Week 2-DNA REPLICATION AND REPAIR Flashcards
What is the central dogma of molecular biology?
DNA - RNA - Protein
What are the three types of stop codons?
- UAA
- UAG
- UGA
How many codons are there in the genetic code?
64 codons
How many amino acids are encoded by the genetic code?
20 amino acids
What does the ‘wobble hypothesis’ refer to?
1 tRNA may bind with +1 codons
What is a mutation?
A permanent alteration in genetic structure
What are the two types of mutations?
- Gross change involving several/many nucleotides
- Change involving a single nucleotide
What is a point mutation?
Change involving a single nucleotide
What are the three types of base substitutions?
- Silent mutation
- Nonsense mutation
- Missense mutation
What is a silent mutation?
No change in amino acid translated
What is a nonsense mutation?
‘Stop’ codon formed
What is a missense mutation?
Change in amino acid translated
What is a frameshift mutation?
Extensive codon changes downstream from insertion or deletion
What is cystic fibrosis inherited in?
Autosomal recessive manner
What is the cytogenetic location of the CFTR gene for cystic fibrosis?
7q31.2 base pairs 117,120,016 to 117,308,718
What does mutagenesis refer to?
The process by which mutations arise
What are the two types of mutation origins?
- Spontaneous
- Induced
What is a tautomeric shift?
Transient change in base structures
What is the role of DNA polymerase during replication?
Synthesizes DNA 5’ to 3’ and has 3’ to 5’ exonuclease activity
What happens if a spontaneous mutation is not corrected?
May undergo mismatch repair following replication
What is xeroderma pigmentosum?
Rare autosomal recessive disorder with elevated risk of developing sunlight-induced cancers
What is the primary defect in xeroderma pigmentosum?
Deficiency in nucleotide excision repair complex
What is the first step toward gene therapy for xeroderma pigmentosum?
Correction of 2 base pair deletion in XPC gene
What is the genetic disorder caused by a defect in the CFTR protein?
Cystic fibrosis
Fill in the blank: The genetic code is _______.
[degenerate]
True or False: All mutations lead to genetic disorders.
False
