View
8.521
Download
3
Category
Tags:
Preview:
DESCRIPTION
bio101
Citation preview
Sylvia S
. Mad
er
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
BIOLOGY10th Edition
Mendelian Patterns of Inheritance
Chapter 11: pp. 189 - 210
1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Parents
eggs
Ee Ee
sp
em
Pu
nn
ett
sq
ua
re
Offspring
E e
E
e
Ee
EeEE
ee
TT tt
tT
Tt
eggs
sp
erm
Offspring
T t
T
t
TT Tt
Tt tt
2
Outline
Blending InheritanceMonohybrid Cross
Law of SegregationModern Genetics
Genotype vs. PhenotypePunnett Square
Dihybrid CrossLaw of Independent Assortment
Human Genetic Disorders
3
Gregor Mendel
Austrian monk Studied science and mathematics at University of
Vienna Conducted breeding experiments with the garden pea
Pisum sativum Carefully gathered and documented mathematical data
from his experiments
Formulated fundamental laws of heredity in early 1860s Had no knowledge of cells or chromosomes Did not have a microscope
4
Gregor Mendel
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Ned M. Seidler/Nationa1 Geographic Image Collection
5
Fruit and Flower of the Garden Pea
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a.
Flower Structure
filament
antherstamen
stigma
style
ovules inovary
carpel
6
Garden Pea Traits Studied by Mendel
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cutting awayanthers
Brushing onpollen fromanother plant
All peas are yellow whenone parent produces yellowseeds and the other parentproduces green seeds.
7
Blending Inheritance
Theories of inheritance in Mendel’s time:Based on blendingParents of contrasting appearance produce
offspring of intermediate appearanceMendel’s findings were in contrast with this
He formulated the particulate theory of inheritance
Inheritance involves reshuffling of genes from generation to generation
8
One-Trait Inheritance
Mendel performed cross-breeding experimentsUsed “true-breeding” (homozygous) plantsChose varieties that differed in only one trait
(monohybrid cross)Performed reciprocal crosses
Parental generation = PFirst filial generation offspring = F1
Second filial generation offspring = F2
Formulated the Law of Segregation
9
Mendel’s Monohybrid Crosses:An Example
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
TT tt
tT
P generation
P gametes
F1 gametes
F2 generation
F1 generation
Tt
T t
sper
m
T
t
TT Tt
Tt tt
Offspring
Phenotypic Ratio
short1tall3
Allele Key
T = tall plantt = short plant
10
Law of Segregation
Each individual has a pair of factors (alleles) for each trait
The factors (alleles) segregate (separate) during gamete (sperm & egg) formation
Each gamete contains only one factor (allele) from each pair
Fertilization gives the offspring two factors for each trait
11
Modern Genetics View
Each trait in a pea plant is controlled by two alleles (alternate forms of a gene)
Dominant allele (capital letter) masks the expression of the recessive allele (lower-case)
Alleles occur on a homologous pair of chromosomes at a particular gene locus
Homozygous = identical alleles
Heterozygous = different alleles
12
Homologous Chromosomes
Replication
alleles at agene locus
sister chromatids
b. Sister chromatids of duplicated chromosomes have same alleles for each gene.
a. Homologous chromosomes have alleles for same genes at specific loci.
G
R
S
t
G
R
S
t
G
R
S
t
g
r
s
T
g
r
s
T
g
r
s
T
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
13
Genotype versus Phenotype
Genotype
Refers to the two alleles an individual has for a specific trait
If identical, genotype is homozygous
If different, genotype is heterozygous
Phenotype
Refers to the physical appearance of the individual
14
Genotype versus Phenotype
15
Punnett Square
Table listing all possible genotypes resulting from a cross
All possible sperm genotypes are lined up on one side
All possible egg genotypes are lined up on the other side
Every possible zygote genotypes are placed within the squares
16
Punnett Square
Allows us to easily calculate probability, of genotypes and phenotypes among the offspring
Punnett square in next slide shows a 50% (or ½) chance The chance of E = ½ The chance of e = ½
An offspring will inherit: The chance of EE =½!½=¼ The chance of Ee =½!½=¼ The chance of eE =½!½=¼ The chance of ee =½!½=¼
17
Punnett Square Showing Earlobe Inheritance Patterns
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Parents
Ee Ee
eggs
spem
Pu
nn
ett
squ
are
Offspring
E e
E
e
Ee
EeEE
e e
Allele key Phenotypic Ratio
unattached earlobes3
1
E = unattached earlobese = attached earlobes
attached earlobes
18
Monohybrid Test cross
Individuals with recessive phenotype always have the homozygous recessive genotype
However, individuals with dominant phenotype have indeterminate genotype
May be homozygous dominant, or
Heterozygous
Test cross determines genotype of individual having dominant phenotype
19
One-Trait Test Cross
Insert figure 11.7a here
Phenotypic Ratio
eggs
a.
sp
erm
t
T
t
Offspring
Tt tt
Tt
tt
Allele Key
short1tall1
T = tall plantt = short plant
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
20
One-Trait Test Cross
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
b.
tT
Tt
Offspring
eggssperm
TT tt
Allele Key
Phenotypic RatioAll tall plants
T = tall plantt = short plant
21
Two-Trait Inheritance
Dihybrid cross uses true-breeding plants differing in two traits
Observed phenotypes among F2 plants
Formulated Law of Independent Assortment
The pair of factors for one trait segregate independently of the factors for other traits
All possible combinations of factors can occur in the gametes Mendel tracked each trait through two generations.
P generation is the parental generation in a breeding experiment. F1 generation is the first-generation offspring in a breeding
experiment. F2 generation is the second-generation offspring in a breeding
experiment
22
Two-Trait (Dihybrid) Cross
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
TtGg
ttgg
TTGG
Offspring
P generation
P gametes
F2 generation
F1 generation
F1 gametes
eggs
sperm
TG Tg
TG
Tg
tg
tG
tG tg
tgTG
TTGg TtGG TtGg
TTGg Ttgg
TtGG ttGG ttGg
TtGg Ttgg ttGg
ttggTTGG
TtGg
TTgg
TtGg
Allele Key
====
TtGg
tall plantshort plantgreen podyellow pod
Phenotypic Ratio
9 tall plant, green pod3 tall plant, yellow pod3 short plant, green pod1 short plant, yellow pod
23
Independent Assortment and Segregation during Meiosis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Parent cell has twopairs of homologouschromosomes.
All possible combina-tions of chromosomesand alleles occur inthe gametes assuggested by Mendel'stwo laws.
All orientations of ho-mologous chromosomesare possible at meta-phase I in keeping withthe law of independentassortment.
At metaphase II, eachdaughter cell has onlyone member of eachhomologous pair inkeeping with the law ofsegregation.
A
A A
A A
A
A
AB
ab
Ab
aB
a
a
a
a
a
a
a
A
AbA
aa a
B
B
BB
B
B
B
B
B
Ba
B
b
b b
A A
b b BB
a a
b
b
b
b
b
A
b
b
either
or
Animation
24
Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
25
Human Genetic Disorders
Genetic disorders are medical conditions caused by alleles inherited from parents
Autosome - Any chromosome other than a sex chromosome (X or Y)
Genetic disorders caused by genes on autosomes are called autosomal disorders Some genetic disorders are autosomal dominant
An individual with AA has the disorder An individual with Aa has the disorder An individual with aa does NOT have disorder
Other genetic disorders are autosomal recessive An individual with AA does NOT have disorder An individual with Aa does NOT have disorder, but is a carrier An individual with aa DOES have the disorder
26
Autosomal Recessive Pedigree Chart
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Autosomal recessive disorders• Most affected children have unaffected parents.• Heterozygotes (Aa) have an unaffected phenotype.• Two affected parents will always have affected children.• Close relatives who reproduce are more likely to have affected children.• Both males and females are affected with equal frequency.
aa aa
Aa Aa
Aa
A? A?
A?
Aa
*
aa A?
A?A?
Key
aa = affectedAa = carrier (unaffected)AA = unaffectedA? = unaffected(one allele unknown)
I
II
III
IV
27
Autosomal Dominant Pedigree Chart
Aa
aa aa aa
aaaaaaaaAa
aa
Aa
Aa A?
Aa
Autosomal dominant disorders• affected children will usually have an affected parent.• Heterozygotes (Aa) are affected.Two affected parents can produce an unaffected child.
•Two unaffected parents will not have affected children.• Both males and females are affected with equal frequency.
*
I
II
III
•
KeyAA = affectedAa = affectedA? = affected(one allele unknown)aa = unaffected
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
28
Autosomal Recessive Disorders
Tay-Sachs Disease
Progressive deterioration of psychomotor functions
Cystic Fibrosis
Mucus in bronchial tubes and pancreatic ducts is particularly thick and viscous
Phenylketonuria (PKU)
Lack enzyme for normal metabolism of phenylalanine
29
Cystic Fibrosis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cl-
H2O
H2O
H2O
Cl-
Cl-
Cl-
Cl-
thick mucus
defectivechannel
nebulizer
percussionvest
© Pat Pendarvis
30
Methemoglobinemia
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Courtesy Division of Medical Toxicology, University of Virginia
Animation
Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
32
Autosomal Dominant Disorders
NeurofibromatosisTan or dark spots develop on skin and darken Small, benign tumors may arise from fibrous
nerve coveringsHuntington Disease
Neurological disorderProgressive degeneration of brain cells
Severe muscle spasmsPersonality disorders
33
A Victim of Huntington Disease
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a: © Steve Uzzell
JJ JK JK JK
JK JJ
KL JK JK JK JK KL JK JK KL KK KL JL JJ
JL JK
JL KL KL
JL JL JL JL JJ KL JJ KL JJ KL KL
a. b.
34
Incomplete Dominance
Heterozygote has phenotype intermediate between that of either homozygote
Homozygous red has red phenotype
Homozygous white has white phenotype
Heterozygote has pink (intermediate) phenotype
Phenotype reveals genotype without test cross
35
Incomplete Dominance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
R1 R2
R1
R2
R1R2
R1R2R1R1
R2R2
R1R2 R1R2
eggs
sperm
Offspring
Key
1 R1R12 R1R21 R2R2
redpinkwhite
36
Multiple Allelic Traits
Some traits controlled by multiple alleles The gene exists in several allelic forms (but each individual only has
two) ABO blood types The alleles:
IA = A antigen on red cells, anti-B antibody in plasma IB = B antigen on red cells, anti-AB antibody in plasma I = Neither A nor B antigens, both antibodies
37
Multiple Allelic Traits
38
Pleioptropic Effects
Pleiotropy occurs when a single mutant gene affects two or more distinct and seemingly unrelated traits. Marfan syndrome have disproportionately
long arms, legs, hands, and feet; a weakened aorta; poor eyesight
39
Marfan Syndrome
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Left): © AP/Wide World Photos; (Right): © Ed Reschke
Chest wall deformitiesLong, thin fingers, arms, legsScoliosis (curvature of the spine)Flat feetLong, narrow faceLoose joints
Skeleton SkinLungsEyes
Mitral valveprolapse
Lens dislocationSevere nearsightedness
Collapsed lungsStretch marks in skinRecurrent herniasDural ectasia: stretching of the membrane that holds spinal fluid
Enlargementof aorta
Heart and blood vessels
AneurysmAortic wall tear
Connectivetissue defects
40
Polygenic Inheritance
Occurs when a trait is governed by two or more genes having different alleles
Each dominant allele has a quantitative effect on the phenotype
These effects are additive
Result in continuous variation of phenotypes
41
Frequency Distributions in Polygenic Inheritance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
F2 generation
F1 generation
P generation
aabbcc
Aabbcc
AaBbcc
AaBbCc
AABbCc
AABBCc
AABBCC
Genotype Examples
1
64—
6—64
15—64
20—64
Pro
po
rtio
n o
f P
op
ula
tio
n
42
X – Linked Inheritance
In mammals The X and Y chromosomes determine gender Females are XX Males are XY
The term X-linked is used for genes that have nothing to do with gender Carried on the X chromosome. The Y chromosome does not carry these genes Discovered in the early 1900s by a group at Columbia
University, headed by Thomas Hunt Morgan. Performed experiments with fruit flies
They can be easily and inexpensively raised in simple laboratory glassware
Fruit flies have the same sex chromosome pattern as humans
43
X – Linked Inheritance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Offspring
eggs
sp
erm
P generation
P gametes
F2 generation
F1 generation
F1 gametes
XRXRXrY
Xr XRY
XRY XRXr
XrXR
XRXrXRXR
XrYXRY
XR
Y
Allele Key
XR = red eyesXr = white eyes
Phenotypic Ratio
females: all red-eyedmales : 1 red-eyed 1 white-eyed
44
Human X-Linked Disorders
Several X-linked recessive disorders occur in humans: Color blindness
The allele for the blue-sensitive protein is autosomal The alleles for the red- and green-sensitive pigments are on the X
chromosome. Menkes syndrome
Caused by a defective allele on the X chromosome Disrupts movement of the metal copper in and out of cells.
Muscular dystrophy Wasting away of the muscle
Adrenoleukodystrophy X-linked recessive disorder Failure of a carrier protein to move either an enzyme or very long chain fatty
acid into peroxisomes. Hemophilia
Absence or minimal presence of a clotting factor VIII, or clotting factor IX Affected person’s blood either does not clot or clots very slowly.
X-Linked Recessive Pedigree
45
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
XBXB XbY grandfather
daughterXBXbXBY XBY XbXb
XbY
XBXb grandsonXBY XBXB XbY
KeyXBXB = Unaffected femaleXBXb = Carrier femaleXbXb = Color-blind femaleXbY = Unaffected maleXbY = Color-blind maleX-Linked Recessive
Disorders
• More males than females are affected.
• An affected son can have parents who have the normal phenotype.
• For a female to have the characteristic, her father must also have it. Her mother must have it or be a carrier.
• The characteristic often skips a generation from the grandfather to the grandson.
• If a woman has the characteristic, all of her sons will have it.
46
Muscle Dystrophy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Abnormal): Courtesy Dr. Rabi Tawil, Director, Neuromuscular Pathology Laboratory, University of Rochester Medical Center; (Boy): Courtesy Muscular Dystrophy Association; (Normal): Courtesy Dr. Rabi Tawil, Director, Neuromuscular Pathology Laboratory,
University of Rochester Medical Center.
abnormalmuscle
normaltissue
fibroustissue
47
Terminology
Pleiotropy A gene that affects more than one characteristic of an
individual Sickle-cell (incomplete dominance)
Codominance More than one allele is fully expressed ABO blood type (multiple allelic traits)
Epistasis A gene at one locus interferes with the expression of a
gene at a different locus Human skin color (polygenic inheritance)
48
Review
Blending InheritanceMonohybrid Cross
Law of Segregation
Modern Genetics Genotype vs. Phenotype Punnett Square
Dihybrid Cross Law of Independent Assortment
Human Genetic Disorders
Sylvia S
. Mad
er
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
BIOLOGY10th Edition
Mendelian Patterns of Inheritance
Chapter 11: pp. 189 - 210
49
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Parents
eggs
Ee Ee
sp
em
Pu
nn
ett
sq
ua
re
Offspring
E e
E
e
Ee
EeEE
ee
TT tt
tT
Tt
eggs
sp
erm
Offspring
T t
T
t
TT Tt
Tt tt
Recommended