Unit 12 - Heredity

father of genetics

Austria Italy Gregor Mendel Germany Poland Austria Czech Republic was born in 1822 in Heinzendorf, Austria, to a peasant farming family.

When he was 21, one of Mendel’s teachers took note of his exceptionally bright mind and persuaded him to join the Augustinian monks. St.Thomas Church, (now Brno, Czechoslovakia)

Rather than study every characteristic of the garden pea, Mendel narrowed his observations to 7 traits For 8 years, Mendel experimented with over 28,000 peas in the large gardens attached to the monastery. Mendel conducted numerous experiments on plants. Mendel narrowed his focus to one particular type of garden pea.

Garden Pea Traits Observed

Seed shape Seed color Pod shape Flower color Flower location Plant size smooth wrinkled yellow green smooth bumpy green yellow Pod color purple white Along stem at tip tall short

In 1866 when Mendel was 44, his experimental results were published... and ignored long after he died.

In 1900, 3 scientists - Carl Correns, Hugo de Vries, and Erich von Tschermak - all independently rediscovered and verified Mendel's principles, marking the beginning of modern genetics. He is now considered the father of genetics.

Genetics & Heredity Heredity-The passing of characteristics from parents to offspring Genetics -The branch of biology that focuses on heredity

Are these inherited traits? Your eye color Your hair color and texture Your height

Are these inherited traits? Your personality Your musical, athletic, and artistic abilities

Think about this…. My parents have brown eyes, why are mine blue?” “My brother is tall. Why am I short?” “Why does my sister have blonde hair while mine is brown?”

Mendel’s studies led to… Alleles- the different versions of a gene (an individual receives one allele from each parent)

Mendel’s studies led to… Dominant- the expressed form of the trait ex. H Recessive- the trait that is not expressed if a dominant allele is present ex. h

Mendel’s studies led to… Genotype- the genetic makeup of an organism (the set of alleles an individual has) ex: Ff or FF Phenotype- the physical appearance of an organism ex. has freckles

Mendel’s studies led to… Homozygous- the two alleles present for a characteristic are the same Ex: hh or HH Heterozygous- the two alleles present for a characteristic are different Ex: Hh

Tongue Roller R = Tongue Roller r = Unable to Roll Tongue

Widow’s Peak W = Widows Peak w = Lack of Widow’s Peak

Free Ear Lobe Attached Ear Lobe E = Free Ear Lobe e = Attached Ear Lobe

Hitchhiker’s Thumb H = Straight Thumb h = Hitchhiker’s Thumb

Bent Little Finger B = Bent Little Finger b = Straight Little Finger

Mid-digital Hair M = Mid-Digital Hair m = Absence of Mid-Digital Hair

Dimples D = Dimples d = Absence of Dimples

Short Hallux H = Short Hallux h = Long Hallux

Short Index Finger S = Short Index Finger s = Long Index Finger

The Theory of Heredity Inherited allele for purple P HOMOZYGOUS purple flower (PP)

The Theory of Heredity Inherited allele for purple P for pink flower (p) HETEROZYGOUS purple flower (Pp)

The Theory of Heredity Inherited allele for pink flower (p) HOMOZYGOUS pink flower (pp)

PREDICTING HEREDITY

Probability The likelihood that a specific event will occur Probability = # of 1 kind of possible outcome Total number of possible outcomes Example: What is the probability that a tossed coin will be heads? ½ or 50%

Probability What is the probability that a couple will have four boys? ½ x ½ x ½ x ½ = 1/16 What is the probability you will win the lottery? 6/50 x 5/49 x 4/48 x 3/47 x 2/46 x 1/45…

Aa x Aa Monohybrid Cross: a cross that shows the possible offspring for one trait Aa A a AA Aa aa Genotypic Ratio: 1:2:1Phenotype: 3 white:1 brown A: White fur a: Brown fur

*genotypic ratio: *phenotypic ratio: *What is the probability of having smooth-nosed offspring? *What is the probability of having two smooth-nosed offspring? Dragons have either smooth or wrinkled noses. Wrinkled is dominant over smooth. If a smooth-nosed female dragon is crossed with a heterozygous wrinkle-nosed male, how many of their offspring are likely to have smooth noses? __ _ _

Fur Color:Coat Texture: B: Black R: Rough b: White r: Smooth BbRr x BbRr Dihybrid Cross: a cross that shows the possible offspring for two traits

BbRr x BbRr First, you must find ALL possible gametes that can be made from each parent. Remember, each gamete must have one B and one R. Dihybrid Cross:

Dihybrid Crosses: a cross that shows the possible offspring for two traits Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth BbRr x BbRr BR bR br bR Br BR br Br BBRRBbRRBbRr BBRrBBrrBbRrBbrr BbRRBbRrbbRRbbRr BbRrBbrrbbRrbbrr BBRr Phenotypic Ratio: 9:3:3:1

Dihybrid Crosses: a cross that shows the possible offspring for two traits BR bR br bR Br BR br Br BBRRBbRRBbRr BBRrBBrrBbRrBbrr BbRRBbRrbbRRbbRr BbRrBbrrbbRrbbrr BBRr How many of the offspring would have black, rough coat? How many of the offspring would have a white, smooth coat? How many of the offspring would have a white, rough coat? 16 1

More Complex Patterns of Heredity –Codominance –Multiple Alleles –Sex-Linked Traits 16 1

Codominance: two dominant alleles are expressed at the same time 16 1 CRCRCRCR CWCWCWCW CRCWCRCW

Codominance 16 1 Sickle-Cell Anemia is another codominant trait. NANA NANA NSNS NANA NSNANSNA NSNANSNA NANANANA NANANANA N A =Normal RBC N S =Sickle Cell RBC

Pedigree Analysis

Pedigree Used to show genetic inheritance over generations in a family

Pedigree Example male female Female Carrier Marriage Offspring

Royal Family Hemophilia People affected by the disease People who are “carriers” for the disease, but do not have symptoms—can pass on to children