Chapter 9: Genes, Mitosis, and Cytokinesis by k2s76I


									    Chapter 9:
Genes, Mitosis, and
   9.1 An Introduction to Genetics

• DNA Deoxyribonucleic Acid
  –   Central for reproduction
  –   Development
  –   Day-to-Day functioning
  –   Contains genome the complete collection of that
      organism’s genetic information
       • Exists in units called genes
       • ½ from mom + ½ from dad
        DNA Contains Instructions For Protein
• How do genes control the development and
  functioning of living things?
    – Instructions genes
    – Workers proteins
• Recall: enzymes chemically active proteins
  that enables of speeds up reactions in living
• How is the gene read to make a protein?
    – Think of the nucleotides as letters in the alphabet.
    – Now a gene is going to arrange those letters a
      certain way to make a sentence for specific
      instruction for building a protein.
    – Letters Nucleotides
    – Sentence  Gene
• Recall: DNA nucleotides
    –   Adenine
    –   Guanine
    –   Cytosine
    –   Thymine
         The Architecture of DNA
• Structure
   – Makes protein production
• Looks like a spiral staircase
   – Handrails
      • sugar (deoxyribose) +
        phosphate bone
   – Staircase
      • NucleotidesA, G, C, & T
• The way in which they are
  ordered codes for a specific
          The Path of Protein Synthesis
1. The DNA helix unwinds (in
2. The gene that codes for a protein
   is read and copied
3. The copy of the gene is in the
   form of mRNA
4. Leaves the nucleus to find a
   ribosome workbench
5. mRNA is read by the ribosome
6. The ribosome brings the proper
   amino acids that match up with
   the mRNA
7. Amino Acids are linked together
8. The mRNA is completely read
   and the protein folds up
    Genetics as Information Management
• Genetics The study of
  – Concerns
     • Storage
     • Duplication
     • Transfer of information encoded
       in Chemical form
  – More like a cookbook recipe
     • The DNA gave the instructions
       and all the combined ingredients
       made the product
        From One Gene to a Collection
• Genome The entire
  collection of Genes
   – Vast history of information
   – Human genome estimated
     30,000 genes
   – Information passed down over
     3.5 billion years of evolution
   – Most cells in your body contain
     a complete copy of an
     organisms geneome
   – The cell only reads the part of
     the genome that is needed
       endocrine cell VS a lymphatic
• Cells duplicate therefore their
  genetic information must be
    The Path of Study in Genetics

• Genetics lies in the path of reproduction
  – Allows things to be
     • Complex
     • Self sustaining entities
   9.2 An Introduction to Cell Division
• How do organisms grow and
   – Always through cell division
   – Cells come from other cells
      • Cells come from cells by dividing
   – 25 million cell divisions occur each
• Why do cells divide?
   – They die and need to be replaced
   – Before “cell division” you must have
     “cell duplication” also known as 
• Mitosis the apportioning of two
  identical quantities
• Cytokinesis the splitting of the
  cellular material
            The Replication of DNA
1. Strands unwind
2. Each single strand
   serves as a template
3. A new strand is created
   by adding new
   nucleotides to the
4. The result two identical
   strands of DNA
5. Each double strand
   contains an old strand
   and a new strand
   9.3 DNA is Packaged in Chromosomes
• DNA double helix is
  packed in the
  condensed form of a
  – The DNA in each cell
    comes divided up and
    packaged into individual
    units of DNA
• Different organisms
  have different numbers
  of Chromosomes
  – Humans 46
  – Onions16
• Eukaryotic
  – Made up of DNA and
    Proteins Chromatin
         Matched Pair of Chromosomes
• In Eukaryotes:
   – Chromosomes come in pairs
      • Not exactly alike
   – One from mom and one from dad
    Defining a matched pair
• Each set of matched pair
  contains similar materials for a
   – If chromosome #1 is responsible
     for eye color both will have
     instructions for eye color
   – the difference is that each parent
     can have a different eye color
• Homologous Chromosomes
  “homologous” the same in size
  and function
               X and Y Chromosome
• Exception to the
  – Sex chromosomes
     • Of the 23 pairs
        – 22 autosomes

• Females
  – one homologous
    sex chromosome
• Males
  – X and a Y
    Chromosome Duplication as a Part of
             Cell Division
• Note: Cell contains other
  organelles that must be
• Cell division has two
  – Mitosis
     • Separation of a cell’s duplicated
       chromosome prior to cytokinesis
  – Cytokinesis
     • the physical separation of one cell
       into two daughter cells
  The Cell Cycle

• Three processes
  1. Growth
  2. Genetic duplication
  3. Cell division
• Two Phases
  1. Interphase the portion of the cell cycle in which
     the cell carries out its work and, in preparation for
     division, duplicates its chromosomes
  2. Mitotic Phase the portion of the cell cycle that
     includes both mitosis and cytokinesis
9.4 Mitosis and Cytokinesis
         9.5 Variations in cell division
1. Animal Cell
  – Protein filaments cleave the
    two cells
2. Plant Cell
  – Problem cell wall
  – Send cell wall and plasma
    membrane components in
    between the cells
3. Prokaryotes
  –   Bacteria Single celled
  –   Singular circular chromosome
  –   Grows Septum to separate them
  –   Faster
      • Bacteria divide ever 20 minutes
      • Human cells 24 hours
• Essay When the Cell Cycle Runs Amok:

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