chapter 13 - dysfunction of homeostasis

Question 1

what is diabetes

Answer 1

• abnormally high blood glucose levels
• hyperglycaemia
• balance between insulin and glucagon usually keeps BG at correct levels
• diabetics don’t produce insulin (1) or their cells have an abnormal resistance to effects of insulin (2)

Question 2

explain the effects of type 1 diabetes

Answer 2

• insulin dependent, begins in childhood
• fault in immune system, destruction of beta cells (no insulin)
• identified through a blood test
• symptoms of increased thirst, frequent urination, hunger, fatigue and blurred vision
• no cure, regular injections of insulin (cells respond), not oral as it is digested
• long term: kidney failure, heart attack, stroke, amputations, blindness, nerve damage

Question 3

explain the effects of type 2 diabetes

Answer 3

• non-insulin dependent, usually occurs in those over 45 (increasingly more young people)
• patients produce insulin but cells of not respond to it
• lifestyle disease
• lack of physical activity, overweight, unhealthy diet, high BP / BC
• detected through fasting blood test
• symptoms: increased thirst, frequent urination, hunger, fatigue, blurred vision
• no cure, treatment of careful diet, regular physical activity, maintaining healthy weight
• long term: heart disease, stroke, kidney disease, eye problems, nerve damage

Question 4

treatment of diabetes using recombinant DNA

Answer 4

• before: insulin was obtained from pancreas of cows and pigs (expensive, limited, had to be purified, allergic reactions / infections were common)
• now: genetically engineered human insulin produced by bacteria, yeast cells (growth medium)

Question 5

explain excess / deficiency of thyroid hormones

Answer 5

• over / under secretion of thyroid hormones
• thyroid is in neck and secretes thyroxine (T4) and triiodothyronine (T3)
• thyroxine: increases metabolic rate, releases energy and heat
• controlled by TSH, imbalance in thyroxine can be due to imbalance in TSH

Question 6

what is hyperthyroidism

Answer 6

• thyroid produces too much thyroxine
• graves disease, enlargement of thyroid, not inherited, generic predisposition
• symptoms: rapid heartbeat, weight loss, increased appetite, fatigue, sweating, anxiety, protruding eyeballs
• treatment: drugs that block thyroid, removal of part or all of thyroid, drink of radioactive iodine that kill thyroid cells by radioactivity

Question 7

what is hypothyroidism

Answer 7

• imbalance of TSH, under secretion of T4, lack of iodine in ones diet
• hashimoto disease, attack on thyroid by persons immune system
• more common than hyperthyroidism
• symptoms: slow heart rate, unexplained weight gain, fatigue, intolerance to cold, swelling of face / goitre
• treatment: inclusion of iodine in diet (compulsory addition of iodine in breads and table salt), tablets containing thyroxine

Question 8

treatment of haemophilia using recombinant DNA

Answer 8

• inherited, blood clotting protein (factor VIII) is in poor supply / missing, unable to form clots
• before: injections of FVIII concentrates, made from human plasma, 1000’s donors required (risk of transmission of disease)
• now: recombinant FVIII, cultured in mammalian cells, eliminates risk of transmission free of other plasma proteins that may cause an immune response

Question 9

what is recombinant DNA

Answer 9

• introduction of DNA into cells, DNA is foreign to that organism or has been modified in some way
• removal / replacement of genes from one organism to another
• identify mutations

Question 10

what are restriction enzymes

Answer 10

• enzyme that cuts a strand of DNA on either side of a gene
• produces a fragment that includes gene
• straight cut: clean break across 2 strands of DNA, ends terminate in blunt ends (base pair)
• staggered cut: fragments with unpacked nucleotides, overhang at break, sticky / cohesive ends, used in recombinant DNA
• recognition site: where enzyme cuts

Question 11

what is a vector and types of vectors

Answer 11

• transfer genetic material from one cell to another, forms transgenic bacterium cultured to produce protein wanted
• bacterial plasmid: small circular strand of DNA, only few genes, able to replicate independently within cell
• viral phage: bacteriophage, virus that infects bacteria

Question 12

what is ligase

Answer 12

• enzyme capable of combining two small components of DNA into one single structure (ligation)

Question 13

what is the process of recombinant DNA technology

Answer 13

1. isolate gene, cut it out using restriction enzyme at recognition site (fragment with sticky ends)
2. isolate plasmid from a bacterial cell, cut it with same restriction enzyme
3. splice the human DNA into plasmid using DNA ligase to join sticky ends
4. treat bacterium so it takes up recombinant plasmid
5. once successful bacterium multiply, either gene / product of gene can be used

Question 14

what is the purpose of recombinant DNA and what does it create

Answer 14

• to isolate and amplify genes or DNA segments and insert them into a bacterial cell, creating a transgenic organism
• transgenic: genome has been altered by transfer of genes, introduced genes become part of genome and are passed down