Protein Synthesis

1
Protein Synthesis
2
(No Transcript)
3
The DNA Code

• It is a universal code.
• The order of bases along the DNA strand codes for
  the order in which amino acids are chemically
  joined together to form a polypeptide

4
From DNA to Protein

• Protein synthesis involves two types of nucleic
  acids
• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)

5
RNA

• RNA, like DNA, is a polymer formed by a sequence
  of nucleotides
• Three Types of RNA
• messenger RNA (mRNA)
• transfer RNA (tRNA)
• ribosomal RNA (rRNA)

6
Differences Between DNA and RNA

• DNA RNA
• double-stranded single-stranded
• sugar deoxyribose sugar ribose
• bases A,T,C,G bases A,U,C,G
• (uracil takes the place of thymine)

7
(No Transcript)
8
Protein Synthesis

• involves two processes
• Transcription the copying of the genetic
  message (DNA) into a molecule of mRNA
• Translation mRNA is used to assemble an amino
  acid sequence into a polypeptide

9
A sequence of 3 bases called a codon codes for
one amino acid
10
(No Transcript)
11
Transcription

• occurs in the nucleus of the cell
• Steps in transcription
• Initiation DNA strand separates and serves as a
  template (pattern) for mRNA assembly. mRNA
  polymerase attaches to the template
  Strand of
  DNA.

12

• 2) Elongation RNA Polymerase attaches to the
  template strand of DNA. Free mRNA nucleotides
  match up to the exposed nucleotides on the DNA
  strand.

13

1. Termination mRNA strand separates from the DNA
   strand when a stop codon is reached and the
   entire gene has been transcribed.
2. the mRNA strand carries the code for the
   production of one polypeptide

14
Translation

• occurs in the cytoplasm of the cell, at the
  ribosome
• Always begins with the mRNA codon AUG
• 1) Initiation mRNA moves out of the nucleus
  and into the cytoplasm to a ribosome

15

• 2) Elongation mRNA is read by the ribosome
  as the anticodons of the tRNA molecules attach to
  their complementary condons on the mRNA molecules
  creating a chain of amino acids.

16

• Termination
• mRNA molecule moves across the ribosome
• tRNA temporarily attaches to the mRNA strand.
• The amino acids are joined by a peptide bond by
  enzymes until a stop codon is reached

17
tRNA Molecule
18

• 4. a polypeptide is produced

19
Animations