11.2 sex-linked

Inheritance & Evolution
1 / 31
volgende
Slide 1: Tekstslide
BiologieMiddelbare schoolvwoLeerjaar 4

In deze les zitten 31 slides, met interactieve quizzen, tekstslides en 2 videos.

Onderdelen in deze les

Inheritance & Evolution

Slide 1 - Tekstslide

Homework
Biozones 159, 160, 161, 164
Assessment questions Glencoe page 319, questions 10-19

Slide 2 - Tekstslide

Learning objectives
You can distinguish between autosomal genes and sex-linked genes
You can explain how the X and Y chromosome determine sex
You can apply the laws of inheritance to sex-linked genes and crosses

Slide 3 - Tekstslide

Slide 4 - Tekstslide

Slide 5 - Tekstslide

Slide 6 - Tekstslide

Slide 7 - Tekstslide

Slide 8 - Tekstslide

Slide 9 - Tekstslide

The X-chromosome holds way more genes than the Y-chromosome. 

Some disease and syndromes linked to the X-chromosome: 
- colour blindness
- hemophilia
- Duchenne muscular dystrophy
- deficiencies
Important gene on the Y-chromosome
SRY-gene: gene that regulates many other genes
If the SRY-gene is present a mammal embryo will develop into a male

Slide 10 - Tekstslide

The gene coding for the proteins in the cones on your retina that help you distinguish between red and green is on the X-chromosome.

How many alleles of this gene will a woman have? Only write down a number.

Slide 11 - Open vraag

The gene coding for the proteins in the cones on your retina that help you distinguish between red and green is on the X-chromosome.

How many alleles of this gene will a man have? Only write down a number.

Slide 12 - Open vraag

There is a difference in the number of alleles between men and women for genes on the X-chromosome (sex-linked genes). Therefore we use a different notation. 

XX for women
XY for men

On the X-chromosome we note in superscript which allele is present on that chromosome. Still a capital letter for dominant and small letter for recessive. 

You still write down the Y-chromosome to show it is a male, but it will not have an allele in superscript.

Slide 13 - Tekstslide

Slide 14 - Video

Complete on paper and upload a picture:

A heterozygous, colourblind woman has children with a colourblind man. This form of colourblindness is sex-linked recessive. Draw the punnett square of this cross.

Slide 15 - Open vraag

Use your punnett square from the previous question:

What is the chance of a colourblind child?
A
0%
B
25%
C
50%
D
100%

Slide 16 - Quizvraag

Use the same punnett square again

What is the chance of a daughter being colourblind?
A
0%
B
25%
C
50%
D
100%

Slide 17 - Quizvraag

Use the same punnett square again:

What is the chance of a son being colourblind?

A
0%
B
25%
C
50%
D
100%

Slide 18 - Quizvraag

Important points sex-linked inheritance: 
  • Women have two X-chromosomes and because of that two alleles 
  • Men have one X-chromosome and because of that one allele 
  • It is possible that the chances of a particular trait are different for men and women 
  • READ carefully what they are asking 
  • DONT FORGET to also write down the X and Y chromosomes and not only the alleles 
  • If the trait is recessive males are more likely to have it than females 
  • If the trait is dominant females are more likely to have it than males 

Slide 19 - Tekstslide

Identifying sex-linked inheritance

Men only have 1 allele. Men ALWAYS receive their X-chromosome from their mom

The allele that fathers have they will always pass on to their daughters. 

In pedigrees with a sex-linked trait, the following rules apply:
- Dominant father = dominant daughters
- Recessive mother =  recessive sons

Slide 20 - Tekstslide

Slide 21 - Video

Upload a picture of your answer:
The grey symbols are people with a disease that is caused by a sex-linked gene. The red symbols are not sick. 7 and 8 are having a child, 11. 11 turns out to be a girl. What is the chance she has the disease?
And what if 11 was a boy?

Slide 22 - Open vraag

In Drosophila (fruit flies) there is a recessive allele that causes veinless wings. This gene is located on the X-chromosome. A female with veinless wings is crossed with a male with normal wings. The F1 offspring that come from this cross and used to cross with each other to form the F2 generation. Which percentage of the F2 females will have veinless wings?

Slide 23 - Open vraag

Slide 24 - Tekstslide

11.3 prenatal diagnostics 
see previous LessonUp or Table 5, page 315



-amniocentesis
- chorionic villus sampling
- fetal blood sampling
- NIPT test https://www.pns.nl/nipt

Slide 25 - Tekstslide

Karyogram
Chromosome portrait
Identify:
- Missing chromosomes
- Extra chromosomes
- Gender

Slide 26 - Tekstslide

Male
Female
Trisomy 21
Trisomy 13
Trisomy 18
Missing chromosome 11
Missing chromosome 19

Slide 27 - Sleepvraag

Male
Female
Trisomy 21
Trisomy 13
Trisomy 18
Missing chromosome 11
Missing chromosome 19

Slide 28 - Sleepvraag

Male
Female
Trisomy 21
Trisomy 13
Trisomy 18
Missing chromosome 11
Missing chromosome 19

Slide 29 - Sleepvraag

Slide 30 - Link

Homework
Biozones 164, 194, 195
Assessment questions Glencoe page 320: 21-33

Slide 31 - Tekstslide