Function/dysfunction- Gene Reg Flashcards
What is the nucleus’s role in the cell
Cell regulation, proliferation, and DNA transcription
What is the central dogma of genetics
DNA —(transcription)—>RNA —(translation) —> Protein
What is the exclusive carrier of information from DNA to Protein ?
mRNA
T/F
RNA can be reverse transcribed into DNA
True
*reverse transcriptase relates to RNA Virus (HIV)
How many bonds are between A-T and C-G in double stranded DNA
AT is double (hydrogen) bond
GC is triple (hydrogen) bond
Why are mitotic chromosomes condensed 500 times more than interphase chromosomes
To prevent physical damage to the DNA as chromosomes are separated and passed to daughter cells
What bonds are between DNA and the histone octamers in each nucleosome
Hydrogen bonds
- hydrophobic interactions
- salt linkages
T/F
DNA is wound around histone Proteins
True
20% of histone protein amino acid residues are lysine or arginine
What is a nucleosome
Basic unit of chromosome packing:
- has 8 histone proteins - histone octamer = protein which DNA is wound around
Protein + DNA =
Chromatin
Euchromatin vs Heterochromatin
Euchromatin
- lightly packed
- undergoes transcription
- most active portion of genome
Heterochromatin
- very condensed
- stains darkly
- genetically inactive
- high concentrated at centromeres and telomeres
What is the position effect?
Activity of a gene depends on relative position on chromosome
- is actively expressed gene is relocated near Heterochromatin it will be silenced
T/F
Copy number variations are detected by comparative genome hybridization and are the basis for our differences as humans
True
What is RNAi
RNA interference
- miRNA inhibit gene expression or translation
- this happens by a miRNA precursor folds on itself and a Dicer enzyme cuts dsRNA into short segments. one strand is degraded and the single strand left is miRNA. The miRNA associates with a protein complex that prevents gene expression by degrading or blocking target mRNA
What are Long terminal repeats?
- identical sequences of DNA repeated
- found at retrotransposons (proviral DNA) ends
- formed by reverse transcription of retroviral RNA
- used by viruses to insert their genetic material into the host genome
What base pairs are found at intron/exon border?
GT is at beginning
AG is at end
- intron is spliced out info
- exon is the info kept
What gives gene diversity
Alternative RNA splicing
*exons and introns
What does HDAC and HAT do?
Histone Deacetylase actively represses gene expression
- keeps chromatin condensed
- have corepressor proteins
Histone acetyl transferase promotes gene expression
- allows chromatin to open and be transcribed
- has coactivator proteins
*both bind to promoter region
T/F
histone protein tails are the target of numerous Post-translational modifications
True
PTM’s occur at the n-terminus
What is DNA methylation ?
PTM
- methyl group added to DNA (cytosine and adenine) by methyl transferase enzymes
- represses gene transcription at gene promoter
What happens when CpG islands are hypermethylated
Transcriptional silencing which can be passed down to daughter cells
- can cause cancer if it is in DNA repair gene
- causes 5-methyl cytosine to become thymine
What does hypomethylation cause
Chromosomal instability and loss of imprinting
Which direction is new DNA synthesized
5’—>3’
DNA polymerase requires a primer with a _______ to begin processing
With a free 3’ -OH group