Human Genetic Traits

1
Human Genetic Traits
2
Beliefs about Heredity
Fig. 1. De la propagation du genre humain, ou
manuel indispensable pour ceux qui veulent avoir
de beaux enfants de lun ou lautre sexe (Paris,
Year VII). Image courtesy of the Bibliothèque
Interuniversitaire de Médecine, Paris.
3
Homunculus
How is heredity passed on Spermist vs Ovists
Spermist conception of a human sperm
4
Homunculus
Leeuwenhoeks black male and white female rabbit
experiments spermist proof
5
Darwin
What he got right.
What he got wrong.

• Acquired characteristics

• Likes produce likes
• Change can be permanent
• There is no limit to cumulative change

Ex. Blind cave animals

• Sex. Repro.- gemmules from all over body are
  packed in sperm and egg
• Blended inheritance

6
Mendelian Genetics
Gregor Mendel
7

• Mendels Three Principles
• Dominance
• Segregation
• Independent Assortment

(1822-1884)
The foundation of classical science
8

• Dominance
• Traits of both parents inherited, but one shows
  over the other
• Traits are not blended

9

• Dominance Mechanism
• Two alleles are carried for each trait
• In true-breeding individuals, both alleles are
  the same.
• Hybrids, on the other hand, have one of each kind
  of allele.
• One trait is dominant, the other trait is
  recessive

10

• Segregation
• Half the gametes (egg or sperm) will carry the
  traits of one parent and half the traits for the
  other parent

Pairs of alleles are separated (segregated)
during meiosis
11
Two different parental characteristics will be
inherited independently of one another during
gamete formation.
Example flower color and leaf shape
12
Human Genome Project

• U.S. govt. project coordinated by the Department
  of Energy and the National Institutes of Health,
  launched in 1986 by Charles DeLisi.
• Definition GENOME the whole hereditary
  information of an organism that is encoded in the
  DNA.
• Project Goal to identify the approximate 100,000
  genes in the human DNA.
• determine the sequences of the 3 billion bases
  that make up human DNA.
• store this information in databases.
• develop tools for data analysis.
• address the ethical, legal, and social issues
  that arise from genome research.

13
Modeled Organisms

• Bacteria (E. coli, influenza, several others)
• Yeast (Saccharomyces cerevisiae)
• Plant (Arabidopsis thaliana)
• Fruit fly (Drosophila melanogaster)
• Mouse (Mus musculus)

14
Craig Venter
Celera Genomics
15
Importance of genetics

• Understanding hereditary diseases and to develop
  new treatments
• Donor matches
• Paternity
• Forensics
• Evolution
• Migration

16
Polynesian Origins
mtDNA
Bismarck Archipelago
3.5ka
http//www.sciencedaily.com/releases/2011/02/11020
3124726.htm
17
Polynesian Origins
18
Genetic Testing

• Would you want to know?
• Ethical concerns
• Cost
• Insurance companies

19
Difference between Meiosis and Mitosis
20
Meiosis I
Interphase
Prophase I
Metaphase I
Anaphase I
Telephase I
21
Crossing Over of Nonsister Chromatids between
Homologous Chromosomes
22
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telephase II
23
(No Transcript)
24
Genetic Testing
25
Gel electrophoresis
26
Polymerase Chain Reaction

• PCR way of copying specific DNA fragments from
  small sample DNA material "molecular
  photocopying"
• Its fast, inexpensive and simple

27
(No Transcript)
28
Genetic Testing
299, looks at specific diseases
23 and me
Paternity Test 99
29
Genetic Definitions

• Genes- genetic material on a chromosome that
  codes for a specific trait
• Genotype- the genetic makeup of the organism
• Phenotype- the expressed trait
• Allel- an alternative form of a gene

30

• 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 is
  recessive

31
Genetic Information
Genes are traits Eye color Ear lobe
connectedness Genes produce proteins Enzymes are
proteins
32
Homologous Chromosomes
gene location
allele specific trait
33
Allele Example
Gene eye color Alleles brown blue green lavend
er
34
Allele Examples
appearance
eye colorhomozygous
35
Allele Examples
appearance
eye colorheterozygous, brown dominant over blue
36
Genotype vs Phenotype
genotype phenotype
homozygous(dominant) heterozygous homozygous (r
ecessive)
appearance
37
Punnett Square
If male female are heterozygous for eye color
male
female
X
brown 3/4 offspring blue 1/4 offspring
38
PKU Each parent carries one gene for PKU.
p
P
P
P
P
P
p
P
p
X
P
p
P
p
p
p
p
Possible genotypes 1PP 2Pp 1pp Possible
phenotypesno PKU PKU
39
Compare this to what would have happened if one
parent was homozygous for sickle cell.
HbA
HbA
HbA
HbA
HbS
HbA
HbA
HbS
HbS
X
HbA
HbA
HbS
HbS
HbS
HbS
HbS
all offspring are carriers of sickle cell trait
40
Where Does Genetic Diversity Come From?

• Mutation
• Chromosomal Aberrations
• Genetic Recombination (e.g., from sexual
  reproduction)

41
Sickle Cell Mutation
NORMAL Hb
CTG ACT CCT GAG GAG AAG TCT Leu Thr Pro Glu
Glu Lys Ser
SICKLE CELL
CTG ACT CCT GAG GTG AAG TCT Leu Thr Pro Glu
Val Lys Ser
mutation
42
Autosomes and Sex Chromosomes
43
Red-Green Color Blindness Sex-linked trait
Y
XC
XC
Y
XC
XC
XC
Normal male
XC
Y
X
XC
Xc
XC
Xc
Xc
Xc
Y
Normal female recessive gene
Possible outcomes XCXC XCXc XCY XcY
Normal female
Normal Female (carrier)
Normal male
Color-blind male
44
allele
gene
E unconnected earlobe e connected earlobe
unconnected
P
EE x ee
E e
gametes
connected
F1
Ee
45
F1
Ee x Ee
1/2 E 1/2 e1/2 E 1/2 e
gametes
E
e
E
EE
Ee
PunnettSquare
e
Ee
ee
F2
1 EE 2 Ee 1 ee
46
Genotypes Phenotypes
Experiment to determinedominant vs. recessive
47
Genetic Sleuthing
My eye color phenotype is brown. What is my
genotype?
48
Complexities

• Multiple genes for one trait
• Example eye color
• Blended traits (incomplete dominance)
• Influence of the environment (UV, smoking,
  alcoholism)

49
Complexities

• Co-dominance-neither allele is recessive and the
  phenotypes of both alleles are expressed.
• Blood types- AB (not O) sickle cell anemia

heterochromia
50
Disorders
Downs Syndrome (chrom 21)
Alzheimers (chrom 1, 10, 14, 19, 21)
Huntingtons (chrom 4)
51
Human Genetic Traits
52
Tongue Roller
R Tongue Rollerr Unable to Roll Tongue
53
Widows Peak
W Widows Peakw Lack of Widows Peak
54
Free Ear Lobe
Attached Ear Lobe
E Free Ear Lobee Attached Ear Lobe
55
Hitchhikers Thumb
Hi Straight Thumbhi Hitchhikers Thumb
56
Bent Little Finger
Bf Bent Little Fingerbf Straight Little
Finger
57
Mid-digital Hair
M Mid-Digital Hairm Absence of Mid-Digital
Hair
58
Dimples
D Dimplesd Absence of Dimples
59
Short Hallux
Ha Short Halluxha Long Hallux
60
Short Index Finger
Ss Short Index FingerS1 Long Index Finger
Sex-Influenced Trait
61
http//www.youtube.com/watch?vgCPuHzbb5hA