biotechnology and evidence for evolution Flashcards
what is the process of PCR
- denaturing: solution is heated to 94˚C, separating the 2 DNA strands
- Annealing: solutions is cooled to 50 - 65˚C. Primers are added and anneal with the complimentary sequence of DNA
- Extension: solution is heated to 72˚C, making a complete copy of template strands. Taq polymerase adds nucleotides to primer to extend a new DNA strand, making a copy of the original DNA template strand.
cycle is repeated 30 times, 1b copies of DNA
why is taq polymerase used in PCR not DNA polymerase?
Taq polymerase is heat loving and remains stable in high temperatures
DNA polymerase can’t be used as the PCR process heats up, and denatures the enzyme
what are the requirements of PCR
DNA strand
taq polymerase
nucleotide bases
primer
list some uses of PCR
shorten length of time to detect hereditary diseases
viral diseases detected through reverse PCR immediately after infection.
what is the process of DNA profiling (electorophoresis)
- DNA is cut into peices of differing length using restriction enzymes
- DNA pieces are placed at negative end of a gel bed
- an electric current is passed through gel
- DNA is negatively charges and moves through gel from negative electrode to positive electrode
- smaller DNA pieces move further than large ones
- forms bands on the gel bed
what are the requirements for DNA profiling/elecorophoresis
DNA strand
restriction enzymes
gel bed
power source
list some uses of DNA profiling
tracing ancestry
identifying hereditary diseases
forensic science
explain the sanger method in DNA sequencing
- copies of DNA from PCR are denatured and split in half
- primer is annealed to template strand
- this is added to a reaction mixture with DNA polymerase, deoxynucleotides (dNTP’s) and dyed deoxynucleotides (ddNTP’s) (missing OH group)
- DNA polymerase adds to the primer dNTP’s until it adds a ddNTP
- this terminates elongation of the sequence (no OH to attach to)
- at the end of the process there are a variety of strands with varying lengths all ending with a ddNTP
- fragments are overlaid to determine sequence of bases on the unknown strand
- fragments are sorted and read out through electrophoresis
what is the purpose of DNA sequencing
determines precise order of nucleotides
sequences easily compared
works out genetic code so we can read bases
list some uses of DNA sequencing
detect particular diseases by comparing DNA sequences
Point mutations and small insertions/deletions are readily identified
what are the uses of recombinant DNA
creating creating vaccines and hormones
identifying presence of mutated genes in an individual and to replace faulty genes
treating disorders such as rheumatoid arthritis, some cancers and cystic fibrosis
Explain the process of recombinant DNA (genetic engineering)
- Gene of interest is isolated and cut out at recognition site using restriction enzymes, producing a staggered cut with sticky ends
- A plasmid is isolated, cutting it with the same restriction enzymes to produce complimentary sticky ends
- They reinsert the gene into the plasmid using the enzyme DNA ligase in the process of ligation
- plasmid is reintroduced into the bacteria and the gene is known as recombinant DNA.
- The bacteria undergoes replication and protein synthetic and produces (mRNA, insulin, or whatever the question asks) and is now a transgenic organism
explain gene therapy for cystic fibrosis
The cystic fibrosis trans-membrane regulator (CFTR) gene has found 900 mutations
Scientists corrected the faulty CFTR genes in cultured cell by adding normal copied of the gene to the culture
Scientists modified a common cold virus to act as a vector to carry normal genes to the CFTR cells in the airways of the lung
Now, scientists are testing aerosol delivery using nebulizers
what are some challenges to cystic fibrosis gene therapy
Getting the gene into the cells more efficiently
How to make the expression of the gene last longer
(once in the cell)
Gene therapy for CF may have to be given repeatedly
until the problem is solved
what is alzheimers disease
Neurodegenerative disease that worsens progressively
Common early symptom is difficulty remembering recent events
As the disease advances, symptoms include language problems, disorientation and mood swings
Gradually body functions are lost leading to death (3 – 9 years)
what are some treatment to alzheimers disease
Good nutrition, physical and social activity generally benefit in ageing and may help reduce the risk of cognitive decline and Alzheimer’s
No medication or supplement decrease risk
No treatment stop of reverse its progression, through some may temporarily improve symptoms.
what is parkinsons disease
Long term degenerative disorder of the CNS that affects the motor system
Early symptoms are tremors, rigidity, slowness of movement and difficulty walking
Cognitive symptoms are depression, anxiety and apathy
Motor symptoms of the disease are from the death of cells in the midbrain, leading to a dopamine deficit
Cause of cell death is poorly understood but involves build up of proteins in the neurons
what are some treatment to parkinson’s disease
No cure, treatment reduces effects of symptoms
Initial treatment is typically with the medications levodopa or dopamine antagonists
As the disease progresses the medications become less effective and produces involuntary muscle movement as a side effect.
what is cell replacement therapy
Uses neural crest stem cells
These are sources from adult hair follicles and are similar to embryonic stem cells, as they are able to differentiate into many different types of cells
Multipotent adult progenitor cells have been identified for blood disorders
These cells are produced from bone marrow and divide endlessly in culture
what is the purpose of tissue engineering
restoring damaged organs and tissues for patients by culturing and growing stem cells as tissues, so they don’t have to undergo transplants or artificial implants
explain the process of tissue engineering
Requires an abundant supply of disease-free cells
Scaffolds are a template for tissue growth and to be porous so nutrients diffuses throughout the whole structure.
Usually need to be biodegradable so they’re absorbed by tissue and not surgically removed
Once a scaffold has been created, stem cells need to be cultured
These cells are seeded on the scaffold to produce a three-dimensional tissue
Cell-covered scaffold is implanted into the patient at the site where new tissue is required.
As new cells grow and divide the scaffold degrades and is absorbed
what is an endogenous retrovirus
An ERV is a viral sequence of DNA that has become part of an organisms genome
ERV’s make up 8% of the human genome
When a retrovirus enters a cell it copies its RNA into our DNA
If it copies its sequence into a gamete, it will appear in the next generation
When comparing the chromosomes and locations of ERV’s across primate species, the same ERV is found in the same location on the DNA.
explain what mitochondrial DNA is
A small circular ring amount of the cell’s DNA is found in the mitochondria
Mitochondrial DNA in the sperm is destroyed at fertilisation, so you inherit mitochondrial DNA directly from your mother
Mitochondrial DNA mutates at a higher rate than nuclear DNA
So by comparing the amount of differences in mitochondrial DNA from 2 individuals an estimate gain can be calculated as to how long ago they shared an ancestor.
what are protein sequences
By comparing the type and sequence of amino acids in similar proteins from different species, the degree of similarity can be seen.
Animals of the same species have the same amino acids in their proteins
The degree of difference between the proteins enables an estimate of the amount of evolution that has taken place, since the 2 species developed from a common ancestor.
Ubiquitous proteins: proteins found in all organisms carrying the same function e.g. cytochrome C (involved in energy production).
