Genetics - part one

1

Simple Genetics (One Gene for One Trait)

n Mendel’s Pea Plants. – Tall or short. – Round or wrinkled. – Etc…

n Dominant & recessive. n Purebred or Hybrid. n Simple Punnett Squares.

1 Gregor Mendel TEST 1 on SLIDES 1-19

2

n Gregor Mendel was a monk who worked with pea plants in the mid 1800’s. Today he is known as “Father of Genetics.”

He was curious about the “factors” acting on inheritance. Are there patterns?

3

What is Genetics?

n Genetics is the branch of biology that deals with heredity.

n Heredity is the passing of traits from

parents to offspring. – Parents à offspring

n Traits are characteristics of an organism.

– Human examples: height, hair, eye color.

Genetics - part one

2

4

n  Gene: a section/piece of DNA on a chromosome that codes for a specific trait.

§  Alleles = alternate forms of a gene (Ex: Blood type A/B/O). §  Genes tend to come in pairs (alleles).

n  DOMINANT: an allele whose trait always shows up in the organism when the allele present.

–  (CAPITAL LETTER)

n  recessive: an allele hidden by dominant. –  (lower case letter)

n  Genotype: genetic makeup; allele combinations. –  (Ex: BB, Bb, bb)

n  Phenotype: physical appearance of an organism

(Ex: Brown hair)

5

How to make a test cross (aka Punnett Square)

Offspring Offspring

Offspring Offspring

Parent #1 alleles

Pare

nt #

2 al

lele

s

6

Genetics - part one

3

7

Diagrams & math can be used to predict the probability that a trait will pass from parent(s) to offspring.

Punnet Squares

8

Complete this test cross between two purebred pea plants:

t

t

T T

T = tall stem t = short stem 9

Genetics - part one

4

10

11

12

Where are genes?

n  Genes & chromosomes come in pairs. Most human cells have 23 pairs of chromosomes in the nucleus containing just under 30,000 genes.

Genetics - part one

5

13

14

CHROMOSOMES

n  Half from each gamete (sperm and egg). n  But what about asexual reproduction???

15

Code Conservation

n  All species on Earth use the same chemical code (GTCA). Biodiversity comes from SNP’s along a gene sequence.

Genetics - part one

6

Terms Must Know n  Allele n  Chromosome n  DNA (GTCA) n  Dominant n  Gene & Genetics n  Genotype n  Heterozygous n  Heredity n  Homozygous n  Hybrid n  Meiosis n  Mutation n  Offspring n  Phenotype n  Probability n  Punnett Square (Cross) n  Purebred n  Recessive n  Traits

Challenge

n  Central Dogma n  Co-dominance n  Dihybrid cross n  Diploid n  Haploid n  Histones n  Gametes n  Locus (Loci) n  Mutagen n  Pedigree chart n  Purines (A & G) n  Pyrimidines (T & C)

16

17

Challenge Mendel’s Dihybrid cross

n We can look at two traits simultaneously using a dihybrid cross.

n Consider shape & color in peas – R: round r: wrinkled – Y: yellow y: green – Cross two heterozygotes RrYy x RrYy – Try in your notes now!

18

RY Ry ry rY

RY Ry ry rY

Genetics - part one

7

19

GENETICS PART TWO

-COMPLEX- NON-MENDELIAN

20

1953

Watson & Crick

DNA Structure understood

Rosalind Franklin 21

Genetics - part one

8

DNA

*Human Genome mapped in 2003 22

Central Dogma DNA à mRNA à Protein

23

The Limits of Mendel’s work

n  Mendel’s experiments with pea plants looked at one gene for one trait. –  This pattern of inheritance is called Mendelian..

§  Some examples: Cheek dimples, face freckles & cleft chins §  Tom Bradyà

n  Few human traits actually obey this model

24

Genetics - part one

9

Polygenic Traits

n  Most human traits are polygenic, which means they are controlled by multiple genes. – This leads to a wide array of phenotypes. – Simple Punnett squares do NOT work for

polygenic traits. § EX: Human height & eye color.

25

Dynamic Development (GxE)

n  Genes interact with their environment (GxE) –  In other words, there is a relationship

between your genetics & the way you live your life. § Nutrition, hormones, sensory input,

physical and, etc…

n Epigenetics: Markers & tags (i.e. methyl

groups), along with histones affect the epigenome of an organism.

26

Mutations

n Mutations are changes in the DNA bases. –  G. T. C. A. – Change can be letter addition,

substitution, deletion or inversion.

n Mutations can be good, bad or indifferent to an organism.

n Mutagens are agents capable of causing a mutation, such as UV light or certain chemicals.

27

Genetics - part one

10

Mutations & Evolution

n Mutations drive evolution. – Since all living things use the same chemicals

(G.T.C.A.) for their “code,” changes are necessary to give rise to new species. § A concept better known as genetic variation.

–  Observed at the taxonomic levels (D.K.P.C.O.F.G.s.)

n Genetic Variation à Biodiversity.

28

Glowing mutant mice, frog/duck genetic mutants.

29

Drug resistant bacteria, mushroom mutant, lungfish, tomato mutations.

30

Genetics - part one

11

31

Quotes:

n “It’s not that I’m so smart, it’s just that I stay with problems longer.” -Albert Einstein.���

���n  “I'm not out there sweating for three hours every day

just to find out what it feels like to sweat.” -Michael Jordan.���

���n  “Some people want it to happen, some wish it would

happen, and others make it happen.” -Michael Jordan.

32

33

CALGENE 1994-1997 First GM Tomato approved by FDA

Genetics - part one

12

34

Faroe Islands (Denmark) ~ 50,000 People. Genome sequencing project for entire population (2013)

Human Genome Project 1987-2003. [~3.3 billion base pairs]