Genetics pt. 2 Flashcards
What suppresses and reverses incorrect folding of proteins?
Molecular chaperones
What is the importance of protein folding?
Must be correctly folded, as protein function is determined by 3D shape
What are the 4 structures of protein folding?
- Primary
- Linear sequence of amino acids
- Secondary
- Hydrogen bonding of peptide
- Tertiary
- 3D folding due to R group
- Quarternary
- 2+ amino acids bond
What are genetic mutations?
Change in nucleotide sequence of gene
Define these terms that have to do with mutations:
- Wild-type
- Mutant
- Natural unchanged gene sequence
- Mutated gene sequence
What causes spontaneous mutations?
Errors in DNA replication when nucelotide shift to different isoform.
What are the 2 mutation forms that can result from spontaneous mutations?
- Transition
- Puring to purine/ pyrimidine to pyrimidine
- Transversion
- Puring to pyrimidine/ pyrimidine to purine
What causes induced mutations?
Being exposed to mutagen (chemical or physical agent)
What are the chemical agents that can cause induced mutations?
-
Base analogs
- Structurally similar to normal base
-
DNA modidying agents
- Chang base’s structure/pairing
-
Intercalating agents
- cause single nucleotide insertion/deletion
What are the physical agents that can cause induced mutations?
- UV light
- Causes pyrimidine dimers to form
- xrays
- Cause nicks, breaks, deletions
What are point mutations?
Involve change in a single nucleotide base of gene.
What are the types of point mutations?
- Addition
- nucleotide inserted into normal sequence
- Deletion
- Nucleotide is removed
- Substitution
- Nucleotide is replaced
What are silent mutations?
What causes them?
Point mutations that occur but do not change the amino acid from codon.
Synonymous codons
What are nonsense mutations?
What do they cause?
Point mutation that causes normal amino acid to become a stop codon.
Cause protein to be not functional
What are missense mutations?
What causes them?
A point mutation that causes normal amino acid to be changed to completely different amino acid.
Non-synonymous codons
What are framshift mutations?
What causes them?
Point mutation that causes the codon triplet to move from normal reading frame.
Caused by insertion or deletion
What are proofreading repairs (mutations)?
First line of defense:
DNA polymerase uses exonucleus to remove error by synthesis errors (not induced mutations)
What is mismatch repair (mutation)?
For when proofreading fails:
Endonuclease removes the error, fillls in correctly
What are excision repairs? (mutation)
Correction of damage that causes distortion in DNA double helix
(endonuclease cuts out)
What are the types of excision repairs?
How are they different?
- Nucleotide excision
- Repair for thymine dimers
- Base excision
- Repair for unnatural bases
What are vertical gene transfers?
What types of organisms use this?
Give an example
Transfer of genes from parent to progeny
All organisms
Meiosis
What are horizontal transfer of genetics?
What organisms use this?
Donor DNA from one organism enters a recipient cell
Bacteria and Archaea
What is conjugation (horizontal transfer)?
What two methods do bacteria use?
Transfer of DNA plasmid by direct cell-to-cell contact
- Sex pilus
- Type IV (secretion)
What is transformation (horizontal transfer of genetics)?
What are the steps it occurs?
Uptake of plasmid/fragment DNA by cell from environment
- Donor cell lyses (releases DNA)
- dsDNA taken by competent cell
- Becomes ssRNA
- Integrated or preserved
What is virus mediated/transduction (horizontal transfer)?
Transfer of genes between bacteria by virus
Can either lyse cell and infect more, or become integrated in genome
