Chapter 3: Mitosis + Meiosis Flashcards
Mitosis
type of cell division done by most of our body cells
Purpose of mitosis
- helps our body grow
- good for repair and damage
What types of cells does mitosis make..
identical cells
What is interphase
process our cells are in most of the time:
- growth
- DNA replication (duplication of chromatids)
- carrying out cell functions
How many chromosomes does a human cell have
46
Stages of mitosis
PMAT: prophase, metaphase, anaphase and telophase
Prophase
- first step in cell division
- nuclear membrane disappears
- spindle fibres from centrioles fan out at opposite poles of the cell
- chromatin condenses into chromosomes
Metaphase
- chromosomes line up by their centromeres in the middle of the cell at the metaphase plate
- spindle fibres attach to the chromosomes
- nucleus disassembled
Anaphase
- spindle fibres pull the chromatids to opposite ends of the cell
- centromeres split
Telophase
- spindle fibres dissolve
- nuclear membrane starts to form around the chromatids
Cytokinesis
responsible for final separation into two cells by splitting the cytoplasm
Meiosis
produces gametes: sperm + egg cells. reduction division
Prophase I
- starts with a diploid cell
- chromatin condenses to chromosomes
- nuclear membrane disappears
- each chromosome pairs with it’s homologous chromosome and crossing over occurs (recombination)
- centrioles move to opposite poles of the cell
- spindle fibers fan out from opposite poles of the cell from centrioles
Crossing over /recombination
chromosomes exchange segments of alleles
(reason why each kid looks different)
Metaphase I
- homologous chromosomes line up at the metaphase plate
- spindle fibers attach to the homologous chromosomes from opposite poles
Anaphase I
- spindle fibers separate the homologous chromosomes to separate poles of the cell
Telophase I
- spindle fibers dissolve
- nuclear membrane reforms
- each chromosome still has it’s sister chromatids but they are no longer identical due to crossing over
Cytokinesis I (meiosis)
separates the cytoplasms of the cell. results in 2 genetically different daughter haploid cells
Meiosis II
DNA does not replication before meiosis II begins
Prophase II
- nuclear membrane disappears
- spindle fibers fan out from centrioles
Metaphase II
- chromosomes line up at the metaphase plate
- spindle fibers attach to the chromosomes
Anaphase II
- spindle fibers separate the chromosomes and move to opposite poles of the cell
Telophase II
- spindle fibers dissolve
- nuclear membrane reforms
Cytokinesis II (meiosis II)
- separates cytoplasm of the cells
- results in 4 genetically different daughter cells
