Download From DNA to RNA

Chapter 10
The Structure and Function
of DNA
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
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DNA: STRUCTURE AND REPLICATION
• DNA:
– Was known to be a chemical in cells by the end of the nineteenth century
– Has the capacity to store genetic information
– Can be copied and passed from generation to generation
• DNA and RNA are nucleic acids.
– They consist of chemical units called nucleotides.
– The nucleotides are joined by a sugar-phosphate backbone.
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Nitrogenous base
(can be A, G, C, or T)
Thymine (T)
Phosphate
group
Sugar
(deoxyribose)
DNA nucleotide
Figure 10.1b
Phosphate group
Nitrogenous base
Sugar
Nucleotide
DNA
double helix
Nitrogenous base
(can be A, G, C, or T)
Thymine (T)
Phosphate
group
Sugar
(deoxyribose)
DNA nucleotide
Polynucleotide
Sugar-phosphate
backbone
Figure 10.1
Watson and Crick’s Discovery of the Double
Helix 1952
• James Watson and Francis Crick determined that DNA is a
double helix.
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• Watson and Crick used X-ray crystallography data to reveal the
basic shape of DNA.
– Rosalind Franklin collected the X-ray crystallography data.
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• The four nucleotides found in DNA differ in their nitrogenous
bases. These bases are:
– Thymine (T)
– Cytosine (C)
– Adenine (A)
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– Guanine (G)
• RNA has uracil (U) in place of thymine.
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• The model of DNA is like a rope ladder twisted into a spiral.
– The ropes at the sides represent the sugar-phosphate backbones.
– Each wooden rung represents a pair of bases connected by hydrogen
bonds.
• DNA bases pair in a complementary fashion:
– Adenine (A) pairs with thymine (T)
– Cytosine (C) pairs with guanine (G)
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Twist
Figure 10.4
Hydrogen bond
(a) Ribbon model
(b) Atomic model
(c) Computer
model
Figure 10.5
How are DNA and RNA
different?
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Comparison of DNA & RNA
 DNA
 RNA
 Double strand
 Single strand
 Contains A, T, G, C
 Contains A, U, G, C
 Only in nucleus
 Goes from nucleus to
ribosome
 Sugar is Ribose
 Sugar is De-Oxyribose
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DNA Replication
• When a cell reproduces, a complete copy of the DNA must pass
from one generation to the next.
• Watson and Crick’s model for DNA suggested that DNA
replicates by a template mechanism.
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Parental (old)
DNA molecule
Daughter
(new) strand
Daughter
DNA molecules
(double helices)
Figure 10.6
Origin of
replication
Origin of
replication
Parental strands
Origin of
replication
Parental strand
Daughter strand
Bubble
Two daughter DNA molecules
Figure 10.7
THE FLOW OF GENETIC INFORMATION
FROM DNA TO RNA TO PROTEIN
• DNA functions as the inherited directions for a cell or organism.
• How are these directions carried out?
• What is the language of nucleic acids?
– In DNA, it is the linear sequence of nucleotide bases.
– A typical gene consists of thousands of nucleotides.
– A single DNA molecule may contain thousands of genes.
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How an Organism’s Genotype Determines Its
Phenotype
• An organism’s genotype is its genetic makeup, the sequence of
nucleotide bases in DNA.
• The phenotype is the organism’s physical traits, which arise from
the actions of a wide variety of proteins.
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• DNA = genes = traits
• DNA = code for Protein Synthesis
• The function of a gene is to dictate the production of a
polypeptide.
• A protein may consist of two or more different polypeptides.
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• DNA specifies the synthesis of proteins in two stages:
– Transcription, the transfer of genetic information from DNA into an
RNA molecule (copy and transfer)
– Translation, the transfer of information from RNA into a protein
(translate)
Protein Synthesis
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Nucleus
DNA
Cytoplasm
Figure 10.8-1
Nucleus
DNA
TRANSCRIPTION
RNA
Cytoplasm
Figure 10.8-2
Nucleus
DNA
TRANSCRIPTION
RNA
TRANSLATION
Protein
Cytoplasm
Figure 10.8-3
• What are the rules for translating the RNA message into a
polypeptide?
• A codon is a triplet of bases, which codes for one amino acid.
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• Of the 64 triplets (codons) :
– 61 code for amino acids
– 3 are stop codons, indicating the end of a polypeptide
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Gene 1
DNA molecule
Gene 2
Gene 3
DNA strand
TRANSCRIPTION
RNA
TRANSLATION
Codon
Polypeptide
Amino acid
Figure 10.10
Second base of RNA codon
First base of RNA codon
Leucine
(Leu)
Leucine
(Leu)
Isoleucine
(Ile)
Serine
(Ser)
Stop
Stop
Proline
(Pro)
Threonine
(Thr)
Met or start
Valine
(Val)
Tyrosine
(Tyr)
Alanine
(Ala)
Histidine
(His)
Glutamine
(Gln)
Cysteine
(Cys)
Stop
Tryptophan (Trp)
Arginine
(Arg)
Asparagine
(Asn)
Serine
(Ser)
Lysine
(Lys)
Arginine
(Arg)
Aspartic
acid (Asp)
Glutamic
acid (Glu)
Third base of RNA codon
Phenylalanine
(Phe)
Glycine
(Gly)
Figure 10.11
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Transcription: From DNA to RNA
• Transcription:
– Makes RNA from a DNA template
– Uses a process that resembles DNA replication
– Substitutes uracil (U) for thymine (T)
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Initiation of Transcription
• The “start transcribing” signal is a nucleotide sequence called a
promoter.
• The first phase of transcription is initiation, in which:
– RNA polymerase attaches to the promoter
– RNA synthesis begins
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Second base of RNA codon
First base of RNA codon
Leucine
(Leu)
Leucine
(Leu)
Isoleucine
(Ile)
Serine
(Ser)
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Stop
Stop
Proline
(Pro)
Threonine
(Thr)
Met or start
Valine
(Val)
Tyrosine
(Tyr)
Alanine
(Ala)
Histidine
(His)
Glutamine
(Gln)
Cysteine
(Cys)
Stop
Tryptophan (Trp)
Arginine
(Arg)
Asparagine
(Asn)
Serine
(Ser)
Lysine
(Lys)
Arginine
(Arg)
Aspartic
acid (Asp)
Glutamic
acid (Glu)
Third base of RNA codon
Phenylalanine
(Phe)
Glycine
(Gly)
Figure 10.11
Termination of Transcription
• During the third phase of transcription, called termination:
– RNA polymerase reaches a sequence of DNA bases called a terminator
– Polymerase detaches from the RNA
– The DNA strands rejoin
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Second base of RNA codon
First base of RNA codon
Leucine
(Leu)
Leucine
(Leu)
Isoleucine
(Ile)
Serine
(Ser)
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Stop
Stop
Proline
(Pro)
Threonine
(Thr)
Met or start
Valine
(Val)
Tyrosine
(Tyr)
Alanine
(Ala)
Histidine
(His)
Glutamine
(Gln)
Cysteine
(Cys)
Stop
Tryptophan (Trp)
Arginine
(Arg)
Asparagine
(Asn)
Serine
(Ser)
Lysine
(Lys)
Arginine
(Arg)
Aspartic
acid (Asp)
Glutamic
acid (Glu)
Third base of RNA codon
Phenylalanine
(Phe)
Glycine
(Gly)
Figure 10.11
Transfer RNA (tRNA)
• Transfer RNA (tRNA):
– Acts as a molecular interpreter
– Carries amino acids
– Matches amino acids with codons in mRNA using anticodons
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DNA strand
TRANSCRIPTION
RNA
TRANSLATION
Codon
Polypeptide
Amino acid
Figure 10.10
Ribosomes
• Ribosomes are organelles that:
– Coordinate the functions of mRNA and tRNA
– Are made of two protein subunits
– Contain ribosomal RNA (rRNA)
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TRANSCRIPTION
TRANSLATION
Gene
mRNA
Polypeptide
DNA
Figure 10.UN5
RNA nucleotides
RNA polymerase
Newly made RNA
Direction of
transcription
Template
strand of DNA
(a) A close-up view of transcription
Figure 10.13a
Cap
Start of genetic
message
End
Tail
Figure 10.17
Amino acid attachment site
Hydrogen bond
RNA polynucleotide
chain
Anticodon
tRNA polynucleotide
(ribbon model)
tRNA
(simplified
representation)
Figure 10.15
Next amino acid
to be added to
polypeptide
Growing
polypeptide
tRNA
mRNA
Codons
(b) The “players” of translation
Figure 10.16b
Amino acid
Polypeptide
P site
mRNA
Anticodon
A
site
Codons
Codon recognition
ELONGATION
Figure 10.19-1
Amino acid
Polypeptide
P site
mRNA
Anticodon
A
site
Codons
Codon recognition
ELONGATION
New
peptide
bond
Peptide bond formation
mRNA
movement
Translocation
Figure 10.19-3
Amino acid
Polypeptide
P site
mRNA
Anticodon
A
site
Codons
Codon recognition
ELONGATION
Stop
codon
New
peptide
bond
Peptide bond formation
mRNA
movement
Translocation
Figure 10.19-4
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Protein Synthesis
DNA:
TTTCAGATCAAATGACCCTCTGTCTAA
DNA: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
mRNA _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
A.A. ____ ____ ____ ____ ____ ____ ____ ____ ____
tRNA _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Second base of RNA codon
First base of RNA codon
Leucine
(Leu)
Leucine
(Leu)
Isoleucine
(Ile)
Serine
(Ser)
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Stop
Stop
Proline
(Pro)
Threonine
(Thr)
Met or start
Valine
(Val)
Tyrosine
(Tyr)
Alanine
(Ala)
Histidine
(His)
Glutamine
(Gln)
Cysteine
(Cys)
Stop
Tryptophan (Trp)
Arginine
(Arg)
Asparagine
(Asn)
Serine
(Ser)
Lysine
(Lys)
Arginine
(Arg)
Aspartic
acid (Asp)
Glutamic
acid (Glu)
Third base of RNA codon
Phenylalanine
(Phe)
Glycine
(Gly)
Figure 10.11
In a DNA double helix, adenine pairs with ______
and guanine pairs with ______.
A) cytosine . . . thymine
B) guanine . . . adenine
C) uracil . . . cytosine
D) thymine . . . cytosine
E) cytosine . . . uracil
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In a DNA double helix, adenine pairs with ______
and guanine pairs with ______.
A) cytosine . . . thymine
B) guanine . . . adenine
C) uracil . . . cytosine
D) thymine . . . cytosine
E) cytosine . . . uracil
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RNA contains the nitrogenous base ______ instead of
______, which is only found in DNA.
A) a deoxyribose sugar . . . a ribose sugar
B) nucleotides . . . nucleic acids
C) uracil . . . thymine
D) cytosine . . . guanine
E) adenine . . . guanine
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RNA contains the nitrogenous base ______ instead of
______, which is only found in DNA.
A) a deoxyribose sugar . . . a ribose sugar
B) nucleotides . . . nucleic acids
C) uracil . . . thymine
D) cytosine . . . guanine
E) adenine . . . guanine
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If one strand of a DNA double helix has the sequence
GTCCAT, what is the sequence of the other strand?
A) ACTTGC
B) TGAACG
C) CAGGTA
D) CAGGUA
E) CUGGTU
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If one strand of a DNA double helix has the sequence
GTCCAT, what is the sequence of the other strand?
A) ACTTGC
B) TGAACG
C) CAGGTA
D) CAGGUA
E) CUGGTU
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What name is given to the collection of traits exhibited
by an organism?
A) holotype
B) genotype
C) typology
D) phenotype
E) morphology
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What name is given to the collection of traits exhibited
by an organism?
A) holotype
B) genotype
C) typology
D) phenotype
E) morphology
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How many nucleotides make up a codon?
A) one
B) two
C) three
D) four
E) five
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How many nucleotides make up a codon?
A) one
B) two
C) three
D) four
E) five
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Transcription is the ______.
A) manufacture of a strand of RNA complementary to
a strand of DNA
B) manufacture of two new DNA double helices that
are identical to an old DNA double helix
C) modification of a strand of RNA prior to the
manufacture of a protein
D) manufacture of a protein based on information
carried by RNA
E) manufacture of a new strand of DNA
complementary to an old strand of DNA
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Transcription is the ______.
A) manufacture of a strand of RNA complementary to
a strand of DNA
B) manufacture of two new DNA double helices that
are identical to an old DNA double helix
C) modification of a strand of RNA prior to the
manufacture of a protein
D) manufacture of a protein based on information
carried by RNA
E) manufacture of a new strand of DNA
complementary to an old strand of DNA
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