently found in males

where are most traits found?

autosomes

why do sex linked traits disproportionately affect males?

the x chromosome contains more than 1000 genes while the y chromosome contains only 12

female chromosomes

XX

male chromosomes

XY

incomplete dominance

when the phenotype in a heterozygous organism is a blend of the 2 homozygote parents