© cengage learning 2015 what would the dna code be, to give you the following polypeptide?...
TRANSCRIPT
© Cengage Learning 2015
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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BiologyConcepts and Applications | 9eStarr | Evers | Starr
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Chapter 10Chapter 10
Control of Gene ExpressionControl of Gene Expression
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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 TTCGAGB) DNA double helix with the sequence AAGCTC for one strand and TTCGAG for the complementary strandC) single DNA strand with the sequence TTCGAGD) single RNA strand with the sequence UUCGAGE) 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 TTCGAGB) DNA double helix with the sequence AAGCTC for one strand and TTCGAG for the complementary strandC) single DNA strand with the sequence TTCGAGD) single RNA strand with the sequence UUCGAGE) 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 . . . RNAB) RNA . . . a polypeptideC) protein . . . DNAD) DNA . . . a polypeptideE) RNA . . . DNA
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Translation converts the information stored in ______ to ______.A) DNA . . . RNAB) RNA . . . a polypeptideC) protein . . . DNAD) DNA . . . a polypeptideE) RNA . . . DNA
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Where is translation accomplished?A) lysosomesB) smooth endoplasmic reticulumC) peroxisomesD) ribosomesE) nucleoli
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Where is translation accomplished?A) lysosomesB) smooth endoplasmic reticulumC) peroxisomesD) ribosomesE) 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 mutationB) result in a shortened polypeptide chainC) result in a missense mutationD) change the location at which transcription of the next gene beginsE) 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 mutationB) result in a shortened polypeptide chainC) result in a missense mutationD) change the location at which transcription of the next gene beginsE) 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) oneB) twoC) threeD) fourE) 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) oneB) twoC) threeD) fourE) five
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Examine the genetic code table, shown below. The codon AGC codes for the amino acid ______.
A) serineB) arginineC) threonineD) alanineE) glycine
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Examine the genetic code table, shown below. The codon AGC codes for the amino acid ______.
A) serineB) arginineC) threonineD) alanineE) 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 sequenceB) a single nucleotide deletion near the end of the coding sequenceC) a single nucleotide in the middle of an intronD) substitution of a base pairE) 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 sequenceB) a single nucleotide deletion near the end of the coding sequenceC) a single nucleotide in the middle of an intronD) substitution of a base pairE) 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