1. Lab 5 – Mitosis 10/13/15

2. Cell cycle:
sequence of events that begins when a cell first arises to the time that it replicates and divides.
The purpose of the cell cycle is to make new cells and ensure that each new cell has the same genetic information
Interphase: includes G1, S, G2. Cell is in this phase 90% of the time!
Growth and maintanence!
Mitosis is just one part of the cell division cycle.
The cell division cycle involves 4 phases which can be grouped into two easy to remember groups. Interphase and Mitosis. Remember Mitosis is occurring in a cell only 10% of the time!
Mitosis: This is what we will look at today.
DNA division. Cell in this phase 10% of the time!

3. Terms and Definitions:
Mitosis: Division of single nucleus into two genetically
identical daughter nuclei.
chromosome: Gene carrying structure in nucleus. Consists of DNA and proteins.
centromere: Small protein, center of the “X”.
Mitosis: Remember, mitosis involves replication and division of the cell nucleus! Cell emphasized, nucleus emphasized.
chromatid: 1 of the 2 identical copies of DNA in duplicated chromosome, ½ of the “X”.

4. The 4 Phases of Mitosis: video
Interphase (90% of the time)
Prophase – DNA coils into X shape chromosome: chromatids paired on centromeres. Nuclear envelope breaks up.
Metaphase – centromeres line up between imaginary poles
Anaphase – sister chromosomes (chromatids) pull away from one another toward the poles
Telophase – chromosomes reach opposite ends of cell, nuclear envelopes form around groups. Two genetically identical daughter cells formed.
early prophase-late prophase
metaphase
anaphase
telophase

5. Interphase, Prophase, Metaphase, Metaphase, Telophase, Daughter cells after division is complete.

6. video video 2! DNA: basics of structure and replication
DNA contains genetic instructions that govern the development and functioning of living organisms.
DNA is a double helix made up of two strands of nucleotides.
Replication – happens in S phase!
two strands are unzipped by Helicase
and each strand is copied individually by DNA polymerase and other enzymes
At the end two double helices exist!
video
video 2!

7. The Spectrum of Cell Division
Mitosis: implications (or) why do we care?
1. When division goes wrong
The Spectrum of Cell Division
Happy Medium
No Cell Division -cell death – necrosis and unregulated apoptosis - bad
Constant cell division–
Cancer - bad
Necrosis and apoptosis – both result in cell death. Necrosis is caused by something external to the cell such as a brown recluse bite, and apoptosis is internal to the cell, programmed cell death. Cancer - cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body.

8. Mitosis: implications (or) why do we care?
Cloning: production of genetically identical cells or organisms.
We manipulate cell cycle to get what we want.
Plants:
Clones created from meristem tissue – undifferentiated tissue in plant.
horticulture and propagating plants - many plants descendent of one plant Examples: bananas, apples, hybrid poplars
Animals:
stem cells
Dolly the sheep (

9. Mitosis: implications (or) why do we care?
Stem Cells – undifferentiated animal cell that can divide via mitosis and produce daughter cells with a specific function for for a specific tissue.
Embryonic Stem Cells: derived from an early embryonic state called the blastocyst (~100 cells). A blastocyst is just a few days old and has not yet implanted into the uterus.
Adult Stem Cells: cells in adult tissues that generate replacements for non-dividing differentiated cells. More differentiated than ES cells.
Umbilical Cord Blood: Another source of stem cells collected from the umbilical cord and placenta at birth. Partially differentiated, but less so than adult stem cells.

10. TODAY:
Don’t do part C

11. FOR QUIZ:
Know cell cycle!!
Know the following definitions:
Chromosome
Sister chromatid
Centromere
DNA replication
Clone
Know phases of Mitosis and what happens in each phase. Be able to produce the drawings required in the manual! I might ask you to draw “Metaphase” or something.
Know products of mitosis (2 identical daughter cells)
Know the consequences of unregulated cell division (cancer) and no cell division (necrosis and apoptosis)