024a Human Genetics.ppt

7/27/2019 024a Human Genetics.ppt

1/36


2/36

Importance of genetics

Understanding hereditary diseases and to

develop new treatments Donor matches

Paternity

Forensics

Evolution


3/36

Genetic Testing

Would you want to know?

Ethical concerns

Cost

Insurance companies

see GATTACA


4/36

Genes- genetic material on a

chromosome that codes for aspecific trait

Genotype- the genetic makeup of

the organism

Phenotype- the expressed trait

Allel- an alternative form of a

gene


5/36

Dominance Mechanism

Two alleles are carried for each trait

In true-breeding individuals, both

alleles are the same (homozygous). Hybrids, on the other hand, have one

of each kind of allele (heterozygous).

One trait is dominant, the other trait isrecessive


6/36

Genetic Information

Genes are traits

Eye color

Ear lobe connectedness

Genes produce proteins

Enzymes are proteins


7/36

Homologous Chromosomes

allele: specific trait

gene: location


8/36

Allele Example

Gene = eye color

Alleles

brownblue

green

lavender


9/36

Allele Examples

appearance

eye color:

homozygous


10/36

Allele Examples

appearance

eye color:

heterozygous,brown dominant

over blue


11/36

Genotype vs Phenotype

homozygous

(dominant)

heterozygous

homozygous(recessive)

genotype phenotype

appearance

Phaner= visible


12/36

Punnett Square

If male & female areheterozygous for eye

color

X

brown: 3/4 offspring

blue: 1/4 offspring

male

female


13/36

PKU

Each parent carries one gene for PKU.

P p

P p

X

P

p

pP

PP

Pp

p

P

p

p

Possible genotypes: 1PP 2Pp 1pp

Possible phenotypes:no PKU PKU


14/36

Compare this to what would have happened

if one parent was homozygous for sickle

cell.

HbA HbA

HbS HbS

X

HbS

HbS

HbAHbA

HbA

HbS

HbA

HbS

HbS

HbA

HbS

HbA

all offspring are carriers of sickle cell trait


15/36

Autosomes and Sex Chromosomes


16/36

Red-Green Color Blindness

Sex-linked trait

XC Y

XC Xc

X

XC

Xc

YXC

X

C

XC

X

C

Y

Xc

XC

Y

Xc

Normal male

Normal female

recessive gene

Possible outcomes: XCXC XCXc XCY XcYNormal

female

Normal

Female(carrier)

Normal

male

Color-blind

male


17/36

Dominance

Most traits show complete

dominance

Blending unexpected


18/36

E unconnected earlobee connected earlobe

allele gene

P EE x ee

gametes E e

F1 Ee

unconnected

connected


19/36

F1 Ee x Ee

gametes1/2 E 1/2 e

1/2 E 1/2 e

E

e

E e

EE Ee

Ee ee

F2

1 EE 2 Ee 1 ee

Punnett

Square


20/36

P

F1

F2

EE, ee

Ee

EE, 2 Ee, ee

50%

100%

75%

1:1

1:1

1:1

generation genotypes unconnected E:e

Basis of the Castle-Hardy-Weinberg Law

phenotypes

ratio of alleles in the population


21/36

Genotypes Phenotypes

Experiment to determinedominant vs. recessive


22/36

Genetic Sleuthing

My eye color phenotype is brown.

What is my genotype?


23/36

Pedigree phenotypes

infer genotypes

Alternative:

look directly at the DNA


24/36

Complexities

Multiple genes for one trait

Example: eye color

Blended traits (incomplete

dominance)

Influence of the environment


25/36

Disorders

Downs Syndrome (chrom 21)

Huntingtons (chrom 4)

Alzheimers (chrom 1, 10, 14, 19, 21)


26/36


27/36

Tongue Roller

R= Tongue Roller

r = Unable to Roll Tongue


28/36

Widows Peak

W= Widows Peak

w = Lack of Widows Peak


29/36

Free Ear Lobe Attached Ear Lobe

E= Free Ear Lobe

e = Attached Ear Lobe


30/36

Hitchhikers Thumb

Hi= Straight Thumb

hi= Hitchhikers Thumb


31/36

Bent Little Finger

Bf= Bent Little Finger

bf = Straight Little Finger Mid digital Hair


32/36

Mid-digital Hair

M= Mid-Digital Hair

m = Absence of Mid-Digital Hair


33/36

Dimples

D = Dimples

d = Absence of Dimples Short Hallux


34/36

Short Hallux

Ha = Short Hallux

ha = Long Hallux

Short Index Finger


35/36

Short Index Finger

Ss = Short Index Finger

S1 = Long Index Finger

*Sex-Influenced Trait


36/36

Pttttthhhhhhhtttt!

Kiss me, you fool.

Documents

024a Human Genetics.ppt