DNA Replication Flashcards
1
Q
Exons and Introns
A
Exons: Coding regions of DNA
Introns: Non-coding regions (98% of the human genome)
2
Q
What are mutations?
A
Non-corrected errors caused by DNA polymerase during replication.
- Very common in microsatellites (many similar repeats leads to slippage, e.g. atgatgatgatg)…e.g. Huntington’s disease.
3
Q
Mutations in mitosis and meoisis
A
- Mutations during mitosis generally have little effect (exceptions such as huntingdon’s, cancer, sudden food allergies)
- Mutations occurring during meiosis are far more impactful
• Cause of variation between individuals
• Crossing over (sharing of genetic material between 2 different chromatids, mother and father) is essential and facilitated by Spo11 protein which initiates double-stranded breaks (cuts)
• Environment can alter where Spo11 cuts a genome
4
Q
The Central Dogma
A
Transcription, mRNA splicing, Translation
5
Q
Transcription
A
- Enzyme RNA Polymerase uses DNA as template & produces complementary, antiparallel RNA strand
- Polymerase binds onto core promoter region, in the presence of transcription factors, initiating transcription
- Only some genes are transcribed in each cell
6
Q
mRNA Splicing
A
mRNA travels out of nucleus, but is still made up of exons and introns, and needs further processing to get rid of introns before being used for protein synthesis: Splicing.
7
Q
Translation
A
- Chain of amino acids produced from spliced mRNA
- Translation occurs across the membrane of the endoplasmic reticulum
- Ribosome facilitates decoding by inducing the binding of tRNAs with complementary anticodon sequences to that of the mRNA
- Amino acids are attached to tRNA and are joined together by the ribosome.
8
Q
Sickle Cell Anemia
A
- Caused by a single point mutation (A to T) in the haemoglobin gene, which causes the 6th amino acid to be valine instead of glutamic acid (short arm of chromosome 11).
- Selected for because of malarial-resistance properties
