Genetics & Heredity

Who was Gregor Mendel? “Father of Genetics”

Who was Gregor Mendel? Austrian monk who studied mathematics and science As a boy he could predict the possible types of flowers and fruits that would result from crossbreeding two plants in his father’s garden

Who was Gregor Mendel? Curiosity about the connection between the color of a pea flower and the type of seed that same plant produced inspired him to begin experimenting with garden peas in Made careful use of scientific methods, which resulted in the first recorded study of how traits pass from one generation to the next.

What is GENETICS? The study heredity of how traits (characteristics) are inherited through the interactions of genes.

What is a GENE? The material that controls which traits are expressed in an organism Genes come in pairs and offspring inherit one copy of each gene from each parent

Define HEREDITY The passing of traits from parent to offspring

Define ALLELE Either member of a pair of genes that determine a trait. The different forms of a trait that a gene may have One form of a gene

Define TRAIT Ways of looking, thinking, or being Traits that are genetic are passed down through the genes from parents to offspring

Describe RECESSIVE (weak) A trait that is covered over, or dominated, by another form of that trait and seems to disappear Hidden when the other copy of the gene contains the dominant allele. A recessive allele shows up only when there is no dominant allele present Shown with a lower-case letter

HOMOZYGOUS or Pure (same) Both alleles [forms of the gene] are the same ex. BB, bb, TT, tt When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive

HETEROZYGOUS or Hybrid (different) When alleles occur in different forms ex. Tt, Bb, Rr When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous Since the dominant gene will be expressed, they are said to be heterozygous dominant

INCOMPLETE DOMINANCE p. 316 snap dragons A blend of 2 traits, resulting in a cross of homozygous. P1 RR x WW No dominance or recessive, all offspring are pink

Describe CO-DOMINANCE When an organism has two different alleles for a gene that does not follow the dominant/recessive pattern The organism shows a trait that is a blend of the traits represented by the two alleles Also called INCOMPLETE DOMINANCE

Describe CO-DOMINANCE P. 317 (checkered chicken) For example: P1 BB x WW Both traits are displayed All the offspring are black and white

Describe DOMINANT (strong) A trait that covers over, or dominates, another form of that trait Trait that always shows up, even when only one of the two alleles is in the dominant form Shown by a capital letter

Define GENOTYPE An organism's genetic makeup Think……(letters) Ex. TT, Tt, tt, RR, rr, Rr

Define PHENOTYPE Outward physical appearance and behavior of an organism think…”what does looks like” Ex. green, round, tall …

What is a PUNNETT SQUARE? A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine A way to show phenotype & genotype A chart that shows all the possible combinations of alleles that can result when genes are crossed

What is a PUNNETT SQUARE? Letters stand for dominant and recessive alleles An uppercase letter stands for a dominant allele Lowercase letters stand for recessive alleles

3 Principles of Heredity Principle of Dominance and Recessive (one trait is masked or covered up by another trait) Principle of Segregation (two alleles (pair of genes) for a trait separate during gamete formations) Principle of Independent Assortment ( each trait is independently inherited)

MULTIPLE ALLELES Traits controlled by more than two alleles Traits controlled by multiple alleles produce more than three phenotypes of that trait

What is meant by MULTIPLE ALLELES? For Example: Blood Types 4 types phenotype Genotype AAA, AO, I A I A, I A i BBB, BO, I B I B, I B I ABAB, I A I B Universal Recipient OOOO, iiUniversal Donor

What is POLYGENIC INHERITANCE? Occurs when a group of gene pairs acts together to produce a trait. The effects of many alleles produces a wide variety of phenotypes. Ex. Hair color, eye color