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 form 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 called 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

Patterns of Inheritance
The Language of Genetics
History

1. The blending hypothesis of the 1800s was discarded

2. Gregor Mendel, the “father of genetics”
   believed that distinct factors (genes) were responsible for inheritance
   Conducted breeding experiments on pea plants
   3. Genetics- the study of how traits are passed from parent to offspring
   The Rules of Chance

   1. Gene- a portion of the chromosome that controls a trait (flower color)
   2. Allele- Either one of the alternate versions of a gene (P or p)
      Genotype- genetic composition (PP or Pp or pp)
      Phenotype- physical appearance (purple or white)
   3. True-breed- an organism that always passes on it characteristics
      Homozygous- two of the same alleles for the same trait

3. Hybrid- an organism that has two different alleles for the same trait
   Heterozygous- two different alleles for the same trait
   5. Dominant- in a hybrid, the allele that is expressed (P-purple)
   6. Recessive- in hybrid, the allele that is not expressed (p- white)
   7. P Generation- parents (PP x pp)
   8. F1 Generation- Children (4/4 Pp)
   9. F2 Generation- grandchildren (¼ PP, ½ Pp, ¼ pp)
   Punnet Squares
   Mendel’s Laws

   1. Individual units, called genes, determine biological characteristics
   2. For each gene, an organism receives one allele from each parent
      Alleles separate from each other (segregation)
      Forming sex cells

4. If an organism inherits different alleles for the same trait, one allele is dominant over the other.
   4. Some genes separate, or segregate independently
   Monohybrid Cross

   1. A monohybrid cross results from crossing two organisms that differ in one characteristic
      Identify the dominant and recessive alleles
      Determine the genotype of each parent and possible gametes
      Set up a Punnet square and cross
      List the genotypes and phenotypes of the offspring in each box
      Determine the solution to the problem
      Dihybrid Cross

5. A dihybrid cross results from crossing organisms that differ in two characteristicsSeed color and shape
   Seed color and shape
   A cross between two hybrids results in a 9:3:3:1 ratio

Inheritance Patterns
Incomplete Dominance
1. Incomplete dominance is when neither gene is totally dominant
2. Produces an intermediate phenotype
Multiple Alleles
1. There are 4 blood types, A, B, AB, and O
Type A
Type AA
Type Ao
Type B
Type BB
Type Bo
Type AB
Type O
2. The gene for o is recessive to A and B
3. A and B are codominant
4. Mixing blood types can result in blood clotting
Polygenic Inheritance
1. Polygenic inheritance is when more than one gene affects a single trait.
Height and skin color
2. Produces a broad range of phenotypes

Environmental Influences
1. The environment can affect an individual's phenotype
Height and weight, coloring, blood count

DNA: The Language of Life (Chapter 11 Lesson)
The Structure of DNA
History

1. 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

2. Adenine and Guanine are Purines (2 rings)

3. Thymine and Cytosine are Pyrimidines (1 ring)

4. 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
   3. Replication is the process used to make a copy of DNA
   4. 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

5. For every gene (recipe) there is a protein

6. Proteins determine the appearance and function of the cell/ organism

7. 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

8. 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

9. 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

   10. Translation is the process of converting information of mRNA into a protein
       tRNA acts as the translator b/w nucleic acids and proteins
       The ribosome is the meeting place for mRNA and tRNA

   11. 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
       Sex-linked Traits

   12. Sex chromosomes carry genes for traits
       Some genes are located on the X chromosomes (females have 2 genes)
       Males have only 1 gene for each of these traits

   13. Thomas Hunt Morgan discovered sex-linked traits (eye color) in fruit flies