Genetics Flashcards

(41 cards)

1
Q

Which bases have 2 carbon - nitrogen rings and are known as purines?

A

A and G

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2
Q

Which bases have a single carbon - nitrogen ring and are known as pyrimidines?

A

C and T

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3
Q

What are the base pairings?

A

A pairs with T

C pairs with G

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4
Q

Which bases have the strongest bond?

A

The bond between C and G is stronger than that of A and T

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5
Q

How many bases and genes are there in the human genome?

A

30,000 genes

3,000,000,000 bases

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6
Q

What are the stages of the cell cycle?

A
Prophase 
Metaphase 
Anaphase 
Telophase 
Cytokinesis
(these all make up mitosis) 
Then; 
G1, S, G2
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7
Q

Where are the checkpoints in the cell cycle?

A

G1 checkpoint towards the end of G1
G2 checkpoint at the end of G2
M check point during mitosis

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8
Q

What is mitosis and what is meiosis?

A

Mitosis is when one diploid parent cell forms two identical diploid daughter cells
Meiosis is when one diploid parent cell forms 4 haploid daughter cells

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9
Q

What is the difference between a mutation and a polymorphism?

A

A mutation is a gene that causes a genetic disorder

A polymorphism is any variation in the human genome that doesn’t necessarily cause disease but can predispose to one

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10
Q

Are all mutations harmful?

A

NO - not necessarily if they don’t affect the coding part of the DNA

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11
Q

Normal number of female and male chromosomes

A

Female 46 XX

Male 46XY

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12
Q

What is an acrocentric chromosome?

A

A chromosome in which the centromere is situated at or very near one end

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13
Q

What symbols are used for the long and short arm of a chromosome?

A

Short arm - p

Long arm - q

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14
Q

What is meant by a ‘Robertsonian Translocation’ ?

A

Two acrocentric chromosomes are stuck end-to-end.

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15
Q

What is meant by balanced and unbalanced chromosome changes?

A

Balanced - There is rearrangement of the chromosomes but all material is still present
Unbalanced- Rearrangement in which there is extra or missing material

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16
Q

Define the term ‘ANEUPLOIDY’

A

Whole extra or missing chromosomes

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17
Q

Down’s Syndrome

18
Q

Edward’s Syndrome

A

Trisomy 18 (death a few days post-birth)

19
Q

Turner’s Syndrome

A

45 X
Female
Mild learning difficulties
Appearance abnormalities

20
Q

Klinefelter Syndrome

A
47 XXY 
Male 
Infertility 
Lack of testosterone 
Poor development of sexual features
21
Q

Genetic tests

A

FISH (examines genes)
Microarray CGH (Detects missing/extra chromosomes)
PCR
NGS

22
Q

What is meant by ‘MOSAICISM’ ?

A

A disease that affects part but not all of the body

23
Q

List 5 types of mutations that can occur in DNA sequences and what term describes the normal/natural sequence

A
Wild Type (normal/natural) 
Premature stop 
Missense 
Deletions
Insertions 
Triplet Expansion
24
Q

What does ‘PENETRANCE’ mean?

A

The likelihood of having a disease if you have a gene mutation

25
What are the differences between mendelian and multifactorial diseases?
Mendelian diseases are high penetrance with a high genetic contribution. Multifactorial diseases are common but have low penetrance and are caused by both genes and the environment!
26
What is an SNP? What is a CNV?
Single Nucleotide Polymorphism Copy number variation - Extra or missing stretches of DNA
27
What is meant by driver and passenger mutations?
Driver mutations drive carcinogenesis | Passenger mutations are incidental and occur because the tumour becomes unstable
28
What is meant by the 'Philadelphia Chromosome' and what does it cause
a 9 to 22 translocation | it drives leukaemia development
29
What is meant by 'imprinting'
Differences in gene expression depending on whether a gene is maternally or paternally inherited
30
What 4 stages make up the central dogma?
Transcription Splicing Translation Post transcriptional modification
31
What is a promotor mutation?
A mutation which stops the action of the 'on switch' involved in producing proteins - this leads to no/reduced transcription
32
What is somatic mosaicism? Does it affect the entire body?
Two populations of cells within an individual due to post-zygotic mutations, it may only affect parts of the body
33
What kind of inheritance would involve a condition only being transmitted from an affected mother to her children?
Mitochondrial Inheritance
34
What kind of inheritance would involve no male to male transmission of the condition?
X-linked inheritance
35
Describe autosomal recessive inheritance?
Involves heterzygous parents having a 1 in 4 chance of having an affected child
36
At which stage of the cell cycle does DNA synthesis occur?
S phase! | G1- S- G2-M...
37
What is the 1st line test for looking at chromosomes?
Microarray CGH
38
What genes stop cells dividing if they are switched on? Which genes cause cells to start diving if they are switched on?
Tumour suppressors Oncogenes
39
Is penetrance higher for mendelian or multifactorial diseases?
Mendelian
40
What does angel man syndrome involve and which chromosome is affected?
Patients have developmental delay and intellectual disability Chromosome 15
41
What is meant by heteroplasmy?
Different daughter cells contain different proportions of mutant mitochondria