Mitosis and Meiosis

 

Mitosis- is a type of division of the nucleus whereby a parent cell separates its chromosomes into _______ identical daughter cells.

 

Steps of Mitosis

  • Interphase- The DNA is all stretched out and tangled like a big bowl of _________ called chromatin. Next the cell duplicates its DNA. Each DNA molecule is called a chromatid and the pair of them are joined by structure called a centromere. ___% of the time a cell is in this stage.
  • Prophase- The DNA has bunched up and is now _________! Centrioles migrate to the two sides of the cell. In late prophase, asters (protein tubes) from the centrioles (spindles if plants) attach to the ________________.
  • Metaphase- In metaphase the chromosomes line up in the __________ of the cell.
  • Anaphase- The asters pull the chromatids _______.
  • Telophase- The cell has now ________ but not split.
  • Cytokinesis- The cell membranes have pinched in and split the cell and its cytoplasm in ____.

 

Mitosis scramble

 

Vocabulary

Somatic
Chromatids
Centromere
Spindles
Aster
Diploid
Parent Cells
Daughter Cells
Homologous pair
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Chromatin

 

Essential Questions:

1. What types of cells undergo mitosis?

2. What are the stages of mitosis and what occurs at each step?

 

Meiosis: a type of nuclear division that occurs only in special reproduction (____) cells. Parent cells divide into four _____________ cells but they contain _____ of the original number of chromosomes (monoploid).

 

 

Steps of Meiosis

Meiosis involves _____ successive cell divisions which produce four monoploid cells.

  • Ist division: Similar to mitosis except the during prophase 1- the two chromosomes from the mother and two chromosomes from the father line up side by side called ________. The 2 sets of chromosomes (sister chromatids) come together forming a ______. The arms of the chromatids now get tangled up and recombine in a new order called crossing over. Next during anaphase 1 the sister chromatids separate with their ___________ intact! Two daughter cells are produced during telophase 1.
  • 2nd division: similar to mitosis but now the chromatids separate during telophase 2 creating 4 haploid cells. Single strands of chromosomes are captured in each cell.

 

Gametogenesis: The creation of sex cells either eggs or sperm by meiosis

Female gametogenesis occurs in the ovaries. Called oogenesis.

It forms one viable egg and ______ tiny polar bodies.

Male gametogenesis creates sperm in the testes. Called spermatogenesis.

It creates _______ viable sperm from one orginal cell.

 

2N/1N

During mitosis, the genetic code of the cells is always __N (one gene set is from the egg and the other from the sperm).

After meiosis, the genetic code is __N (only 1/2 of the normal number of genes are present).

This is called Haploid or ___________ .

After fertilization, the genetic code of the cell is restored to ___N or Diploid.

 

Vocabulary

Haploid
Monoploid
Diploid
Sex cell
Gonads (male and female)
Sister Chromatids
Gametogenesis
Oogenesis
Spermatogenesis
Polar bodies
Synapsis
Tetrad
Crossing Over

Essential Questions:

  1. Where does meiosis take place?
  2. What is the difference in chromosome number of a somatic cell compared to a sex cell (gamete)?
  3. Why is it important for meiosis to result in 1/2 the normal number of DNA?
  4. Why is meiosis called reduction division?
  5. Why is it a genetic advantage for a species to undergo meiosis and then fertilization as opposed to vegetative reproduction?
  6. What does haploid vs diploid mean?
  7. How is spermatogenesis different from oogenesis?
  8. How does meiosis differ from mitosis?