6.1 CELLULAR CONTROL Flashcards

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1
Q

Define mutation

A
  • A random change in DNA base sequence which may create a non functioning protein or give advantage to the organism
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2
Q

State four mutagenic agents

A
  • UV
  • Gamma
  • X-ray
  • Carcinogens
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3
Q

State the two types of mutation

A

1) Substitution mutation
2) Insertion or deletion/indel mutation

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4
Q

State the three forms of substitution mutations

A

1) silent
2) nonsense
3) missense

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5
Q

Define silent mutation

A
  • When the altered base triplet still codes for the same amino acid as before
  • Protein structure not altered
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6
Q

Define nonsense mutation

A
  • When the altered base triplet codes for a different amino acid than before
  • Protein structure altered
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7
Q

Define missense mutation

A
  • When the altered base triplet codes for a stop codon
  • Protein structure altered and shortened
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8
Q

State and explain what type of insertion or deletion/indel mutations cause a frameshift

A
  • A single base insertion/deletion
  • Because genetic code is non overlapping and read in groups of three bases
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9
Q

Describe expanding triple nucleotide repeats

A
  • number of repeat triple nucleotides increases during meiosis from generation to generation
  • (-CAG CAG CAG-)
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10
Q

State the cause of huntingtons disease

A
  • Expanding triple nucleotide repeats
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11
Q

State the regulatory mechanism at transcriptional level gene expression

A
  • Lac operons for prokaryotes and eukaryotes
  • Transcription factors ONLY for eukaryotes
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12
Q

State the regulatory mechanism at post-transcriptional level gene expression

A
  • The editing of primary mRNA and removal of introns to produce mature mRNA
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13
Q

State the regulatory mechanism at post-translational level gene expression

A
  • Protein activation by cyclic AMP
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14
Q

Define operon

A
  • a group of genes that function as a single transcription unit
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15
Q

Draw a lac operon section of DNA

A
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16
Q

State the function of lacZ and lacY section on the lac operon

A
  • Structural genes that code for the enzymes lactose permease and B-galactosidase
17
Q

State the function of promotor region on the lac operon

A
  • Where the enzyme RNA polymerase attaches to begin transcription for lacZ and lacY
18
Q

State the function of operator region on the lac operon

A
  • Where the repressor protein lacL attaches to prevent RNA polymerase from attaching to the promoter to inhibit transcription
19
Q

State the function of regulatory gene next to the lac operon

A
  • Codes for the repressor protein lacL
20
Q

Explain what E.coli does as part of transcriptional level gene expression

A
  • E.coli metabolises glucose as a respiratory substrate
  • If glucose is absent and the disaccaride lactose is present, then lactose induces the production of the enzymes lactose permease and B-galactosidase
21
Q

State the two enzymes that lactose induces

A

1) Lactose permease
2) β-galactosidase

22
Q

State the function of the enzyme lactose permease

A
  • Allows lactose to enter the bacteria cell
23
Q

State the function of the enzyme B-galoactosidase

A
  • Hydrolyses the dissacaride lactose into glucose and galactose
24
Q

Explain how the expression of the regulatory gene (I) inhibits transcription

A
  • When regulatory gene (I) is expressed, it produces a repressor protein
  • This repressor protein then binds to the operator region (lacO)
  • This prevents RNA polymerase from binding to the promotor region (P)
  • Therefore, inhibiting transcription of lacZ and lacY
  • Thus, the two eznymes for lactose metabolism are not made, genes are “off”
25
Q
A