chapter 9 - biotechnology Flashcards
1
Q
what is the genome and human genome project
A
- G: complete set of genetic information of an organism
- HGP: international research effort aimed at mapping the location of genes in all 46 chromosome in the human genome
2
Q
what is PCR
A
- technique used to artificially multiply sections of DNA through a series of repeated cycles of duplication
3
Q
explain the process of PCR
A
- denaturation: separates double helix by heating to 92-96
- annealing: temp. is dropped so primers can anneal to strands at 50-65
- -> primer: segment of DNA complimentary to the sample sequence of DNA which initiates replication by taq polymerase
- elongation: of primers, synthesis of new strands by making a complete copy of templates at 72 degrees
- -> taq polymerase: heat stable polymerase, does not breakdown when heated
4
Q
what is the purpose of PCR
A
- hereditary disease: sickle cell, cystic fibrosis, amplifies to then sequence gene in question
- forensic science: amplify single drop of blood or semen or strand of hair, can later produce DNA fingerprint
- ancestry: relationships between ancestors, amplification of DNA found in fossils
5
Q
what is gel electrophoresis
A
- determines ones DNA fingerprint / profile (unique for each individual) by separating DNA fragments according to size
6
Q
explain the process of gel electrophoresis
A
- make agarose gel and add comb to form wells, allow to set
- DNA samples are died with a tracking die
- bed of semi solid agarose gel is place in an electrophoresis tank with buffer solution (conducts electricity)
- DNA samples are loaded into wells
- electric current is passed through the chamber
- DNA (-) moves through gel via reptation (snaking through pores of gel), towards positive electrode
- shorter migrate faster and are pulled towards +
- pattern of bands separated by size
- ethidium bromide stains DNA (fluoresce when illuminated under UV light)
7
Q
what is DNA profiling
A
- determining individuals DNA profile via special enzymes that cut DNA at specific base sequences leaving pieces of various lengths
8
Q
explain the process of DNA profiling
A
- PCR: artificially amplify DNA through repeated cycles of duplication
- profiling: DNA is treated with restriction enzymes to cut DNA at specific sequences
- electrophoresis: separates fragments according to size
9
Q
what is the purpose of DNA profiling
A
- tracing ancestry, paternity tests, forensic science
- hereditary disease: identify mutated gene, compared to a DNA ladder where length and position of diseases are known
10
Q
what is DNA sequencing and what is involved
A
- determination of precise order of nucleotides in a sample of DNA
- dNTP: DNA nucleotide, contain OH group acts as ‘hook’ to allow new nucleotide to add to existing chain
- ddNTP: dideoxy-nucleotide, chain terminating, labelled with characteristic fluorescent dye, lack OH, no ‘hook’
11
Q
explain the process of DNA sequencing
A
- DNA sample, primer, DNA polymerase, dNTP and ddNTP combined in tube
- denaturation, annealing and elongation occur
DNA polymerase continues adding dNTP’s until a ddNTP is added, synthesis stops and strand ends - millions of DNA molecules are present, strand terminated at any position
- ends with fragments with labelled dyes indicating final ddNTP
- electrophoresis: DNA is transferred to polyacrylamide gel (more porous and selective)
- gel placed in DNA sequences for electrophoresis, fragments migrate according to size
- detected as it passes a laser beam (bottom)
- ddNTP emits coloured light of characteristic wavelength, recorded as coloured band
- computer inputs raw data and outputs a chromatogram with coloured peaks of a fluorescent intensity representing each letter in sequence
12
Q
what is the purpose of DNA sequencing
A
- shows whether a person will develop an inherited disease by comparing sequences, changed alleles can be detected
- point mutations and insertions / deletions are readily identified
- sickle cell, cystic fibrosis,
13
Q
what is a hereditary disease
A
- caused by defective genetic information being transmitted from parents to their children
14
Q
what is a mutation
A
- particular gene may quite suddenly change from original structure and produce a different characteristic
- change in genetic material and can therefore be passed on to future generations
15
Q
what is a genetic probe
A
- locates a gene in a chromosome by pairing to specific DNA sequence
- involves pairing a short known segment of DNA or RNA with a matching sequence of bases on a chromosome
- DNA of known structure is marked with radioactive isotope
- used to detect presence of alleles responsible for hereditary disease
16
Q
what is gene therapy
A
- treats or cures abnormalities by replacing faulty genes with healthy ones
- occurs of single cell gene disorders
- CF: thick sticky mucous in lungs and pancreas, mutation in CFTR gene, modified cold virus acts as vector to transfer healthy genes to CFTR cells
- HD: mutation of chrom. 4 gene IT15, damage to nerve cells, physical, mental and emotional changes, modified virus delivers corrective gene into brain cells to boost natural shield against effects of mutation
17
Q
what is tissue engineering
A
- restores healthy tissues or organs, eliminates need for tissue / organ transplants or artificial implants
- requires abundant supply of stem cells, induced to grow on scaffold of natural or synthetic material to produce 3D tissue
- scaffold is template for tissue growth, must have high pore sizes that enable cell growth and diffusion of nutrients
- tissue growth must equal degradation of scaffold
18
Q
what is cell replacement therapy
A
- treatment which makes use of culturing of embryonic stem cells to replace damaged cells with healthy ones
- no scaffold, involves replacement of individual cells not entire organs / tissues
19
Q
what are the ethics concerned surrounding gene therapy and cell replacement therapy
A
- GP: does not alter genome, can’t pass on healthy gene to offspring as new healthy cells are somatic not gametes, viruses are used as vectors (risk of infection / immune response / side-effects / allergic reaction), unknown long term effects on individual or subsequent generations
- CRP: use of embryos (taking life away), cost / affordability, and unknown long term effects
