Cell Division

The Cell Cycle

•______sequence of cell ______and ______during an organism’s life

•90% of cell life is spent in ______

•Then it may go into ______& ______

Interphase (has 3 mini-phases)

•G1(first growth) phase = ______

•S (synthesis) phase = ______

•G2 (2nd growth) phase = ______

•Then will go into MITOSIS & CYTOKINESIS (depending on cell type)

Phases of the Cell Cycle

a. prophase

b. G1

c. telophase

d. metaphase

e. G2

f. cytokinesis

g. S

h. anaphase

Mitosis and Meiosis

•Mitosis:

-division of ______(body) cells

-results in two ______cells that are ______

•Meiosis

-division of ______(sex cells)

IPMAT

The Cell Cycle is Carefully Controlled

Key ______points which feedback ______from the cell ______the next step

Controlled by ______!

  1. ______CHECKPOINT (G1) – Start – Nerve/muscle cells stop here
  1. ______CHECKPOINT (G2) – Enzymes
  1. ______CHECKPOINT – Back to G1 phase

When Control is Lost – CANCER

Cancer = Cell growth is ______- does not ______to control mechanisms.

Causes: ______that cause over-production of ______molecules – (accelerator) or by in-activating proteins that ______the cell cycle (brakes)

______and ______linked to increased cancer risk.

Change in Chromosome Number

Trisomy = humans with ____ than 2 copies of chromosomes - ______development

Karyotype = a ______of the chromosomes in a dividing cell.

Disjunction = when egg/sperm cells form – each chromosome and homologue separate – sometimes one or more chromosomes _____ to separate - ______distribution.

Down Syndrome - ___ copies of chromosome ____ - NONDISJUNCTION

Change in Chromosome Structure

Mutations – A ______in an organism’s ______structure.

  1. Deletion = piece of chromosome ______off completely – lacks of a set of ______- fatal
  1. Duplication = chromosome fragment ______to hom. chromosome - ____ copies of a gene set
  1. Inversion = chromosome piece reattaches to ______chromosome, but in ______orientation.
  1. Translocation = chromosome piece reattaches to a ______chromosome.

MITOSIS

  • ______ things happen!

1. Cell preparing to divide

2. Genetic material ______

  • Chromosomes______!

1. Chromosomes thicken and shorten

-become visible

-2 chromatids joined by a centromere

2. ______ move to the opposite sides of the nucleus

3. ______ disappears

  • Chromosomes ______!

1. Chromosomes arrange at equator of cell

2. Become attached to spindle fibres by centromeres

3. Homologous chromosomes do not associate

  • Chromosomes get pulled ______

1. Spindle fibres contract pulling chromatids to the opposite poles of the cell

  • Now there are almost______!

1. Chromosomes uncoil

2. Spindle fibres disintegrate

3. Centrioles replicate

*Cell Divides and Cytokinesis occurs

CYTOKINESIS = cell splits

Review – List the stages of Mitosis in order.

______- ______- ______- ______- ______

Meiosis

Meiosis - ______that produces only haploid cells (half the number of chromosomes).

*______

*______

*______

Meiosis Occurs in Two Stages

Follows the same order as MITOSIS but it does it ______.

Meiosis I

  • Homologous chromosomes are separated into ______.

Interphase

  • ______

Prophase I

  • ______
  • ______

Crossing Over

  • Exchanging corresponding segments of ______
  • Important because it gives a new combination of ______.

Crossing Over

Metaphase I

  • ______

Anaphase I

  • ______

Telophase I

  • ______
  • ______

Meosis II

  • ______of each chromosome are separated into separate cells.

Prophase II

  • ______

Metaphase II

  • ______

Anaphase II

  • ______

Telophase II

  • ______
  • ______

End Result of Meiosis and Cytokinesis

  • ____ new cells each with half as much ______information as the parent.

Mitosis and Meiosis Practice Quiz

  1. Mitosis is a cellular process that produces
  2. Two genetically identical daughter cells
  3. Four genetically identical daughter cells
  4. Two similar, but not genetically identical daughter cells
  1. The first stage of mitosis where chromatin condenses to form chromosomes is
  2. Interphase
  3. Prophase
  4. Anaphase
  1. The part of the cell cycle where a cell spends most of the time carrying on metabolism
  2. Interphase
  3. Prophase
  4. Metaphase
  1. The stage of mitosis where the chromosomes line up at the cells’ equator
  2. Prophase
  3. Metaphase
  4. Anaphase
  1. The stage of mitosis where the spindle fibers pull the chromatids toward the centrioles
  2. Prophase
  3. Anaphase
  4. Telophase
  1. The stage of mitosis shown in the diagram.
  2. Prophase
  3. Metaphase
  4. Anaphase

7. The stage of mitosis shown in the diagram.

  1. Metaphase
  2. Anaphase
  3. Telophase

8. What is the function of a centromere?

a. To hold sister chromatids together

b. To pull the chromosomes

c. To push the chromosomes

9. How many gametes form from a parent cell that undergoes meiosis I & II?

a. 2 b. 3 c. 4

10. Gametes have the ______number of chromosomes

a. Diploid

b. Haploid

c. Polyploid

11. A zygote has the ______number of chromosomes

a. Diploid

b. Haploid

c. Polyploid