Mutations And Genes (Miss Reynolds) Flashcards
Mutation
A change to the nucleotide sequence of DNA.
Mutagenic agent
Increase rate of mutations (above normal)
When do most mutations occur and why?
Interphase, longest stage
Substitution
One base is swapped for another
Addition
An extra base is added
Deletion
A base is removed
Which types of mutation cause a frame shift?
Addition and Deletion
Inversion
A sequence of bases is repeated.
Duplication
One or more bases repeated.
Tumour suppressor genes
Slow cell division.
Proto-oncogenes
Stimulate cell division.
When are proto-oncogenes switched on?
When growth factors bind to protein receptors on the cell surface membrane.
Oncogenes
Permanently switched on, even in the absence of growth factors, caused by a mutation.
Benign tumour
Not cancerous, slower growth, don’t invade other tissues and are most of the time harmless.
Malignant tumours
Uncontrolled growth / rapid, cancerous, can spread to other tissues
What does oestrogen cause in terms of cell division?
Increased cell division
Stem Cells
Can divide and differentiate to become different types of cell. Can divide for all of the organisms lifetime.
Induced pluripotent stem cells
Treating unipotent stem cells with transcription factors that make them pluripotent.
How do you create induced pluripotent stem cells?
A modified virus as a vector inserts transcription factor genes from pluripotent cells into Dna of unipotent stem cells.
What type of stem cells are adult and embryonic stem cells?
Embryonic - pluripotent, adult - multi-potent
How can stem cells be used in medicine?
Replace faulty/damaged cells, to grow new organs which have the same antibodies so no rejections/donors needed.
Ethical issues of stem cells
Taking them from embryos kills them, right to life.m
Genetics
Study of biological processes and phenotypes and their functional molecules.
Genome
All genes present in a species.
Epigenetics
Study of stable cellular and physiological traits.
Benefits of human genome project
Better and early diagnosis of disease, control systems for drugs.
PCR
A technique used to amplify one sample of DNA thousands of times over to create a large enough sample for extensive analysis.
Uses of PCR
Paternity, tests, detecting mutations and DNA profiling.
Gene Therapy
Replacing genes with healthy ones.
Somatic gene therapy
Copies of the corrected gene are inserted directly in to cells of sufferer. Does not prevent the disease occurring in the next generation and has to be repeated many times as effects do not last.
Germ line therapy
The corrected gene is inserted into a fertilised egg produced via IVF, permanent but currently illegal.
How is cystic fibrosis treated with gene therapy?
A vector is introduced to the correct gene into cells of the lung.
What is cystic fibrosis caused by?
Mutant recessive alleles.
Problems with gene therapy
Limited success due to liposomes not being small enough and adenoviruses causing infection, also patients have to undergo multiple rounds as effects are short lived.
Summary of gene therapy
Identify gene responsible for disorder, make copies of normal gene by PCR, insert copies into vectors, infect affected cells with vectors and activate the healthy gene.
DNA probes
Short single stranded section of DNA that has some sort of label attached to it.
Uses of DNA probes
- Genetic counselling (identifying carriers of a disease and most effective treatment)
- Genetic screening (parents can see if they are carriers of specific alleles, diagnose + treat before symptoms show)
Genetic fingerprinting
DNA of every individual is unique.
Uses of genetic fingerprinting
Solving medical problems (i.e paternity tests), gauging genetic diversity.
Methylation effects
More methylation - terminates transcription.
Acetylation of histones effects
Less acetylation of histones - terminates transcription.
DNA interference
Controlling gene expression by preventing transcription.
