Flashcards in Genetics Deck (41)
Which bases have 2 carbon - nitrogen rings and are known as purines?
A and G
Which bases have a single carbon - nitrogen ring and are known as pyrimidines?
C and T
What are the base pairings?
A pairs with T
C pairs with G
Which bases have the strongest bond?
The bond between C and G is stronger than that of A and T
How many bases and genes are there in the human genome?
What are the stages of the cell cycle?
(these all make up mitosis)
G1, S, G2
Where are the checkpoints in the cell cycle?
G1 checkpoint towards the end of G1
G2 checkpoint at the end of G2
M check point during mitosis
What is mitosis and what is meiosis?
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
What is the difference between a mutation and a polymorphism?
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
Are all mutations harmful?
NO - not necessarily if they don't affect the coding part of the DNA
Normal number of female and male chromosomes
Female 46 XX
What is an acrocentric chromosome?
A chromosome in which the centromere is situated at or very near one end
What symbols are used for the long and short arm of a chromosome?
Short arm - p
Long arm - q
What is meant by a 'Robertsonian Translocation' ?
Two acrocentric chromosomes are stuck end-to-end.
What is meant by balanced and unbalanced chromosome changes?
Balanced - There is rearrangement of the chromosomes but all material is still present
Unbalanced- Rearrangement in which there is extra or missing material
Define the term 'ANEUPLOIDY'
Whole extra or missing chromosomes
Trisomy 18 (death a few days post-birth)
Mild learning difficulties
Lack of testosterone
Poor development of sexual features
FISH (examines genes)
Microarray CGH (Detects missing/extra chromosomes)
What is meant by 'MOSAICISM' ?
A disease that affects part but not all of the body
List 5 types of mutations that can occur in DNA sequences and what term describes the normal/natural sequence
Wild Type (normal/natural)
What does 'PENETRANCE' mean?
The likelihood of having a disease if you have a gene mutation
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!
What is an SNP?
What is a CNV?
Single Nucleotide Polymorphism
Copy number variation
- Extra or missing stretches of DNA
What is meant by driver and passenger mutations?
Driver mutations drive carcinogenesis
Passenger mutations are incidental and occur because the tumour becomes unstable
What is meant by the 'Philadelphia Chromosome' and what does it cause
a 9 to 22 translocation
it drives leukaemia development
What is meant by 'imprinting'
Differences in gene expression depending on whether a gene is maternally or paternally inherited