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
DNA, RNA, and Protein Synthesis
Standards
• SPI 3210.4.1 Identify the structure and function of
DNA.
• SPI 3210.4.2 Associate the process of DNA
replication with its biological significance.
• SPI 3210.4.3 Recognize the interactions between
DNA and RNA during protein synthesis.
Chapter 10
Section 1 Discovery of DNA
Objectives
• Relate how Fred 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
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.
#https://www.youtube.com/watch?v=t9xBHPz_3ro
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
Click below to watch the 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
Possible issues?
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
Section 3 DNA Replication
DNA Replication Visual Concept:
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
10-4 RNA and Protein
Synthesis
RNA, like DNA, consists of long chains of nucleotides.
Three differences between DNA and RNA
- the sugar is ribose
- single stranded
- contains uracil instead of thymine
*base pairings are A-U and C-G
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
Click below to watch the 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
10-4 RNA and Protein
Synthesis
Chapter 10
10-4 Messenger RNA (mRNA)
1.
2.
3.
4.
5.
6.
Single, uncoiled, straight strand of nucleic acid
Found in the nucleus & cytoplasm
Copies DNA’s instructions & carries them to the ribosomes where
proteins can be made
mRNA’s base sequence is translated into the amino acid sequence of a
protein
Three consecutive bases on mRNA called a codon (e.g. UAA, CGC,
AGU)
Reusable
Chapter 10
10-4 RNA and Protein
Synthesis
Ribosome
Ribosomal RNA
Chapter 10
10-4 Ribosomal RNA (rRNA)
•Globular shape
•Helps make up the
structure of the
ribosomes
•Ribosomes are the
site of translation
(making
polypeptides)
•rRNA & protein make
up the large
•& small subunits of
ribosomes
Chapter 10
10-4 RNA and Protein
Synthesis
Amino acid
Chapter 10
10-4 Transfer RNA (tRNA)
Single stranded molecule containing 80
nucleotides in the shape of a cloverleaf/hairpin
- Carries amino acids in the cytoplasm to
ribosomes for protein assembly
-Three bases on tRNA that are
complementary
to a codon on mRNA are called anticodons
(e.g. codon- UUA; anticodon- AAU)
- Amino Acid attachment site
across from anticodon site on tRNA
-Enters a ribosome & reads mRNA
codons and links together correct
sequence of amino acids to make
a protein
-Reusable
Chapter 10
10-4 Transcription
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
DNA
RNA
Chapter 10
10-4 Transcription
Transcription: the copying of the DNA into a complementary
strand of RNA
- uses the enzyme RNA polymerase
During transcription, RNA polymerase binds to DNA and separates
the DNA strands. RNA polymerase then uses one strand of
DNA as a template from which nucleotides are assembled into a
strand of RNA.
The enzyme binds to the region DNA known as the promoter
region.
Chapter 10
10-4 Transcription
1.DNA helicase (enzyme) uncoils the DNA molecule
2.RNA polymerase (enzyme) binds to a region of DNA called the
promoter which has the start codon AUG to code for the amino acid
methionine
3.Promoters mark the beginning of a DNA chain in prokaryotes, but
mark the beginning of 1 to several related genes in eukaryotes
4.The 2 DNA strands separate, but only one will serve as the template
& be copied
5.Free nucleotides are joined to the template by RNA polymerase in the
5’ to 3’ direction to form the mRNA strand
6.mRNA sequence is built until the enzyme reaches an area on DNA called
the termination signal
7.RNA polymerase breaks loose from DNA and the newly made mRNA
8.Eukaryotic mRNA is modified (unneeded sections snipped out by
enzymes & rejoined) before leaving the nucleus through nuclear
pores, but prokaryotic RNA is not
All 3 types of RNA called transcripts are produced by this method
Chapter 10
10-4 RNA and Protein
Synthesis
RNA Editing
Before it leaves the nucleus, RNA is
edited. Splicing occurs by
removing introns and fusing
exons together.
10-4 RNA and Protein
Transcription – Processing of
Synthesis
The Genetic Code
The genetic code is read in three
letter segments called codons.
There are 64 different codon
possibilities that code for only 20
amino acids
-AUG is the start codon
-there are 3 stop codonsUAA, UAG, UGA
Gene Information
10-4 RNA and Protein
Synthesis
Chapter 10
10-4 Translation
Translation: the decoding of mRNA into an amino acid
sequence
During translation, the cell uses information from
messenger RNA to produce proteins
- anticodon: the three letter sequence on tRNA that
binds with mRNA
Chapter 10
10-4 Translation
1. mRNA brings the copied DNA code from the nucleus to the cytoplasm
2. mRNA attaches to one end of a ribosome; called initiation
3. tRNAs attach the correct amino acid floating in the cytoplasm to
themselves
4. tRNA with its attached amino acid has 2 binding sites where they join the
ribosome
5. The tRNA anticodon “reads” & temporarily attaches to the mRNA codon in
the ribosome
6. Two amino acids at a time are linked together by peptide bonds to make
polypeptide -chains (protein subunits); called elongation
7. Ribosomes) move along the mRNA strand until they reach a stop codon
(UAA, UGA, or UAG); called termination
8. tRNA’s break loose from amino acid, leave the ribosome, & return to
cytoplasm to pick up another amino acid
Chapter 10
Lysine
tRNA
Translation direction
mRNA
Ribosome
Chapter 10
10-4 Translation
Polypeptide
Ribosome
tRNA
mRNA
Chapter 10
Section 4 Protein Synthesis
Chapter 10
Section 4 Protein Synthesis
Types of RNA
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 Video
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.
http://www.changethethought.com/tag/human-genome/
Chapter 10
Section 4 Protein Synthesis