DNA and GENES

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DNA and GENES

• Chapter 11

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DNA The molecule of heredity

• Deoxyiribonucleic Acid has complete
  instructions for manufacturing all proteins
  organisms need to maintain life, all genetic info
• Protein importance all actions required by body
  depend on enzymes that are proteins
• Enzymes control all chemical reactions needed
  for life such as eating, running, thinking.
• DNA structure polymer of repeating subunits of
  nucleotides therefore one long molecule
• Nucleotides made up of
• Simple sugar deoxyribose
• Phosphate group phosphorus with 4 O2
• Nitrogen base C ring structure with 1 or more C
  atoms

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• Nitrogen bases are called purines and prymadines
• 1. Purines double ringed adenine and guanine
• 2. Prymadines single ringed thymine,
  cytosine
• These pair together by H2 bond in specific
  parings called complimentary bases and occur in
  equal numbers A-T C-G
• Zippers on pg 290
• Each strand of DNA has a nucleotide that pairs up
  with its compliment on the other strand forming
  the double helix
• The sequence of these four different nucleotides
  is what makes the organisms different

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Replication

• Separation of Strands decrease H2 bonds of base
  pairs therefore DNA unzips
• Base Pairing single strand builds its
  compliment
• by pairing with free nucleotides of another
  strand A-T, C-G
• This allows great accuracy therefore genetic
  info constant during cell division and
  reproduction
• Bonding Bases sugar and phosphate parts bond
  adjacent nucleotide forming a new strand
• Results produces 2 new molecules of DNA each
  with one from original and one from new
  synthesized from free nucleotide

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11.2 DNA to Protein

• Sequence of DNA nucleotides contains information
  to produce proteins
• Each Human cell is made up of -80,000 genes
• RNA ribonucleic acid has 3 differences from DNA
• 1. Single strand
• 2. Sugar ribose
• 3. Nitrogen base Uracil instead of Thymine
  therefore Adenine binds to Uracil on RNA
• Purpose of RNA to take instructions from DNA to
  build proteins by putting amino acids in proper
  order
• 20 different a.a. in different sequences make
  1000s or proteins

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• 3 Types of RNA
• 1. mRNA messenger RNA brings info from DNA in
  nucleus to cytoplasm
• 2. rRNA ribosomal RNA clamps onto mRNA
• use info to put a.a. in correct order
• 3. tRNA transport RNA transports a.a. to
  ribosomes so they can make a protein
• Transcription
• Results in 1 strand of mRNA which has info from
  DNA for making proteins
• Occurs in the same manner as DNA replication only
  RNAA attaches to DNA strand as it unzips
• Bases bind using uracil instead of thymine, A-U,
  C-G

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Genetic Code Table 11.2

• Codon 3 nitrogen bases in mRNA code for
  specific a.a. and determines their order
• Translation figure 11-8
• Process in which the order of bases in mRNA codes
  for a.a. order in a protein
• Anticodon 3 nucleotides bond to codon of mRNA
  and carries a specific a.a.
• Section 11.3 Genetic Changes
• Mutation is any change in DNA sequence that
  also changes the protein it codes for. It can
  affect one gene or an entire chromosome

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• 1. Reproductive cells altered gene becomes
  part of genetic makeup of offspring therefore
  passing mutation onto future generations causing
  new characteristics
• 2. Body Cells (somatic) mutations only affects
  individual and may result in cancer causes
  environmental like exposure to radiation
• Point Mutations ( figure 11.10A) change in a
  single base pair of DNA during translation
  process
• Frameshift Mutations (figure 11.10B) the
  deletion or addition of a single base in DNA
  shifts the reading of codons by one base
• Chromosomal Mutations changes that occur in the
  chromosomes during mitosis and meiosis 4
  typesdeletions, insertions, inversions,
  translocations

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• Causes of Mutations
• 1. Spontaneous mutations occur during DNA during
  replications
• 2. Environmental
• 3. Mutagens
• high energy radiation x-rays, cosmic rays,
  ultraviolet light, nuclear radiation deletions
• chemical-dioxins, asbestos, benzene, cyanide,
  formaldehyde substitutions
• Radiation high temperatures - substitutions
• Repairing DNA repair mechanisms that fix
  mutations evolved in form of enzymes that proof
  read DNA and replace incorrect nucleotides with
  correct nucleotides works very well