Heredity o Heredity the passing of traits from

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

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

GREGOR MENDEL o First known geneticist and “father of genetics” o Studied 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 o A Dominant trait will always be expressed and will “mask” mask or hide a recessive trait o Example: Hh (shows dominant trait even though it contains a recessive allele)

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

o Example: Example 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” hides the blue allele.

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

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

Purebred 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.

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

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

Phenotype o The PHYSICAL trait that shows, regardless of genotype is called a PHENOTYPE o For instance, Blue or Brown Eyes.

Multiple Alleles o Three or more alleles for a particular gene.

Co-Dominance o Two different alleles (both dominant) o Both alleles are present in the phenotype.

Incomplete Dominance o Two different alleles (both recessive or not dominant over the other) o Neither allele is present in the phenotype, creating a new trait. o Example – Red flower bred with a white flower creating a pink flower

Complete Dominance, Co. Dominant and Incomplete Dominance Co-Dominant Incomplete Dominance Alleles RR Red Red Rr Red/White Pink rr White R-Red r- White

Using a Punnett Square… o Used to help predict Mendelian genetics

Steps for using the Punnett square: 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 B b B BB Bb bb So you would predict: 1/4 offspring to be BB, or Brown Eyes 2/4 or 1/2 to be Bb, or Brown Eyes and 1/4 to be bb or Blue eyes

Using a Punnett Square Clip

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

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

Practice Problem #2 b bb bb bb

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 G g G GG Gg gg

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 r r R Rr Rr r rr rr

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 X XX XX Y XY XY