Chapter 9: Genes, Mitosis, and Cytokinesis

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

• DNA? Deoxyribonucleic Acid
• Central for reproduction
• Development
• Day-to-Day functioning
• Contains genome? the complete collection of that
  organisms genetic information
• Exists in units called genes
• ½ from mom ½ from dad

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DNA Contains Instructions For Protein Production

• 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 things
• 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

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The Architecture of DNA

• Structure?
• Makes protein production possible
• 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 protein

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The Path of Protein Synthesis

• The DNA helix unwinds (in nucleus)
• The gene that codes for a protein is read and
  copied
• The copy of the gene is in the form of mRNA
• Leaves the nucleus to find a ribosome? workbench
• mRNA is read by the ribosome
• The ribosome brings the proper amino acids that
  match up with the mRNA
• Amino Acids are linked together
• The mRNA is completely read and the protein folds
  up

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Genetics as Information Management

• Genetics? The study of Heredity
• 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

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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 cell
• Cells duplicate therefore their genetic
  information must be duplicated

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The Path of Study in Genetics

• Genetics? lies in the path of reproduction
• Allows things to be
• Complex
• Self sustaining entities

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9.2 An Introduction to Cell Division

• How do organisms grow and develop?
• Always through cell division
• Cells come from other cells
• Cells come from cells by dividing
• 25 million cell divisions occur each second
• Why do cells divide?
• They die and need to be replaced
• Before cell division you must have cell
  duplication also known as ? replication
• Mitosis? the apportioning of two identical
  quantities
• Cytokinesis? the splitting of the cellular
  material

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The Replication of DNA

• Strands unwind
• Each single strand serves as a template
• A new strand is created by adding new nucleotides
  to the template
• The result two identical strands of DNA
• Each double strand contains an old strand and a
  new strand

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9.3 DNA is Packaged in Chromosomes

• DNA double helix is packed in the condensed form
  of a chromosome?
• 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 Chromosomes
• Made up of DNA and Proteins? Chromatin

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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 gene
• 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

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X and Y Chromosome

• Exception to the Rule
• Sex chromosomes
• Of the 23 pairs
• 22 autosomes? nonsex chrmosomes
• Females?
• one homologous sex chromosome XX
• Males?
• X and a Y

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Chromosome Duplication as a Part of Cell Division

• Note Cell contains other organelles that must be
  doubled.
• Cell division has two components
• Mitosis
• Separation of a cells duplicated chromosome
  prior to cytokinesis
• Cytokinesis
• the physical separation of one cell into two
  daughter cells

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The Cell Cycle

• Three processes
• Growth
• Genetic duplication
• Cell division
• Two Phases
• Interphase? the portion of the cell cycle in
  which the cell carries out its work and, in
  preparation for division, duplicates its
  chromosomes
• Mitotic Phase? the portion of the cell cycle that
  includes both mitosis and cytokinesis

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http//www.youtube.com/watch?vVlN7K1-9QB0
9.4 Mitosis and Cytokinesis
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9.5 Variations in cell division

• Animal Cell
• Protein filaments? cleave the two cells
• Plant Cell
• Problem cell wall
• Send cell wall and plasma membrane components in
  between the cells
• Prokaryotes
• Bacteria? Single celled
• Singular circular chromosome
• Grows Septum to separate them
• Faster
• Bacteria divide ever 20 minutes
• Human cells 24 hours

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• Essay When the Cell Cycle Runs Amok Cancer