MEIOSIS Flashcards
What does meiosis produce?
Daughter cells that are genetically different from each other
What creates genetic diversity in mitosis?
• Recombination
What is recombination?
Involves chromatids swapping genes between themselves
What are the various steps that involve that four daughter cells are not genetically identical?
- Recombination
- Crossing Over
- Segregrations of homologous chromosomes
What does the first division create?
Two daughter cells
What does the second division do?
Leads to the production of four daughter cells
What is the prophase stage?
Prophase II
• Chromosomes pair up
• Pair of sister chromatids can be seen using a light microscope
• Centrioles divides in 2, forming 2 daughter centrioles
• Nuclear membrane breaks down
What is the metaphase stage?
- Replicated chromosomes line up down middle of cell
- Centrioles move to opposite poles of the cell, forming spindle
- Chromosomes move to central region of spindle
- Each becomes to spindle thread by its centromere
What is the anaphase stage?
- Sister chromosomes pulled apart towards opposite ends of the cell
- Sister chromatids separated as centromere splits
- Each sister chromosomes effectively become individual chromosomes
- Each one genetically unique
- Spindle fibers shorten
- This pulls sister chromatids further and further away from each other
What is telophase stage?
New nuclear envelope forms around each chromatid
• Spindle breaks down and disappears
• Chromatids uncoil and can no longer be seen under a light microscope
What is cytokinesis stage?
• Cytoplasm and surface membrane divide, creating four independent haploid daughter cells.
How does mitosis differ to meoisis?
Mitosis
• 2 daughter cells are genetically identical to parent cell
• Doesn’t contribute to genetic diversity
• Mutations sometimes occur
How does random fertilisation affect genetic diversity?
Random fertilisation of gametes increases genetic diversity
• Gametes all have varied genetic content
• Combining gametes increases diversity of gene distribution
