Heredity o Heredity parent to offspring o Heredity = the passing of traits from parent to offspring

Genetics genes oTraits are controlled by genes, so therefore, inherited o Genetics is the study of how traits are inherited

GREGOR MENDEL father oFirst known geneticist and “father of genetics” pea oStudied pea plants

Asexual Reproduction Reproduction involving only one parent organism; offspring are identical to parent (clone).

Sexual Reproduction Process in which two parents contribute genes to form a new individual; offspring are more diverse

Chromosomes An organized structure of DNA (contains genetic info) found in the nucleus

Genes Segment of DNA, found on a chromosome, that determines the inheritance of a particular trait.

Alleles One of a pair of genes that determine a specific trait

DOMINANT mask oA Dominant trait will always be expressed and will “mask” or hide a recessive trait oExample: Hh (shows dominant trait even though it contains a recessive allele)

RECESSIVE dominantA recessive trait can only be expressed if there are no dominant alleles present Example: hh (2 recessive alleles)

oExample dominant brown hides oExample: Eye color—Brown color is dominant and blue is recessive. A person can have a brown allele and a blue allele but still have brown eyes because the brown allele is dominant and “hides” the blue allele.

Rr Example: R= dominant r = recessive capital lower caseGenerally, dominant alleles are represented with a capital letter, and recessive alleles are represented with a lower case letter.

Homozygous An organism that has two identical alleles for a trait Example: HH or hh

same homozygousFor example: BB or bb. o“Purebred” species have two alleles of the same trait, and therefore would be represented by two of the same letters. This is also called homozygous. For example: BB or bb. Purebred

Heterozygous lettersAn organism that has two different alleles for a trait represented by two different “letters” For instance: Bb

genotypeBB, Bb, or bb. oThe alleles present in the organism are referred to as its genotype. For instance, BB, Bb, or bb. Genotype

PHYSICAL PHENOTYPE oThe PHYSICAL trait that shows, regardless of genotype is called a PHENOTYPE. BlueBrown oFor instance, Blue or Brown Eyes. Phenotype

oThree or more alleles for a particular gene. Multiple Alleles

oTwo different alleles (both dominant) oBoth alleles are present in the phenotype. Co-Dominance

oTwo different alleles (both recessive or not dominant over the other) oNeither allele is present in the phenotype, creating a new trait. oExample – Red flower bred with a white flower creating a pink flower Incomplete Dominance

Complete Dominance, Co- Dominant and Incomplete Dominance Complete Dominance Co-DominantIncomplete Dominance Alleles RRRed RrRedRed/WhitePink rrWhite R-Red r- White

Using a Punnett Square… oUsed to help predict Mendelian genetics

Steps for using the Punnett square: (genotype) 1)One parent’s alleles (genotype) go along the top 2)The other parent’s alleles go down the side. 3)You fill in the squares like doing the communicative property of multiplication. 4)See Below:

Steps for using the Punnett square: Let’s say the parents are Bb and Bb (the same genotype for eye color). What would be their phenotype? Brown Eyes BbBb B b So you would predict: 1/4 1/4 offspring to be BB, or Brown Eyes 1/2 Brown 2/4 or 1/2 to be Bb, or Brown Eyes 1/4Blue and 1/4 to be bb or Blue eyes BB bbBb

Using a Punnett Square Clip

Heredity Heredity by Brainpop 1What do we call different forms a gene may have for a trait? 2What height of pea plant (tall or short) did Mendel find to be dominant? 3Which kind of trait can’t be passed from parent to child? a)Eye colorb) heightc) broken arm

Let’s try some practice problems…

Practice Problem #1 Predict the fur color of the offspring of a brown heterozygous hamsters and a white homozygous hamster. Brown is dominant. White is recessive. Use any letter you like.

Practice Problem #1 Bbbb Bbbb B b bbbb

Practice Problem #2 Predict the offspring of 2 white homozygous cows. Black is dominant over white. Use any letter you like.

Practice Problem #2 bb bbbb

Practice Problem #3 Predict the offspring of 2 Grey Heterozygous rats. Gray is dominant over white, which is recessive. Use any letter you like.

Practice Problem #3 GGGg gg G g GgGg

Practice Problem #4 Predict the pea shape of the offspring of one Heterozygous Round Pea plant and one homozygous wrinkled pea plant. Round is dominant over wrinkled. Use any letter you like.

Practice Problem #4 Rrrr Rrrr R r rrrr

Practice Problem #5 you don’t have to write this one down… What are the chances of having a boy or a girl? How would you solve this one?

Practice Problem #5 XXXY XXXY XXXX