recitation 11 ncRNA Flashcards
what are ncRNAs
any RNA that does not encode polypeptide used in DNA replication, gene regulation, genome defense and other cell processes
general function of ncRNAs can perform
scaffold, guide, alteration of protein function, ribozyme, blocker, decoy
scaffold
binding sites for multiple components
guide
can guide 1 molecule to a specific location in a cell
alteration of protein function
can alter that protein structure and can have variety of effects
ribozyme
RNA molecule with catalytic activity
Blocker
physically prevent and block a cellular process from happening
decoy
some ncRNAs recognize other ncRNAs and sequester them and prevents them from working
HOTAIR
ncRNA that can change chromatin structure, and acts as scaffold which guides 2 histone-modifying complexes to correct target genes
CRISPR-Cas system
defends against bacteriophages in prokaryotes
Cas9
a protein that binds to RNA allowing it to target and destroy foreign DNA
PIWI interacting RNAs (piRNAs) and PIWI proteins
interact with PIWI proteins and inhibit movements of transposable elements
Mutations
change in the DNA sequence
what is the need for mutations
introduces genetic variability, foundation for evolutionary change, mutation rate
Types of Mutations
neutral, deleterious, beneficial, conditional, suppressor, point mutations, frameshift mutations,
neutral mutation
does not alter protein function
deleterious mutation
lowers chance of survival and/or reproduction
beneficial mutation
enhances survival and /or reproductive success
conditional mutation
only affects phenotype under specific conditions
suppressor
a second mutation that counters the phenotypic effect of the first mutation
point mutations
base substitutions in which one base pair is altered
frameshift mutations
insertions or deletions causing a shift in reading frame
transition point mutations
changes of a pyrimidine to another pyrimidine or a purine to another purine
transversion
change of a purine to a pyrimidine or vice versa
missense mutation in coding sequence
alter the amino acid sequence
silent mutations in the coding sequence
does not alter the amino acid sequence
nonsense mutations in coding sequence
change a codon to a stop codon
spontaneous mutation occurrence
mutations arise from replication errors and base modifications
induced mutation occurrence
mutation occurs by contact with environmental agents
deprivation in a spontaneous mutation
removal of a purine resulting in a purification site
reanimation in spontaneous mutations
removal of an amino group from cytosine
tautomeric shift
change in base structure allowing A-C and G-T base pairing
oxidative stress in spontaneous mutations
reactive oxygen species damage DNA
chemical mutagens- induced mutations
covalently modify nucleotide structure
physical mutagens- undecided mutations
ionizing radiation
DNA repair mechanisms
repair systems counteract genetic damage that would result in genetic diseases and cancer
direct repair- DNA repair mechanims
fixes structure
base excision repair
fixes abnormal nucleotide
mismatch repair mechanism
fixes base pair mismatch
homologous recombination repair
fixes double-stranded breaks
non-homologous end joining
fixes double-stranded breaks
photoreactivation repair
removes thymine dimers caused by UV light
Nucleotide excision repair
repair of a damaged single strand where you have another strand to use as a template to repair the damaged information
homologous recombination repair
fixes double stranded breaks by using sister chromatid as the template to allow DNA polymerase to copy the undamaged sequence into the damage strand
why are double-stranded breaks more difficult to repair
you can lose large portions of a chromosome
