Genetics - Guide to the Human Genome for Clinicians Flashcards
What is the structure of DNA?
Two strands bind in antiparallel form with a sugar backbone and bases A, T, C and G. Slide 12
What are the four bases in an RNA molecule?
AUCG. Slide 12
What is DNA normally arranged like?
A ball of string. Slide 16
When does DNA take form of the chromosomal shape?
At metaphase. Slide 17
How is a chromosome formed?
The DNA associates with proteins e.g. histones and wraps round them. Slide 20
What is the order of the cell cycle?
G1 - S - G2 - M phase. Slide 23
Which is the leading strand in DNA replication?
3’ to 5’. Slide 24
What is the lagging strand in DNA replication?
5’ to 3’, is completed in little segments. Slide 24
What are 3 examples of DNA damage?
DNA strand breaks, chemical crosslinking and mismatched base. Slide 25
What happens if DNA cannot be repaired?
Risk of getting cancer. SLide 26
What is an example of a genetic disease if DNA strands break?
BRCA1, BRCA2, RAD51, BR - breast cancer. Slide 26
What is an example of a genetic disease of UV or chemical crosslinking?
Xeroderma Pigmentosa. Slide 26
What is an example of a genetic disease of a mismatched base?
Hereditary Colorectal Cancer. Slide 26
When does DNA replication occur?
S phase. Slide 27
During mitosis what happens?
One diploid parent cell forms two diploid daughter cells, are NOT identical as there may be mutations. Slide 29
What happens during meiosis?
One diploid parent cell becomes 4 haploid daughter cells, each one different. Slide 32
What is the structure of RNA?
Single stranded, ribose in backbone (not deoxyribose) and has uracil instead of thymine. Slide 33
What is the amount of protein produced determined by?
Rate of transcription
Rate of splicing to mRNA
Half life of mRNA
Rate of processing polypeptide. Slide 36
What happens to the coded RNA in brief terms?
DNA is transcribed to pre mRNA. Pre mRNA is spliced to form mRNA. mRNA is translated to a protein where the protein is modified for its function. Slide 37
What are examples of sequence variations within a gene?
Changes in promotor and exon sequences. Slide 41
What are examples of sequence changes in the DNA between genes?
Single Nucleotide Polymorphisms (SNPs)
Larger deletions or duplications. Slide 41
What is a polymorphism?
Any variation in the human genome that has a population frequency of greater than 1%
OR
Any variation in the human genome that does not cause a disease in its own right. Slide 42
What is a mutation?
A gene change that causes a genetic disorder
OR
Any heritable change in the human genome. Slide 43
Why does everyone not look the same?
Each copy of the genome is slightly different, as DNA replication is imperfect so new genetic variants come about. Slide 50
