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Biology 12Mrs. Knowles
DNA & Gene expression: Chapters 24 & 25
Discovery of DNA
1. Chargaff’s rule
2. Hershey and Chase experiment
3. Francis & Crick’s model
Biology 12Mrs. Knowles
Structure of DNA
Polynucleotide with three subunits:
1)
2)
3)
Purines:
Biology 12Mrs. Knowles
Pyrimidines:
Double helix:
Complementary base pairing:
Biology 12Mrs. Knowles
Antiparallel strands
Replication
Purpose:
semiconservative process:
STEPS:
1) DNA helicase2) DNA polymerase3) DNA ligase
Results:
Biology 12Mrs. Knowles
RNA structure
DNA RNASugar
Bases
Strands
Helix?
Biology 12Mrs. Knowles
Types of RNA:
1) Messenger RNA (mRNA)
2) Ribosomal RNA (rRNA)
3) Transfer RNA (tRNA)
Biology 12Mrs. Knowles
Checkpoint:
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Differentiate between purines and pyrimidines including examples of each.
What three components make up DNA?
What are the structural differences between ribose and deoxyribose? Between thymine and uracil?
Biology 12Mrs. Knowles
Gene expressionOverall goal:
Overall process:
Gene:
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Transcription
Recall that the overall goal is:
Location of transcription:
1) Synthesis of mRNAPromoter region:
RNA polymerase
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2) Processing of mRNA (primary -> mature mRNA)A) Cap
B) Poly-A tail
C) Introns removed, exons joined together
Introns:
Exons:
Ribozyme:
3) Mature mRNA leaves nucleus
Biology 12Mrs. Knowles
Translation
Overall purpose:
The triplet code:
Why triplet?
Codon:
Start codon:
Stop codons:
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tRNA:
its role:
anticodon:
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Ribsomes
Made of:
Made at:
Binding sites:
Polyribosome:
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Steps in translation:
1) Chain initiationWhat is involved:
Step 1:
Step 2:
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2) Chain elongation
Step 3:
Step 4:
Step 5:
Step 6:
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3) Chain termination
Step 7:
Step 8:
Biology 12Mrs. Knowles
Levels of gene control
1) Unpacking of DNA
2) Transcription
3) mRNA processing
4) translation
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5) protein activity
6) signaling between cells
When gene control fails: cancer
Characteristics of cancer cells:
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Proto-oncogenes
Tumor-suppressor genes
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Gene mutations
Definition:
Causes:
i. Errors in replication
ii. Mutagens
iii. transposons
Types of mutations:
i. Frameshift mutations
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ii. Point mutations
DNA Technology
1) Cloning
i) Reproductive cloning
ii) Therapeutic cloning
2) Recombinant DNA (rDNA)
Biology 12Mrs. Knowles
3) Polymerase chain reaction
4) Fingerprinting
Biotechnology-genetic engineering
1) Transgenic bacteria
2) Transgenic plants
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3) Transgenic animals
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