Biotechnology 2 Flashcards
Outline what recombinant DNA technology is
What is it used for
Modified, synthetic DNA; made by inserting genes from one source into a DNA molecule from a different source (genetically modified/GMO)
-Replacing faulty genes
-Treat cystic fibrosis, diabetes, some cancers.
-Identify mutations
-determine inheritance of hereditary diseases
Define “transgenic organism”
Organism which has genetic material from another artificially inserted
Explain what restriction enzymes are and why they are important for the purpose of creating recombinant DNA
Restriction enzymes cut strands of DNA at a specific sequence of nucleotides (recognition site)
Found in bacteriophages and restricts duplication - stopping infection of bacterial cells by viruses
Describe what a recognition site is
specific sequence of nucleotides at which an enzyme cuts a strand of DNA
How does recombinant DNA technology work
1.Gene is isolated + cut using restriction enzyme in a staggered cut
2. isolated plasmid then cut with same restriction enzyme in a staggered cut
3. straight cut=clean break across strands of DNA=blunt end
4. staggered cut=fragment with sticky ends=unpaired nucleotides overhang at break
5. DNA ligase then splice (bind) gene (donor DNA) into the vector (plasmid)
6. virus (containing modified DNA) inserts its base sequence into bacterial cell, which then expresses the inserted human gene
7.bacteria is left to divide and produce clones
8.bacteria now able to produce protein using donor DNA
Outline how a virus can be used as a vector to create recombinant DNA
virus (containing modified RNA) inserts its base sequence into host cell, which then expresses the inserted human gene.
What are possible treatments for diabetes using gene therapy
Can reprogram alpha to beta cells using vectors
1.Virus containing proteins inserted into the pancreas
2. proteins change gene expression, cause alpha cells to produce insulin
3.new “beta cells” are resistant T-cells attack as are slightly different to regular ones
4. This would not be a lasting ‘cure’ and has been shown to work in mice for 4months
What is gene therapy
What are it’s two types
Limitations?
Use of genetic material to treat/prevent disease by identifying faulty genes and inserting healthy ones
limitations: treats single gene disorders as
-tissue hard to access
-requires continual replacement
Exvivo-removes persons own cells, delivers outside of body. Modified cells then return
Invivo-gene delivered directly into person
Describe what a recognition site is
A specific sequence of nucleotides at which an enzyme cuts a strand of DNA
Give the function of the enzyme DNA ligase
Capable of combining two small component of single strand DNA into one single structure
Define the term “synthetic hormone”
State two ways in which hormones can be artificially made
a hormone that has been artificially created
-chemically and using recombinant DNA
How is the functioning bacterial cell that can be used to make synthetic insulin produced
Cut out required gene using restriction enzyme
Bacterial plasmid/DNA removed from bacterial cell
Bacterial plasmid/DNA cut with the same restriction enzyme
Gene (for human insulin) inserted into bacterial plasmid/DNA
Recombinant plasmid is inserted into a bacterial cell
How is synthetic thyroxine produced
using chemical ingredients
hormone replacement therapy: daily doses of a synthetic form of the thyroid hormone, thyroxine e.g.
Describe the human genome project
Collaboration of scientists to determine the order of the bases for all human DNA. Huge impact on disease treatment.
Explain what cell replacement therapy is
using Parkinson’s and Alzheimer’s disease as examples
Replacing damaged cells w/stem cells (can differentiate into specialised cells)
potential treatment for neurogenerative disorders like
Park.-replace dying neurons with healthy neuronal tissue from embryos (controversial as unethical)
Distinguish between cystic fibrosis and huntington’s
cystic-recessive genetic disorder=short life expectancy
huntingtons-single gene disorder caused by gene mutation
Distinguish between parkinsons and alzheimers
parkinsons- slow damage to nerve cells that produce dopamine vital for smooth control of muscles/movement.
symptoms:tremors, shaking, stiffness
alzheimers-changes in brain leading to deposits of protein and loss of connection bwn neurons
symptoms:memory loss, imparied reasoning/judgement
Define tissue engineering
to restore healthy tissues/organs for patients and eliminate need for tissue or organ transplants/artificial implants
-reduce risk of rejection as patients own cells used
In what ways can gene therapy be achieved
-Replacing mutant gene with healthy
-fixing/inactivating gene
-inserting new gene that will fight disease
-make immune system recognise diseased cells
Describe DNA profiling. How does it occur
DNA profile can be created from a small sample of DNA (e.g. from the saliva or a fingerprint on a glass, or very old/damaged DNA)
-From single sample many copies can be produced using a technique called the PCR
-DNA profiles are created using a process called gel electrophoresis
What can DNA profiling be used for
-individual’s identity/parentage.
-anthropological research
-detecting genetic variations and/or mutations
Describe the process of gel electrophoresis
Technique table to separate DNA strands based on their lengths.
1.Restriction enzymes cut DNA into smaller lengths separated by gel electrophoresis
2.DNA pieces placed in wells in gel that is immersed in solution of an electrolyte.
3.Electrodes at either end of the gel -negative electrode is closest to the DNA and positive electrode is at the opposite side.
4.when electric current passed through gel, negatively charged DNA moves towards the positive electrode.
5.smaller DNA pieces move faster than larger, so are located further from negative electrode when current is stopped.
6.results in pattern of bands similar the barcodes
-banding pattern is an individual’s DNA profile
What is PCR
Polymerase chain reaction. Technique focusing specific bit of DNA code to make billions of DNA copies
What are the three steps of thermocycling
Denaturing: two strands of DNA separate
annealing: short section of DNA=primers are bound to the separated strands
extension/synthesising: short section of DNA extended to make longer strands
What occurs during denaturation? Temperature?
95 degrees. Breaks hydrogen bonds holding complementary base pairing and the two DNA strands separate
What occurs during annealing?
Temperature?
Temperature decreased to about 50 degrees. Allows short strands of DNA called primers to bind to complementary end sequences of single DNA strands.
What occurs during extension/synthesising?
Temperature?
Mimics DNA replication. Activates DNA polymerase which is used to attached complementary nucleotides at the end of paired primers. This extends nucleotide chain and creates new strand of DNA.
What are phylogenetic trees. What are there use?
Dendrograms. Represent evolutionary relationships derived from a common ancestor.
-base of tree=common ancestor
-branches of tree are organisms arisen from common ancestor
-point of separation=speciation event
What are some uses for PCR
Detect harmful bacteria
Paternity testing
Identify species
Identify viruses/viral infections
Test for inherited diseases
Amplify small samples of DNA left at crime scenes
How did TAQ polymerase improve PCR technique
-Allow for heat tolerance in DNA polymerase
-preventing inactivation of polymerase
-Now heat at higher temperature can separate DNA strands therefore increasing efficiency while decreasing waste and cost.
How does PCR provide evidence for evolutionary relationships
Teeth, bones, hold DNA after organism dies. PCR can help learn about extinct lineages like mastodens
Forensic scientists can use PCR to learn about past relationships i.e. diet and infections
What is DNA sequencing? Describe the method
Determination of precise order of nucleotides in a sample of DNA
1. Synthetic nucleotide lacking OH group added to growing strand (dideoxy ribonucleotides (ddNTP’s)
2. Synthetic nucleotide stops elongation of sequence because there is no OH group for next nucleotide to attach
3.Happens at each nucleotide sequence creating different lengths of DNA sequence (can be separated using gel electrophoresis)
4.Order of nucleotides can be determined by knowing which base added to length
What happens when DNA is formed
-sugar molecule loses H atom form hydroxy group
-each nucleotide loses 2x phosphate groups
Uses for sanger method of DNA sequencing
-identify mutations or to compare DNA from different organisms
(identify inherited disorders like sickle-cell anaemia, cystic fibrosis, some forms of cancer)
-maternity/paternity tests (father/mother dispute)
-compare species in order to track evolutionary changes
Describe ethical considerations of genetic information
-Autonomy: self determining to be tested/not tested, to know/share information, decide own future independent of genetic information
-Confidentiality: sensitive treatment of genetic information accessed only by authorised access
-Equity: right to fair/equal treatment regardless of genetic information
-Privacy: right to be left alone and make decisions regarding genetic testing and resulting information, independent of others
Describe DNA code of organisms and how it differs overtime.
All living organisms use same DNA code. New are gained by mutation and lost by natural selection/genetic drift.
DNA code different for different species.
As species change overtime, more difference in DNA
How is DNA or protein sequences used as evidence
-more similarities in DNA sequence bwn two species=more closely related they are
-more difference in DNA sequence=more distantly related
Define comparative genomics
comparison of genome sequences of different species, areas of similarities and differences are identified.
Preserved genes and genes supplying different characteristics can then be discovered.
Define junk DNA
Non-coding regions of DNA (no function or purpose)
Define endogenous retroviruses and it’s function
Long stretch of non-functional DNA.
-store genetic info as RNA. RNA genome copied into DNA (reverse transcription)
-DNA inserted into on of host cell’s chromosomes
How does a retrovirus become endogenous. How will this effect offspring
if copied it’s DNA into cell whose chromosome is inherited by next generation
-offspring of infected will have copy of ERV in same location (8% of genome) in specific locations
How is ERV evidence for evolution
Close relatives, human and chimpanzee, have same ERV inserted into genome of common ancestor, as they both have located in similar chromosomes
Define mitochondrial DNA. vs nuclear
Minimal DNA found in mitochondria
-small circular molecule
-inherited only from mother
-5-10 in each mitochondria
-code for 37 genes (24 for tRNA) (13 for enzymes in cell resp.)
-has increased rate of mutation than nuclear DNA, proportional to time passed
-closeness in relations depends on similarities in mtDNA
nuclear is linear, code for thousands, from mother and father (chromosomes)
How are protein sequences utilised in evidence for evolutionary relationships?
linked amino acids in precise sequence
can be compared between two species by viewing amino acids
difference in sequences enables estimate of ranfe of evolution bwn species form common ancestor. increase time=increase number of amino acids different
-animals of same species have identical amino acid sequence
Define ubiquitous proteins
present proteins in all species that carry out same function
What is cytochrome C and it’s function
performs step in production of cellular energy
-104 amino acids in humans, 37 found at same position in every sequenced cytochrome C molecules
Describe bioinformatics
using computer technology to compare genetic sequences (DNA or protein)
-detect mutations
What us meant by annotation in bioinformatics
identifies location of genes and coding regions of genome
-trace evolution of large number of organisms by measuring change in DNA
