Mitosis

1
Mitosis

• Division of regular (somatic) cells

2
Mitosis

• Division of somatic cells (body)

Daughter Cells
Somatic Cell
3
DNA
P

• Special type of protein
• See Chapter 3.6
• Nucleotide
• Sugar (deoxyribose, 5C sugar)
• Base
• Phosphate
• Nucleic acid
• Formed of nucleotides
• RNA (single stranded)
• DNA (double stranded)

base
sugar
P
base
sugar
P
base
sugar
4
DNA
P
base
sugar
P
base
sugar
P
base
sugar
5
DNA

• Double helix
• Hydrogen bonds between each of the helices

6
Pack it up

• Nucleosome
• DNA plus histone proteins
• Histones allow DNA to spool around them

See Fig 8.3
7
Chromosomes

• Strands of DNA
• Each human has 23 pair (diploid or 2n)
• One from your mother
• One from your father

8
Chromosome
DNA molecule with attached proteins
Sister chromatids
One from Mom One from Dad
Look at figure 8.2
9
Summary of DNA

• Nucleotides- the genetic code (sugar, base,
  phosphate)
• Nucleic acid- chain of nucleotides
• DNA- double stranded double helix with hydrogen
  bonds between strands
• Nucleosome- DNA wrapped around histones
• Sister chromatids- formed prior to mitosis
• Two copies of each chromosome- one from each
  parent (diploid)
• 23 Chromosomes per human in somatic cells

10
Mitosis

• First you duplicate DNA
• Why?
• You have 2 pairs of 23 chromosomes
• If cell splits, you will only have 1 pair
• Duplicate DNA, cell splits, still have 2 pair

Sex chromosomes- X and Y XX is female in
humans, XY is male
11
Interphase

• Prior After Mitosis
• G1 period
• 90 of cell life spent here
• Cell goes about its business
• S period
• DNA is duplicated
• G2 period
• Cell prepares to divide
• Cannot see DNA- uncoiled as chromatin

12
1. Prophase

• DNA becomes visible as chromosomes
• Nuclear membrane dissolves
• Centrioles migrate to opposite poles
• Spindle fibers form

Easy to remember- Prophase- proceeding into
mitosis
13
2. Metaphase

• Spindle fibers attach to centromeres
• Chromosomes line up at midline of the cell

Pole
Spindle Equator
Pole
Easy to remember- metaphase, DNA at middle
14
3. Anaphase

• Spindle fibers pull apart centromeres
• One chromatid goes to each centriole (they look
  like Vs)

Easy to remember- anaphase, apart they go
15
4. Telophase

• Chromatids reach centrioles
• Mitosis ends when new nuclear membranes form
• Some evidence of cell dividing

Easy to remember- telophase, terminal phase
16
Last part- Cytoplasmic division

• Technically not in mitosis
• Animal cell- pinching of cell membrane- cleavage
• Plant cell- formation of new cell wall- cell
  plate
• DNA becomes non-visible, back to chromatin
• Daughter cells enter G1 period of interphase

17
Cancer

• Uncontrollable mitosis (no G1)
• Cells cease to do what they are supposed to be
  doing in favor of dividing.
• Pancreatic cancer- no longer in interphase
• Cease production of insulin
• Incomplete digestion of food
• Diabetes, abdominal pain, weight loss
• Cancer does not poison your body

18
Henrietta Lacks

• 1951, a poor 31 Year old African American mother
  of 4 was dying of cervical cancer _at_ Johns Hopkins
  Hospital
• Dr. George Gey- sampled some of the cancerous
  cells, found they could live indefinitely and
  multiply outside the body
• She died 6 months later, but cells live on
• HeLa cells
• Used to study many different diseases
• Cure for Polio

19
Lab- Mitosis

• Cell Reproduction Lab part 1
• Microscopes
• Onion root tip meristem (plant mitosis)
• Whitefish blastula (animal mitosis)
• Mitosis model
• Beads and magnetic centrioles
• Turn in questions from handout
• END of LAB!!!