Transcript DNA and Genes

Chapter 11
Chapter 11, Section 1
 Determines
an organism’s traits
 Produces proteins
 Long
 Polymer
of repeating subunits (nucleotides)
3

Parts:
Simple Sugar


Phosphate Group


Deoxyribose
Phosphate with 4 oxygen
Nitrogenous Base


Carbon ring with 1 or more nitrogen
Four types:
 Adenine (A)
 Guanine (G)
 Cytosine (C)
 Thymine (T)
 Nucleotides
form chains
 Phosphate group of one nucleotide bonds to
sugar of another nucleotide
 Complementary
base pairs held with weak
hydrogen bonds


Adenine and Thymine
Guanine and Cytosine
 Discovered
DNA structure
 Double Helix
 Also involved: Maurice Wilkins and the other
by Rosalind Franklin
 Use
white board
 Use
white board
 Use
laminated pieces
 Use



Play-Doh
Circles for Phosphate
Squares for Sugar
Triangles for Nitrogen Bases
 Results
from the differing sequences of the
four different nucleotides
 Determine


relatedness
evolutionary relationships
What would be closely related to the chimp?
 During
interphase – before meiosis or mitosis
 Four Steps
 DNA
double helix unzips
 Hydrogen bonds between nitrogenous bases
split
 Result: 2 nucleotide strands with their
nitrogenous bases exposed
 Base
Pairing – free nucleotides
base pair with exposed
nucleotides


Adenine with Thymine
Guanine with Cytosine
 Result:
each strand builds its
complement
 Sugar
and phosphate parts of
adjacent nucleotides bond
 Result: new backbone for each
strand
 Two
molecules of DNA are
formed
 Semi-Conservative
Replication – each new
molecule has one strand from
the original molecule and
one strand that has been
newly synthesized from free
nucleotides
Chapter 11, Section 2
 Polymer
made of amino acids (monomer)
 Control bodily functions
 DNA is responsible for constructing

Use amino acids
 Deoxyribonucleic
Acid
 Composed of nucleotides
 Gives instructions on how to make protein
 Ribonucleic
acid
 Composed of nucleotides
 Single stranded
 Sugar = ribose
 Replaces thymine (nitrogenous base) with
uracil

Base pairs with adenine
 Messenger

Brings info from DNA in the nucleus to cytoplasm
 Ribosomal

RNA (rRNA)
Ribosomes clamp onto the mRNA and use its info
to assemble the amino acids in the correct order
 Transfer

RNA (mRNA)
RNA (tRNA)
Transports amino acids to the
ribosome to assemble the protein
 On
mRNA
 Each set of three nitrogen bases
 Codes for a specific amino acid
 On
tRNA
 Each set of three nitrogen bases
 Carries a specific amino acid
 Page
297
 Answer all questions


Everyone needs to write answers
Answer can be written in notes
 Universal
 ie:


UAC codes for the amino acid tyrosine
ALWAYS
In bacteria, birch trees, bison and every other
living thing on the planet
 Evidence
that all life on Earth evolved from a
common origin
 Four
nucleotides
 20 Amino Acids
 Proteins are built from long chains of DNA

DNA lined-up end-to-end in all the human cells of
an adult would stretch to about 60 billion miles
(about 60 times the distance from the sun to
Pluto, the outer most fake planet)
 Double

stranded DNA to single stranded RNA
mRNA
 Sugar
is now ribose
 Uracil is used (instead of thymine)
 Occurs in nucleus
DNA
RNA
polymerase
Codon
1
Codon
2
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Complementary
triplets
Promoter
Triplet 4
mRNA
strand
Codon
1
2
4
Codon
3
Codon 4
(stop signal)
RNA
nucleotide
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
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Figure 3-18
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DNA
Gene
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
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Figure 3-18
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DNA
RNA
polymerase
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Triplet 4
Complementary
triplets
Promoter
2
4
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
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Figure 3-18
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DNA
RNA
polymerase
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Triplet 4
Complementary
triplets
Promoter
Codon
1
2
4
RNA
nucleotide
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
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Figure 3-18
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DNA
RNA
polymerase
Codon
1
Codon
2
Triplet 1
1
Triplet 2
2
Triplet 3
3
Gene
Complementary
triplets
Promoter
Triplet 4
mRNA
strand
Codon
1
2
4
Codon
3
Codon 4
(stop signal)
RNA
nucleotide
KEY
Adenine
Guanine
Cytosine
Uracil (RNA)
Thymine
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Figure 3-18
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 From
mRNA to protein
 Takes place at the ribosomes
 Uses tRNA
 Carry


Anticodon
Opposite nitrogenous bases from codon
Used to attach to codon on mRNA
 Carry
1 specific amino acid
 Happen
on ribosome (made of rRNA and protein)
 tRNA bring in first amino acid by attaching it’s
anticodon to mRNA’s codon
 Ribosome moves down
 Next tRNA brings in next amino acid by
attaching it’s anticodon to mRNA’s codon
 2 amino acids bond
 First tRNA detaches
 Repeats until protein is constructed
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
The small and large ribosomal subunits
interlock around the mRNA strand.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Large
ribosomal
subunit
Thymine
Start codon
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next mRNA
codon.
mRNA strand
The first amino acid is detached from
its tRNA and is joined to the second
amino acid by a peptide bond. The
ribosome moves one codon farther
along the mRNA strand; the first tRNA
detaches as another tRNA arrives.
The chain elongates until the stop
codon is reached; the components
then separate.
Small ribosomal
subunit
Peptide bond
Completed
polypeptide
Stop
codon
Large
ribosomal
subunit
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Figure 3-19
1 of 6
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
mRNA strand
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
2 of 6
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
The small and large ribosomal subunits
interlock around the mRNA strand.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
mRNA strand
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Large
ribosomal
subunit
Figure 3-19
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NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
The small and large ribosomal subunits
interlock around the mRNA strand.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
mRNA strand
Large
ribosomal
subunit
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next mRNA
codon.
Stop
codon
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
4 of 6
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
The small and large ribosomal subunits
interlock around the mRNA strand.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Thymine
Start codon
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next mRNA
codon.
mRNA strand
Large
ribosomal
subunit
The first amino acid is detached from
its tRNA and is joined to the second
amino acid by a peptide bond. The
ribosome moves one codon farther
along the mRNA strand; the first tRNA
detaches as another tRNA arrives.
Peptide bond
Stop
codon
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
5 of 6
NUCLEUS
mRNA
The mRNA strand binds to the small
ribosomal subunit and is joined at the
start codon by the first tRNA, which
carries the amino acid methionine.
Binding occurs between complementary base pairs of the codon and
anticodon.
The small and large ribosomal subunits
interlock around the mRNA strand.
Amino acid
KEY
Adenine
Small
ribosomal
subunit
tRNA
Anticodon
tRNA binding sites
Guanine
Cytosine
Uracil (RNA)
Large
ribosomal
subunit
Thymine
Start codon
A second tRNA arrives at the
adjacent binding site of the
ribosome. The anticodon of the
second tRNA binds to the next mRNA
codon.
mRNA strand
The first amino acid is detached from
its tRNA and is joined to the second
amino acid by a peptide bond. The
ribosome moves one codon farther
along the mRNA strand; the first tRNA
detaches as another tRNA arrives.
The chain elongates until the stop
codon is reached; the components
then separate.
Small ribosomal
subunit
Peptide bond
Completed
polypeptide
Stop
codon
Large
ribosomal
subunit
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 3-19
6 of 6
 Page
299
 Answer all questions
Chapter 11, Section 3
 Any
change in the DNA sequence
 May





have large effect or no effect
be helpful or harmful
cause cancer
lead to natural selection and evolution
occur in reproductive cells or body cells
 Change
in a single base pair in the DNA
 Ie: THE DOG BIT THE CAT
THE DOG BIT THE CAR
 Single
base is added or deleted from DNA
 Shifts the reading of codons by one base
 Ie: THE DOG BIT THE CAT
THE DOG BIT ETH ECA T
 Disrupt
distribution of genes to gametes
during meiosis
 Cause nondisjunction

Homologous chromosomes cannot pair correctly
when they have an extra or are missing a part

Deletion
ABC DEF GHI
 ABC DFG HI


Insertion



ABC DEF GHI
ABC BCD EFG HI
Inversion
ABC DEF GHI
 ADC BEF GHI


Translocation
ABC DEF GHI and WXYZ
 WXA BCD EFG HI and YZ

 Page
305
 Answer all questions
 Page
306
 Answer all questions
 Anything
that is capable of causing mutations
 Ie: radiation (X-Rays, UV light, nuclear
energy), chemicals, high temperatures
 Mistakes
rarely happen
 When they do, there are repair mechanisms

Enzymes
 Greater
exposure to mutagen, less chance
the mistake will be corrected
 19
Multiple Choice
 12 Completion
 5 Short Answer/Essay