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Biology > Module 6.1 - Cellular Control > Flashcards

Module 6.1 - Cellular Control Flashcards

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1
Q

How can different proteins be made despite all cells having the same DNA? (4)

A
  • Not all genes in a cell are expressed/ transcribed
  • Cells show different gene expression
  • They determine the cell structure and control cell processes for more gene expressions
  • Therefore different proteins can be formed
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2
Q

What are the levels where gene expression can be controlled? (3)

A
  • Transcriptional
  • Post-transcriptional
  • Post-translational level
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3
Q

What is gene expression also known as? (1)

A
  • Protein synthesis
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4
Q

Gene expression at the transcriptional level? (2)

A
  • Controlled by altering the rate of transcription of gene
  • Controlled by transcription factor
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5
Q

Activators? (1)

A
  • Factors that increase the rate of transcription
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6
Q

Repressors? (1)

A
  • Factors that decrease the rate of transcription
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7
Q

Shape of the transcription factor? (2)

A

-Determines whether it can bind to DNA or not
- Can sometimes be altered by the binding of some molecules

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8
Q

How does the environment control the synthesis of some proteins? (2)

A
  • Amount of certain molecules in an environment or a cell can control the synthesis
  • By affecting transcription factor binding
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9
Q

Transcription factor binding in eukaryotes? (1)

A
  • Transcription factors bind to specific DNA sites near the start of their target genes
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10
Q

Transcription factor binding in prokaryotes? (1)

A
  • Control of gene expression involves binding to operons
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11
Q

Operon? (3)

A
  • A section of DNA that contains a cluster of structural genes
  • Genes are transcribed together
  • They control elements and act as a regulatory gene
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12
Q

Structural genes? (2)

A
  • Code for useful proteins like enzymes
  • Control elements promoter and operator
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13
Q

Promotor? (1)

A
  • A DNA sequence located before the structural genes that RNA polymerase binds to
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14
Q

Operator? (1)

A
  • A DNA sequence that transcription factors bind to
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15
Q

Regulatory genes? (1)

A
  • Codes for an activator or repressor
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16
Q

Where is the enzyme needed to respite lactose found? (2)

A
  • Lac operon
  • Lac operon has three structural genes
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17
Q

Three structural genes of lac operon? (2)

A
  • lacz, lacy and lacA
  • Produce proteins that help the bacteria digest lactose
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18
Q

Lac operon when Lactose is not present? (4)

A
  • Regulatory gene (lacl) produces the lac repressor
  • Repressor is a transcription factor
  • It binds to the operator site
  • Blocks transcription because RNA polymerase can’t bind to the promoter
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19
Q

Lac operon when Lactose is present? (4)

A
  • Lactose binds to the repressor
  • Changes repressor’s shape
  • No longer bind to the operator site
  • RNA polymerase can begin transcription of structural genes
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20
Q

Introns? (1)

A
  • Eukaryotic DNA sections that don’t code for amino acids
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21
Q

Exons? (1)

A
  • Eukaryotic DNA section that code for amino acids
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22
Q

Introns and exons during transcription? (2)

A
  • Are copied into mRNA
  • Forms primary mRNA transcripts (pre-mRNA)
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23
Q

Pre-mRNA? (1)

A
  • mRNA strands containing introns and exons
24
Q

How are introns removed from pre-mRNA strands? (5)

A
  • Splicing
  • Introns are removed
  • Exons are joined
  • Forming mRNA
  • Takes place in nucleus
25
Q

What happens to the mature mRNA after post-transcriptional level? (1)

A
  • Leaves nucleus for translation
26
Q

Proteins at the post-translational level? (2)

A
  • Some proteins aren’t functional after synthesis
  • They need to be activated to work
27
Q

Protein activation controlled by? (2)

A
  • Hormones or sugars bind to cell membranes
  • This triggered cAMP production
28
Q

cAMP at the post-translational level? (2)

A
  • cAMP activates proteins inside cells by altering 3D structure of an enzyme
  • Makes enzyme more or less active
29
Q

How does CAMP activate protein kinase A (PKA)? (4)

A
  • PKA is an enzyme made of four subunits
  • CAMP binds & causes a change in the enzyme’s 3D structure
  • Releases the active subunits
  • PKA is now active
30
Q

Body plan? (1)

A
  • General structure of an organism that are arranged in a particular way
31
Q

What controls the development of a body plan? (2)

A
  • Proteins
  • Help set up the basic body plan so that everything is in the right place
32
Q

What genes code for the proteins that control body plan development? (1)

A
  • Hox genes
33
Q

Hox genes? (3)

A
  • Similar Hox genes found in animals, plants and fungi
  • Body plan development in controlled similarly interspecies
  • Have regions called homeobox sequence
34
Q

Homeobox genes? (2)

A
  • Highly conserved
  • Sequence have changed very little during the evolution of different organisms
35
Q

How do Hox genes control development? (3)

A
  • Homeobox sequences code for a part of the protein called the homeodomain
  • Homeodomain binds to specific sites on DNA
  • This enables the protein to work as a transcription factor
36
Q

Where do proteins bind to work as a transcription factor? (2)

A
  • DNA at the start of developmental genes
  • Activates or represses transcription
37
Q

Apoptosis’ role in the development of body plans? (2)

A
  • Programmed cell death
  • Refines body parts
38
Q

Steps in the breaking down of the cell after apoptosis? (3)

A
  • Enzymes inside the cell break down important cell components
  • Cell begins to shrink and breaks up into fragments
  • Cell fragments are engulfed by phagocytes and digested
39
Q

Mitosis and differentiation role in the development of body plans? (1)

A
  • Create the bulk of the body parts
40
Q

How is the correct body plan developed? (1)

A
  • During development, genes that control apoptosis and genes that control mitosis are switched on and off in appropriate cells
41
Q

How do the genes that regulate apoptosis and the cell cycle respond to stimuli? (3)

A
  • Internal stimulus - DNA damage: if detected during the cell cycle, genes that cause the cycle to pause or trigger apoptosis are expressed
  • External stimulus - lack of nutrients available: genres that prevent mitosis are expressed
  • External stimulus: pathogen attack: gene that trigger apoptosis are expressed
42
Q

Types of mutations? (3)

A
  • Substitution
  • Deletion
  • Insertion
43
Q

Substitution mutations? (2)

A
  • One or more bases are swapped for another
  • e.g. ATGCCT becomes ATTCCT
44
Q

Deletion mutations? (2)

A
  • One or more bases are removed
  • eg. ATGCCT becomes ATCT
45
Q

Insertion mutations? (2)

A
  • One or more bases are added
  • e.g. ATGCCT becomes ATCACCT
46
Q

What are the effects of mutations in proteins? (3)

A
  • Order of DNA bases = order of amino acids
  • Mutation alters primary structure = altered protein codes = alters final 3D shape of protein
  • Protein may not work properly
47
Q

What are the three effects of a mutation? (3)

A
  • Neutral
  • Beneficial
  • Harmful
48
Q

Neutral effects - degenerate code? (3)

A
  • The genetic code is degenerate
  • E.g. TAT and TAC code for tyrosine
  • If TAT is changed to TAC, it won’t affect the amino acid
49
Q

Neutral effects - substitution mutations? (4)

A
  • The mutation produces a triplet that codes for a different amino acid
  • But the amino acid is chemically similar to the original
  • So there will be little change in functions of the amino acid
  • E.g, (AGG) and (AAG) are coded for by similar triplets - substitution mutation can swap the amino acids
50
Q

Neutral effects - Silent? (3)

A
  • The mutated triplet codes for an amino acid not involved with the protein’s function
  • They are silent
  • E.g. triplet is located far from enzyme’s active site - so protein can work normally
51
Q

Beneficial effects? (2)

A
  • Advantageous effect on an organism
  • E.g. antibiotic resistance for bacteria
52
Q

Harmful effects? (2)

A
  • Disadvantageous effect on an organism
  • Cystic fibrosis
53
Q

Cystic fibrosis? (3)

A
  • Caused by deletion mutations of three bases in the gene that codes for the CFTR protein
  • The mutated CFTR protein folds incorrectly and then breaks down
  • This leads to excess mucus production which affects the lungs
54
Q

CFTR? (1)

A
  • Cystic fibrosis transmembrane conductance regulator
55
Q

How can a harmful effect cause the loss of production of a protein? (3)

A
  • Mutation occurs at the start of a gene
  • RNA polymerase can’t bind to it and begin transcription
  • The protein coded for by the gene won’t be made

Biology (10 decks)

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