Download Human Genetics PowerPoints Notes

Two copies of each autosomal gene affect
phenotype (physical).
• Mendel studied
autosomal gene traits,
like hair texture.
Autosome –
chromosome with genes
not related to sex of
organism (body cells)
Dwarfism and Longevity
BIO.B.2.1.1 Describe and/or predict
observed patterns of inheritance (i.e.,
dominant, recessive, co-dominance,
incomplete dominance, sex-linked,
polygenic, and multiple alleles).
• Amniocentesis
• Incomplete dominance
• Co-dominance
• Carrier
• Polygenic
• Epistatic
• Autosomes
• Pedigree
• Karyotype
Several methods help map human chromosomes.
• Karyotype - a picture of all chromosomes in a cell.
XY
• Karyotypes can show changes in chromosomes.
– deletion of part of a chromosome or loss of a
chromosome
– large changes in chromosomes
– extra chromosomes or duplication of part of a
chromosome
Karyotype
The arrangement of all the chromosomes found in a cell.
Includes:
Autosomes: chromosome pairs 1-22
Sex Chromosomes: chromosome pair 23
Female =
XX
Male = X Y
23rd pair
Female sex
chromosomes
XX
Process Box 1:
What information can you determine from a karyotype. Use the terms
autosomes and sex chromosomes.
Amniocentesis
A medical technique used to collect the chromosomes of a developing
fetus. It is done by inserting a needle into the womb and gathering
cells in the amniotic fluid.
FEMALE
“Autosomes”
MALE
Sex Chromosomes (they
determine male or female)
Who determines the sex of the
offspring?
Father – he can provide an X or
Y chromosome
Egg
X
X
XX
XX
X
X
Body Cell
X
XX
XX
XY
XY
X
XY
Body Cell
Y
Y
Sperm
1female:1male
We were all female
• Genes on sex chromosomes are called sex-linked genes.
.
– Y chromosome - male characteristics .
– X chromosome - genes affects many traits.
Males can pass on X or Y
Females only pass on X
East German Olympic team
Process Box 2:
King Henry VIII is known for being ‘angry’ with his wives and blamed them for
not producing a son. Explain why King Henry VIII should have found fault with
himself.
• Males have an XY genotype.
– All of a male’s
sex-linked genes
are expressed.
– Males have no
second copies of
sex-linked genes
– Y chromosome is
much smaller
Females can carry sex-linked genetic disorders.
• Males (XY) express all of their sex linked genes.
• Expression of the disorder depends on which parent carries
the allele and the sex of the child.
X chromosome carries about 1100 genes while the Y carries about 250
Sex-linked disorder: Color Blindness
1. Genetic disorder found on the sex chromosome X
2. Known as a “sex-linked” because its found on chromosome 23
3. Normal Color Vision (N) = Dominant
Colorblindness (n) = Recessive
2.
Can’t distinguish between colors
3.
More boys, than girls, are color blind…..WHY?
• Color blindness is a
problem in which red or
green look like shades
of gray or other colors.
Jets vs Bills
• The gene is carried on
the X chromosome and
is a recessive trait.
XN
XNXN = normal female
XNXn = female, normal vision
(carrier)
XNY = normal vision male
XnY = color blind male
XN
Y
Xn
XNXN
XNXn
XNY
XnY
Sex-linked disorder: Color Blindness
XN
XN
Color blind Dad and Normal mother produces….
Two normal sons
Xn
XN Xn XN Xn
Y
XN Y
XN
XN
2 “carrier” daughters (NOT color blind)
XN Y
Xn
XN XN XNXn
Normal Dad and Carrier mother
produces….
1 color blind son, 1 normal son
1 “carrier” daughter, 1 normal daughter
Y
XN Y
Xn Y
What is the only way to get a color-blind daughter??
Sex-linked disorder: Hemophila
1. Recessive genetic disorder found on the sex chromosome X
2.
Disease in which blood doesn’t clot properly.
3.
Normal Blood Clotting (N) = Dominant
Hemophilia (n) = Recessive
Royal family pedigree
Rasputin
Sex-linked disorder: Hemophila
XH
XH
Affected dad and Normal Mother produces….
Two normal sons
Xh
XH Xh XH Xh
Y
XH Y
XH
2 “carrier” daughters
XH Y
Xh
Normal Father and Carrier Mother produces….
XH
XH XH XH Xh
1 color blind son, 1 normal son
1 “carrier” daughter, 1 normal daughter
Y
XH Y
Xh Y
What cross will ALWAYS yield you 100% affected sons?
– Carrier – has an allele for as trait or disease that is
not expressed.
– Carrier does not have disease symptoms but can
pass it on to offspring.
___
___
___
___
__ __
___
__ __
TOP PARENT: A CARRIER
MOM: A CARRIER
SIDE PARENT: AFFECTED
DAD: AFFECTED
-Dominant allele disorders are rare.
-They affect TWO genotypes
-Pure Dominant
-Heterozygous
Huntington’s disease is an example of a disease caused
by a dominant allele. (Danny with Huntington’s Disease)
Process Box 3:
What does it mean to have a
sex-linked trait?
Why do men have a greater chance of being
‘affected’ with certain sex-linked traits/disorders?
Process Box 4:
Is this a “sex-linked” trait or an
“autosomal trait” if the gene is
found on …
a.
b.
c.
d.
Chromosome 12 and the gene is dominant?
Chromosome 23 and the gene is dominant?
On the X chromosome and it is dominant?
On the X chromosome and it is recessive?
Do Now
• In a family, the father does Not have
hemophilia and the mother is a carrier.
What is the chance that they will have a
child with hemophilia?
XN
y
XN
Xn
XNXN
XNXn
XNy
Xny
1XNXN : 1XNXn : 1XNy
:
1Xny
1 normal female
1 normal ‘carrier’ female
1 normal male
1 hemophiliac male
25% chance of having a child effected with hemophilia
The child WILL ALWAYS BE A MALE!!!!
50/50 chance for a male child to have hemophilia
• Some traits are neither totally dominant nor totally
recessive.
• Incomplete dominance - when neither gene is totally
dominant to the other
- Heterozygous phenotype is intermediate between the
two homozygous phenotypes
– Example: White flowers and red flowers produce
pink flowers
Incomplete Dominance
X
Straight
Curly
Pink
There is a third
color that exists in
the heterozygous
type. It’s a. mixture
between the two
homozygous types.
Incomplete Dominance
Incomplete Dominance
Incomplete Dominance
Incomplete dominance
• Codominant - alleles will both be completely expressed.
– Codominant
alleles are
neither
dominant nor
recessive.
– The ABO blood
types result
from
codominant
alleles.
Example – red and white flower produce a
flower with BOTH colors
• Many genes have more than two alleles.
Co-dominance
Heterozygous type shows BOTH phenotypes
exist TOGETHER
Co-dominance
Co-dominance
Co-dominance
Process Box 5:
Describe the difference between co-dominance and
incomplete dominance. Write/or draw an example of codominance and incomplete dominance.
Incomplete: INBETWEEN
BLEND
Codominant: COEXIST
By the results, determine if the traits code for: complete
dominance, incomplete dominance, or codominance:
Brown x White = Brown ___________________
Tall x Short = Medium___________________
Blood A x Blood B = AB ___________________
Sickle Cell Anemia
• Disease in which the body makes sickle-shaped red blood cells.
Sickle-shaped cells don’t move easily through your blood vessels.
They’re stiff and sticky and tend to form clumps and get stuck in the
blood vessels
•The disorder is found on chromosome
11. and is therefore not sex-linked.
• The Oxygen carrying hemoglobin can
not carry oxygen as efficiently and the
odd-shaped cells can easily clot and
break. Fatigue, pain, and organ failure
due to lack of oxygen supply are
common symptoms of sickle cell
anemia.
• It is common in the African community
Actual blood cells
Sickle Cell Anemia
Codominance Practice
•
Genes for blood cells:
• R = Round blood cells
• R’ = Sickle Cells
R
R’
Genotypes for blood cells
RR = normal blood
R
RR’ = some sickle cells, some
normal cells
R’R’ = has sickle cell anemia
Tebow touchdown
R’
RR
RR’
RR’
R’R’
Complete the following crosses, Report the genotypes and phenotypes of the offspring
R = round blood cell
R’ = sickle shape
RR: Round cells
RR’ = sickle cell trait
R’R’: sickle cell anemia
Mixed Cells x Hybrid
---------- x ---------R’
R
Round Blood Cells x Hybrid
---------- x ---------EXPECTED
R
R
EXPECTED
R’ R’
R’ R
RESULTS
1 sickle cell anemia
--------------------------
R’
R’ R
R’ R
R R’ R
RR
2 mixed cells
-------------------------1 normal cells
--------------------------
R
RR
RR
R’
Sickle Cell Anemia x Pure Round
---------- x ----------
R’
R’
R R’ R
R’ R
R
R’ R
R’ R
EXPECTED
RESULTS
4 mixed cells
--------------------------
2-------------------------normal cells
--------------------------
All Round Cells x All Sickle Cells
---------- x ----------
R’
R
--------------------------
--------------------------
RESULTS
2-------------------------mixed cells
R
R’ R
R’
R’ R
EXPECTED
RESULTS
4-------------------------mixed cells
--------------------------
R’ R
R’ R
--------------------------
WRITTEN CONCLUSION
•
•
•
•
•
INTRO
VARIABLE
DATA
ANALYSIS
EXTENSION
1. Blood Type
4 different blood types
• there are _________________________
Blood Type
Genes
Blood Type A
IAIA or IAi
Blood Type B
IBIB or IBi
Blood Type AB
IAIB
Blood Type O
ii
How many
alleles for blood
are there? 3
How many blood
types are there? 4
• Hypothesis:
• What crosses will produce sickle cell trait
versus sickle cell anemia
Which blood types are compatible for transfusion??
Yes or No ?
O
B
A
AB
B
Yes
A
No
AB
Yes
A
No
Yes
O
AB
IB
IB
IA
IA
IA IB
IAIB
I AIB
IAIB
4___________
type AB blood
IB
___________
___________
i
IA
i
I AIB
IBi
IAi
ii
IA
IB
IA i
IBi
1-AB blood
1-hetero
A blood
___________
1-hetero B blood
1-pure
O blood
___________
___________
IA
IA
IA IA
IB
IA IB
IA
i
IB
IAIB
IBIB
i
i
I Ai
IAi
ii
ii
i
1-pure
A blood
___________
2-AB blood
i
1-pure
B blood
___________
IA
___________
2-hetero A blood
i
2O blood
___________
IA i
IBi
IA
i
IA IA
IAi
2-hetero
A blood
___________
2-heteroB blood
___________
IAi
ii
___________
2-hetero A blood
___________
1- O blood
IB
IB
IA
IA
IA IB
IAIB
I AIB
IA
4___________
type AB blood
___________
___________
___________
IAIB
IA
IB
___________
IB
___________
A mother with type O crossed with a father
with heterozygous type A
i
i
i
IAi
IAi
ii
ii
IB
___________
i
___________
An AB mother with an O father
IA
IB
IA
IA
i
i
IAi
IBi
i
IAi
IBi
2-hetero
A blood
___________
2-heteroB blood
___________
Two heterozygous type A’s crossed
IA
IA
2-hetero A blood
___________
2- O blood
i
___________
IA IA
IAi
i
IAi
ii
___________
2-hetero
A blood
1- O blood
___________
Blood type statistics…
• If there are 100 people in the room:
39 will be O+
7 will be O34 will be A+
6 will be A9 will be B+
2 will be B3 will be AB+
and only 1 in 200 will be ABNote: The + and – is the presence (or absence) of a third
antigen (Rh).
• Polygenic traits
are produced
by two or more
genes.
Order of dominance:
brown > green > blue.
• Epistatic gene - can interfere with the
expression of all other genes.
Mice have 5
genes that
control fur
color.
2 genes for
general color
1 for shading
1 for spots
1 epistatic
gene for color
that overrrules
all other genes
• Phenotype is a combination
of genotype and
environment.
• The sex of sea turtles
depends on both genes
and the environment.
Warm eggs develop into
females
• Height is an example of a
phenotype strongly affected
by the environmental factors
such as early nutrition and
health care.
Process Box 6:
Using the words below, make two list that
you would associate with the following types
of genes: Epistatic
Polygenic
Many
Over-ride
Interaction
Several
Multiple
Dominant Range One
Control
Rule
Boss
Various
Albinism
Eye color
• Linked genes are not inherited together
every time.
• Chromosomes exchange homologous genes during
meiosis.
Crossing over – 7:00
Linkage maps – map of location of genes on a chromosome.
• The closer together two genes are, the more likely
they will be inherited together.
• Cross-over frequencies are related to distances
between genes.
• Cross-over frequencies can be converted into map units.
– gene A and gene B cross over 6.0
percent of the time
– gene B and gene C
cross over 12.5 percent
of the time
– gene A and gene C cross over 18.5 percent of the
time
Pedigree - chart for tracing genes in a family.
• Phenotypes are used to infer genotypes on a pedigree.
• Autosomal genes show different patterns on a pedigree
than sex-linked genes.
Widow’s peak: W = widow’s peak
w = non widow’s peak
• If the phenotype is more common in males,
the gene is likely sex-linked.
Colorblindness: M = normal vision m = colorblindness
Process Box 7:
In a pedigree, what shape represents the male?
You can gather useful information from
studying pedigree diagrams. List the ‘hints’
that help you determine ways that you can
determine if it is sex-linked or autosomal.