Normal and abnormal development: genetic, congenital and acquired disease

Question 1

When do genetic diseases materialise

Answer 1

Early in childhood

Question 2

Other than environmental and genetic causes of a disease, what else results in a disease

Answer 2

1. Other diseases predisposing you to causative factors

Question 3

How do other disease pre-dispose you to others

Answer 3

1. Pre-neoplastic conditions (diseases pre-disposing to tumours)
2. Permissive effect

Question 4

What is a permissive effect

Answer 4

Environmental agents that are not normally pathogenic will cause a disease.

Question 5

What two ways other than genetic abnormalities can increase disease risk in a baby

Answer 5

1. Nutritional deprivation

2. Transplacental transmission of environmental agents

Question 6

What four reasons are there for an increase in disease incidence with age

Answer 6

1. Probability of contact with an environmental cause increases with duration of exposure risk
2. Disease may depend on cumulative effects of one or more environmental agents
3. Impaired immunity with ageing increases susceptibility of some infections
4. Latent interval between exposure causes appearance of symptoms to take decades

Question 7

what are two outcomes of polymorphic variations

Answer 7

1. Changes in characteristics (brown hair vs blond)

2. No visible effects at all (e.g. blood types)

Question 8

Name three polymorphic variations that give the greatest disease susceptibility to an individual

Answer 8

1. HLA Types
2. Blood groups
3. Cytokine genes

Question 9

What are HLA genes normally referred to as

Answer 9

antigens

Question 10

What are class I antigens

Answer 10

1. Expressed on the surface of all nucleated cells (recognised by immune system)

Question 11

What are class II antigens

Answer 11

1. Expressed on the surface of cells that interact with T lymphocytes by physical contact - initiate immune response

Question 12

Two ways diseases may be associated with HLA types

Answer 12

1. Infective microbes may have similar antigens to host cells
2. Gene predisposing to a disease is closely linked to HLA gene

Question 13

What HLA group is found on organs/cells that are subjected to autoimmune attacks

Answer 13

1. Express class II types

Question 14

What two diseases are closely related to blood groups

Answer 14

1. Duodenal ulceration - group O

2. Gastric carcinoma - group A

Question 15

How many gene tend to be involved in most inherited abnormalities

Answer 15

A single gene - these conditions are monogenic

Question 16

How many base pairs are found in each of the 23 pairs of chromosomes

Answer 16

10^7 base pairs

Question 17

Describe the structure of DNA

Answer 17

1. Wrapped as a double-helix around histone proteins - nucleosomes
2. DNA strands then coiled to form a chromatin fibre

Question 18

How many pairs of chromosomes are called autosomes

Answer 18

22

Question 19

What proportion of nuclear DNA encodes for functional genes

Answer 19

10%

Question 20

What is the role of ‘satellite’ DNA

Answer 20

Maintains chromosome structure

Question 21

Where are telomeres located

Answer 21

Found on the ends of each chromosome

Question 22

Role of telomeres

Answer 22

Needed for chromosomal replication

Question 23

What happens to the DNA when there is a lack of telomerase

Answer 23

The telomeres shorten with each mitotic division until the cell is incapable for further replication

Question 24

define a centrimorgan

Answer 24

the distance between two gene loci

Question 25

How does the process of gene linkage and recombination show

Answer 25

allows defective genes to be identified by tracking inheritance of neighbouring DNA in affected individuals and families

Question 26

How many base pairs are found in the homeobox genes

Answer 26

183 base-pairs

Question 27

What two ways are HOX genes controlled by

Answer 27

1. Endocrine regulation | 2. Vitamin A

Question 28

Mitochondrial DNA vs nuclear DNA

Answer 28

1. Circular double-stranded conformation 2. High rate of spontaneous mutation 3. Few introns 4. Maternal inheritance looks liked bacterial dna

Question 29

Why are mitochondria derived from the cytoplasm of mother's ovum

Answer 29

1. The head of the fertilising spermatozoon consists of the entire nucleus

Question 30

What gender will mitochondrial disorders effect the most

Answer 30

Male and females equally

Question 31

What do genes in mitochondrial DNA encode for

Answer 31

Enzymes in oxidative phosphorylation

Question 32

What would mitochondrial defects tend to effect

Answer 32

tissues with high energy requirements like neurones and muscle cells

Question 33

Define alleles

Answer 33

Two genes at an identical place on a parr of chromosomes

Question 34

Define heterozygous

Answer 34

Allele at a particular locus are different

Question 35

In what genotype are recessive genes expressed in

Answer 35

Homozygous

Question 36

Define karyotype

Answer 36

The chromosomal constitution of a cell or individual

Question 37

What colour can we use to see the 46 chromosomes in human nuclei more clearly

Answer 37

Colchicine

Question 38

How does Colchicine allow the 46 chromosomes show up

Answer 38

Inhibits polymerisation of tubulin, preventing formation of the mitotic spindle along which the chromosomes migrate and block cell division in metaphase.

Question 39

How does counting the 46 chromosomes help with abnormal chromosomes

Answer 39

SHOW ABNORMAL NUMBERS OF CHROMOSOMES (TRISOMY)

Question 40

How often do random polymorphic variations occur in nuclear DNA

Answer 40

1 in 200 base pairs

Question 41

In what two ways can polymorphic variation arise

Answer 41

1. Substitution of a single base on the DNA strand | 2. Presence of variable numbers of tandem repeats of base sequences

Question 42

How are variations in DNA detected

Answer 42

By determining variations in size of DNA fragments collected

Question 43

What is the PCR technique

Answer 43

1. Primers bind to complementary base pairs on the DNA template strands 2. DAM polymerase amplifies DNA fragment 3. High temperature to separate DNA strands 4. free nucleotides incorporate not newly synthesised DNA segments.

Question 44

What two disorders can single gene defects cause

Answer 44

1. Structural | 2. Metabolic

Question 45

What genotype do you need to have inherited a single gene defect that results in biochemical abnormalities

Answer 45

Recessive

Question 46

What genotype do you need to have inherited for a single gene defect that results in structural abnormalities

Answer 46

Dominant

Question 47

What four ways can result in a single gene defect

Answer 47

1. Deletion of a gene 2. Point mutation (substitution of a nucleotide) 3. Insertion/Deletion 4. Translocation

Question 48

What are the main three outcomes of a genetic alteration

Answer 48

1. Loss of function 2. Gain of function 3. Lethal

Question 49

Define toxicology

Answer 49

Study of environmental chemicals that cause disease

Question 50

What is the effect of acid/peroxides on tissues

Answer 50

1. Digest or denature proteins 2. Damage structural integrity of the tissue 3. Necrotic effect on skin cells

Question 51

How do chemicals cause disease metabolically

Answer 51

They can interrupt the metabolic pathway

Question 52

How can chemical agents effect DNA

Answer 52

Can cause genetic mutations (mutagens) 1. Teratogenic 2. Carcinogenic

Question 53

Define teratogenic

Answer 53

chemical agents effect embryogenesis leading to congenital malformations

Question 54

How can small molecules act as haptens in the body

Answer 54

They are too small to act as an antigen but accomplish this by binding to a larger molecule

Question 55

What part of a cigarette causes cancer

Answer 55

The carcinogens (hydrocarbons) in the smoke can cause tumours + carbon monoxide

Question 56

Define trauma

Answer 56

Mechanical injury to tissues

Question 57

Define pyrexia

Answer 57

Increased body temperature

Question 58

Where is pyrexia mediated

Answer 58

Interleukins on the hypothalamus

Question 59

Why is local heating of the skin dangerous

Answer 59

Coagulates proteins and disrupts structure and function of cells

Question 60

Define these terms: First degree burns Second degree burns Third degree burns

Answer 60

1. Skin redness 2. Epidermal necrosis and blistering of skin 3. Epidermal and dermal necrosis

Question 61

How is thermal injury useful in clinical environments

Answer 61

Can be used to coagulate tissues and stop bleeding

Question 62

Define a congenital disease

Answer 62

Present at birth

Question 63

Define inherited disease

Answer 63

Caused by inherited genetic abnormality

Question 64

Define acquired disease

Answer 64

By non-genetic environmental factors

Question 65

Define hypertrophy

Answer 65

Increase in size of tissue caused by an increase size of the constituent cells

Question 66

Define hyperplasia

Answer 66

Increase in size of tissue caused by an increase in NUMBER of constituent cells