Plant Genetics

1
Plant Genetics

• Modified by Georgia Agriculture Education
  Curriculum Office
• June, 2002

2
Biotechnology

• pest resistance
• herbicide resistance
• environmental stress resistance
• nutritionally complete plants
• flowers with unusual colors
• delayed ripening/softening
• specific nutritional qualities
• product uniformity

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Central Dogma of Molecular Biology
DNA RNA Protein
transcription
translation
replication
4
Proteins

• Enzymes catalysts
• Structural Components, e.g., membranes,
  cytoskeleton

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Proteins

• Chain of amino acids linked by peptide bonds
• H O
• C N
• H2N C COOH H
• di-peptide (2 amino R acids)
  tri-peptide (3)
• R variable group polypeptide (gt3)
• 20 common amino acids differ by the R group

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DNA vs. RNA

• 4 bases guanine (G), cytosine (C), adenine (A),
  thymine (T)
• G-C A-T
• deoxyribose sugar
• double stranded
• nucleus

• 4 bases guanine (G), cytosine (C), adenine (A),
  uraacil (U)
• G-C A-U
• ribose sugar
• single stranded
• rRNA, mRNA, tRNA
• synthesized in nucleus (nucleoi for rRNA)
  function in cytosol

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Major Compounds of life
Macromolecule Simple Molecule Structure
4. Nucleic Acids nucleotides (DNA
RNA) (sugar phosphate N-base)
NH2
N
N
N
adenine (N-base) ribose (sugar)
N
O
O
HO - P - O
O
OH OH
phosphoric acid
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Function Major Compounds of Life

• Nucleic Acids
• genetic information/heredity
• protein synthesis

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RNA

• rRNA
• RNA protein form ribosomes
• mRNA
• carries DNA code to cytosol for protein synthesis
  on the ribosomes
• read in triplets called codons (5 to 3)
• tRNA
• carries amino acids to mRNA and matches up by
  base-pairing of triplet anti-codon with mRNA
  codon triplet

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Double-Stranded DNA Molecule
complementary base-pairing
5
3
T G G C A TT C A C G A T T GG A C A
H-bonds
A C C G T AA G T G C T A A CC T G T
3
5
sugar-P backbone (phospho-diester bonds)
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TRANSCRIPTION
DNA
RNA
5
3
T G G C A TT C A C G A T T GG A C A
3
DNA
U
A
C G
A
C
U
U
A
3
5
C
A C C G T AA G T G C T A A CC T G T
G
G
U
5
RNA strand
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TRANSLATION
RNA Protein
triplet codons
mRNA
5
3
U G G C C A U U C A C G A U
A C C G G U
triplet anti-codons
A AG
3
4
amino acids/ peptide chain
2
1
5
tRNAs
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