DNA Replication, Transcription, and Translation - PowerPoint by jcf58551

VIEWS: 0 PAGES: 27

									DNA Replication, Transcription,
      and Translation
       The Making of a Protein
     DNA Replication
• Process by which DNA
  copies itself
• Happens when
  chromosomes copy
  themselves before
  mitosis and meiosis
      Steps of DNA Replication:
1. DNA untwists
2. DNA unzips (separates)
3. Corresponding free-
   floating nucleotides
   attach to original sides
   to form new base pairs
4. DNA reforms                  Identical
5. 2 strands twist into helix   Strand
   animation
Complementary
base pairing allows
each strand of
DNA to serve as a
template for DNA
replication
SEMI-CONSERVATIVE REPLICATION


DNA Replication –
Something old and
something new in the
daughter molecules,
known as semi-
conservative replication
(part of the original
DNA is conserved)
 RNA - Ribonucleic Acid
“DNA Messenger & Taxi”

RNA Structure & Function

From DNA to Protein
           What is RNA?
 Organic Molecule
 Nucleic Acid
 Three types
  mRNA = messenger
  tRNA = transfer
  rRNA = ribosomal (combines
  with proteins to form
  ribosomes)
       Where is RNA located?
mRNA -in nucleus &
   cytoplasm         rRNA
tRNA - only in
   cytoplasm
rRNA – found in         mRNA
   ribosomes
   (cytoplasm)
                        mRNA

                      tRNA
         What is RNA’s structure?
                       1. Nucleotides=
•   Phosphate (Acid)     a. Phosphoric Acid
•   Sugar-Base           b. Ribose sugar
•   Phosphate (Acid)     c. Nitrogenous Bases:
•   Sugar-Base             Adenine-Uracil
•   Phosphate (Acid)       Guanine-Cytocine
•   Sugar-Base         2. Single Strand
•   Phosphate (Acid)   3. No Twisted helix
•   Sugar-Base
    Comparison of RNA & DNA:
•   Acid            Acid          Acid
•          Uracil
    Sugar-Base              --
                    Sugar- Thymine -Sugar
•   Acid            Acid          Acid
•   Sugar-Base
                    Sugar- Base -Sugar
•   Acid
                    Acid          Acid
•   Sugar-Base
•   Acid            Sugar- Base- Sugar
                    Deoxy-
                    ribose
•   Ribose
    Sugar-Base      Acid          Acid
      RNA              DNA Ladder
     What are mRNA’s functions?
mRNA=
•   Copies the DNA code
•   Goes out into the
    cytoplasm to tell the
    cell what to do in
    order to stay alive
•   Delivers message to
    ribosomes (protein
    factories)
    Why not send the original DNA
              code out?
• DNA is the master       Original DNA
  copy – must be
  protected
• DNA might be damaged!             DNA in the
• DNA can’t fit through             nucleus is
  nuclear pores                     safe
• mRNA components are
  reused
• To copy more messages
                             mRNA -copy
                  Transcription
1. mRNA is copied from DNA
2. Occurs in the nucleus
3. Steps:
•   DNA untwists
•   Unzip one gene in DNA
•   RNA codons line up to
    corresponding bases on one
    side of DNA
•   mRNA detaches from the
    DNA
                                  DNA: GAG
•   mRNA moves out of the         AAC TAG
    nucleus and into the          TAC
    cytoplasm
                                  RNA: CUC
                                  UUG AUC
                                  AUG
  RNA Review:
                  mRNA has:
           mRNA   • Single strand
    A             • Ribose sugar
           U      • Uracil instead
    T
           A        of thymine
    C               bases
           G      • Nuclear
    G               membrane
           C        allows it to
DNA Code            leave!
Transcription
                      DNA                   mRNA
                            mRNA
                                                        Cytoplasm
                                                        of cell


                       Nucleus



  Transcription         Then the mRNA              Once in the
  happens in the        that has been              cytoplasm, the
  nucleus. An RNA       made moves out of          mRNA is used to
  copy of a gene is     the nucleus into           make a protein
  made.                 the cytoplasm
How does mRNA tell the cell
       what to do?
• mRNA is a message that codes for a
  protein
• Proteins are made in the cytoplasm
  and work to keep the cell alive
• Translation (protein synthesis):
  Process of making a protein
• Proteins are made up of amino acids
  (small building blocks)
Transcription Review



        QuickTime™ an d a
           decompressor
  are need ed to see this p icture .
There are 20 different types of amino acids

               Protein




             Amino Acids
    Protein Synthesis
Assembling Proteins from the
     DNA Instructions
               tRNA:
       Amino
               • in cytoplasm
       acid
               • Picks up an amino
                 acid
               • “Taxis” the amino
                 acid to the
tRNA             ribosome protein
                 factories
             Translation
• Conversion of the message (mRNA code)
  into a protein by the ribosome factories
                                                    Nucleus

     Translation
                                        Cytoplasm
1. mRNA moves out of nucleus and into
     cytoplasm
2. mRNA attaches to a ribosome
3. Transfer RNA (tRNA) decodes the       Ribosome
     mRNA and brings amino acids to
     build up the protein

  tRNA

                     Amino acid

Anticodon (3 bases on tRNA):
Matches up to codons on mRNA
4. Protein (chain of amino acids)
     detaches from ribosome and goes
     off to work in the cell
                4. Polypeptide
                Chain of
                amino
                acids grows




                2. Peptide
1. tRNA         bond forms
  delivers      3. tRNA leaves
   amino acid   ribosome
Putting It All Together
Genetic Code
Code that matches codons in mRNA to amino acids on tRNAs

mRNA
codons
(3 bases)

Amino                                Stop codon – codes for
acids                                the end of the mRNA (no
                                     amino acid added)



                                      Different codons code for
                                      different amino acids!!!
             Summary:
DNA Replication:   Protein Synthesis:
                   Transcription:
• Make duplicate
                   - make mRNA from DNA
  DNA                 (in nucleus, moves out
• In nucleus          into cytoplasm)
• Copy the         Translation:
  chromosomes      - make protein from
                      mRNA code using
• Occurs before       amino acids (on
  mitosis and         ribosome in
                      cytoplasm)
  meiosis
Translation Review



       QuickTime™ an d a
          decompressor
 are need ed to see this p icture .

								
To top