Unit 8 Flashcards
How do alterations to tumour suppressor genes lead to cancer. (4)
- Increased Methylation (of tumour suppressor genes)
- Mutation
- Tumour suppressor genes are not transcribed
- Results in uncontrollable cell division
What is a Transcription Factor (3)
- Protein that moves from cytoplasm to DNA
- TF binds to specific gene to specific part of the DNA to the promoter
- Leads to mRNA production
How does oestrogen stimulate Transcription? (6)
- Oestrogen diffuses through the cell membrane
- Attaches to receptor
- Receptor changes shape
- Receptor leaves protein complex which inhibited its action
- Oestrogen receptor binds to promoter region
- Enables RNA polymerase to transcribe target gene
Describe RNA Interference (3)
- siRNA binds to cell’s mRNA by specific bas pairing
- So prevents mRNA being read by ribosomes
- Prevents translation
Define Epigenetics (2)
- Heritable changes in gene function
- Without changes to the base sequence of DNA
Describe how methylation leads to cancer (3)
- Methyl groups added to both copies of a tumour suppressor gene
- The transcription of tumour suppressor genes is inhibited
- Leading to uncontrolled cell division
Describe the method of in-vivo cloning with the use of an antibiotic resistant marker gene (8)
- Isolate wanted gene from another organism
- Using restriction endonuclease
- Produces sticky ends
- Use ligase to join wanted gene to plasmid
- Include marker gene
- Add plasmid to bacteria to grow colonies then replica plate onto the medium where the maker gene is expressed
- Not killed therefore they have the antibiotic resistance gene and probably the wanted gene
Describe the process of in-vitro cloning using PCR (9)
- DNA heated to 90 to 95
- Strands separate
- Cooled to temperature below 70
- Primers bind
- Nucleotides attach
- By complementary base pairing
- Temperature 70-75
- DNA polymerase joins nucleotides together
- Cycle repeated
Describe the use of DNA probes in gene testing (4)
- Probe will attach
- Attaches to one DNA strand
- As a result of complementary base pairings
- Radioactivity detected on film by autoradiography
Outline the process of genetic fingerprinting (10)
- DNA extracted from sample
- DNA cut into segments using restriction endonucleases
- Must leave VNTR
- DNA fragments separated using electrophoresis
- Detail of process e.g. Mixture put into wells on gel and electric current passed through
- Immerse gel in alkaline solution
- Southern blotting with nylon
- DNA fixed to nylon using UV light
- Radioactive marker added complementary to VNTR
- Areas with probe identified using X-ray film
Definition of Stem Cells (1)
- Undifferentiated cells that can continually divide and become specialised
Describe what Totipotent stem cells are (2)
- Stem cells that can divide and produce any type of body cell.
- Found only in a limited time in early mammalian embryos
Describe what Pluripotent Cells are (2)
- Can become almost any type of cell
- Found in embryos
- Used in research to treat human disorders, such as Parkinson’s
How are Multipotent and Unipotent cells similar but also different? (3)
- Both Stem Cells are found in mature mammals and can divide to form a limited number of different cell types.
- Multipotent cells, located in bone marrow, can differentiate into a limited number of cells
- Unipotent cells can only differentiate into one kind of cell, so skin to skin cell
Describe and explain how the polymerase chain reaction (PCR) is used to amplify a DNA fragment (4)
- Requires DNA polymerase, DNA nucleotides and primers
- Heat to 95C to break hydrogen bonds
- Reduce temperature so primers bind to DNA
- Increase temperature, DNA polymerase joins nucleotides
