Chapter 3 - Mendelian Genetics

transmission genetics

the study of how traits move from parents to kids

traits

features or characteristics of an organism, like eye color or hair type

selfing

when a plant fertilizes itself (like using its own pollen)

reciprocal crosses

switching which parent has which trait to see if inheritance changes

unit factor

another word for gene

phenotype

what the organism looks like, or shows, like purple flowers

genes

pieces of DNA that control traits

alleles

different versions of a gene, like tall vs short

genotype

the combination of alleles an organism has, like Tt or tt

homozygote

having two identical alleles for a trait (like TT or tt)

heterozygote

having two different alleles for a trait (Tt)

testcross

crossing an unknown organism with a homozygous recessive to find out its genotype

dihybrid cross

mating experiment that looks at two traits at the same time

product law

the change of two independent events happening together = multiplying their probabilities

transcription factor

a protein that tells a gene when to turn on or off

rescue experiment

adding a normal gene back to fix a mutant and see if the trait comes back

chromosomal theory of inheritance

genes are located on chromosomes, which carry traits from parents

locus

the location of a gene on a chromosome

sum law

the chance of either two events happening = add their probabilities

chance deviation

small differences from expected results that happen just by luck

null hypothesis

the idea that there’s no real difference between what you expect and what happens

chi-square (x²) analysis

a math test to see if your results match what you expect

pedigree

a family tree that shows how traits are passed down

consanguineous

parents that are related by blood (like cousins)

proband

the first person in a family to be studied for a trait or disease

recessive mutations

mutations that only show up when there’s no normal allele hiding them

monohybrid cross

mating experiment between two organisms looking for just one trait (like Dd x Dd, looking for only D)

transposable elements

pieces of DNA that can jump around in the genome (can break or change the gene, which sometimes causes mutations)