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Introduction to Evolution and Genetics > Molecular basis of human disease > Flashcards

Molecular basis of human disease Flashcards

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1
Q

Do genetics have a role in all diseases?

A

Genetics plays a role, to a greater or lesser extent, in all diseases.

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2
Q

What is the nature vs nurture arguement?

A

What you are depends on your nature (biological or genetic predisposition that impacts ones traits) or nurture (how you were brought up)

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3
Q

What contributes to disease processes?

A

Variations in our DNA and differences in how that DNA functions (alone or in combinations), alongside the environment contribute to disease processes.

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4
Q

Define nature

A

“nature” refers to the biological/genetic predispositions that impact one’s human traits — physical, emotional, and intellectual.

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5
Q

Define nurture.

A

Nurture,” in contrast, describes the influence of learning and other “environmental” factors on these traits. eg: your upbringing.

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6
Q

Define disease.

A

A disease is a disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury

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7
Q

Give some examples of diseases.

A
  • Infectious diseases (common cold)
  • Deficiency diseases (scurvy)
  • Mendelian hereditary diseases (sickle cell disease)
  • Non-Mendelian hereditary diseases (anxiety, depression, Cardiovascular disease risk)
  • Physiological diseases – including autoimmune diseases
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8
Q

Define mendelian hereditary disease

A

Disorders which occur when specific mutations in single genes — called germline mutations — are inherited from either of one’s two parents.

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9
Q

Examples of mendelian hereditary diseases.

A

cystic fibrosis, sickle cell disease, and Duchenne muscular dystrophy.

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10
Q

Define non-mendelian hereditary diseases.

A

conditions that are caused by factors other than changes in DNA sequence, such as environmental exposures or errors during embryonic development.

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11
Q

Define Deficiency diseases

A

diseases caused by a deficiency of nutrients. E.g. vitamin deficiency. E.g. rickets caused by lack for vitamins + lack of sunlight.

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12
Q

Define epigenetics

A

Epigenetics is the study of how your behaviours and environment can cause changes that affect the way your genes work.

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13
Q

What may happen if parent individuals have a poor diet?

A

Parent individuals with a nutrient-poor, high-fat, or high-sugar diet may transmit altered
DNA methylation states to offspring that result in metabolic or developmental disorders

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14
Q

What is dna bound to?

A

DNA is bound to histones, look slike beans on a string.

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15
Q

How are methol groups added to dna?

A

DNA can be methylated. Methol groups are added to Cs.

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16
Q

What has an effect on the expression of genes?

A

both epigenetics and dna changes.

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17
Q

Define genetic disorder.

A

Agenetic disorderis adiseasethat is caused by a change, or mutation, in an individual’s DNA sequence

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18
Q

What are the 3 types of genetic disorder?

A
  • Single-gene disorders
  • Chromosomal disorders
  • Complex disorders
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19
Q

WHat are single-gene disorders?

A

Single-gene disorders, where a mutation affects one gene: sickle cell anaemia, cystic fibrosis

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20
Q

What are chromosomal disorders?

A

Chromosomal disorders, where chromosomes (or parts of chromosomes) are missing/changed/imbalanced - Down syndrome is a chromosomal disorder

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21
Q

What are complex disorders?

A

Complex disorders, where there are mutations in two or more genes. Often lifestyle and environment play a role. Colon cancer is an example but so are potentially cardiovascular disease, schizophrenia, depression, bipolar disorder

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22
Q

What diseases/disorders are predictable?

A
  • Mendelian (single gene) disorders can be predicted
    • In contrast, infectious diseases are less predictable
  • Risk of recurrence is also predictable
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23
Q

What diseases can be predicted before symptoms even begin?

A

Pre-symptomatic testing is possible
- Some inherited illnesses can be predicted before symptoms start – genes present in every cell. e.g. cystic fibrosis

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24
Q

What techniques are used to predict diseases before they begin?

A

antenatal testing
newborn screening, heel prick blood test (plasma IRT), carrier testing, cheek cells or blood test

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25
Q

Certain diseases are more prevalent in…

A

Certain diseases are more prevalent in certain populations. Eg Tay-Sachs diseases in eastern and central European Ashkenazi jewish ancestry.

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26
Q

What happens in Tay-Sachs disease?

A

neurons destroyed (brain/spinal cord)

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27
Q

What therapy can be used to cure genetic diseases?

A

Gene therapy

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28
Q

What disease can be cured with viral vector gene therapy?

A

Adenosine deaminase deficiency

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29
Q

WHat are the ethical concerns of gene therapy?

A
  • toxicity
  • inflammation
  • cancer
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30
Q

Whats CFTR stand for?

A

CFTR = Cystic fibrosis transmembrane conductance regulator

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31
Q

Why is the name of a gene italicized?

A

When talking about a gene we italicize the name. When talking about a protein, we do not.

32
Q

What causes Cystic Fibrosis?

A

Cystic fibrosis is caused by mutations in the CFTR gene, which encodes a chloride channel located on the surface of certain epithelial cells

33
Q

Describe the process causing cystic fibrosis?

A

1) Child inherits one chromosome from mother and one father
2) CFTR gene contains code to create CFTR chloride channel
3) Chloride transport in and out of cell.

34
Q

How many amino acids make up the CFTR protein?

A

1,480 amino acids

35
Q

Where is CFTR protein located?

A

Located on the surface of many cells in the body

36
Q

How many chains of amino acids does a CFTR protein contain?

A

CFTR protein contains a single chain of amino acids

37
Q

How many functional regions/domains does CFTR have?

A

5 functional regions/domains.

38
Q

What are the 5 functional regions of CFTR protein?

A

2 transmembrane domains
2 cytoplasmic nucleotide-binding domains
1 regulatory domain

39
Q

Whats the role of each domain of CFTR?

A

Each domain has a special function - transporting chloride through the cell surface.

40
Q

What do mutations cause?

A

Mutations cause a range of cystic fibrosis symptoms – Cl- transport

41
Q

How do mutations affect the protein?

A

Mutations often affect the three-dimensional structure of the protein

42
Q

WHat do mutations prevent CFTR from doing?

A

Prevents CFTR from reaching the membrane.

43
Q

How does cystic fibrosis affect the lungs?

A
  • Decreased chloride transport coupled with excess sodium reabsorption
  • Dehydration of airway surface liquid and mucus gel layer
  • Risk of infection
44
Q

How does cystic fibrosis affect the pancreas?

A

Lack of pancreatic enzymes and bicarbonate secretion – digestive malabsorption.

45
Q

What is cancer?

A

Cancer – a group of disorders caused by gene alterations

46
Q

What percentage of cancers are environmentally induced?

A

90% are environmentally induced (smoking, UV sun rays)

47
Q

Are cancer hereditary or not?

A

Most cancers not obviously hereditary (susceptibility)

48
Q

How are some cancers more hereditarily based than others?

A

Hereditary component / susceptibility to some cancers (breast)

49
Q

How long does cancer take to develop?

A

Often takes years to develop (sequence / combination of gene mutations)

50
Q

Are all cancers genetic?

A

All cancers are genetic (unnatural function 1 or more genes)
- Genetic changes affect cell cycle control

51
Q

What is the cell cycle in simple terms?

A

The cell cycle is how cells decide they are going to divide. There are proteins which slow down / speed up the cell cycle.

52
Q

Why must cell cycle be controlled?

A

Cell cycle must be controlled, otherwise, cancer begins.

53
Q

What do cell cycle checkpoints do?

A

Cell cycle checkpoints ensure events occur in the correct sequence.

54
Q

How is cell cycle controlled / how is rate of cell division controlled?

A

There are proteins which slow down / speed up the cell cycle.

55
Q

What happens if the gene for a protein meant to slow or step the cell cycle mutates?

A
  • cells divide uncontrollably
    • cells do not differentiate correctly
56
Q

Where is telomerase active?

A

Active in germ cells (the cells that make sperm and eggs) and some adult stem cells.

57
Q

What do telomerase and other similar cells need to do?

A

These are cell types that need to undergo many divisions, or, in the case of germ cells, give rise to a new organism with its telomeric “clock” reset.

58
Q

Describe the role of telomeres?

A

To prevent the loss of genes as chromosome ends wear down, the tips of eukaryotic chromosomes have specialized DNA “caps” calledtelomeres.

59
Q

At which end does DNA begin replicating?

A

DNA replicates by polymerising at the 3 prime end. Replication BEGINS AT THE 3 PRIME END.

60
Q

WHere are telomeres located?

A

At the end of chromosomes

61
Q

What are telomeres?

A

Telomeres are repeats of sequences of bases, and can be syntheised by telomerase.

62
Q

What happens if telomeres die?

A

If telomeres die, they are resynthesized by telomerase.

63
Q

When do cancer cells mutate?

A

Random spontaneous mutation

64
Q

Give an example of environmental cause of cancer?

A

e.g. carcinogens, some viruses

65
Q

How are genes responsible for cancer?

A

Genes – cell cycle progression, cell growth, cellular adhesion.

66
Q

What does a proto-oncogene do?

A

help cells grow and divide to make new cells, or to help cells stay alive

67
Q

What does a protooncogene become once it mutates?

A

an oncogene.

68
Q

What do tumour-suppressor genes do?

A

halt uncontrolled cell growth

Responsible for:
DNA repair, cellular adhesion, cell cycle control, cell death

69
Q

How do oncogenes cause cancer?

A

amplify the signalling roles of proto-oncogenes

70
Q

What is p53 and what does it do?

A

a barrier to cell cycle progression until certain events are completed. It does this by apoptosis.

71
Q

What happens to p53 in cancer?

A

In cancer, P53 is not active, so cells cant die, since they don’t go through apoptosis.

72
Q

What type of study is used to compare nature vs nurture?

A

Twin studies are used to compare nature vs nurture

73
Q

How are twins used to determine nature vs nurture?

A

You can compare disease in separate twins.
You can work out what proportion is nature and what proportion is nurture.

74
Q

What is a meta-analysis?

A

A meta-analysis is combing a bunch of previously found research data .

75
Q

What did a meta-analysis on twins conclude on the argument of nature vs nurture?

A

A meta-analysis of twin studies (14 million pairs of twins), 17804 traits, 2748 published papers – finds that genetics accounts for 50% of differences and the environment also 50%

Introduction to Evolution and Genetics (18 decks)

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