Human Traits and Mendelian Genetics

Genetic Vocabulary Genetics – Heredity – Traits – Gametes – The study of inheritance Heredity – The passing on of characteristics from parents to offspring Traits – Characteristics that are inherited Gametes – Sex cells (sperm and egg)

Genetic Vocabulary Genotype – Phenotype – Heterozygous – Homozygous – The genes that you can’t see. (B, b) Phenotype – The physical trait that is observed (Black or white) Heterozygous – Different (Hh) Homozygous – Same (HH)

Genetic Vocabulary Dominant – Recessive – Alleles – a trait that will appear in the offspring if one of the parents contributes it. (Upper case letters) Recessive – a trait that must be contributed by both parents in order to appear in the offspring. (Lower case letters) Alleles – One member of a pair or series of genes that occupy a specific position on a specific chromosome.

DNA is found in your chromosomes.

30,000 genes are inherited in every human.

Traits that you inherit

Cleft “Butt” Chin

Free and Attached Ear Lobes

Widow’s Peak

Clasping Hands

Bent Little Finger

Hitch-hikers Thumb

Long palmar muscle

Mid-digital Hair

Eye Shape Almond shaped eyes Round shaped eyes

Hair on back of hand

Freckles

Tongue Rolling

Tongue Folding

Dimples

Skin Color

Unibrow

Baldness

P.T.C. Paper Phenylthiocarbamide, also known as PTC, or phenylthiourea, is an organic compound having the unusual property of either tasting very bitter, or being virtually tasteless, depending on the genetic makeup of the taster. The ability to taste PTC is a dominant genetic trait. The test to determine PTC sensitivity is one of the most common genetic tests on humans. About 70% of people can taste PTC

Mendel and His Pea Plants

GREGOR MENDEL The “father” of genetics Lived from 1822-1884 Austrian Monk Published his work in 1866, but no one took him seriously until 1900. Studied Pea Plants!

MENDEL’S EXPERIMENTS

Mendel experimented with 7 different characteristics

Mendel Got Lucky for 2 Big Reasons First, he had a lot of time…he was a monk. This let him do LOTS of experiments with the peas! Each trait had 2 options. This was key because he could tell if it was one way or the other.

Mendel and his laws Law of Segregation Law of Independent Assortment During fertilization, gametes randomly pair to produce four combinations of alleles Law of Independent Assortment Genes for different traits are inherited independently of each other

Monohybrid Cross – Cross of a single trait

There are two terms used to describe the genes an organism has compared to what an organism looks like

PHENOTYPE physical characteristics (Tall, Brown)

GENOTYPE the genetic makeup (TT,Tt)

Check For Understanding Is the following information the PHENOTYPE OR GENOTYPE of an organism. The Giraffe is spotted Answer: Phenotype

How can we determine what the offspring are going to be?

PUNNETT SQUARES

PUNNETT SQUARES show the possible combination of alleles in a cross

Punnett Squares show the probability of getting a certain type of offspring

THE PARENTS GENOTYPES DAD = Tt (heterozygous) MOM = Tt (heterozygous) PHENOTYPES DAD = Tall MOM = Tall

PUNNETT SQUARES T t T T T T t T t t t t

THE OFFSPRING GENOTYPES 1TT:2Tt:1tt (1:2:1) TT (homozygous dominant) Tt (heterozygous) tt (homozygous recessive)

What are the PHENOTYPES? THE OFFSPRING What are the PHENOTYPES? 3 Tall: 1Short TT (tall) Tt (tall) tt (short)

Cross a heterozygote with another heterozygote (for hair color where Black is B, b = blonde). Find the genotype and the phenotype

B b B B B B b B b b b b

THE OFFSPRING GENOTYPES 1BB:2Bb:1bb (1:2:1) BB (homozygous dominant) Bb (heterozygous) bb (homozygous recessive)

THE OFFSPRING PHENOTYPES 3 Brown :1 Blonde (3:1) BB (Brown) Bb (Brown) bb (Blonde)

Cross a dominant homozygote with a heterozygote (for nose size where big nose is N and small nose is n). Find the genotype and the phenotype

N N N N N N N N N n n n

Albinism

PRACTICE!

1. Cross a homozygous dominant with a homozygous recessive (for height where T is dominant and tall). Find the genotype(s) and the phenotype(s)

2. Cross a heterozygote with a recessive (for height where T is dominant and tall). Find the genotype(s) and the phenotype(s)

3. Cross a heterozygote with another heterozygote (for skin color where Black is B, b = white). Find the genotype(s) and the phenotype(s)