Launch

Correct the following false statements to make them true statements:

“We write the haploid number as 4N” “Somatic cells and sex cells both

undergo meiosis” “An example of a somatic cell is eggs” “An example of a germline cell is a brain

cell”

Mendelian Genetics

Mendelian Genetics

Mendelian Genetics is the study of how traits are passed down from parents to offspring

Father of Genetics

Gregor Mendel is considered to be the father of genetics

Gregor Mendel was an Austrian priest who made a lot of scientific discoveries about inheritance by studying peas and flowers.

Inheritance

Inheritance is the passing of traits from parents to offspring

Gene

A certain portion of DNA that codes for a specific protein Ex: Genes for hair color, eye color,

hormones, etc.

The rest of DNA is known as junk DNA.

Gene

Some traits are complex and require multiple genes Skin color

Allele

Alleles are different forms of one gene. Example:

The gene is hair color The alleles might be brown hair, blonde hair,

red hair, black hair, etc.

Genotype

The genotype is the way we describe the genetic make-up of an individual.

The genotype always consists of two letters: one for the allele from the mother, one for the allele from the father Rr, SS, dd

Phenotype

The phenotype is the physical appearance that is made as the result of an individual’s genotype.

The things we see!

Genotype

Alleles are either dominant or recessive.

When a dominant allele is present, you only see the dominant phenotype even if the recessive allele is also present.

Hh

Dominant

Dominant genes only require one allele to express the dominant phenotype.

Dominant alleles are represented in genotypes with a capital letter.

Examples: HH, Dd, SS, Tt,

Recessive

Recessive genes require both alleles to express the recessive phenotype.

Recessive alleles are represented in genotypes with a lower case letter.

Examples: hh, dd, ss, tt,

Heterozygous

Individuals are heterozygous for a gene when they receive a dominant allele from one parent and a recessive allele from another parent.

Rr, Ss, Tt, Uu

Think-Pair-Share

Why do individuals heterozygous for a gene always produce a dominant phenotype?

Homozygous

Individuals are homozygous when they receive the same allele from both parents Individuals are either homozygous

dominant or homozygous recessive

RR, rr, SS, ss

Exit Slip

1. __________ do mitosis, __________ do meiosis A. brains cells, heart cells B. eggs, sperm C. sperm, brain cells D. brain cells, eggs

2. If an individual is “Hh” for a trait1. Is this individual homozygous or heterzygous?2. Have a dominant or recessive trait?