Genetics Chapter 2 Section 2

The passing of traits from parents to offspring What is genetics? The passing of traits from parents to offspring Also referred to as heredity

Why is studying genetics important? Allows us to understand how traits are passed from generation to generation Allows us to understand how traits change over time Treatments and cures for diseases can be developed

First scientist to determine the basic principles of genetics Who is Gregor Mendel? Father of Genetics Austrian monk First scientist to determine the basic principles of genetics Without the knowledge of DNA and chromosomes

What is an allele? Alternate forms of the same gene Each trait of an individual is determined by two alleles Results in dominant and recessive traits

What makes a trait dominant? Alleles will show their effect on phenotype whenever they are present Represented by a capital letter Homozygous—TT Heterozygous—Tt

What makes a trait recessive? Alleles will only show their effect on phenotype when both alleles are present Represented by lower case letter Always homozygous—tt

What is the principle of segregation? States that each parent passes only one of the alleles for a trait to its offspring Explains variation among offspring Why you don’t look exactly like your sibling

How are traits passed from parents to offspring? Suppose that a parent has three pairs of chromosomes with a different trait on each pair. The traits can be called A, B, and C.

Each trait has two different alleles—A and a, B and b, and C and c. Parent can pass down any combination of these three alleles to their offspring This example has 8 different possible combinations

What is a Punnett square? A Punnett square is a model that is used to predict the possible offspring of crosses between different organisms of known genotypes

Punnett square practice with SpongeBob !!