AC

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

    1. 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

    2. 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

    3. 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

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