Biology Blueprint Of Life section 4

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Biology Blueprint Of Life section 4
2014-05-05 07:35:43
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  1. What does a nucelotide consist of
    • A sugar
    • A phosphate
    • A nitrogen base
  2. What is a chromosome
    An organised structure of DNA and protein
  3. What is a codon
    A unique triplet code
  4. What is DNA replication
    The production of 2 identical double stranded molecules of DNA from an original double helix molecule
  5. Describe the process of DNA replication
    • DNA double helix unwinds 
    • Enzyme called helicase causes the DNA to progressively unwind

    • DNA unzips (2 strands separate)
    • -Weak hydrogen bonds between complementary bases break     

    -Exposure of nucleotide bases

    Nucleotides are added to each single stand

    • Enzyme called DNA polymerase picks up nucleotides and slots them to
    • complementary base partner
  6. What is the significance of DNA replication
    • o   Replication ensures that the
    • genetic code of a cell is passed to each new daughter cell that arises from it

    • o   An exact replica/copy is needed
    • so that the new cells have the same, distinctive message that the original cell
    • had

    o   Genetic material is transmitted

    -From one cell to another during mitosis: growth, repair, maintenance

    -From one generation to another in meiosis: sexual reproduction
  7. What is RNA
    • Nucleic acid
    • single stranded
    • has uracil(U) instead of Thymine(T)
  8. What is mRNA
    (Messenger RNA)

    A type of RNA

    Single stranded not twisted into helix

    • Function – intermediate molecule that carries information from DNA to
    • ribosome in cytoplasm
  9. What is tRNA
    • (Transfer RNA)
    • A type of RNA
    • Occurs in cytoplasm
  10. What is rRNA
    • A type of RNA
    • Forms a structural part of the ribosome
  11. What is transcription
    When the code on a DNA strand is written across onto a strand of mRNA
  12. Describe the process of transcription
    Part of the DNA in the nucleus unzips as it would if it were about to duplicate

    RNA nucleotides pair up with the nitrogen bases on the exposed strands of DNA

    • Base pairing in transcription
    • U-A
    • A-T
    • G-C
    • C-G
  13. What is translation
    mRNA carries the coded message from DNA into the cytoplasm. The message then has to be changed into another 'language' or translated, to be able to make polypeptide chains.
  14. Describe the process of translation
    • mRNA attaches to a ribosome
    • mRNA codons match with tRNA anticodons
    • tRNA brings an amino acid to a ribosome
    • A polypeptide is built as amino acids join together at the ribosome
  15. What is a protein
    A large complex macromolecule made up of one or more long chains called polypeptides
  16. What are polypeptides
    • The overall structure of protein
    • Arrangement of amino acids determines configuration of protein
  17. What is a mutation
    • A change in genetic material- change in the sequence of nucleotides in DNA
    • Most are harmful
    • 2 types: Large scale mutations & point mutations
  18. Describe Large scale mutations
    Also known as chromosomal mutations

    -These mutations involve changes to parts,whole or set of chromosomes

    e.g. Down syndrome
  19. Describe point gene mutations
    • These mutations are chemical changes in one or a few base pairs so that the allele of a gene changes 
    • Can lead to production of an abnormal protein
  20. What is a mutagen
    Chemicals or radiation that increase the likelihood of a mutation occuring

    The rate of mutation is directly proportional to the dose received and length of exposure

    Chemical mutagens: ingested chemicals (smoking), irritants/poisons

    Biological mutagens: viruses

    Mutagenic radiation: ionising radiation, ultra-violet (sunlight, tanning salon)

    • Examples:
    • Marie Curie- exposed to large amounts of radiation due to research-developed many illnesses and died to leukimea

    Survivors of Hiroshima suffer physical mutations
  21. Describe the concept of Punctuated Equilibrium in evolution
    Theory of punctuate equilibrium proposes that evolution occurs in short bursts of rapid change, followed by long periods of stability within population

    -Put forward by Stephen Jay Gould and Niles Eldridge based on fossil evidence

    -Differs from Darwins theory of gradualism

    • -Suggested that if evolution was gradual, there would be fossil remains to
    • show these ongoing changes