Meiosis

Meiosis
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BiologieMiddelbare schoolvwoLeerjaar 4

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Meiosis

Slide 1 - Diapositive

Did you even think...
- why organisms with sexual reproduction have the correct number of chromosomes?
- why genetic variation is possible although mitosis ends up with 2 identical daughter cells? 

Slide 2 - Diapositive

Learning objectives
  • You can list and describe the phases of meiosis
  • You can describe changes in number of chromosomes during meiosis
  • You can explain changes in DNA content during meiosis
  • You can explain the importance of meiosis (in terms of genetic variation)

Slide 3 - Diapositive

Cell cycle and cell division

Interphase: G1, S, G2
Cell division: Mitosis or Meiosis

Slide 4 - Diapositive

Meiosis
  • PMAT (twice)
  • Meiosis I:  
    - Splitting homologous pairs
    - 2n --> n+n
  • Meiosis II:
    - Splitting chromatids
    - n --> n+n: end result is 4 haploid cells

Slide 5 - Diapositive

Prophase I
  • Nuclear membrane brakes down
  • Spindle appears
  • Homologous pairs are together
  • Crossing over occurs

Slide 6 - Diapositive

Metaphase I
  • Chromosomes line up on the equator in pairs
  • Homologous pairs still together
  • Spindle fibers connect to one member of the pair 

Slide 7 - Diapositive

Anaphase I
  • Spindle fibers pull the homologous pairs apart
  • Sister chromatids stay attached! 

Slide 8 - Diapositive

Telophase I
  • Nuclear membranes form 

Slide 9 - Diapositive

Cytokinesis
  • Cytoplasm splits
  • Each cell is now haploid 

Slide 10 - Diapositive

Prophase II
  • Nuclear membrane brakes down
  • Spindle fiber forms
  • No crossing over! 

Slide 11 - Diapositive

Metaphase II
  • Chromosomes line up at the equator
  • Each chromosome connects to two spindle fibers 

Slide 12 - Diapositive

Anaphase II
  • Chromatids are pulled apart! 

Slide 13 - Diapositive

Telophase II
  • Nuclear membranes form 

Slide 14 - Diapositive

Cytokinesis
  • Cytoplasm splits
  • 4 unique haploid cells are formed

Slide 15 - Diapositive

Which best describes the number of chromosomes for Meiosis I?
A
2n -> 2n+2n
B
2n -> n + n
C
n -> n+n
D
n -> 2n +2n

Slide 16 - Quiz

Which best describes the number of chromosomes for Meiosis II?
A
2n -> 2n+2n
B
2n -> n + n
C
n -> n+n
D
n -> 2n +2n

Slide 17 - Quiz

Final result of meiosis is:
A
2 genetically identical daughter cells
B
4 genetically identical daughter cells
C
2 genetically different daughter cells
D
4 genetically different daughter cells

Slide 18 - Quiz

Crossing over takes place during:
A
Prophase I
B
Prophase II
C
Anaphase II
D
Metaphase II

Slide 19 - Quiz

Does crossing over occur between homologous pairs?
A
true
B
false

Slide 20 - Quiz

Exercise: Recognizing the phases of Meiosis

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Fill in the worksheet: Meiosis. Recognizing the phases.
Consult presentation, your neighbour for help
10' to work on
Upload the document to the Google Classroom



Slide 21 - Diapositive

Homework
  • Watch the video on the next slide
  • Read pages from the book 105-109 

Slide 22 - Diapositive

Slide 23 - Vidéo