DNA Function & Structure Flashcards
Give an example of DNA in physiology?
DNA, RNA, protein
Give examples of DNA in pathology?
Genetic diseases
Viruses
Cancer
Give an example of DNA in diagnostics?
Mutation analysis
Microbiology
Forensic medicine
Give an example of DNA in therapy?
DNA as drug target
Gene therapy
Risk assessment
Give an example of DNA in biotechnology?
Production of biomedicines
Delivery vectors
Gene products
What are prokaryotes?
No nuclear membrane, DNA arranged often in a single chromosome
What are eukaryotes?
DNA is in the nucleus. Bound to proteins (chromatin complex)
What are functions of DNA?
•DNA as template and regulator for transcription and protein synthesis.
•DNA is the genetic material, structural basis of heredity and genetic diseases
Why is cell cycle control and DNA repair so important in medicine?
Cancer
Oncogenes
Proto-oncogenes
Cell cycle control
DNA repair
How fast is DNA replication?
About 700-1000 bp per second
How much work needs to be done in DNA replication?
6 billion base pairs
Prior to cell division where does DNA open at?
Replication fork
DNA replication is…
Semi-conservative
What enzymes are used in DNA replication?
Polymerases (5’ to 3’)
Helicase
Ligase
Nuclease
Primase
Topoisomerase
What enzyme opens the DNA strands?
Helicase
What keeps the DNA strands open?
Single stranded binding proteins (SSB)
What enzyme unwinds the strands?
Topoisomerase
What does DNA polymerase do?
Has editing function
Detects incorrect insertion of base and will excise and repeat
What can damage our DNA?
Chemical
Radiation
Spontaneous insertion of incorrect bases during replication
Product of incomplete combustion of hydrocarbons
Barbecued food is a good source
Smoking
What does ionising radiation do to DNA?
Damages bases
Causes breaks in phosphate backbone
What does UV do to DNA?
Damages bases, in particular the formation of thymine dimers
What is benzopyrene?
Adduct: forms chemical bonds with DNA, forms a bulky group that disrupts replication
What happens if you break both strands of DNA?
Non-disjunction
Mutation
What is p53?
Tumour suppressor gene
What does p53 do?
Detects DNA damage and turns on repair mechanisms
Can pause the cell cycle until repair is carried out
Causes apoptosis
What happens if there is a mutation in p53?
Cancer
Why would we want to develop drugs that interfere with DNA replication?
To prevent cancer
What do phosphodiester bonds do?
Hold the sugars together forming the backbone of the DNA molecule
What is heterochromatin?
Condensed form of DNA, greater density then usual
What is enchromatin?
Lightly packed form of chromatin, less dense
What happens in a polymerase chain reaction (PCR)?
Choose your region of DNA to be amplified
Heat to separate strands
Cool and add primers
Add heat-stable DNA polymerase
Heat and cool (with primers and DNA polymerase present)
Repeat heating and cooling cycle
Multiple heating and cooling cycles
Present in about 10^6 copies
What happens when there is a mutation in the p53 gene?
Li-fraumeni syndone
