Download DNA, RNA and Protein

Nucleic Acid Structure
and Function
Structures of DNA and RNA
Duplication of DNA
Production of RNA and Protein
Information Flow From DNA
replication
(S phase)
Gene: sequence
of DNA that codes
for a protein
DNA
transcription
RNA
translation
Protein
(G1 and G2
phases)
Macromolecules: Polymers
Made of Repeating Monomers
Macromolecule
Carbohydrates
Lipids
Proteins
Monomer Unit
Nucleic Acids
Nucleotides
Sugars
Fatty acids
Amino acids
phosphate
base
DNA and RNA Structure
DNA
Primary
Structure
Chain of
nucleotides
RNA
Chain of
nucleotides
Secondary Double helix Single
folded chain
Structure
Nucleotide =
phosphate + sugar + nitrogen-containing base
Three Parts of Nucleotide Structure
NH2
Phosphate Group
OH
HO
P
O
HC
O
N C
C
N
CH
C
N
CH2 O
N
Deoxyribose
Nitrogenous
H or H
Base
(1
of
5)
Ribose
H
H
OH
H
5-Carbon Sugar
DNA and RNA Structure
DNA
Purine
bases
Pyrimidine
bases
5-carbon sugar
Adenine (A)
Guanine (G)
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Cytosine (C)
Uracil
(U)
deoxyribose
ribose
OH
Phosphate
RNA
H
PO4
OH
PO4
OH
Clarification Pause
Turn to a partner and identify the
differences between DNA and
RNA structure
Nucleotide Chain
Nucleotides are joined
together by dehydration
synthesis
The phosphate of one
nucleotide is joined to
sugar of next
nucleotide, forming a
“sugar-phosphate
backbone”
3’ end
A
C
G pairs with C
T
A
A
T
G
C
A
T
3’ end
has free sugar
G
5’ end
has free phosphate
•Two polynucleotide
chains
•In opposite
orientations
•Held together
by hydrogen
bonds
•Twisted into a
helix
T
DNA Structure
A pairs with T
5’ end
Chemical Bonding
Covalent
Bond
Strong
Atoms
Formation of
Share
Nucleotides
Electrons and Chains
Hydrogen
Bond
Weak
Atoms
Pairing of
“Share” a Nucleotide
Hydrogen Bases in
Opposite
Chains
T
C
A
G
Applying Your Knowledge
In the DNA double helix, which base
is paired with adenine?
1. Adenine
2. Cytosine
3. Guanine
4. Thymine
5. Uracil
DNA Replication
DNA Replication
DNA replication is semiconservative.
Each strand is used as a template to
produce a new strand.
AGCTAGCTAGCT
TCGATCGATCGA
AGCTAGCTAGCT  AGCTAGCTAGCT
TCGATCGATCGA
old
new
AGCTAGCTAGCT
 TCGATCGATCGA
new
old
TCGATCGATCGA
DNA Replication
DNA replication requires
1. Enzymes, including DNA polymerase
that adds nucleotides in a 5’3’ direction.
2. nucleotides
3. energy
5’—A G C T — 3’
3’— T C G A — 5’
5’— A G C T— 3’
3’—T C G A — 5’
Outcome of DNA Replication
Applying Your Knowledge
1.
2.
3.
4.
Two new chains
Two old chains
One old and one new chain
One helix has two new chains
and one has two old chains
5. None of these is correct.
After DNA replication, what is the composition
of the new double-helical molecules?
Transcription = Production of RNA Using
DNA as a Template
•DNA chains separate
•ONE DNA chain is used
as a pattern to produce
an RNA chain
•RNA chain is released
and the DNA chains
reform the double-helix
In DNA In RNA
A
U
T
A
G
C
C
G
Transcription
Transcription requires
1. Enzymes, including RNA polymerase
that adds nucleotides in a 5’3’ direction.
2. nucleotides
3. energy
3’---TACAAAGAGACT---5’
5’---ATG TTTCTC TGA---3’
3’---TACAAA GAGACT---5’ DNA template
5’---AUGUUUCUCUGA---3’ mRNA
5’---ATG TTTCTC TGA---3’
Applying Your Knowledge
What is the sequence of an RNA molecule
transcribed from a DNA template strand
that reads 3’-ATG-5’?
1. 5’-TAC-3’
2. 5’-CAU-3’
3. 5’-AUG-3’
4. 5’-UAC-3’
5. 3’-TAC-5’
Products of Transcription
• Messenger RNA
Contains the code words for
the sequence of amino
acids in a specific protein
CODON = group of three
nucleotides acting as a
code word for an amino acid
Products of Transcription
• Transfer RNA
“Translates” the message by
bringing a specific amino acid into
the correct position on the growing
protein chain
Has ANTICODON = a group of
three nucleotides on a tRNA that
recognizes a mRNA codon
Has amino acid attachment site
mRNA
In mRNA In tRNA
A
U
U
A
G
C
C
G
Genetic
Code
Chart is written as a CODON dictionary, reading 5’3’
Products of Transcription
• Ribosomal RNA
One of the structural
components of the
ribosome
Ribosome = organelle
where protein
synthesis occurs
Has sites to bind both
mRNA and tRNA
for tRNA
for tRNA
small ribosomal
subunit
mRNA binding site
Applying Your Knowledge
Which molecule contains the information
for assembling the amino acids in the
correct order in the protein?
1. rRNA
2. tRNA
3. mRNA
4. All of these
5. None of these
Translation
At the ribosome, codons in mRNA are
recognized by tRNA anticodons to place
amino acids in the specific sequence specified
by the DNA.
Three Stages of Translation:
Initiation- assemble components to start process
Elongation- add amino acids in repeated cycles
Termination- release protein product
Translation
Initiation
mRNA binds to ribosome
First tRNA binds to mRNA
met
UAC
5’---AUGUUUCUCUGA---3’ mRNA
Translation
Elongation
Next tRNA binds to mRNA
met phe
UACAAA
5’---AUGUUUCUCUGA---3’ mRNA
Translation
Elongation
Amino acids are joined
First tRNA is released
UAC
met phe
AAA
5’---AUGUUUCUCUGA---3’ mRNA
Translation
Elongation
Ribosome moves by one codon
UAC
met phe
AAA
5’---AUGUUUCUCUGA---3’ mRNA
Translation
Elongation (second cycle)
Next tRNA binds to mRNA
UAC
met phe leu
AAA GAG
5’---AUGUUUCUCUGA---3’ mRNA
Translation
Elongation (second cycle)
Amino acids are joined
Second tRNA is released
UAC
met phe leu
GAG
5’---AUGUUUCUCUGA---3’ mRNA
AAA
Translation
Elongation (second cycle)
Ribosome moves by one codon
UAC
met phe leu
GAG
5’---AUGUUUCUCUGA---3’ mRNA
AAA
Translation
Termination
Termination factor binds to stop
codon
UAC
met phe leu
T
GAG
5’---AUGUUUCUCUGA---3’ mRNA
AAA
Translation
Termination
Protein chain is released
Other components separate
met phe leu
UAC
T
GAG
AAA
5’---AUGUUUCUCUGA---3’ mRNA
Applying Your Knowledge
If the mRNA sequence for codons 5, 6, and 7 of
a protein is 5’-AAG-AUU-GGA-3’, what is
the amino acid sequence in the protein?
1. Gly-ile-lys
2. Arg-leu-glu
3. Glu-leu-arg
4. Asn-met-gly
5. Lys-ile-gly