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NAME:_________________
Biology 2
DNA and RNA
Chapter 10 (p. 184 - 206)
Griffith’s Experiment:
Tried to figure out how bacteria give people pneumonia.
What information did this experiment provide?
Transformation:
Hershey-Chase Experiment:
Experimented with bacteriophages to determine which part of the virus (protein coat or DNA core)
entered the host and passed on genes.
What information did this experiment provide?
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Avery’s Experiment:
Tried to figure out which molecule in the heat-killed bacteria was most important for the transformation.
What information did this experiment provide?
_______ is the genetic transforming molecule.
Components and Structure of DNA:
This was deduced by Watson and Crick using 3 pieces of information: 1) DNA is made of 4 nucleotides
2) Chargaff’s Rules, and 3) X-Ray evidence.
DNA is a nucleic acid polymer made of 4 different monomers called nucleotides.
The 4 nucleotides are:
Each nucleotide contains 3 parts:
Adenine and guanine are classified as purines:
Thymine and cytosine are classified as pyrimidines:
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Chargaff’s Rules:
What can be concluded from Chargaff’s discovery?
Franklin’s X-Ray Evidence: Used X-ray diffraction
What information about DNA is provided?
Watson and Crick used the information to determine the structure of DNA.
Double helix:
Complementary strands:
Base-pairing rule:
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DNA and Chromosomes:
DNA is packed very tightly to form a chromosome and to fit inside of the cell’s nucleus. Prokaryotes
only have a single loop of DNA. Eukaryotes have multiple linear chromosomes. A human cell contains
1m of DNA. How does DNA fit into the small nucleus?
DNA Replication (in nucleus):
DNA must be duplicated before it can be divided by mitosis or meiosis.
Prokaryotes have one point at which replication begins in both directions.
Eukaryotes have multiple points at which replication begins in both directions.
Replication forks:
Bidirectional:
Advantage of multiple replication forks and bidirectional replication?
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Semi-conservative:
How does the actual replication process occur?
Enzymes:
1. Helicase: “Hacks”
2. DNA polymerase: “Pairs” and “Proofreads”
3. Ligase: “Links”
RNA and Protein Synthesis:
The double helix explains how DNA can be replicated. It does not explain how a gene works. Steps to
making a gene work:
1. Transcribe DNA to RNA
2. Edit the RNA
3. Translate the RNA into a functional protein using the genetic code
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Structure of RNA:
RNA is a polymer of nucleotides (this is just like DNA).
Differences between RNA and DNA:
1. Single-stranded
2. Ribose:
3. Uracil:
Types of RNA:
Different types of RNA perform different functions, all revolving around protein synthesis.
The synthesis of amino acids is controlled by all 3 RNA types:
1. Messenger RNA (mRNA):
2. Ribosomal RNA (rRNA):
3. Transfer RNA (tRNA):
Transcription (in nucleus): DNA pre mRNA
RNA polymerase:
RNA Editing (in nucleus): pre mRNA  mRNA
Introns:
Exons: “Expressed”
Splicing:
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Translation (in cytoplasm): mRNA amino acids (protein)
mRNA serves as instructions to create an amino acid sequence, or protein. If the “instructions” are
changed, the protein created may also change.
Ribosome (rRNA):
Codon:
Anticodon:
Steps:
Genetic Code:
Rules:
1. Information is carried on codons.
2. There are specific START and STOP codons.
3. Codons do not overlap.
4. There are no nucleotide spacers between codons.
5. The message is decoded into protein by anticodons on tRNA that are complementary the codons
of mRNA.
6. Code is universal.
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The entire process:
Mutations: (Group activity)
Point mutations:
Substitutions:
Frameshift mutations:
Deletions:
Insertions:
Which one is more likely to lead to dramatic changes in protein?
Why?