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Biology Module 6 > 6.1 Cellular Control > Flashcards

6.1 Cellular Control Flashcards

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1
Q

Gene mutation

A

Change in the dna sequence

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2
Q

Mutagen

A

Anything that promotes a mutation

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3
Q

Point mutation

A

Substitution
Change in dna sequence
Can be silent, missense or nonsense

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4
Q

Silent

A

when there’s a mutation which codes for the same amino acid, the mutation is silent because the primary secondary tertiary and quaternary structure will not be changed

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5
Q

Missense

A

change to the base sequence of DNA that leads to a change in amino acid. Could lead to a harmful protein, non functional protein or a beneficial protein e.g. sickle cell anaemia

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6
Q

Nonsense

A

New triplet codes for a stop codon

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7
Q

Indel mutations long name

A

Insertion/deletion mutations

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8
Q

When can Indel mutations be okay

A

If it occurs in a multiple of 3

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9
Q

What are Indel mutations

A

When nucleotides are inserted/deleted from gene + bc genetic code is non overlapping the triplets change which causes a frame shift

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10
Q

Are all mutations harmful

A

No can be beneficial, neutral, non functional

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11
Q

Frame shift

A

caused by insertion/deletion mutations = cause all further amino acids to be changed including start/stop codons.

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12
Q

Tandem repeats

A

Repeating triplets at the end of certain genes.

each time the gene replicates through meiosis, the number of triplets increases.

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13
Q

What is the effect of tandem repeats

A

certain diseases e.g. Huntington can be caused when a threshold is reached

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14
Q

Can genes be switched on

A

Yes on or off depending on it’s need

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15
Q

Operon

A

section of DNA that contains cluster of genes that are under the control of a promoter + all transcribed together as well as control elements and a regulatory gene

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16
Q

Intron

A

non coding region of DNA

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17
Q

Exon

A

coding region of DNA

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18
Q

Bacteria’s fav source of respiration

A

Glucose

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19
Q

What do prokaryotic cells do when glucose is absent

A

Use lactose as a substrate

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20
Q

What enzymes is lactose processed using

A

Lac y and Lac Z

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21
Q

What does lac y code for

A

Lactose permease

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22
Q

What does lac z code for

A

Beta galactosidase

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23
Q

What does lactose permease do

A

makes cell more permeable to lactose and more lactose can enter to be used

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24
Q

What does beta galactosidase do

A

breaks down lactose into glucose and galactose

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25
Q

What is lac operon

A

section of genes that code for enzymes which allows the bacteria to use lactose as a source of energy.

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26
Q

What happens when I is transcribed

A

Produces a repressor protein which binds to lac o

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27
Q

Lac operon diagram

A
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28
Q

What happens to lac operon under the presence of glucose

A

the regulatory gene is transcribed and the repressor protein is made
2. The repressor protein binds to lac O (operator region). This prevent rna polymerase from binding to the promoter region.
3. This prevents the genes Lac z and Lac y from being transcribed
4. The genes are switched off

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29
Q

What happens to lac operon under the presence of lactose and no glucose

A

I is still transcribed but lactose binds to the repressor protein
1. Under the absence of glucose and the presence of lactose. Lactose binds to the repressor protein. = causes a conformational change
2. This causes a change in shape which prevents it from binding to lac o.
3. This means rna polymerase can bind to the promoter region.
4. This allows Lac z and Lac y to be transcribed. This allows lactose to be metabolised/ the genes are switched on.

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30
Q

Ways eukaryotic cells can change the expression of DNA

A
  • change expression at transcriptional level
  • At post transcriptional level
  • At post translational level
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31
Q

Transcriptional level modifying

A

transcription factors = proteins or short non coding pieces of rna so they can slide along the dna and bind to diff promoter regions for diff genes and either suppress transcription or promote transcription

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32
Q

What can transcription factors do

A

Bind to promoter region + inhibit or allow rna polymerase to bind to the promoter region = either enables or doesn’t allow transcription to occur of the respective gene

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33
Q

Promoter region

A

control of region of every gene

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34
Q

Why are transcription factors important

A

Some regulate our cell cycle

35
Q

Examples of genes involved in regulating our cell cycle + how

A

tumour suppressant gene and proto-oncogene
Code for transcription factors

36
Q

What would happen if the tumour suppressant gene and proto-oncogene had a mutation

A

Cancer

37
Q

Exon

A

code for amino acids

38
Q

Introns

A

section of a gene that doesn’t code for an amino acid

39
Q

Post transcriptional modifying

A

Alternative splicing can produce diff version of mRNA
Removing introns to produce mature mRNA

40
Q

What is splicing

A

Removing introns + joining exons together from primary mRNA = produces mature mRNA

41
Q

Differences in splicing

A

can join the exons in diff ways which means one mRNA can code for multiple proteins. This all depends on splicing

42
Q

Splicing enzyme

A

Endonuclease

43
Q

Post translational level modification

A
  • When you’ve made your proteins and you wanna switch them on or off
44
Q

How are enzymes activated

A

Through phosphorylation

45
Q

activation of proteins by phosphorylation

A

using cyclic AMP activates protein kinase A (enzyme that phosphorylated things) = phosphorylated transcription factor to activate it . (Whole lipid transcription factor process) The proteins can be enzymes or transcription factors

46
Q

Diagram of activation of proteins by phosphorylation

A
47
Q

Homeobox genes

A

codes for transcription factors that code for our body plan

48
Q

Hox genes

A

Sub cell of homeobox genes that animals have

codes for transcription factors that code for our body plan

49
Q

What do hox genes do

A

controls our axis e.g. how the embryo develops

50
Q

Mutation in hox gene

A

Causes problems w development e.g. arms and legs not where they should be

51
Q

Are homeobox and hox genes highly conserved?

A
  • highly conserved through evolution
  • sequence practically same as that from a million years ago
52
Q

Why are homeobox genes so highly conserved

A

anytime they’ve been changed, they’re not favoured so important for axis to stay this way

53
Q

When are homeobox genes expressed

A

active + expressed really early on + lie themselves on an axis (anterior to posterior/front to back) and they get switched on in an order from anterior to posterior

54
Q

What do homeobox genes code for

A

transcription factors e.g. for mitosis and apoptosis

55
Q

Hayflick constant

A

limit of how many times a cell can divide before dying. Important bc too many cells leads to tumours

56
Q

Homeodomain

A

hox genes have homeobox sequences that code for ‘homeodomauns’. Acts as a transcription factor

57
Q

What genes regulate hox genes

A

Gap genes and pair rule genes

58
Q

What is apoptosis controlled by

A
  • highly controlled process
  • internal stimuli (hormones, psychological stress, damage to dna)
  • external stimuli (temperature, change in light intensity, pathogen attack, lack of nutrients, drugs)
59
Q

What does nitric oxide do to apoptosis

A

Induces it

by making the inner mitochondrial membrane more permeable to hydrogen ions which damages the proton gradient so proteins are released + suppresses the function of apoptotic inhibitor proteins.

60
Q

Steps of apoptosis

A
  • enzyme breaks down the cell cytoskeleton
  • The cytoplasm becomes dense w tightly packed organelles
  • The cell surface membrane changes and small protrusions called blebs form
  • Chromatin condenses, the nuclear envelope breaks and DNA breaks into fragments
  • The cell breaks into vesicles which are ingested by phagocytosis cells = so cell debris doesn’t damage any other cells or tissues
61
Q

What does apoptosis do

A

Removes harmful cells

62
Q

What can too much apoptosis lead to

A

Cell loss and degeneration

63
Q

How does failure of the control mechanism during development lead to deformity (hox genes)

A

Hox gene doesn’t activate transcription factor
Molecules signalling apoptosis not produced
Apoptosis doesn’t occur

64
Q

Which processes are important in determining body plan of organism

A

Apoptosis and mitosis

65
Q
A

B

66
Q
A

C

67
Q
A

Shape of antigens on cell surface membrane

68
Q

State what structural detail of a polypeptide is altered by gene mutations.

A

Sequence of amino acids

69
Q

Explain how it is possible for a mutation to have no effect on the protein produced from that gene.

A

Some triplets code for the same amino acid
So the amino acid sequence isn’t altered

70
Q

Explain how a mutation could alter the protein so that it no longer performs its correct function in the cell

A

Insertion will cause frame shift
All triplets down stream will be different
Protein will have diff sequence of amino acids
Tertiary structure will be different

71
Q
A

Anatomical

72
Q

Describe and explain how a tiger with striped fur may have evolved from a non-striped ancestor.
In your answer you should discuss the different types of genes that might be involved in the creation of the striped patter in the tiger’s fur.

A

Regulatory genes control expression of other genes
Genes switched on or off during development
Recessive Epistasis preventing expression of pigment gene

Mutations = selective pressure of prey availability = adaptation helped tigers camouflage
- striped tigers = greater survival probability = more likely to produce = beneficial allele passed onto next gen

73
Q
A
74
Q

Describe how gene expression can be regulated after transcription.

A

Primary mRNA modified = removal of introns to produce mature mRNA
Alt splicing can produce diff versions mRNA

75
Q
A

Bonds contain energy + can be broken by enzymes
H/OH can form H bonds w water = soluble

76
Q

Suggest and explain why lactose is unable to cross membranes.

A

Too big = unable to pass between phospholipids

77
Q
A
78
Q
A

B produces repressor protein which binds to promoter region and stops transcription

79
Q

Investigations into the activity of genes that control body plan frequently use fruit flies and mice.
One reason fruit flies are used is that there are fewer public concerns about the ethics of using flies.
Suggest two other reasons why fruit flies are chosen for research into genes controlling the development of body plan.

A

Low cost
Rapid production

80
Q

Suggest two reasons why mice are chosen as a suitable species for investigation. Into activity of genes that control body plan

A

Similar to humans
Low cost

81
Q
A
82
Q

One type of gene is known as a homebox gene.
The base sequences of homeobox genes in humans and chimpanzees are almost identical.
What conclusions about the evolutionary relationship between humans and chimpanzees can be drawn from this piece of evidence?

A

Little because homeobox genes are highly conserved

83
Q

Explain why some regions of DNA can be described as ‘non-coding.

A

Not present in mature mRNA and not translated

84
Q

Suggest why non-coding regions of DNA show more variation.

A

Not selected against

Biology Module 6 (6 decks)

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