Function And Dysfucntion Supplement (1) Flashcards
What are the three parts of the central dogma of Genetics
- Replication
- Transcription - genetic info carried by DNA is transcribed into RNA
- Translation - the information carried in mRNA is translated into proteins
DNA is what and what?
Double stranded and anti-parallel
Why are mitotic chromosomes condensed?
To prevent physical damage to the DNA as chromosomes are passed on to daughter cells
What four pairs of proteins make up the Histone-Octamer?
H2A
H2B
H3
H4
Heterochromatin stains what color throughout cell cycle?
Very dark
When did Watson and Crick describe the structure of DNA?
When did K, K, and H determine the genetic code?
1953
1966
What is an intron?
Position where the gene expresses a protein
Where does acetylation attach an acetyl group on genes?
On the free lysine residue
What is post-translational modification?
Altering of Histone proteins with their DNA
Usually occurs at H3 and H4 on the tails
Describe DNA Methylation
Methyl groups added to the DNA molecule (cytosine and adenine) by methyl transferase enzymes
This changes the activity of the DNA segment without changing the sequence
Represses gene transcription when at gene promoter region
What key processes is DNA Methyl involved in
Genomic imprinting X-chromosome inactivation Repression of transposable elements Aging Carcinogenesis
Describe hypomethylation
Chromosome instability
Loss of imprinting
Seen in promoter CpG Islands
Describe hypermethylation
Associated with gene promoters
Can arise secondary to gene silencing
Can be a target for epigenetic therapy
Seen in Gene promoter CpG islands
Describe DNA Helicase
Unwinds DNA
Comprised of 6 identical subunits
Uses ATP to undergo a conformational change to split DNA apart
What do Topoisomerase inhibitors do as anti-cancer agents
Block the cell cycle
Generate single and double stranded breaks
Harms integrity of the genome
Leads to apoptosis
What is the purpose of germ cells
Low mutation rates that maintain the species
What is the purpose of somatic cells
Low mutation rates avoid uncontrolled cancer
What protein spell checks the new DNA
DNA polymerase
How can UV damage hurt DNA
Can cause a covalent linkage between two adjacent pyrimidine dimers (T-T) or (C-T)
Describe depurination
A or G cut from DNA spontaneously via hydrolysis of the N-glycosidic bond between the base and deoxyribose group
Describe deamination
The amino group of purine or pyrimidine bas is hydrolyzed such that:
Adenine to hypoxanthine
Guanine to xanthine
Cytosine to uracil
Methylation of CpG causes what
Silence of genes responsible for cancer repair
What agents cause cross-links within DNA
Nitrogen mustard
Cisplatin
Mitomycin C
Carmustine
What agents cause alkylation of DNA
Dimethyl sulfate
Methyl methansulfonate
What specific agent causes intercalation of DNA
Thalidomide
Describe mismatch excision repair
Proofreading by DNA dependent DNA polymerase
MutS and MutL do what respectively
Muts binds to DNa while MutL scans for nicks and triggers degradation of the nicked strands
What are the three causes of double strand breaks
Ionizing radiation
Replication errors
Oxidizing agents
Describe cockayne’s syndrome
Defect in transcription-coupled repair
Causes growth retardation, skeletal abnormalities, and sensitivity to sunlight
What are the side effects of rifampicin
Upregulation of hepatic cytochrome enzymes, which causes an upregulation of other drugs (warfin and contraceptive hormones)
Makes patient haver red urine, sweat, and tears for a brief time
What PTM’s work on lysine
Sumoylation
Ubiquitination
acetylation
Methylation
What PTM works on serine and threonine
Phosphorylation
Epigentetics are affected by what factors
Development Enviropnement Drugs Aging Diet
ATG begins what
Start of translation which is initiated by methionine
Where does DNA methylation occur in humans
5 position on the pyrimidine ring of cytosine residues
Forms 5-methylcytosines which promotes silenced genes
