Molecular Genetics

Question 1

What are chromosomes 1-22?

Answer 1

Autosomes

Question 2

What is the 23rd chromosome pair?

Answer 2

Sex chromosomes

Question 3

What are males?

Answer 3

XY

Question 4

What are females?

Answer 4

XX

Question 5

What are alleles?

Answer 5

Different forms of one gene

Question 6

What are allotypes?

Answer 6

Different forms of one protein

Question 7

What is polymorphic?

Answer 7

Alternative forms of one gene = many alleles

Question 8

What is oligomorphic?

Answer 8

Few forms of one gene = few alleles

Question 9

What is monomorphic?

Answer 9

No polymorphism

Question 10

What is homozygous?

Answer 10

Same allele on both inherited chromosomes

Question 11

What is heterozygous?

Answer 11

Different allele on both inherited chromosomes

Question 12

Describe mitosis

Answer 12

Division of somatic cells
2 daughter cells from 1 parent cell

Question 13

What does not change in mitosis?

Answer 13

No. of chromosomes

Question 14

When does the DNA duplicate in mitosis?

Answer 14

Before entering mitosis

Question 15

Describe meiosis

Answer 15

Division of germline cells
Only in gamete formation
1 diploidic cell produces 4 haploid gametocytes

Question 16

How many chromosome do cells have in mitosis?

Answer 16

46 chromosomes (2n)

Question 17

How many chromosome do cells have in meiosis?

Answer 17

23 chromosomes (n)

Question 18

What is a mutation?

Answer 18

Change in genetic material

Question 19

What are the basic types of DNA mutation?

Answer 19

Missense mutation = different amino acid
Nonsense mutation = chunkated protein
Frameshift mutation

Question 20

What are the classes of genetic diseases?

Answer 20

Chromosomal disorders
Monogenic disorders
Multifactorial disorders
Polygenic disorder
Somatic disorders
Mitochondrial disorders

Question 21

What is an example of a chromosomal disorder?

Answer 21

Down syndrome

Question 22

What is an example of monogenic chromosomal disorder?

Answer 22

Cystic fibrosis
Sickle cell anaemia
Haemophilia A

Question 23

What is an example of multifactorial disorder?

Answer 23

Ischemic heart disease

Question 24

What are monogenic (single gene) disorders caused by?

Answer 24

Change in just one or both copies of particular pair of genes

Question 25

What is autosomal dominant?

Answer 25

One chromosome affected (heterozygote)

Question 26

What is autosomal recessive?

Answer 26

Both chromosomes affected (homozygous)

Question 27

What is X-linked?

Answer 27

Mutation on X chromosome

Question 28

What are examples of autosomal dominant inheritance?

Answer 28

Huntington disease Marfan syndrome

Question 29

For it to be autosomal recessive what must happen?

Answer 29

BOTH parents need to be a carrier

Question 30

What are examples of autosomal recessive disorder?

Answer 30

Sickle cell disease CF Spinal muscular atrophy

Question 31

If you're a carrier of sickle cell disease, what will happen?

Answer 31

Small changes in haemoglobin shape BUT doesn't effect O take up

Question 32

Describe autosomal dominant

Answer 32

Heterozygote (Aa) or homozygote (AA) Least 1 affected parent

Question 33

Describe autosomal dominant: achondroplasia

Answer 33

Change in transmembrane domain of FGFR3

Question 34

What is FGFR3 involved in?

Answer 34

Cartilage to bone transition

Question 35

What does achondroplasia do?

Answer 35

Inhibits bone growth

Question 36

Describe autosomal recessive

Answer 36

Very rare Homozygote (aa)

Question 37

Describe autosomal recessive: sickle cell anaemia

Answer 37

Single nucleotide substitution

Question 38

What happens to haemoglobin in patients with sickle cell anaemia?

Answer 38

Hb polymerises under low O =distorts RBC shape = affects O transport

Question 39

What is the vaso-occlusive/pain crisis?

Answer 39

Distorted RBC shape = gets stuck = blocks blood vessel = pain

Question 40

What is dactylitis?

Answer 40

Painful swelling of hands + feet which occurs in infants

Question 41

Describe autosomal recessive: CF

Answer 41

Mutation in CFTR gene

Question 42

What is it if 2 affected people have an unaffected child?

Answer 42

Dominant pedigree Aa = parents aa = child

Question 43

What is it if 2 unaffected people have an affected child?

Answer 43

Recessive pedigree Aa= parents aa = child

Question 44

What are examples of X-linked recessive?

Answer 44

Haemophilia Fragile X syndrome

Question 45

Describe X-linked recessive

Answer 45

Acts as recessive traits in females (XX) Dominant traits in males (XY)

Question 46

Describe X-linked recessive: haemophilia

Answer 46

B = deficiency factor IX A = deficiency factor VIII Inversion mutation

Question 47

What is an inversion mutation?

Answer 47

Genetic sequence flipped after duplication

Question 48

What are the management of haemophilia?

Answer 48

Joint immobilisation + physical therapy COX-2 inhibitors

Question 49

Describe X-linked dominant

Answer 49

BOTH male + female affected

Question 50

What is an example of X-linked dominant?

Answer 50

Rett syndrome

Question 51

Describe Rett syndrome

Answer 51

X-linked MECP2 Loss of language, cognitive + motor abilities

Question 52

Describe Y-linked dominant

Answer 52

Very rare = sex-linked Mutations on Y chromosome

Question 53

Describe mitochondrial inheritance

Answer 53

Mitochondrial DNA inherited only through egg

Question 54

What is polygenic inheritance?

Answer 54

Trait coded by a number of altered + unaltered genes working together

Question 55

What are examples of polygenic inheritance?

Answer 55

Alzheimer's Diabetes Cancer Eczema

Question 56

What are examples of congenital malformations of multifactorial disorders?

Answer 56

Cleft lip Heart defects

Question 57

What are examples of adult onset disorders of multifactorial disorders?

Answer 57

Diabetes Epilepsy Hypertension Ischaemic HD Glaucoma

Question 58

What are numerical chromosome abnormalities?

Answer 58

Gain or loss of complete chromosomes

Question 59

What is the common cause of numerical chromosome abnormalities?

Answer 59

Non-disjunction

Question 60

What are the chromosome aberrations?

Answer 60

Deletion Translocation Inversion

Question 61

What is translocation?

Answer 61

Section shifts from one chromosome to another

Question 62

What is inversion?

Answer 62

Section gets snipped off + reinserted the wrong way around

Question 63

What is a terminal deletion?

Answer 63

Removed off end

Question 64

What is an interstitial deletion?

Answer 64

Deleted from the middle

Question 65

What is autosomal trisomy?

Answer 65

When a chromosome has an extra copy

Question 66

Describe autosomal trisomy: down syndrome

Answer 66

Trisomy 21

Question 67

Describe autosomal trisomy: Edwards syndrome

Answer 67

Trisomy 18 Multiple malformations 90% die before 5 months

Question 68

Describe autosomal trisomy: Patau syndrome

Answer 68

Trisomy 13 Multiple malformations Most die few weeks after birth

Question 69

Describe anomalies of sex chromosome number: klinefelter syndrome

Answer 69

XXY Males Infertility = do NOT produce sperm

Question 70

Describe anomalies of sex chromosome number: Turner syndrome

Answer 70

X Females

Question 71

What are the possible treatment for genetic diseases?

Answer 71

Correct metabolic consequences Replace absent enzyme Remove excess stored product Correct basic genetic abnormality

Question 72

What are the different types of gene therapy?

Answer 72

Replacement Correction Augmentation

Question 73

What is replacement gene therapy?

Answer 73

Mutant gene removed + replaced with a normal gene

Question 74

What is correction gene therapy?

Answer 74

Mutated area of affected gene would be corrected + remainder left unchanged

Question 75

What is augmentation gene therapy?

Answer 75

Introduction of foreign genetic material into cell to compensate for defective product of mutant gene