Genetics Flashcards
(56 cards)
1
Q
What 2 factors add together to produce disease?
A
- environment
- genes
2
Q
Explain DNA structure
A
- double stranded
- anti-paralel
- deoxyribose sugar
- A-T , C-G
3
Q
What is the name of the protein DNA wraps around to produce chromosomes?
A
- histone
4
Q
How many bonds between cystosine and guanine?
A
- 3
5
Q
How many bonds between adenine and thymine?
A
- 2
6
Q
Which direction is DNA read and replicated?
A
- 5’ –> 3’
7
Q
What are the steps of the cell cycle?
A
- G1
- S
- G2
- M
8
Q
At which stage in the cell cycle does DNA synthesis occur?
A
- S phase
9
Q
What is mitosis?
A
- 1 diploid parent produces 2 identical diploid cells
10
Q
What is meiosis?
A
- 1 diploid parent produces 4 haploid cells
11
Q
what occurs during meiosis?
A
- crossing over
- gamete production
12
Q
What is the differences in RNA compared to DNA
A
RNA:
- single stranded
- ribose sugar
- uracil replaces thymine
13
Q
Explain the processes from DNA to protein
A
- DNA transcribed to pre mRNA
- pre mRNA spliced to mRNA
- mRNA translated to protein
- protein modified and moved around cell
14
Q
What is the definiton of a polymorphism?
A
- any variation in the human genome with a population frequency of greater than 1%
- doesnt cause disease in own right, but can predispose
15
Q
What is the definition of a mutation?
A
- a gene change that causes a genetic disorder
16
Q
What causes variations within genes?
A
- changes in promotor sequences
- changes in exon sequences
17
Q
How are chromosomes recognised?
A
- banding patterns
- length
- position of the centromere
18
Q
What is the name given to a chromosome where the short arm doesnt really matter?
A
- acrocentric
19
Q
Define balanced chromosomal arrangement
A
- all chromosomal material is present
20
Q
Define unbalanced chromosomal arrangement
A
- extra or missing chromosomal material
21
Q
Define anueploidy
A
- whole extra or missing chromosome
22
Q
Define transloaction
A
- rearrangement of chromosomal material
23
Q
Down syndrome genetic makeup?
A
- trisomy 21
- 47XY + 21
24
Q
What is a robertsonian translocation?
A
- two afrocentric chromosomes stuck end-to-end
25
Turners syndrome genetic make up?
45 X
26
Edwards syndrome genetic make up
47 XY + 18
| - trisomy 18
27
Klinefeleter syndrome genetic make up
47 XXY
28
What is the 1st line chromosome test?
- microarray CGH (aCGH)
29
what is a disadvantage of aCGH?
- Doesn't detect balance rearrangements
30
Define mosaicism
- different cells have different genetic constitution
31
What 2 chromosomal abnormalities may cause cancer?
- activation of oncogenes
| - deletion of tumour suppressor genes
32
What are the functions of introns?
- non-coding regions
- regulation of genes
- spacing out of genes
33
What is a mutation?
- a genetic variation that causes disease
34
What is a polymorphism?
- a genetic variation that may not cause disease in its own right
35
What is a point mutation?
- a single nucleotide base is changed, inserted or deleted
36
What does ">" represent on the c.
- substitution
37
What does "c." represent when describing mutations?
- change to the mature mRNA
38
What does "p." represent when describing mutations?
- change to the peptide (protein) sequence
39
What does "wild type" mean?
- the "normal"
40
Define penetrance
- the likelihood of having a disease if you have the gene mutation
- 100% penetrance = 100% you will have the disease
41
Define mendelian disorders?
- caused by a change in a single gene
42
What are examples of non-mendelian disorders?
- methylation/imprinting
- mitochondrial inheritance
- mosaicism
43
autosomal dominant mutations are seen in ____ generation(s)
- all generations
44
If a parent is affected with an autosomal dominant mutation, what is the risk that a child will also be infected?
- 50% risk of child being infected
45
Autosomal recessive mutations require ___ copies of the gene to cause disease
- 2 copies
46
In autosomal recessive mutations usually ____ generation(s) are affected.
- one generation
47
What is the risk of a child being affected if both parents are a carrier of an an autosomal recessive mutation?
- 25% risk
48
Explain X linked recessive diseases?
- gene fault lies on the X chromosome
- female may be carrier but will show no sign of disease (except if X inactivated)
- 1/2 of male children effected
- 1/2 of female children carriers
49
If an affected male, with X linked recessive mutation has 2 children, boy and a girl. What are their individual risks?
- Male - 0% (no male-to-male transmission)
| - all of female children will be affected
50
What are SNPs?
- Single Nucleotide Polymorphism
| - most have no/little effect
51
Cancers can be described as genetic disease at a ____ level
- somatic
52
Methylation usually occurs on the ___ bases just before the ____ bases
- cytosine
| - guanine
53
What are oncogenes activated by?
- point mutations
- translocations
- gene amplifications
54
Name an example of an oncogene?
- RAS
| - MYC
55
Tumour supressor mutations are ___
| dominant or recessive?
- recessive
56
Examples of tumour supressors?
- pRb
| - p53
