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biology > Gene Expression > Flashcards

Gene Expression Flashcards

1
Q

Give examples of mutagenic agents

A

High energy ionising radiation

Chemicals

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2
Q

What type of gene mutations are possible

A 
Deletion
Substitution
Addition
Duplication
Inversion
Translocation
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3
Q

Describe the gene mutation Duplication

A

One or more bases are repeated

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4
Q

Describe the gene mutation inversión

A

Base sequence is spliced and reinserted in reverse order

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5
Q

Describe the gene mutation translocation

A

Base sequence removed from. One chromosome and reinserted into another

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6
Q

Describe the posible outcomes of the gene mutation deletion

A

Frame shift resulting in non functional DNA

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7
Q

Describe the posible outcomes of the gene mutation substitution

A

No effect due to degenerate code or in intron

Formation of stop codon or different Amino acid

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8
Q

Describe the posible outcomes of the gene mutation addition

A

Frame shift resulting in non functional DNA

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9
Q

Describe the posible outcomes of the gene mutation Duplication

A

Frame shift right resulting in non functional DNA if sequence multiplied is not a multiple of 3

Frame shift to the right

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10
Q

Describe the posible outcomes of the gene mutation inversión

A

Change to one Amino acid

Or no chnage due to degenerate code

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11
Q

Describe the posible outcomes of the gene mutation translocation

A

Frame shift resulting in non functional DNA

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12
Q

When do gene mutations occur

A

During DNA replication

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13
Q

Why is differentiation and specialisation important in cells

A

No one cell can provide the optimum conditions for every function

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14
Q

How does a zygote divide

A

By mitosis

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15
Q

How can a zygote produce all the body cells in a human

A

All cells contain the same genes but some are switched on or off to allow for a particular function

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16
Q

What occurs during differentiation

A

Certain genes are switched off or on

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17
Q

Why is specialisation more efficient than not having specialised cells

A

Conserve energy and resources that might go to waste in mechanisms unnecessary for a particular function

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18
Q

Define a stem cell

A

A cell that retains the ability to become specialised

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19
Q

Why are xylem and red blood cells unable to differentiate

A

They are so specialised that they don’t have a nucleus and so don’t have the genes that can be turned off or on for specialisation

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20
Q

What general properties do stem cells possess

A

Able to divide and renew themselves over a long period of time

Unspecialised

Can differentiate into other specialised cells

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21
Q

What are the main sources of stem cells

A

Bone marrow
Embryo
Umbilical cord blood
Placenta

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22
Q

How are stem cells classified

A

By their ability tot differentiate

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23
Q

Define totipotent stem cells and give example sof where they are found

A

Can differentiate into any cell

Early embryo

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24
Q

Define pluripotent stem cells and give example sof where they are found

A

Can differentiate into almost any cell

embryonic and fetal stem cells

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25
Q

Define multipotent stem cells and give example sof where they are found

A

Can differentiate into a limited number of cells

Adult stem cells and Umbilical cord blood

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26
Q

Define unipotent stem cells and give example sof where they are found

A

Can differentiate into one type of cell

Adult tissue

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27
Q

Define the steps to forming a cardiomyocyte

A

Totipotent cell in Embryo
Pluripotent cell
Multipotent cell able to differentiate into any muscle cell
Unipotent cell only able to differentiate into cardiomyocyte

Cardiomyocyte

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28
Q

What do induced pluripotent cells derive from

A

Unipotent cells

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29
Q

How are induced pluripotent cells produced

A

Genes otherwise not expressed are expressed

Induce transcriptional factor synthesis

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30
Q

What do ips cells prove

A

That all cells contain same genes

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31
Q

How are ips cells different to embryonic stem cells

A

Able to self renew and unlimited number of times

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32
Q

What is the advantage of ips cells

A

They can replace embryonic stem cells in research

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33
Q

What disease can be cured using heart cells produced from stem cells

A

Heart damage

Eg from heart attack

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34
Q

What disease can be cured using skeletal muscle cells produced from stem cells

A

Muscular dystrophy

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35
Q

What disease can be cured using beta cells produced from stem cells

A

Type 1 diabetes

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36
Q

What disease can be cured using nerve cells produced from stem cells

A 
Parkinsons
Ms
Strokes
Alzheimers
Paralysis
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37
Q

What disease can be cured using blood cells produced from stem cells

A

Leukemia

Inherited blood diseases

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38
Q

What disease can be cured using skin cells produced from stem cells

A

Burns and wounds

39
Q

What disease can be cured using bone cells produced from stem cells

A

Osteoporosis

40
Q

What disease can be cured using cartilage cells produced from stem cells

A

Osteoarthritis

41
Q

What disease can be cured using retina cells produced from stem cells

A

Macular degeneration

42
Q

Pros of using embryonic stem cells

A

Saves a life of a human already suffering

Embryos from ivf would go to waste anyways

Laws against cloning provide protection against any exploitation

43
Q

Cons of using embryonic stem cells

A

Every Embryo has the potential for life

People undermine the respect for life

Move towards reproductive cloning (research knowledge used in other countries with less restrictions)

Embryos are not the only source of stem cells

44
Q

How is gene expression controlled

A

Regulation of transcription and translation

45
Q

Define transcriptional factor

A

Protein complex with different subunits that binds to DNA and stimulates transcription

46
Q

Why does each gene have a different transcriptional factor associated with the stimulation of transcription

A

Each TF has a very specific shape that is only complementary to the promotor region of a specific DNA sequence

47
Q

How do transcriptional factors stimulate transcription

A

By binding to the promotor region before a gene, attracting Co factors and stimulating transcription

48
Q

Define promotor sequence

A

Base sequence before gene that TF binds to

49
Q

Describe how inhibitor molecules work

A

Block DNA binding site preventing action of TF

Competitive inhibition

50
Q

How do steroid hormones stimulate transcription

A

Diffuse through bilayer
Bind to TF and activate it
TF changes shape so DNA binding site is comp to promotor region
TF diffuses through nuclear pore into nucleus
Binds to promote region and attracts cofactors
Transcription is stimulated

51
Q

Give an example of a steroid hormone.

A

Oestrogen

52
Q

How can gene expression be reduced

A

Using small interfering RNA

53
Q

Explain how small interfering RNA works

A

An enzyme cuts a large double stranded RNA into smaller sections

One of the two strands combines with an enzyme which is activated using ATP

SiRNA forms hydrogen bonds with the mRNA via comp base pairing

Enzyme cuts mRNA into small sections

No more translation of MRNA

54
Q

Define epigentics

A

When environmental factors cause heritable changes in gene expression or function without changing the DNA base sequence

55
Q

What environmental factor might affect the epigenome

A

Diet
Exercise
Light exposure
Hormon levels

56
Q

How do tags affect gene. Expression

A

Determine shape of DNA histone complex

57
Q

How does the shape of a DNA histone complex affect transcription

A

Less condensed or compact = easier binding of transcriptional factors and RNA polymerase

More transcription

58
Q

How does acetyl action affect transcription

A

More acetyl groups = less condensed = more transcription

Make histones less positive so repel DNA

59
Q

What do acetyl groups attach to

A

Histones

60
Q

How does methylation affect transcription

A

More methylation = more condensed = less transcription

Methyl groups prevent binding of transcriptional factors and RNA polymerase.

Attract proteins that condense DNA histones complexes by inducing deacetylation

61
Q

What occurs to epigenetic tags in the early stages of Embryo development

A

Most tags are erased but some remain

62
Q

What two genes play the largest role in cancer development

A

Tumor suppressor genes and protooncogenes

63
Q

How can epigenetic therapy be used

A

Inhibit enzymes involved in methylation to reactivate genes to treat cancer

Diagnostic tests to determine levels of methylation and acetylation

64
Q

Why must epigenetic therapy be very targeted

A

Because normal cells will turn cancerous if also treated

65
Q

How do malignant tumors differ from benign ones

A

They grow larger
Cancerous
Grow rapidly
Have large dark nuclei due to more DNA
Unspecialised cells as opposed to specialised ones
No adhesion molecules produced so metastasis
No dense tissue capsule so fingerlike projections extend into neighbouring tissue
More likely to be lifethreatening
Systemic affects not localised
Must use radio or chemotherapy to remove not surgery
More frequent reoccurances

66
Q

Describe how metastasis occurs

A

Tumor enlarges and grown lymphatic vessels
Tumor cells squeeze into blood and lymphatic vessels
Tumor cells circulate in blood, adhere to blood vessel walls and squeeze into healthy tissue and metastasis
Tumor cells circulate via lymph and metastasis within lymph Nodes

67
Q

What ways can tumors circulate around the body

A

Blood lymph

68
Q

How does one cell cause a tumor

A

Single cell mutates to have uncontrolled cell division

Cell in lineage mutates again causing differences in appearance and growth

69
Q

Define oncogene

A

Mutated proto oncogene causing genes that stimulate cell division to be permanently switched one

70
Q

How can an oncogene lead to cancer

A

Permanently switch on receptor protein for growth factors so cell division occurs despite lack of growth factors

May code for growth factor protein which is produced in excess amounts

Lead to uncontrolled cell division

71
Q

How do growth factors lead to gene transcription

A

Growth factor binds to cell receptor

Causes transcriptional factor to be activated

Transcriptional factor enters nucleus and Activates transcription

72
Q

Define tumor suppressor gene

A

Gene to slow down cell division, repair mistakes in DNA and initiate apoptoisis

73
Q

How can mutated tumor suppressor genes lead to cancer

A

Causes gene to be silenced

Non functional growth factor protein produced

Lead to uncontrolled cell division

74
Q

Define hypermethylation

A

Over methylation

75
Q

Define hypomethylation

A

Under methylation

76
Q

How can hypermethylation lead to cancer

A

Hypermethylation of tumor suppressor gene in promotor region

Gene is inactivated (DNA histone complexes more compact)

77
Q

How does hypomethylation lead to cancer

A

Less methylation of oncogenes occurs

DNA histone complexes are less compact so more transcription

Uncontrolled cell growth

78
Q

How is oestrogen produced in post. Menopausal women

A

Not produced in ovaries

More produced in fat cells of breast

79
Q

Why is the risk of breast cancer higher in post menopausal women

A

More oestrogen produced by fat cells in breast
Oestrogen causes activation of transcriptional factors
If the transcriptional factor is complementary to a proto oncogene then tumor occurs
So higher risk of tumor
Tumor occurs = even more oestrogen produced
White blood cells drawn to tumor so more oestrogen produced

80
Q

What occurs during a genome project

A

DNA is mapped out

Genes are mapped onto chromosomes

81
Q

Define bio informatics

A

Science of celle ting and analysing complex biological data

82
Q

How is DNA sequenced

A

Using whole genome shotgun sequnceing

DNA is cut into smaller pieces so more easily sequenced

Algorithms align overlapping segments to assemble entire genome

83
Q

How has DNA sequnceing been used for medical advances

A

Single nucleotide polymorphisms detected and associated with certain diseases

Medical screening for snps for early diagnosis and intervention

84
Q

How has DNA sequnceing been used

A

Genome sequnceing

Medical advances

Identification of evolutionary links

85
Q

Define proteome

A

All proteins coded for by genome

86
Q

Define complete proteome

A

All proteins coded for in particular organism at certain time and conditions

87
Q

Define cellular proteome

A

All proteins coded for in particular cell at certain time and condition

88
Q

How can DNA technology be used in simple organisms

A

Genome exploited and use to help cure and provide knowledge about disease

Genes from extreme files used to clean environment

89
Q

Why is the determination of a simple organisms genome easy

A

No histones
Only one piece of circular DNA
No intorns

90
Q

Why is the determination of a complex organisms genome hard

A

Intorns

Genes used in the control of other genes expression

91
Q

What is the main dilemma when sequcing the human genome

A

Who’s DNA should be used

92
Q

How do tumor suppressor genes work

A

They code for a protein that activate apoptoisis or control mitosis

93
Q

What affects do transcriptional factors have

A

Activate RNA polymerase

biology (28 decks)

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