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Chapter 10
DNA, RNA, and Protein Synthesis
Table of Contents
Section 1 Discovery of DNA
Section 2 DNA Structure
Section 3 DNA Replication
Section 4 Protein Synthesis
Chapter 10
Section 1 Discovery of DNA
Objectives
• Relate how Griffith’s bacterial experiments showed
that a hereditary factor was involved in
transformation.
• Summarize how Avery’s experiments led his group to
conclude that DNA is responsible for transformation
in bacteria.
• Describe how Hershey and Chase’s experiment led
to the conclusion that DNA, not protein, is the
hereditary molecule in viruses.
Chapter 10
Section 1 Discovery of DNA
Griffith’s Experiments
• Griffith’s experiments showed that hereditary material
can pass from one bacterial cell to another.
• The transfer of genetic material from one cell to
another cell or from one organism to another
organism is called transformation.
Chapter 10
Section 1 Discovery of DNA
Griffith’s Discovery of Transformation
Chapter 10
Section 1 Discovery of DNA
Transformation
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Visual Concept
Chapter 10
Section 1 Discovery of DNA
Avery’s Experiments
• Avery’s work showed that DNA is the hereditary
material that transfers information between bacterial
cells.
Chapter 10
Section 1 Discovery of DNA
Hershey-Chase Experiment
• Hershey and Chase confirmed that DNA, and not
protein, is the hereditary material.
Chapter 10
Section 1 Discovery of DNA
The Hershey-Chase
Experiment
Chapter 10
Section 1 Discovery of DNA
Hershey and Chase’s Experiments
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Visual Concept
Chapter 10
Section 2 DNA Structure
Objectives
• Evaluate the contributions of Franklin and Wilkins in
helping Watson and Crick discover DNA’s double
helix structure.
• Describe the three parts of a nucleotide.
• Summarize the role of covalent and hydrogen bonds
in the structure of DNA.
• Relate the role of the base-pairing rules to the
structure of DNA.
Chapter 10
Section 2 DNA Structure
DNA Double Helix
• Watson and Crick created a model of DNA by using
Franklin’s and Wilkins’s DNA diffraction X-rays.
Chapter 10
Section 2 DNA Structure
DNA Double Helix
• DNA is made of two nucleotide strands that wrap
around each other in the shape of a double helix.
Chapter 10
Section 2 DNA Structure
DNA Double Helix, continued
• A DNA nucleotide is made of a 5-carbon deoxyribose
sugar, a phosphate group, and one of four
nitrogenous bases: adenine (A), guanine (G),
cytosine (C), or thymine (T).
Chapter 10
Section 2 DNA Structure
DNA Nucleotides, continued
• Bonds Hold DNA Together
– Nucleotides along each DNA strand are linked by
covalent bonds.
– Complementary nitrogenous bases are bonded by
hydrogen bonds.
Chapter 10
Section 2 DNA Structure
Complementary Bases
• Hydrogen bonding between the complementary
base pairs, G-C and A-T, holds the two strands of a
DNA molecule together.
Chapter 10
Section 3 DNA Replication
Objectives
• Summarize the process of DNA replication.
• Identify the role of enzymes in the replication of DNA.
• Describe how complementary base pairing guides DNA
replication.
• Compare the number of replication forks in prokaryotic and
eukaryotic cells during DNA replication.
• Describe how errors are corrected during DNA replication.
Chapter 10
Section 3 DNA Replication
How DNA Replication Occurs
• DNA replication is the process by which DNA is
copied in a cell before a cell divides.
Chapter 10
Section 3 DNA Replication
How DNA Replication Occurs, continued
• Steps of DNA Replication
– Replication begins with the separation of the DNA
strands by helicases.
– Then, DNA polymerases form new strands by
adding complementary nucleotides to each of the
original strands.
Chapter 10
DNA Replication
Section 3 DNA Replication
Chapter 10
Section 3 DNA Replication
How DNA Replication Occurs, continued
• Each new DNA molecule is made of one strand of
nucleotides from the original DNA molecule and one
new strand. This is called semi-conservative
replication.
Chapter 10
Section 3 DNA Replication
Replication Forks Increase the Speed of Replication
Chapter 10
Section 3 DNA Replication
DNA Errors in Replication
• Changes in DNA are called mutations.
• DNA proofreading and repair prevent many
replication errors.
Chapter 10
Section 3 DNA Replication
DNA Errors in Replication, continued
• DNA Replication and Cancer
– Unrepaired mutations that affect genes that control
cell division can cause diseases such as cancer.
Chapter 10
Section 4 Protein Synthesis
Objectives
• Outline the flow of genetic information in cells from DNA to
protein.
• Compare the structure of RNA with that of DNA.
• Describe the importance of the genetic code.
• Compare the role of mRNA, rRNA,and tRNA in translation.
• Identify the importance of learning about the human genome.
Chapter 10
Section 4 Protein Synthesis
Flow of Genetic Information
• The flow of genetic information can be symbolized
as DNA
RNA
protein.
Chapter 10
Section 4 Protein Synthesis
RNA Structure and Function
• RNA has the sugar ribose instead of deoxyribose
and uracil in place of thymine.
• RNA is single stranded and is shorter than DNA.
Chapter 10
Section 4 Protein Synthesis
Comparing DNA and RNA
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Visual Concept
Chapter 10
Section 4 Protein Synthesis
RNA Structure and Function, continued
• Types of RNA
– Cells have three major
types of RNA:
• messenger RNA
(mRNA)
• ribosomal RNA
(rRNA)
• transfer RNA
(tRNA)
Chapter 10
Section 4 Protein Synthesis
RNA Structure and Function, continued
• mRNA carries the genetic “message” from the
nucleus to the cytosol.
• rRNA is the major component of ribosomes.
• tRNA carries specific amino acids, helping to form
polypeptides.
Chapter 10
Section 4 Protein Synthesis
Types of RNA
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Visual Concept
Chapter 10
Section 4 Protein Synthesis
Transcription
• During transcription, DNA acts as a template for
directing the synthesis of RNA.
Chapter 10
Transcription
Section 4 Protein Synthesis
Chapter 10
Section 4 Protein Synthesis
Genetic Code
• The nearly universal genetic code identifies the
specific amino acids coded for by each threenucleotide mRNA codon.
Chapter 10
Section 4 Protein Synthesis
Translation
• Steps of Translation
– During translation, amino acids are assembled
from information encoded in mRNA.
– As the mRNA codons move through the ribosome,
tRNAs add specific amino acids to the growing
polypeptide chain.
– The process continues until a stop codon is
reached and the newly made protein is released.
Chapter 10
Section 4 Protein Synthesis
Translation: Assembling Proteins
Chapter 10
Section 4 Protein Synthesis
The Human Genome
• The entire gene sequence of the human genome, the
complete genetic content, is now known.
• To learn where and when human cells use each of the
proteins coded for in the approximately 30,000 genes
in the human genome will take much more analysis.