Cell Growth and Division

1

• Cell Growth and Division
• Cell Cycle
• Sequence of events that occurs in a cell from
  mitosis to mitosis.
• 5 parts
• G1 phase cell growth occurs (make new proteins
  organelles).
• S phase DNA is copied in preparation for
  mitosis.
• G2 phase Organelles needed for nuclear division
  are made.
• Mitosis nuclear division.
• Cytokinesis cytoplasm divides.
• Interphase G1 S G2 phases.

2

• Figure 10-4 page 245

3

• Mitosis
• Chromosome structure

4

• Done to produce more cells (growth and
  replacement).
• Occurs in somatic cells (body cells) not sex
  cells (gametes)
• 4 steps
• Prophase
• Nuclear membrane nucleolus disappear.
• Chromosomes condense become visible.
• Centrioles form move to poles.
• Spindle fibers first appear.

5

• Metaphase
• Spindle fibers attach to centromere (center of
  chromosome).
• Chromosomes line up at the equator.
• Anaphase
• Sister chromatids spilt.
• Chromosomes (now w/ only 1 chromatid) move to
  opposite poles.
• Telophase
• Nuclear membrane nucleolus reappear.
• Chromosomes spread out become invisible.
• Spindle fibers disappear.

6

• Figure 10-5 page 246-47

7

• Cytokinesis division of the cytoplasm.
• After mitosis, one cell with two nuclei.
• Animals cytoplasm pinches in (cleavage furrow)
• Plants cell plate forms in the center and works
  towards the cell wall.
• Figure 10-6 page 248

8

• Uncontrolled cell growth
• Cancer uncontrolled cell growth (tumor).
• Causes
• Smoking/chewing tobacco
• Radiation exposure (X-rays, tanning beds, etc.)
• Viruses
• Other (chemicals, defective genes, etc.)

9

• Production of Sex Cells
• Meiosis
• Nuclear division that reduces the number of
  chromosomes by half.
• Production of gametes (sex cells sperm eggs)
• Homologous chromosomes pairs of the same
  chromosomes
• Humans 46 chromosomes (23 pairs)
• Diploid both homologs are present (2N)
• Haploid only 1 chromosome of each homolog pair
  is present. (1N)

10

• 2 parts
• Meiosis I
• Meiosis II
• Meiosis I
• Prophase I 2N
• Chromosomes become visible.
• Nuclear membrane nucleolus disappear.
• Spindle fibers appear.
• Synapsis (pairing of homologs) occurs.
• Forms a tetrad (4 chromatids 2 chromosomes).
• DNA may be exchanged between tetrad (crossing
  over) genetic variety

11

• Metaphase I 2N
• Tetrads move to equator by the spindle fibers.
• Anaphase I 2N -gt 1N
• Tetrad splits, however each chromosome still has
  two chromatids.
• Telophase I 1N
• Cytoplasm divides.
• Nuclear membrane nucleolus reappear.
• Spindle fibers disappear.
• Now have two cells.

12

• Meiosis II (1N)
• Prophase II
• New spindle fibers form.
• Nuclear membrane nucleolus disappear.
• Metaphase II
• Chromosomes move to equator by spindle fibers.
• Anaphase II
• Sister chromatids are split with each chromatid
  moving to opposite poles.
• Telophase II
• Same as Telophase I.
• Have 4 cells now.

13

• Figure 11-15 page 276 77 Meiosis I

14

• Meiosis II

15

• Summary15
• Start End
• Mitosis 1 cell, 2N 2 cells, 2N
• Meiosis 1 cell, 2N 4 cells, 1N
• Human gamete Production
• Males 4 (1N) sperm cells from Meiosis.
• Starts at puberty
• Females 1 egg (1N) 3 polar bodies (garbage).
• Starts in the womb but not completed until
  ovulation.

16

• Figure 11-7, page 278

17

• Deoxyribonucleic acid, DNA double helix
  molecule that carries hereditary information for
  genes.
• Structure
• Composed of 3 parts
• Deoxyribose (sugar)
• Phosphate group
• Nitrogen base
• Double helix shape
• Discovered by James Watson and Francis Crick.
• Twisted ladder shape.

18

• Figure 12-7 page 294
• Four Nitrogen Bases
• Adenine (A) Purine
• Guanine (G)
• Thymine (T) Pyrimidine
• Cytosine (C)

19

• Bonding patterns
• G C (3 bonds)
• A T (2 bonds)
• Replication process of copying a DNA molecule.
• Needed for mitosis (S phase)
• Ribonucleic acid, RNA single strand nucleic
  acid used for protein synthesis.
• Different from DNA
• Single stranded
• Ribose not Deoxyribose
• Uracil instead of Thymine (A U)

20

• Types
• Messenger RNA (mRNA) carries message from DNA
  to make proteins.
• Transfer RNA (tRNA) brings amino acids to
  ribosome to make proteins.
• Ribosomal RNA (rRNA) makes up the ribosomes.
• Figure 12-12 page 300

21

• Transcription process of making RNA from DNA.
• DNA ? all types of RNA
• Ex

22

• Protein synthesis formation of proteins using
  genetic code from DNA and carried out by RNA.
• Translation process of forming proteins from
  mRNA.
• mRNA leaves nucleus (nuclear pores) and goes to
  ribosomes.
• mRNA is grouped into 3 consecutive bases called
  codons.
• Each codon corresponds with a certain amino acid.

23

• Figure 12-17 page 303

24

• DNA transcription mRNA translation
  proteins
• tRNA has a compliment (opposite) base sequence to
  the codon called anticodon.
• The amino acid that corresponds with the codon is
  attached to the tRNA.

25

• Figure 12-18 page 304

26

• Mutations spontaneous changes in a gene or
  chromosome.
• Many types
• Single Base switch
• Ex
• Normal Mutation
• DNA ATG CGA GTG CGA
• RNA UAC GCU CAC GCU
• AA Tyrosine Histidine - Arginine
• - Arginine

27

• Single Base Deletion
• Ex
• Normal Mutation
• DNA ATG CGA T AGC GAT
• RNA UAC GCU A UCG CUA
• AA Tyrosine Serine - Leucine
• - Arginine
• Environmental factors may cause, but not always.
• Not passed to offspring unless occurs in gametes
  (sex cells)