Mitosis And the cell cycle Cell division All

Mitosis And the cell cycle

Cell division All complex organisms originated from a single fertilized egg. Every cell in your body started here, through cell division the numbers are increased Cell then specialize and change into their various roles

DNA P base • Contains information for proteins sugar • Nucleotide • Sugar (deoxyribose, 5 C sugar) • Base • Phosphate P base • Nucleic acid • Formed of nucleotides • RNA (single stranded) • DNA (double stranded) sugar P base sugar

DNA P P base sugar P P base sugar

DNA • Double helix • Hydrogen bonds between each of the helices

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

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

Chromosome DNA molecule with attached proteins Sister chromatids One from Mom One from Dad

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 pairs of chromosomes per human in somatic cells

The cell cycle

Interphase • Prior & After Mitosis • G 1 period • 90% of cell life spent here • Cell goes about it’s business • S period • DNA is duplicated • G 2 period • Cell prepares to divide • Cannot see DNA- uncoiled as chromatin

Mitosis • Division of somatic cells (body)Daughter Cells Somatic Cell

Mitosis • All daughter cells contain the same genetic information from the original parent cell from which it was copied. • Every different type cell in your body contains the same genes, but only some act to make the cells specialize – e. g. into nerve or muscle tissue.

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

Parent cell Chromosomes are copied and double in number Chromosomes now split 2 daughter cells identical to original

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

2. Metaphase • Spindle fibers attach to centromeres Pole • Chromosomes line up at midline of the cell Spindle Equator Pole Easy to remember- metaphase, DNA at middle

3. Anaphase • Spindle fibers pull apart centromeres • One chromatid goes to each centriole (they look like V’s) Easy to remember- anaphase, apart they go

4. Telophase • Chromatids reach centrioles • Mitosis ends when new nuclear membranes form • Some evidence of cell dividing Easy to remember- telophase, terminal phase

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 G 1 period of interphase

Cancer • Uncontrollable mitosis (no G 1) • 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