biotechnology and evidence for evolution

Question 1

what is the process of PCR

Answer 1

1. denaturing: solution is heated to 94˚C, separating the 2 DNA strands
2. Annealing: solutions is cooled to 50 - 65˚C. Primers are added and anneal with the complimentary sequence of DNA
3. 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

Question 2

why is taq polymerase used in PCR not DNA polymerase?

Answer 2

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

Question 3

what are the requirements of PCR

Answer 3

DNA strand

taq polymerase

nucleotide bases

primer

Question 4

list some uses of PCR

Answer 4

shorten length of time to detect hereditary diseases

viral diseases detected through reverse PCR immediately after infection.

Question 5

what is the process of DNA profiling (electorophoresis)

Answer 5

1. DNA is cut into peices of differing length using restriction enzymes
2. DNA pieces are placed at negative end of a gel bed
3. an electric current is passed through gel
4. DNA is negatively charges and moves through gel from negative electrode to positive electrode
5. smaller DNA pieces move further than large ones
6. forms bands on the gel bed

Question 6

what are the requirements for DNA profiling/elecorophoresis

Answer 6

DNA strand

restriction enzymes

gel bed

power source

Question 7

list some uses of DNA profiling

Answer 7

tracing ancestry

identifying hereditary diseases

forensic science

Question 8

explain the sanger method in DNA sequencing

Answer 8

1. copies of DNA from PCR are denatured and split in half
2. primer is annealed to template strand
3. this is added to a reaction mixture with DNA polymerase, deoxynucleotides (dNTP’s) and dyed deoxynucleotides (ddNTP’s) (missing OH group)
4. DNA polymerase adds to the primer dNTP’s until it adds a ddNTP
5. this terminates elongation of the sequence (no OH to attach to)
6. at the end of the process there are a variety of strands with varying lengths all ending with a ddNTP
7. fragments are overlaid to determine sequence of bases on the unknown strand
8. fragments are sorted and read out through electrophoresis

Question 9

what is the purpose of DNA sequencing

Answer 9

determines precise order of nucleotides

sequences easily compared

works out genetic code so we can read bases

Question 10

list some uses of DNA sequencing

Answer 10

detect particular diseases by comparing DNA sequences

Point mutations and small insertions/deletions are readily identified

Question 11

what are the uses of recombinant DNA

Answer 11

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

Question 12

Explain the process of recombinant DNA (genetic engineering)

Answer 12

1. Gene of interest is isolated and cut out at recognition site using restriction enzymes, producing a staggered cut with sticky ends
2. A plasmid is isolated, cutting it with the same restriction enzymes to produce complimentary sticky ends
3. They reinsert the gene into the plasmid using the enzyme DNA ligase in the process of ligation
4. plasmid is reintroduced into the bacteria and the gene is known as recombinant DNA.
5. The bacteria undergoes replication and protein synthetic and produces (mRNA, insulin, or whatever the question asks) and is now a transgenic organism

Question 13

explain gene therapy for cystic fibrosis

Answer 13

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

Question 14

what are some challenges to cystic fibrosis gene therapy

Answer 14

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

Question 15

what is alzheimers disease

Answer 15

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)

Question 16

what are some treatment to alzheimers disease

Answer 16

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.

Question 17

what is parkinsons disease

Answer 17

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

Question 18

what are some treatment to parkinson’s disease

Answer 18

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.

Question 19

what is cell replacement therapy

Answer 19

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

Question 20

what is the purpose of tissue engineering

Answer 20

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

Question 21

explain the process of tissue engineering

Answer 21

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

Question 22

what is an endogenous retrovirus

Answer 22

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.

Question 23

explain what mitochondrial DNA is

Answer 23

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.

Question 24

what are protein sequences

Answer 24

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).

Question 25

How scientists can use protein sequencing to discover evolutionary relationships (WACE question)

Answer 25

Every protein has a specific sequence of amino acids

Amino acids are arranged in a sequence

Similarity of amino acid sequences are evidence of close evolutionary relationship.

Question 26

what is bioinformatics

Answer 26

Information from biological data (electrophoresis data, DNA percentages etc.)

The greater the similarities in a specific gene, the closer evolutionary relationship between the 2 species

Combines computer, science, statistics, mathematics and engineering to analyse biological data

Techniques such as image and signal processing are used to extract results from raw data

Testing highlights the amount of similarity between species

Question 27

what are the causes of alzheimers disease

Answer 27

Cause is poorly understood, has genetic and environmental factors associated with its development

Disease process is associated with plaques, tangles and loss of neuronal connections in the brain.