The cell cycle, DNA, and protein synthesis Cell division by steepslope9876


									              The cell cycle, DNA,                                              Cell division
                                          •         = the reproduction of cells
              and protein synthesis       •         1. Mitosis produces somatic cells (= all body cells except sex cells
                                          •         2. Meiosis produces sex cells (= ♂ sperm and ♀ eggs)
                                                        – We’ll cover meiosis with the reproductive system chapter

• We will be
  covering bits
  and pieces of
  Ch. 19 (the cell
  cycle) and Ch.
  21 (DNA and

                     The cell cycle

                                      structure during the cell cycle
2 main parts:

                                        Changes in chromosome
• 1. Interphase –
  normal cell
  functions; prep
  for cell division
  (e.g. DNA
   – Most somatic
     cells spend
     majority of lives
     in interphase
     varies by
     cell type)
• 2. Cell division/

          Overview of mitosis

                                                Stages of cell division
                                               (mitosis) – continued on next slide

                                               • = division of cytoplasm after mitosis; last stage of cell division

Stages of cell division (mitosis), continued

       Review of                                                          DNA replication
       structure…                                                         • Occurs during the “S”
                                                                            (middle) part of
                                                                            interphase of the cell
•    …so that we can better
     understand DNA replication
     and protein synthesis                                                • DNA polymerases =
                                                                            enzymes that link the
•    Remember, for DNA:                                                     adjacent nucleotides
      – A is complementary to T
                                                                            of each new
      – C is complementary to G

     Gene expression is protein synthesis                                          Needs for protein synthesis
                 transcription                 translation                • 1. Instructions:
       DNA                        mRNA                          protein      – Genes on DNA in nucleus
                                                                          • 2. An assembly site:
    • Gene = a segment of DNA that contains a sequence of                    – Ribosomes (which are made up of rRNA + proteins) in cytoplasm
      nucleotide bases that codes for a specific polypeptide or           • 3. A courier:
      protein                                                                – mRNA (messenger RNA) takes instructions from nucleus to assembly
                                                                               site in cytoplasm
    • Transcription: information stays in the same language
                                                                          • 4. Raw materials:
      (nucleotide base sequence)
       – Takes place in nucleus                                              – Amino acids in cytoplasm
                                                                          • 5. Transport of raw materials to assembly site:
    • Translation: information is translated from nucleotide base            – tRNA (transfer RNA) carries amino acids to ribosome
      sequence to amino acid sequence
       – This is the actual “protein synthesis” part this whole process
       – Takes place in cytoplasm

                      The genetic code                                                            Transcription
•   Codon = three (3) nucleotide bases in a specific sequence that code for
    one amino acid                                                            • = making an mRNA copy of a DNA gene in the nucleus
•   So a gene contains all the codons needed to code for a specific
    polypeptide                                                               • RNA polymerase = the enzyme that makes it happen
     – May be hundreds or thousands of bases long                             • The finished mRNA transcript will leave the nucleus and
                                 (mRNA codons)
                                                                                travel to a ribosome in the cytoplasm

                            Translation                                         Ribosomes: the workbenches on
•   = assembling amino acids into                                              which proteins are built (translation)
    a polypeptide at the ribosome
    according to the mRNA
•   Anticodon = 3 base sequence
    of tRNA that is complementary
    to a mRNA codon
     – Determines which amino acid
       the tRNA can carry

•   Remember, for RNA:
     – A is complementary to U
     – C is complementary to G



                            Review: DNA vs. RNA


Review: the 3 types of RNA


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