problems with synapses

Question 1

where is dopamine normally secreted?

Answer 1

midbrain & motor cortex

Question 2

what happens in parkinson’s

Answer 2

dopamine secreting neurones in the basal ganglia die

-> motor cortexes get less dopamine & there is a loss of control of muscular movements

Question 3

symptoms of parkinson’s

Answer 3

stiffness & tremors of muscles
slowness of movement
poor balance

Question 4

how can parkinson’s be treated?

Answer 4

slowing dopamine loss
drugs
dopamine antagonists
deep brain stimulation

Question 5

how is the loss of dopamine slowed?

Answer 5

MAO inhibitors
they inhibit monoamine oxidase, the enzyme that is responsible for the breakdown of dopamine
MAOB is used

Question 6

how is parkinson’s treated with drugs?

Answer 6

can’t use dopamine itself - can’t cross from blood to brain.

• > L-dopa ( precursor in the manufacture of dopamine ) can be given
• > converted into dopamine in the brain

Question 7

what are dopamine agonists?

Answer 7

drugs that directly activate the dopamine receptor, mimic the role of dopamine but triggering action potentials

Question 8

what is the problem with too much dopamine?

Answer 8

cause of schizophrenia

Question 9

how can excess dopamine be treated?

Answer 9

drugs that block the binding of dopamine to its receptor sites
side effect: induce the symptoms of parkinson’s

Question 10

what does seratonin do ?

Answer 10

plays an important part in defining someone’s mood

Question 11

where are the neurones that secrete seratonin?

Answer 11

brainstem

-> axons extend into the cortex, cerebellum & sc

Question 12

what has a lack of seratonin been linked to?

Answer 12

depression

Question 13

what is the cause of depression

Answer 13

no one cause, it’s multi factorial
-> several genes may be involved, but probably only confer a susceptibility to the condition, with environmental factors also contributing

Question 14

what gene is known to increase the susceptibility to depression

Answer 14

5-HTT -> codes for a transporter protein that controls seratonin reuptake

people with the short version are more likely to develop depression after a stressful life event

Question 15

what does depression depend on?

Answer 15

environmental factors to act as triggers

Question 16

during depression, what may be related to to low levels of neurotransmitters being released?

Answer 16

fewer nerve impulses than normal are being transmitted around the brain
-> seratonin pathways have a number of abnormalities in people with depression

Question 17

what is a measure of the influence of genes on characteristics?

Answer 17

degree of similarity between monozygotic twins

Question 18

what are SSRIs and how do they help?

Answer 18

selective serotonin reuptake inhibitor

• > blocks only the reuptake of serotonin from the synaptic cleft
• > maintains a higher level of and so increase the rate of nerve impulses in serotonin pathways, reducing some symptoms

Question 19

how can drugs affect synaptic transmission?

Answer 19

• a chem with similar molecular structure to a neurotransmitter is likely to bind to the same receptor sites, perhaps stimulating the post synaptic neurone
• others may prevent neurotransmitter release

Question 20

what does MDMA affect?

Answer 20

thinking mood and memory
anxiety & altered perceptions

short term- changes in behaviour and brain chemistry
long term- changes in behaviour and brain structure

Question 21

what does MDMA do?

Answer 21

increases the serotonin concentration in the cleft by binding to molecules in the presynaptic membrane that are responsible for transporting the serotonin back into the cytoplasm
-> prevents it’s movement from the cleft

Question 22

what are some negative side effects if MDMA?

Answer 22

clouded thinking
disturbed behaviour
dry mouth
muscle spasms & hyperthermia

repeated use - irregular heartbeat, muscle breakdown, kidney failure

Question 23

why can MDMA lead to depression

Answer 23

the drug has stimulated so much serotonin release that the cells cannot synthesise enough to meet the demand one it has gone

Question 24

what has helped us understand the way genes control phenotype

Answer 24

HGP

Question 25

what is a genome

Answer 25

all the DNA of an organism

Question 26

what other genomes have been sequenced?

Answer 26

yeast
worms
flies

Question 27

which was the 1st chromosome to be fully sequenced?

Answer 27

22

Question 28

how many bases is the human genome?

Answer 28

3 200 000 000

Question 29

what is an SNP?

Answer 29

a DNA seq variation that occurs when a single nucleotide in the genome sequence is altered in at least 1% of the species population
-> scientists think the possession of certain SNPs predispose them to a disease

Question 30

what does BCRA2 code for

Answer 30

breast cancer

Question 31

what causes total colour blindness?

Answer 31

CNGA3 + CNGB3

code for subunits of a protein channel in photoreceptor cells in the retina

Question 32

what genes are associated with parkinson’s?

Answer 32

DJ1 + PINK1

Question 33

knowing genes that predispose means what?

Answer 33

it is possible to locate a candidate gene on DNA and screen it for mutations in affected individuals

Question 34

having 2 alleles of APOE4 mean what

Answer 34

10x more likely to get alzheimer’s

Question 35

what is a drug target?

Answer 35

a specific molecule that a drug interacts with to bring about its effect

Question 36

what issues need to be adresssed regarding drugs / genetics

Answer 36

• implications ( ie. applying for health insurance )
• who should decide when they’re used
• confedentiality
• expense