BASIC GENETICS TERMSTerms you’ve gotta know

GENE

A section of DNA that has information about a specific trait of an organism

A chromosome is a chunk of DNA and genes are parts of chromosomes

ALLELE

Each form of a gene OR each option for each gene

Example: attached or unattached earlobes are the alleles for the gene for earlobe shape

DOMINANT/RECESSIVE

Dominant: a genetic factor that blocks another genetic factor

Recessive: a genetic factor that is hidden by the presence of a dominant factor

Question: Using pea plants, how did Mendel figure out that genes are either dominant or recessive?

HOMOZYGOUS/HETEROZYGOUS

Homozygous: two alleles for a gene that are the SAME

Heterozygous: two alleles for a gene that are DIFFERENT

You get one allele from your mom and one from your dad.

If you get the same from your mom and dad, you are homozygous for that trait.

If your mom gave you a different allele than your dad, you are heterozygous for that trait

GENOTYPE

Alleles that make up an organism. Your genotype is which genes you have!

Genotype is written in letters It is usually the first letter of the dominant

trait to make it easier Choose a letter for each of these traits. Write

both the dominant and the recessive genotype allele letters Free Earlobes Freckles Dimples Tongue-roller

Tt

GENOTYPE

Now, using your letters from before write a genotype for a person without freckles

Write a genotype for a person with freckles

GENOTYPE-HETEROZYGOUS AND HOMOZYGOUS

A Heterozygous genotype means an organism has both the dominant and the recessive allele

Homozygous recessive means an organism has 2 recessive alleles

Homozygous dominant means an organism has 2 dominant alleles

Write a heterozygous genotype for handedness

Write a homozygous dominant and a homozygous recessive genotype for handedness

PHENOTYPE

Observable traits and all characteristics of an organism

What you look like (your phenotype) is based on what your genotype is (your genes)

What will the phenotype of these genotypes be:

PP, Pp, pp (Dominant is purple flowers, recessive is white flowers)

RR, Rr, rr (Round peas are dominant to wrinkled peas) YY, Yy, yy (Yellow peas are dominant to green peas)

GENOTYPE/PHENOTYPE PRACTICE

What is the genotype for white flowers? What are the genotypes for purple flowers? What phenotypes will result from these

genotype: PP, Pp, pp

You’ve got it!! Now you are a genetics super star