when gender matters
DESCRIPTION
When Gender Matters (Biology)TRANSCRIPT
![Page 1: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/1.jpg)
HEREDITY: INHERITANCE
AND VARIATION
UNIT I - MODULE 2
![Page 2: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/2.jpg)
When Gender Matters
![Page 3: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/3.jpg)
How is sex/gender determined and inherited?
![Page 4: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/4.jpg)
FemaleXX
X X
MaleXY
X Y
FemaleXX
FemaleXX
MaleXY
MaleXY
![Page 5: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/5.jpg)
KEY CONCEPT:You will observe in the Figure, all egg
cells receive an X chromosome; while half of the sperm cells receive X chromosomes and the other half receive Y chromosomes.
If an egg is fertilized by a sperm with a Y chromosome, as shown in the Figure, the offspring is male. When an egg is fertilized by a sperm carrying an X chromosome, the offspring is female. Note that there is a 50 percent chance of having a male or female offspring. The greater the number of offspring, the greater is the chance of getting the expected 1:1 ratio of male and female.
![Page 6: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/6.jpg)
Have you seen a man with hairy ears?What about a woman with hairy ears?
That is an example of a Y-Linked trait called Hypertrichosis pinnae auris, a
genetic disorder in humans that causes hairy ears.
![Page 7: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/7.jpg)
Since the trait is found in the Y chromosome, then ONLY MALES can
have the trait. A father who has the condition will pass it on to all his sons and they, in turn, will pass it on to their
own sons.
![Page 8: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/8.jpg)
INTRODUCTION
There are three kinds of sex-related inheritance:
1. sex-linked genes
2. sex-limited traits
3. sex- influenced traits
![Page 9: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/9.jpg)
Sex-Linked Genes Genes located on the X chromosomes
are called X-linked genes. Genes on the Y chromosomes are
called Y-linked genes. An example of an X-linked trait in
humans is hemophilia. A person suffering from hemophilia could die from loss of blood even from a small wound because the blood either clots very slowly or does not clot at all. Another example of an X-linked trait is color blindness.
![Page 10: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/10.jpg)
SEX - LINKED GENES The X chromosome with the gene for color blindness is
represented as XC, while the one without is represented as X.
GENOTYPES AND PHENOTYPES OF COLOR BLINDNESS IN HUMANS
GENOTYPE PHENOTYPE1. XX Normal Female2. XXC Normal Female, carrier of the gene
3. XCXC Color-blind female4. XY Normal male5. XCY Color-blind male
![Page 11: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/11.jpg)
When Gender Matters
![Page 12: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/12.jpg)
Solve problems related to sex-linked traits
![Page 13: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/13.jpg)
1. Activity Sheet
2. Pen
![Page 14: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/14.jpg)
1. Read the given problem: A. Color-blindness is a recessive, sex-linked
disorder in humans. A color-blind man has a child with a woman who is a carrier of the disorder.
KEY: X = normal vision Xc = color-blindness
![Page 15: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/15.jpg)
2. Illustrate using a Punnett square the probability of having children who will have normal vision and children who will be color-blind.
![Page 16: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/16.jpg)
1. What is the genotype of the male?
2. What is the genotype of the female?
3. What is the chance that the child will be color-blind?
4. What is the chance that a daughter will be color-blind?
5. What is the chance that a son will be color-blind?
![Page 17: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/17.jpg)
When Gender Matters
![Page 18: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/18.jpg)
X
XC
XXC
(Normal Female, carrier of gene)
XY(Normal Male)
XCXC
(Color-blind Female)
XCY(Color-blind
Male)
Color-blind Man
XC Y
Wom
an, c
arrie
r of
Dis
orde
r
![Page 19: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/19.jpg)
1. What is the genotype of the male? XCY
2. What is the genotype of the female? XXC
3. What is the chance that the child will be color-blind? 50%
4. What is the chance that a daughter will be color-blind? 25%
5. What is the chance that a son will be color-blind? 25%
![Page 20: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/20.jpg)
Sex - Linked traits are inherited through the X chromosomes.
![Page 21: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/21.jpg)
Males have only one X chromosome. Thus, if they inherit the affected X, they will have the disorder.
![Page 22: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/22.jpg)
Females have two X chromosomes. Therefore, they can inherit/carry the trait without being affected if it acts in a recessive manner.
![Page 23: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/23.jpg)
A man and his wife both have normal color vision but a son has red-green color blindness, a sex-linked recessive trait.
The man sues his wife for divorce on grounds of infidelity. Can Genetics prove evidence supporting his case?
![Page 24: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/24.jpg)
Color blindness is a recessive trait. The onlyway to have a child born that way is if both parents carry the gene. Assuming neither parent is color blind, both could still be carrying the gene and not know it.
So, if the father is tested and does not have the gene at all, he has a case. But he may well have the gene as a recessive trait. In this case, he is "half of the reason."
![Page 25: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/25.jpg)
A man and his wife both have normal color vision but a daughter has red-green color blindness, a sex-linked recessive trait.
The man sues his wife for divorce on grounds of infidelity. Can Genetics prove evidence supporting his case?
![Page 26: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/26.jpg)
X
X
XX(Normal Female)
XY(Normal Male)
XX(Normal Female)
XY(Normal Male)
HUSBAND
X Y
WIF
E
![Page 27: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/27.jpg)
W
W
RW(ROAN)
WW(WHITE)
RW
(ROAN)WW
(WHITE)
ROAN MALE
R W
WH
ITE
FE
MA
LE
![Page 28: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/28.jpg)
YES
The daughter displays the sex-linked recessive which means she got a recessive from both parents. Since the man does not display the recessive, he does not carry it, so the daughter has a different father.
![Page 29: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/29.jpg)
1. What is sex-limited trait?
2. Give examples of sex-limited traits in animals.
![Page 30: When Gender Matters](https://reader030.vdocument.in/reader030/viewer/2022033010/55cf94cd550346f57ba47c31/html5/thumbnails/30.jpg)
Thank You
Mr. Christopher A. LunaScience 9 Teacher
GFMNHS -MAINJuly 10, 2014