crambiochem Flashcards
(399 cards)
What does it mean for genetic code to be commaless?
Read from a fixed starting point as a continuous sequence of bases
What does it mean for genetic code to be non-overlapping?
Read from a fixed starting point
What does it mean for genetic code to be universal?
Genetic code is conserved throughout evolution
What are the properties of the genetic code?
- Unambiguous.
- Degenerate/redundant.
- Commaless/nonoverlapping
- Universal
When is genetic code not commaless/nonoverlapping?
In some viruses
What are exceptions to universality of genetic code?
- Mitochondria
- Archaebacteria
- Mycoplasma
- Some yeasts
Name that mutation: Same amino acid, often with a base change in 3rd position of codon
Silent mutation
What kind of mutation is called: silent
Same amino acid, often with a base change in 3rd position of codon
What mutation is masked by tRNA wobble?
Silent mutations
Name that mutation: Changed amino acid whose structure is dissimilar to proper amino acid
Missense mutation (not conservative)
Name that mutation: Changed amino acid whose structure is similar to proper amino acid
Conservative missense mutation
What kind of mutation is called: missense
Amino acid is changed. If the structure of the new amino acid is similar to the original, it is called conservative.
Name that mutation: Change resulting in early stop codon
Nonsense mutation
Mnemonic: Stop the nonsense!
What kind of mutation is called: nonsense
Change resulting in early stop codon
Mnemonic: Stop the nonsense!
Name that mutation: change resulting in misreading of all nucleotides downstream, usually resulting in a truncated protein
Frame shift mutation
What kind of mutation is called: frameshift
change resulting in misreading of all nucleotides downstream, usually resulting in a truncated protein
Mutations ordered by decreasing severity of damage
- Nonsense
- Missense
- Silent
Eukaryotic genome: single/multiple origins of replication
multiple
Prokaryotic genome: single/multiple origins of replication
single
Eukaryotic genome: Trigger for replication
Consensus sequence of AT-rich base pairs
Prokaryotic genome: Describe DNA replication
Continuous bidirectional DNA synthesis on leading strand and discontinuous (Okazaki fragments) on lagging strand
Enzyme function: DNA topoisomerases
Create a nick in the helix to relieve supercoils
DNA Topoisomerase I: Mechanism
cuts one strand, passes the other through it then reanneals the cut strand
DNA Topoisomerase II: Mechanism
cuts both strands, and passes an unbroken double strand through it then reanneals the cut strand