human genetics. how many pairs of chromosomes are in each of our body cells? a.32 b.23 c.46 d.16 23...
TRANSCRIPT
![Page 1: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/1.jpg)
Human Genetics
![Page 2: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/2.jpg)
How many pairs of chromosomes are in each of our body cells?
A. 32B. 23C. 46D. 16
23 pairs! This is 46 total; we get 23 from mom & 23 from dad.
![Page 3: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/3.jpg)
Body cells are also known as what?
A. GametesB. HistonesC. ChromatinD. Somatic Cells
Somatic Cells!
![Page 4: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/4.jpg)
Which cells in our bodies do NOT have all 46 chromosomes?
A. GametesB. HistonesC. ChromatinD. Somatic Cells
Gametes! Gametes are also known as sex cells. THESE ARE SPERM & EGG CELLS!
![Page 5: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/5.jpg)
How many chromosomes do human sperm or egg cells contain?
A. 32B. 23C. 46D. 16
23! They do NOT get 2 copies of each chromosome; they just get 1!
![Page 6: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/6.jpg)
Gametes – Sperm & Egg Cells
• All gametes are haploid.
• In humans, that means each egg cell & each sperm cell has 1 copy of each chromosome (23 total chromosomes).– Egg Cells: all human egg cells carry 23 chromosomes, 1 of
which is a single X chromosome– Sperm Cells: in males, there are 2 types of sperm cells – 1
carries an X chromosome & 1 carries a Y chromosome
![Page 7: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/7.jpg)
The 2 Types of Chromosomes
• Autosomes: non-sex chromosomes– Of the 46 chromosomes, 44 of them (22 pairs) are
autosomes.
• Sex Chromosomes: the last 2 chromosomes; they determine the sex of the person– Females have 2 X chromosomes (XX).– Males have 1 X and 1 Y chromosome (XY).
Is this person male or female?
![Page 8: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/8.jpg)
When a sperm & egg cell combine, half the time the fertilized eggs (zygotes) are female & half of the time
they’re male.
![Page 9: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/9.jpg)
FUN FACT!
There are actually slightly more men on Earth than women.
WHY? Shouldn’t it be half & half?
Since the Y chromosome is so much smaller, it’s lighter. That means that
the sperm cells that carry the Y chromosome can swim a little faster! This gives them an advantage & they can reach the egg cell more quickly!
![Page 10: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/10.jpg)
Karyotypes – what’s that?
![Page 11: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/11.jpg)
Karyotypes
• Scientists can analyze an individual’s chromosomes by taking a picture of cells during mitosis.
Why does this need to be done during mitosis?
• It’s easiest to view chromosomes during mitosis, because they are condensed!
![Page 12: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/12.jpg)
Karyotypes
• From a picture of chromosomes, scientists can cut & paste to arrange the chromosomes in pairs to form a karyotype.
The last pair (#23) is the sex chromosomes.
![Page 13: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/13.jpg)
A. Man B. Woman
Woman!There are 2 X
chromosomes, but no Y chromosome!
![Page 14: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/14.jpg)
A. Man B. Woman
Man!It’s not labeled, but you can see that 1 of the sex chromosomes
is much smaller than the other (the X & the Y).
![Page 15: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/15.jpg)
Why is karyotyping important?
![Page 16: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/16.jpg)
Using Karyotypes• Genetic disorders can be identified by looking at an
individual’s karyotype.
Down Syndrome can be confirmed even before the baby is
born!
![Page 17: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/17.jpg)
Human Chromosome Disorders
How often do they occur?
• Relatively high frequency in humans, but most embryos are spontaneously aborted– Developmental problems result from biochemical
imbalances.
About 60% of first trimester miscarriages are due to chromosome disorders.
Between 5-10% of stillborn deliveries are due to
chromosome disorders.
![Page 18: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/18.jpg)
Human Chromosome Disorders
• Some conditions are survivable.
How do chromosome disorders occur?
![Page 19: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/19.jpg)
Chromosome Abnormalities
• Incorrect number of chromosomes/mutations within the chromosome– Nondisjunction: chromosomes don’t separate properly
during meiosis– Chromosome Mutations: deletion, inversion, duplication,
translocation
![Page 20: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/20.jpg)
Remember!
• During meiosis, a diploid cell (2 copies of each chromosome) divides & produces 4 haploid gametes (sperm or egg).– Gametes only have 1 copy of each chromosome!
![Page 21: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/21.jpg)
Nondisjunction
• Sometimes, chromosomes may not separate properly during meiosis; this is called nondisjunction.
• If nondisjunction occurs, abnormal numbers of chromosomes (1 extra or 1 missing) are found in gametes & chromosomal disorders may result.
![Page 22: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/22.jpg)
Nondisjunction
• Homologous chromosomes don’t separate properly during Meiosis 1.
OR
• Sister chromatids fail to separate during Meiosis 2.
![Page 23: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/23.jpg)
![Page 24: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/24.jpg)
Nondisjunction
• Trisomy: cells have 3 copies of a chromosome– In trisomies, the gamete
of one parent donated 2 of one type of chromosome to the child & the gamete of the other parent donated 1 (like normal).
![Page 25: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/25.jpg)
Nondisjunction
• Monosomy: missing 1 chromosome– In monosomies, the gamete of one parent donated 1
chromosome & the other parent did not donate any.
![Page 26: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/26.jpg)
Down Syndrome• Trisomy 21
– Every 1 in 700 children born in the US have Trisomy 21.
Chromosome 21 is the smallest, but an
abnormality still has severe effects.
![Page 27: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/27.jpg)
Down Syndrome vs. Age of Mother
Mother’s ageIncidence of Down
Syndrome
Under 30 <1 in 1000
30 1 in 900
35 1 in 400
36 1 in 300
37 1 in 230
38 1 in 180
39 1 in 135
40 1 in 105
42 1 in 60
44 1 in 35
46 1 in 20
48 1 in 16
49 1 in 12
Women are born with all the egg cells they’ll ever have.
So, a 35 year old woman has 35 year old egg cells.
![Page 28: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/28.jpg)
Other Examples of Disorders caused by Nondisjunction
• Klinefelter’s Syndrome – XXY (male)• Turner’s Syndrome – XO (female)
As long as there’s at least 1 Y chromosome, the karyotype is male!
![Page 29: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/29.jpg)
Klinefelter’s Syndrome
• XXY– 1/2000 live births– Have male sex organs, but
are sterile– Feminine characteristics
• Some breast development
• Lack of facial hair– Tall– Normal intelligence
![Page 30: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/30.jpg)
Turner’s Syndrome
• XO (1 X chromosome)– 1/5000 births– Varied degrees of effects– Webbed neck– Short stature– Sterile
![Page 31: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/31.jpg)
Jacob’s Syndrome
• XYY– 1/1000 live births– Extra Y chromosome– Slightly taller than average– More active– Normal intelligence, slight
learning disabilities– Delayed emotional maturity– Normal sexual development Some men will never know
they have Jacob’s Syndrome!
![Page 32: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/32.jpg)
Trisomy X
• XXX– 1/2000 live births– Produces healthy females!
• All but 1 X chromosome are inactivated.
Most mammals leave only 1 X chromosome activated in their cells. The inactivated chromosome(s) are
called barr bodies!
![Page 33: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/33.jpg)
Remember! Chromosomal Mutations
• Error in replication:– Deletion: loss of a
chromosomal segment– Duplication: repeat a
segment
• Error in crossing over:– Inversion: reverses a
segment– Translocation: move
segment from 1 chromosome to another
![Page 34: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/34.jpg)
How do we know if a growing embryo has a chromosome abnormality?
Genetic Testing!• Amniocentesis: a syringe takes a sample of the embryo cells,
then stains & photographs the chromosomes– Analysis of the karyotype
![Page 35: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/35.jpg)
The Human Genome Project
• The genome of many organisms has been determined, including the human genome!
• Now, we are analyzing the code, finding genes coding for different traits, & discovering ways to isolate them & manipulate them.
• In gene therapy, an absent gene or faulty gene is replaced by a normal, working gene!
Video – Blind Dog Gene Therapy
![Page 36: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/36.jpg)
Pedigrees – what are those?
![Page 37: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/37.jpg)
Pedigrees
• Similar to a family tree; both are used to show relationships in a family
• Used to demonstrate how traits are passed from 1 generation to another
• Genetic counselors use pedigrees to follow how genetic disorders are inherited.
![Page 38: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/38.jpg)
Pedigrees
• People who are heterozygous for a recessive genetic disorder (they are unaffected) are called carriers.– Sometimes, carriers of traits may be represented as a half-
shaded shape or a shape with a dot in the middle.
![Page 39: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/39.jpg)
Pedigree Symbols
• Square: male• Circle: female• Shaded: affected individual
• Open: unaffected• Horizontal Line: marriage• Vertical Line & Bracket:
descendants of a marriage
![Page 40: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/40.jpg)
female male
marriage parents children
![Page 41: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/41.jpg)
Most genetic disorders are caused by mutations on autosomes (non-sex chromosomes).
• Autosomal Recessive Disorders: albinism, cystic fibrosis, tay-sachs disease
• Autosomal Dominant Disorders: achondroplasia (common form of dwarfism)
• Codominant Disorders
![Page 42: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/42.jpg)
• Could this trait be inherited as a simple autosomal recessive?• Could this trait be inherited as a simple autosomal dominant?• Could this trait be inherited as a simple X-linked recessive?• Could this trait be inherited as a simple X-linked dominant?• Could this trait be inherited as a simple Y-linked trait?
![Page 43: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/43.jpg)
• Could this trait be inherited as a simple autosomal recessive?• Could this trait be inherited as a simple autosomal dominant?• Could this trait be inherited as a simple X-linked recessive?• Could this trait be inherited as a simple X-linked dominant?• Could this trait be inherited as a simple Y-linked trait?
![Page 44: Human Genetics. How many pairs of chromosomes are in each of our body cells? A.32 B.23 C.46 D.16 23 pairs! This is 46 total; we get 23 from mom & 23 from](https://reader036.vdocument.in/reader036/viewer/2022062315/5697c0081a28abf838cc6a4e/html5/thumbnails/44.jpg)
Draw the Pedigree!
• An unaffected man marries a woman who is a carrier for Duchenne Muscular Dystrophy, which is attributed to an X-linked gene.
• They have 4 children, 1 son with Duchenne, 1 carrier daughter and a daughter & son who are unaffected.
• The child with Duchenne Muscular Dystrophy dies in childhood.
• The carrier daughter marries and has 3 children of her own, 2 of which are carriers and 1 daughter of which is unaffected.