Download Chapter 5 Gases

What would the DNA code be, to give
you the following polypeptide?
Met-arg-asp-ala-tyr-thr-val-pro-stop
mRNA
___ ___ ___ ___ ___ ___ ___ ___ ___
DNA
___ ___ ___ ___ ___ ___ ___ ___ ___
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The Messenger:
mRNA
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2
Biology
Concepts and Applications | 9e
Starr | Evers | Starr
Chapter 10
Control of Gene Expression
©
Learning2015
2015
© Cengage
Cengage Learning
10.1 What Is Gene Control?
• A typical cell in your body uses only about
10 percent of its genes at one time
– Some genes affect structural features and
metabolic pathways and are expressed in
many cell types
– Others genes are expressed only by certain
subsets of cells (e.g., globin in RBCs)
– Control over gene expression allows cells to
respond to changes in their environment
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Gene Expression Control
• The “switches” that turn a gene on or off
are molecules or processes that trigger or
inhibit the individual steps of its expression
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10.2 How Do Genes Control Development
in Animals?
• As an animal embryo develops, its cells
differentiate and form tissues, organs, and
body parts
– Driven by cascades of master gene
expression
• The products of master genes affect the
expression of many other genes
– Final outcome is the completion of an intricate
task such as the formation of an eye
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What Are Some Outcomes of Gene
Control in Prokaryotes?
• Operon: group of genes together with a
promoter–operator DNA sequence that
controls their transcription
– Although first discovered in bacteria, operons
also occur in archaea and eukaryotes
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The lac Operon
• An operon called lac allows E. coli cells to
metabolize lactose
• The lac operon includes three genes and a
promoter flanked by two operators
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The lac Operon
• Three genes of the lac operon:
– One gene encodes a transport protein that
brings lactose across the plasma membrane
– Another gene encodes an enzyme that breaks
the bond between lactose’s two
monosaccharide monomers, glucose, and
galactose
– A third gene encodes an enzyme whose
function is still being investigated
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Lactose Intolerance
• An individual’s ability to digest lactose
declines at a species-specific age
– In the majority of human worldwide, the switch
occurs at about age five, when expression of
the gene for lactase shuts off
– Results in the condition lactose intolerance
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Lactose Intolerance
• When lactase production slows, lactose
passes undigested through the small
intestine
– The lactose ends up in the large intestine,
which hosts huge numbers of E. coli etc.
– The E. coli switch on their lac operons,
resulting in the production of gaseous
products – causing distention and pain
– Other metabolic products lead to diarrhea
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Lactose Intolerance
• Not everybody is lactose intolerant
– About one-third of human adults carry a
mutation that allows them to digest milk
– This mutation is more common in some
populations than in others
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Lactose Intolerance
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10.6 Application: Between You
and Eternity
• A mutated version of BRCA1 and/or
BRCA2 genes is often found in breast and
ovarian cancer cells
• The RNA product of the XIST gene does
not properly coat one of the two X
chromosomes in breast cancer cells
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Application: Between You and Eternity
• Why does the RNA product of an
unmutated XIST gene not properly coat an
X chromosome in cancer cells?
– The BRAC1 protein physically associates with
the RNA product of the XIST gene
– Researchers restored proper XIST RNA
coating—and proper X chromosome
inactivation—by restoring the function of the
BRCA1 protein in breast cancer cells
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If a strand of DNA has the sequence AAGCTC,
transcription will result in a(n) ______.
A) single RNA strand with the sequence TTCGAG
B) DNA double helix with the sequence AAGCTC for
one strand and TTCGAG for the complementary
strand
C) single DNA strand with the sequence TTCGAG
D) single RNA strand with the sequence UUCGAG
E) RNA double helix with the sequence UUCGAG for
one strand and AAGCUC for the complimentary
strand
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If a strand of DNA has the sequence AAGCTC,
transcription will result in a(n) ______.
A) single RNA strand with the sequence TTCGAG
B) DNA double helix with the sequence AAGCTC for
one strand and TTCGAG for the complementary
strand
C) single DNA strand with the sequence TTCGAG
D) single RNA strand with the sequence UUCGAG
E) RNA double helix with the sequence UUCGAG for
one strand and AAGCUC for the complimentary
strand
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Translation converts the information stored in ______
to ______.
A) DNA . . . RNA
B) RNA . . . a polypeptide
C) protein . . . DNA
D) DNA . . . a polypeptide
E) RNA . . . DNA
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Translation converts the information stored in ______
to ______.
A) DNA . . . RNA
B) RNA . . . a polypeptide
C) protein . . . DNA
D) DNA . . . a polypeptide
E) RNA . . . DNA
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Where is translation accomplished?
A) lysosomes
B) smooth endoplasmic reticulum
C) peroxisomes
D) ribosomes
E) nucleoli
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Where is translation accomplished?
A) lysosomes
B) smooth endoplasmic reticulum
C) peroxisomes
D) ribosomes
E) nucleoli
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A mutation within a gene that will insert a premature
stop codon in mRNA would ______.
A) result in a polypeptide that is one amino acid
shorter than the one produced prior to the mutation
B) result in a shortened polypeptide chain
C) result in a missense mutation
D) change the location at which transcription of the
next gene begins
E) have the same effect as deleting a single nucleotide
in the gene
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A mutation within a gene that will insert a premature
stop codon in mRNA would ______.
A) result in a polypeptide that is one amino acid
shorter than the one produced prior to the mutation
B) result in a shortened polypeptide chain
C) result in a missense mutation
D) change the location at which transcription of the
next gene begins
E) have the same effect as deleting a single nucleotide
in the gene
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What is the smallest number of nucleotides that must
be added or subtracted to change the triplet grouping
of the genetic message?
A) one
B) two
C) three
D) four
E) five
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What is the smallest number of nucleotides that must
be added or subtracted to change the triplet grouping
of the genetic message?
A) one
B) two
C) three
D) four
E) five
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Examine the genetic code table, shown below.
The codon AGC codes for
the amino acid ______.
A) serine
B) arginine
C) threonine
D) alanine
E) glycine
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Examine the genetic code table, shown below.
The codon AGC codes for
the amino acid ______.
A) serine
B) arginine
C) threonine
D) alanine
E) glycine
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A mutation would be most harmful to the cells if it
resulted in ______.
A) a single nucleotide insertion near the start of the
coding sequence
B) a single nucleotide deletion near the end of the
coding sequence
C) a single nucleotide in the middle of an intron
D) substitution of a base pair
E) deletion of a triplet near the middle of the gene
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A mutation would be most harmful to the cells if it
resulted in ______.
A) a single nucleotide insertion near the start of the
coding sequence
B) a single nucleotide deletion near the end of the
coding sequence
C) a single nucleotide in the middle of an intron
D) substitution of a base pair
E) deletion of a triplet near the middle of the gene
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10/8 Protein Synthesis
9
10/10
Genes
10
10/15
Mitosis
11
10/17
Meiosis
12
10/22
Genotype &
Phenotype
13
10/24
Biotechnology
14
10/29
Exam #2
10/31
Begin Evolution
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