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Karyotypes and Sex-Linked Traits

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Karyotypes and Sex-Linked Traits What is a karyotype? Picture of your chromosomes Arranged from largest to smallest quickly identify chromosomal changes http://www ... – PowerPoint PPT presentation

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Title: Karyotypes and Sex-Linked Traits


1
Karyotypes and Sex-Linked Traits
2
  • Diagnose the karyotypes in the back of the room
    at your table.
  • Make sure to include
  • Case number
  • Boy or girl
  • Number of chromosomes
  • Normal or abnormal
  • (if abnormal, what is the
    problem?)

3
What is a karyotype?
  • Picture of your chromosomes
  • Arranged from largest to smallest
  • quickly identify chromosomal changes
  • http//www.biology.arizona.edu/human_Bio/activitie
    s/karyotyping/karyotyping2.html

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6
  • Genetics Disorders and Mutations

7
Mutations
  • are changes in the genetic material
  • can be good or bad
  • can be on a single gene or the whole chromosome

8
  • Genetic Disorder
  • abnormal condition that a person inherits
    through genes or chromosomes.
  • They are caused by mutations or changes in a
    persons DNA.

Write down 3 disorders that have affected someone
you know.
9
  • Cystic Fibrosis
  • Genetic disorder where the body produces
    abnormally thick mucus in the lungs and
    intestines making respiration and digestion
    difficult
  • caused by a mutation in a gene. The product of
    this gene is a chloride ion channel important in
    creating sweat, digestive juices and mucus.
  • One in four babies are born with cystic fibrosis
  • Most common among Northern European descent

10
  • Sickle Cell Anemia
  • Sickle cell is a genetic disorder that affects
    the bloods hemoglobin. Hemoglobin is the
    protein in your blood that carries oxygen.
  • Sickle-cell anemia is caused by a point mutation
    in protein chain of hemoglobin, replacing the
    amino acid glutamic acid with the amino acid
    valine
  • The sickle shape of the cell doesnt allow the
    red blood cell to carry very much oxygen.
  • Most common among African American descent

Famous People with Sickle Cell Disease Miles
Davis, jazz musician. Paul Williams, singer (The
Temptations) Georgeanna Tillman, singer (The
Marvelettes) Tionne "T-Boz" Watkins, singer
(TLC)
11
  • Hemophilia
  • Hemophilia is a genetic disorder in which a
    persons blood clots VERY slowly or not at all.
  • A person with hemophilia can bleed to death from
    a paper cut or scrape.
  • This is sex-linked disorder on the X chromosome.
  • Queen Elizabeth suffered from this disorder.

This man received a vaccine. This is what having
hemophilia did to is body.
12
  • Down Syndrome
  • Down Syndrome is a genetic disorder that occurs
    when an individual receives an extra copy of a
    chromosome.
  • A mistake occurs during Meiosis I the
    chromosomes failed to separate correctly
    (non-disjunction) therefore leaving an extra copy
    of chromosome 21.

13
  • Doctors use tools like amniocentesis and
    karyotypes to help detect most diseases.

14
4 Types of Genetic Disorders
  • 1. Single gene
  • Change in the DNA sequence
  • More than 6000 known disorders
  • Autosomal or sex linked
  • 1 in 200 births
  • Examples
  • cystic fibrosis, sickle cell anemia, Marfan
    syndrome, Huntingtons disease

15
Types of Genetic Disorders
  • 2. Multi-factoral
  • combination of environmental factors and
    mutations in multiple genes
  • more complicated
  • Examples
  • heart disease, high blood pressure, Alzheimers
    disease, arthritis, diabetes, cancer, and obesity

16
Types of Genetic Disorders
  • 3. Chromosomal
  • abnormalities in chromosome structure as missing
    or extra copies or gross breaks and rejoining
  • Example
  • Down Syndrome

17
Types of Genetic Disorders
  • 4. Mitochondrial
  • rare type of genetic disorder
  • caused by mutations in the non-chromosomal DNA of
    mitochondria

18
?
19
Here are some genetics disorders, some you have
heard about and some you havent.
20
Turners Syndrome
1 in 5,000 births 45 chromosomes X only 23
MonosomyNondisjunction
21
Turners Syndrome
96-98 do not survive to birth No menstruation No
breast development No hips Broad shoulders and
neck
22
Cri-Du-Chat Syndrome
1 in 216,000 births 46 chromosomes XY or XX 5
Deletion of lower arm
23
Cri-Du-Chat Syndrome
Moon-shaped face Heart disease Mentally
retarded Malformed larynx Normal lifespan
24
Aniridia-Wilms Tumor Syndrome
1 in 50,000,000 births 46 chromosomesXY or
XX 11 Deletion of upper arm
25
Aniridia-Wilms Tumor Syndrome
Mentally retarded Growth retarded Blindness Tumors
on kidneys Short lifespan
26
Thirteen Q Deletion Syndrome
1 in 500,000 births 46 chromosomesXY or XX 13
Deletion of lower arm
27
Thirteen Q Deletion Syndrome
Mentally retarded Deformed face No thumbs Heart
disease Short lifespan
28
Prader-Willi Syndrome
1 in 5,000,000 births46 chromosomes XY97
XX3 15 Deletion of lower arm
29
Prader-Willi Syndrome
Small bird-like head Mentally retarded Respiratory
problems Obesity Short lifespan
30
Eighteen Q Deletion Syndrome
1 in 10,000,000 births 46 chromosomesXY or
XX 18 Deletion of lower arm
31
Eighteen Q Deletion Syndrome
Mentally retarded Heart disease Abnormal hands
and feet Large eyes Large ears Normal lifespan
32
Cat-Eye Syndrome
1 in 1,000,000 births 46 chromosomesXY or
XX 22 Deletion of bottom arm
33
Cat-Eye Syndrome
Fused fingers and toes Mentally retarded Small
jaw Heart problems Normal lifespan
34
Four-Ring Syndrome
1 in 10,000,000 births 46 chromosomesXY or
XX 4 Inversion
35
Four-Ring Syndrome
Cleft palate Club feet Testes dont descend Short
lifespan
36
Down Syndrome Trisomy
1 in 1,250 births 47 chromosomesXY or XX 21
Trisomy Nondisjunction
37
Down Syndrome
Short, broad hands Stubby fingers Rough
skin Impotency in males Mentally retarded Small
round face Protruding tongue Short lifespan
38
Pataus Trisomy Syndrome
1 in 14,000 births 47 chromosomesXY or XX 13
Trisomy Nondisjunction
39
Pataus Trisomy Syndrome
Small head Small or missing eyes Heart
defects Extra fingers Abnormal genitalia Mentally
retarded Cleft palate Most die a few weeks after
birth
40
Edwards Trisomy Syndrome
1 in 4,400 births47 chromosomes XX80
XY20 18 Trisomy Nondisjunction
41
Edwards Trisomy Syndrome
Small head Mentally retarded Internal organ
abnormalities 90 die before 5 months of age
42
Jacobs Syndrome
1 in 1,800 births 47 chromosomesXYY only 23
Trisomy Nondisjunction
43
Jacobs Syndrome
?
Normal physicallyNormal mentally Increase in
testosterone More aggressive Normal lifespan
44
Klinefelter Syndrome
1 in 1,100 births 47 chromosomesXXY only 23
Trisomy Nondisjunction
45
Klinefelter Syndrome
Scarce beard Longer fingers and
arms Sterile Delicate skin Low mental
ability Normal lifespan
46
Triple X Syndrome
1 in 2,500 births 47 chromosomesXXX only 23
TrisomyNondisjunction
47
Triple X Syndrome
Normally physically Normal mentally Fertile
48
?
49
  • There are traits that are controlled by one gene
    with 2 alleles. Often, one is dominant and the
    other is recessive
  • Example
  • widows peaks and dimples.

50
  • Some traits are controlled by a gene with
    multiple alleles 3 or more for a single trait.
  • For example blood types and skin color in
    humans.

51
  • There are 44 chromosomes that we call autosomal
    chromosomes.
  • However, there are 2 chromosomes that determine
    our sex and we call them sex chromosomes.
  • These 46 chromosomes all carrier genes on them
    that determine our traits.

52
  • Out of our 23 pairs of chromosomes, 1 pair is the
    sex chromosomes (X and Y).
  • Female XX
  • Male XY

53
  • Question What is the probability that your
    parents will have a boy or girl?
  • XY (dad) x XX (mom)

Y
X


Phenotype 50 boy 50 girl
X
XX
XY
Genotype 50 XX 50 XY
X
XX
XY
54
  • Question?
  • If my parents have 5 boys in a row, what is
    the chance they will have a girl the next time?

50
55
  • Sex-linked gene
  • Some traits are carried on the sex chromosomes.
    Genes on the X or Y chromosomes are sex-linked
    genes.
  • These traits are passes on from parent to child.
    Sex- linked genes can be recessive or dominant.
  • MALES are more likely to have a sex-linked trait
    because they only have ONE X and Y. The allele
    is USUALLY on the X chromosome.
  • Ex. colorblindness, hemophilia, hairy ears,
    muscular dystrophy

56
Are you colorblind?
What numbers do you see?
57
  • Carrier person who has one recessive allele and
    one dominant allele for a trait or heterozygous
    for that trait (only women can be carriers).
  • Example
  • Hemophiliac carrier XHXh
  • Colorblind carrier XBXb

58
  • Sex linked Punnett Squares
  • Question
  • What is the probability that a carrier female
    and a colorblind male will have a girl who is
    colorblind (b colorblind, B normal)?

Y
Xb
Phenotype 25 normal boy 25 colorblind boy 25
normal girl 25 colorblind girl


XBXb
XBY
XB
Xb
XbXb
XbY
59
Try this one on your own
  • Question
  • What is the probability that a homozygous
    (normal vision) female and a colorblind male will
    have a girl who is colorblind (b colorblind, B
    normal)?

60
Parents XBXB x XbY
Xb
Y
Phenotype 50 normal girls 50 normal boys


XBXb
XBY
XB
XB
XBXb
XBY
61
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