Genetics1. What is genetics?2. How are Punnett Squares used to describe the genetic relationship between parent to offspring?

GeneticsGenetics is the study of heredity, which is a biological process where a parent passes certain genes onto their offspring. Genes are inherited from both parents through sexual reproduction. These genes express specific traits or characteristics.

Gregor MendelMendel is the “Father of modern genetics”. Born in 1822, he was a monk from Austria who discovered the basic principles of heredity. He experimented on pea plants and showed that their traits follow a particular pattern.

ReviewChromosomes are found in the nucleus of a cell and carry genes. Genes are segments of DNA on a chromosome and are responsible for inherited traits.

Vocabulary

• Genotype - the genetic makeup of an organism. • Phenotype – the appearance of an organism based on its genotype, plus environmental factors

AllelesAlleles are variants (differences) in a gene. They occur on a fixed spot on a chromosome. In humans an allele might indicate blood type, colorblindness, or many other traits.

Dominant/RecessiveDominant or recessive describes how likely it is for certain phenotype traits to pass from parent to offspring.

• Dominant Alleles – show their effect with only one copy of the allele• Recessive Alleles – show their effect with two copies of the allele

What does the allele indicate in

this pair of homologous

chromosome?

Inherited TraitsInherited traits genetically determine characteristics. They come from both parents, so offspring has a combination of both parents’ genes.

• Examples: skin, hair, and eye color, height, and freckles

Vocabulary• Homozygous Dominant – carries two copies of the same

dominant allele (BB)• Homozygous Recessive – carries two copies of the same

recessive allele (bb)• Heterozygous – carries two different alleles (Bb)

Punnett SquareA Punnett square is a diagram used by geneticists to determine the probability (chance) of an offspring having a particular phenotype. If the A represents red flowers and a represents green flowers, what are the chances of the flowers being green?

Probability is expressed in a percentage. It examines just one of the many genes that get passed on during

sexual reproduction and shows all possible way the offspring could inherit the gene from two parents.

Blue Eyes -

RecessiveBrown Eyes - Dominant