ch 8+9.1 Flashcards
recombinant DNA technology
The procedures used to produce recombinant DNA, involving introducing DNA into a cell from a different type of organism or DNA that has been modified in some way. Also known as genetic engineering.
genetically modified organism
Answer: An organism produced by genetic engineering.
An organism that has had DNA from another species introduced into it artificially.
transgenic organism
vector
A bacterial plasmid, viral phage or other such agent used to transfer genetic material from one cell to another.
plasmid
In a bacterial cell, small circular strands of DNA distinct form the main bacterial genome; composed of only a few genes and able to replicate independently within cells.
Describe the function of:
a restriction enzymes
Restriction enzymes cut strands of DNA at a specific sequence of nucleotides.
Describe the function of:
DNA ligase.
DNA ligase is an enzyme capable of combining two small components of single-strand DNA into one single structure.
What vector is used in the production of insulin by recombinant DNA technology?
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Answer: A plasmid. Circular strands of DNA distinct from the main bacterial genome.
Explain how recombinant DNA technology is used to produce a vaccine for hepatitis B.
The gene for the surface antigen on the virus is isolated and added to the plasmid. The plasmid is introduced into a yeast cell. When the yeast cell divides, the new cells also contain the plasmid with the gene for the antigen. This gene allows the yeast cells to produce the antigen protein, which can be collected and purified.
Artificial breeding
Artificial breeding
Selection of characteristic:
Selecting which male and female organisms to breed
Isolation of the gene:
If desired traits are bred, there is an increased chance of the gene being passed on
Incidence in the next generation
Able to increase or decrease the incidence of certain genes
Efficiency
Low efficiency
Genetic engineering
selection…isolation….incidence….efficient
Selection of characteristic:
Identifying the organisms with the desired characteristic
Isolation of the gene:
DNA is added or removed from the genome
Incidence in the next generation
Able to increase or decrease the incidence of certain genes
Efficiency
high efficiency
Explain why it is possible for an organism of one species to use a gene from another species to produce a protein.
It is possible if the gene from one species is spliced into the genome of the other species. This is recombinant DNA and the organisms is a genetically modified organism (GMO). The GMO will produce the protein from the introduced gene.
Explain the importance of complementary bases with respect to inserting a fragment of DNA into a vector.
Complimentary bases will allow hydrogen bonds to form between the DNA fragment and the vectors genome. DNA Ligase is then able to join the backbone of each strand. If the bases were not complimentary then the splicing and uptake of the inserted gene would not be successful.
Define ‘hyperglycaemia’ and explain why a lack of insulin results in this condition.
Hyperglycaemia is a condition where a person has abnormally high blood glucose levels. Insulin normally acts to bring down blood glucose levels, so a lack of insulin will result in higher than normal blood glucose.
What causes type 1 diabetes?
Answer: Type 1 diabetes is an autoimmune disease where the person’s immune system destroys beta cells in the Islets of Langerhans in the pancreas.
List the symptoms of hyperthyroidism.
Answer: Rapid heartbeat, weight loss, increased appetite, fatigue, sweating, anxiety and protruding eyeballs (Grave’s disease)
Explain why goitre occurs.
Answer: If there is a lack of iodine in the diet, the thyroid gland becomes enlarged in an effort to increase hormone production.
Explain why iodine supplements are used to treat some forms of hypothyroidism.
Answer: Thyroxine molecule contains four iodine molecules, and a tri-iodothyronine molecule contains three iodine molecules. If there is a lack of iodine in the diet, the thyroid gland is unable to make enough hormones, resulting in hypothyroidism
Define ‘gene therapy’, and give an example of its possible use.
Answer: Gene therapy is the replacement of faulty genes with healthy genes. Research is currently concentrating on single-gene disorders such as cystic fibrosis, Huntington’s disease, muscular dystrophy and sickle-cell anaemia.
List three ways that gene therapy could possibly correct faulty genes.
Answer:
• Replacing a mutated gene with a healthy copy
• Fixing or inactivating mutated gens
• Inserting a new gene that will fight the disease
• Making the immune system recognise diseased cells.
Explain why it is important to diagnose cystic fibrosis at infancy.
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Answer: Early diagnosis will allow a low-fat, high-carbohydrate and high-protein diet to be established. This will allow CF parents to keep their child as healthy as possible and to delay or prevent serious lifelong health problems related to CF.
Why is it possible that cell replacement therapy could be used to treat patients with Alzheimer’s or Parkinson’s disease?
Answer: Alzheimer’s disease is a progressive disorder that causes brain cells to degenerate and die. This results in a loss of brain volume, memory loss and dementia. Current treatment includes acetylcholine drugs, or drugs that inhibit acetylcholinesterase. Cell replacement therapy could be used to replace the brain cells lost to Alzheimer’s and to produce acetylcholine within the body.
Parkinson’s disease is a progressive, degenerative neurological condition that affects the control of body movements. It is caused by the death of neurons that produce dopamine in the brain. Cell replacement therapy could be used to replace the neurons lost, and to produce the required level of dopamine in the brain.
Discuss why gene therapy for type 1 diabetes is focused on introducing the gene into alpha cells.
Answer: Type 1 diabetes is caused by an autoimmune disease that destroys beta cells in the pancreas. Gene therapy is used to reprogram the alpha cells to produce insulin as alpha cells are not damaged by the autoimmune disease.
Tissue engineering utilises a scaffold for the tissues to grow on. Explain why this is necessary, and why it needs to be biodegradable.
Answer: The scaffold is required to generate a three-dimensional tissue. The scaffold serves as a template for tissue growth and can allow for diffusion of nutrients and to encourage cells to grow at the same rate and size. They need to be biodegradable so they can be absorbed by the surrounding tissue and not have to be surgically removed.
Chromosomal Mutations
DELETION- part of chromosome is lost
DUPLICATION- Section of chromosome occurs twice
INVERSION – part breaks off and rejoins wrong way around.
TRANSLOCATION- part of chromosome breaks off and rejoins wrong chromosome
NONDYSJUNCTION- during meiosis a chromosome pair does not separate so one daughter cell has one less and one has one more (aneuoloidy)
gene mutations
deletion
insertion
substitutions
Cystic fibros
symptoms
cause
treatmens
genetic disorder
thick sticky mu\cos secreted by mucos glands
traps bacteria making them seseptible to infection
lung damage
pancreas also affected preventing enzymes for digestion
low fat high carb and protein
gene therapy
inherited ressesive allele
different types of mutations
missense- change in amino acid, change in protein produced
nonsense- change in base sequence to the code stops, so shorter protein is produced unable to function
neutral- change in amino acid but is of the same type so the structure will not change enough to change protein
silent- do not cause a change in amino acid so no change
gene mutations 2
duchenne muscular dystrophy
cystic fibrosis
chromosomal mutations
down
patau
klinefelter
criduchat
Turner syndrome
patau syndrome
chromosome
symptoms
partial trisomy extra chromo 13
intellectual disability and\ ectra finger on each hand
cleft palate
80%die within a month of birth
klinefelter
sex chromo xxy
normal as boys then develop as adults
small testes no sperm, noobs sometimes intellectually disabled
Turner syndrome
sex chromosome x monosomy
short stature lack sexual characteristics and infertile
lethal recessive
tay sachs
disorder of lipid metabolism thats is inherited ina autosomal recessive pattern
mutation of hexa gene that codes for enzyme beta h (breaks down toxic substances in brain and spinal chord
the accumulation of gm2 gangoslide detrys neurons
deaty early childhood
Explain how errors in DNA replication and cell division can result in mutations and give an example of a condition caused by each of these types of mutations. (4 marks)
DNA replication
The double helix unwinds and copies of the two strands are made but a deletion / insertion / inversion / translocation / substitution occurs which alters the sequence
Albinism / Duchenne muscular dystrophy / Tay Sachs / cystic fibrosis / other acceptable answers
Cell division
Homologous chromosomes fail to separate / non-disjunction occurs
Down syndrome / Klinefelter’s syndrome / Turners syndrome / other acceptable answers
Suggest how mutations affect the process of natural selection.
Mutations contribute to variation in the gene pool of the population
Which allows some organisms to be offered a survival advantage
Or reduces their chances of survival
When conditions change / when selection pressures are different
(g) Explain the relationship between carbon dioxide concentration and blood pH.
Carbon dioxide combines with water to form carbonic acid
Which breaks down to form hydrogen ions and bicarbonate ions
Carbon dioxide is carried in the blood as bicarbonate ions
Hydrogen ions determine blood pH
