Mitosis and Miosis

Cellular Basis of Life
The Cell Cycle
Growth, Repair, & Reproduce

1. All cells come from other cells
   2. The division of cells allows living things to:
   Repair damage
   Grow
   Reproduce offspring
   Asexual
   Sexual
   Chromosomes
2. DNA usually exists in the nucleus as chromatin “string”
   Before cells divide, DNA duplicates & and condenses
   Chromosomes are DNA wound around proteins (histones)
   Sister chromatids joined at the centromere
   The Cell Cycle
3. Interphase (90%): cell does normal cell activities and:
   G1- increases proteins, organelles, and size
   S- duplicates DNA
   G2- increases supplies for cell division
   2. Mitotic phase- division of cell *
   Mitosis (M)- nucleus divides (PMAT)
   Cytokinesis- cytoplasm divides
   The Mitotic Phase
   The Stages of Mitosis
4. Prophase- DNA condenses
   Nucleus disappears
   Spindle fibers appear and attach to kinetochores
   2. Metaphase- DNA lines up in the middle
   3. Anaphase- DNA separates
5. Telophase- Opposite of Prophase
   Cytokinesis
6. Animal cells pinch in the middle (cleavage furrow)
7. Plant cells from a cell plate in the middle

New cells are called daughter cells.
Reproduction in Prokaryotes

1. Binary fission- 1 cell divides into 2 daughter cells
   Asexual reproduction
   Divide every 20 minutes
   Sexual Reproduction
   Homologous Chromosomes

2. Chromosomes can be examined by amniocentesis
   The display of the chromosomes is called karyotype
   2. Each chromosome has a twin referred to as a homologous chromosome
   homologous pairs contain the same type of information
   The genes may have different versions of the same trait
   Ex: (eyes: blues/brown)
   Diploid and Haloid Cells

   1. Diploid cells (2n) have two sets of homologous chromosomes
      Human’s body cell (46)
      23 homologous pairs (numbered 1-23)
      One set from each parent
      Pair #23 are the sex chromosomes
      Female- XX
      Male- XY
      All the other pairs calle autosomes

3. Haploid cells (n) have one set of chromosomes
   Human sex cells (23)
   3. When two sex cells (gametes) are joined (fertilization) a zygote is formed
   Cancer

4. Benign tumor is a mass of normal cells

5. Malignant tumor is a mass of cancer cells
   Cancer is a disease caused when cells divide and grow out of control
   When cancer spreads, it is called metastasis
   Cancer is treated by:
   Radiation
   Chemotherapy
   Meiosis & Variations
   The Stages of Meiosis

6. Meiosis I: separation of homologous pairs
   Prophase I: Crossing over b/w homologous pairs
   Metaphase I: homologous pairs line up
   Anaphase I: homologous pairs separate
   Telophase I: homologous pairs sometimes relax (interkinesis)

7. Meiosis II (same as mitosis): separation of sister chromatids
   Causes of Genetic Variations

   1. Crossing over
      Synapsis occurs by forming tetrads
      Exchange of DNA between homologous pairs
      Different chromosomes are produced through genetic recombination
   2. Independent assortment
      Homologous pairs of chromosomes are separated randomly
      2n possible combinations of 223 = 8 million
      Mitosis vs. Meiosis
   3. Mitosis produces:
      2 cells
      Diploid (2n)
      genetically identical
   4. Meiosis produces:
      4 cells
      Haploid
      genetically different

DNA: The Language of Life (Chapter 11 Lesson)
The Structure of DNA
History
4. DNA- Deoxyribonucleic Acid
Hereditary material of the cell
Makes up genes
Determines the traits of all living things
Located in the nucleus
Nucleotides
1. DNA (polymer) is composed of long chains of four different nucleotides (monomers)
2. Each nucleotide has:
phosphate group
sugar (deoxyribose)
nitrogenous base
adenine A
thymine T
guanine G
cytosine C
3. Adenine and Guanine are Purines (2 rings)
4. Thymine and Cytosine are Pyrimidines (1 ring)
5. DNA strands form when nucleotides join together
Repeating sugar-phosphate “Backbone”
nitrogenous bases are lined up
6. Two strands join together by hydrogen bonds
The Double Helix
1. Franklin & Wilkins and Watson & Crick determine the structure
2. DNA resembles a twisted ladder
Sugar-phosphate on the outside
Complementary nitrogenous bases pair on the inside
A - T
C - G
DNA Replication & Mutations
DNA Replication
1. Replication is the process used to make a copy of DNA
2. During DNA replication:
The two complementary strands separate to form templates
Free nucleotides line up with complementary bases
New strands are covalently bonded
Enzymes control the process
Replication is semi-conservative
Protein Production
From Gene to Protein

1. For every gene (recipe) there is a protein
2. Proteins determine the appearance and function of the cell/ organism
3. DNA → RNA → protein
   Transcription
   Translation
   4. The genetic code consists of 3 letter codes (codon)
   Each condon stands for a particular amino acid
   “All” organisms share this code
   RNA
4. RNA (Ribonucleic Acid) differs from DNA:
   Sugar (ribose)
   Single Strand
   2. Types of RNA
   mRNA (message) copy of the recipe
   rRNA (ribosome) stove
   tRNA (transfer) utensils
   Transcription
5. Transcription is the process of converting the information of DNA onto mRNA
   Similar to DNA replication except:
   Uses RNA nucleotides (U pairs with A)
   Only 1 gene is copied
   mRNA leaves the nucleus
   Translation
6. Translation is the process of converting information of mRNA into a protein
   tRNA acts as the translator b/w nucleic acids and proteins
   The ribsome is the meeting place for mRNA and tRNA
7. Steps in reading mRNA:
   AUG is the code for start
   As each code word is read, amino acids are added
   UAA, UAG, or UGA are the codes for stop
   3. Protein is completed and released