biotech part 1

when is the population predicted to become 9 billion

2100

what is the difference between micronutrients and macronutrients? what is the world daily calories?

micronutrients: vitamins and nutrients

macronutrients: water, proteins, carbohydrates and fats

2870 calories

what was impact of the green revolution on chronic hunger of the world?

reduced from 40% to 20%, but 800 million people still undernourished

why is micropropagation sterile?

cause the meristem is sterile

what is molecular breeding and why is it useful?

find DNA marker closely linked to fruit character→ follow it in progeny of cross→ use the marker to identify the seedlings that bear red fruit

so don’t need to wait for fruiting plant to see which ones to grow

how do we find markers from molecular breeding?

generate a fingerprint of parent via using random DNA markers (e.g. single nucleotide polymorphisms from genome sequencing)

find markers linked to the phenotype

check the linkage is close

use markers to identify in seedling stage

how can different species plants be crossed? e.g. wheat and rye

-treat plant tissue w enzymes to remove cell wall

-creates protoplasts

-fuse protoplasts from different genotypes

-use polyethylene glycol or electric pulse

what are some barriers to reproduction between different species?

pre fertilisation: asynchrony of flowering, floral morphology, self-incompatibility

post fertilisation: hybrid weakness

what are some ways of overcoming barriers to cross species breeding?

-embryo rescue: culture embryos that otherwise die

what are the steps in using plants as factories e.g for perfumes, flavours, drugs/dyes

understand the biochemistry→ find the genes → express them in plant cells → harvest the chemicals

what are some problems with using plant cells as factories?

de-differentiaion alters genes expressed, enzymes produced, metabolites produced

what % of the 252 drugs considered basic and essential by the WHO are exclusively of flowering plant origin?

11%

what does taxol do? where is it from?

anti-cancer drug, binds MT, stops cell division

from Pacific Yew tree T. brevifolia

what does a gene in the Tu plasmid code for? causes mass of undifferentiated cells

cytokinin, u can relace the genes that cause the crown gall w transgenes

what are the steps of regeneration of plants from tissue culture?

1. incubate leaf discs w Agrobacterium

2. balance cytokinin and auxin to induce callus growth

3. add more cytokinin to induce shoot growth

4. add more auxin to induce root growth

5. transfer to soil and gradually reduce humidity

where are somatic vs autonomic nervous system nerves going to?

somatic- to skeletal muscle

autonomic-visceral organs (also includes sympathetic & parasympathetic)

what are the characteristics of the endocrine system?

-wireless

-specificity of target cell binding

-hormones carried in the blood to long distance

-slow and long-lasting response

-controls long lasting activities (e.g. growth)

-involuntary

-influences CNS output

what are the characteristics of the nervous system?

-wired system

-anatomical connection w target cells

-neurotransmitters diffuse through short distances

-rapid and brief response

-coordinates fast and precise response

-voluntary/ involuntary

-influences endocrine output

-other non-regulatory functions

how fast is endocrine vs nervous system response?

endocrine is sec to hours

nervous is msec to sec

what is characteristic of the human cortex and all primates, not all mammals?

undergone gyrification

what is gray matter and white matter?

gray- primarily cell bodies

white- myelinated neurites projecting from neurons

in the PNS, how many pairs are there of cranial nerves, spinal nerves?

cranial: 12 pairs

spinal: 31 pairs

what are the estimates of the ratio of neurones to glia

1:1 to 1:50

what do astrocytes do?

delivery of molecules to/from the vasculature, activate in response to injury, neuroinflammation/ degeneration

what are the differences between non-reactive and reactive astrocytes?

non-reactive- trophic support of neurons, synapse formation and maintenance, clearance or neurotransmitters

reactive- damage neurons, activate microglia, some phagocytic activity

what do microglia do

-survey for damaged material and pathogens

-important roles in development & pruning excess synapses

-inflamed in response to pathogens, injury, and neurodegeneration

how do microglia change when activated?

increased motility, phagocytosis, and release of immune factors (cytokines)

what do Oligodendrocytes & Schwann cells do?

oligodendrocytes- myelinate multiple axons

Schwann cells- myelinate single axons

all motor neurons are myelinated, and some sensory

what are the different cell culture models?

stable cell lines- easily grown, derived from tumours

primary neuronal cultures- derived from model organisms

human stem cell derived- from skin cells of living patients

how can behavioural responses manipulated?

pharmacologically

genetically

e.g. in models of of developmental disorders and neurodegenerative disease

what are some examples of excitable cells?

-muscle (myocytes, cardiomyocytes)

-endocrine cells

-neuronal cells

what are some mb properties of excitable cells?

-hydrophobic lipids

-channels/ pumps facilitate cross mb transport of ions and molecules

-channels/ pumps are selective, based on size, charge and solubility of substrates

how do you measure the electrophysiological activity of a neuron?

use an intracellular electrode to measure internal voltage, extracellular electrode, measure the difference in voltage

what is resting potential in excitable cells?

the point at which difference in ion concentrations are stable across a mb

-permeable to passive diffusion by K+, Na+ (via ATP pump) and Cl- (leaky channels)

-impermeable to intracellular large anions

what does the Na+ -K+ pump work?

3 intracellular Na+ for 2 extracellular K+

why are further K+ not diffusing out?

negative intracellular electrostatic force prevents it

membrane potential is mostly due to potassium. what other ions have an impact?

sodium- have low permeability (E_Na= +55mV)

chloride- passively distributed and dependent on Na+ and K+ distribution (E_Cl= -60mV)

what are the stages of APs?

depolarisation: rapid positive change in mb potential from -70mV to +30mV

repolarisation: rapid negative change in potential (depolarisation-repolarisation spike ~1ms)

hyperpolarisation: mb potential becomes more negative than resting potential

afterpolarisation: mb potential returns to resting potential state

what is threshold stimulus typically

~15mV higher than resting potential

what is the difference between the absolute refractory period and relative refractory period?

absolute refractory- neurone cant be stimulated during a spike

relative- during hyperpolarisation, after polarisation, a suprathreshold stimulus is required to trigger an AP

what are refractory periods important for?

unidirectionality of AP

an upper limit on firing rate

how do APs move along an axon?

differences in membrane induce a local circuit

current spreads from the negative active zone to positively charged surrounding membrane

refractory period blocks travel in reverse direction

where in a neuron are APs triggered?

hillock (voltage gated sodium channels are enriched within the hillock region)

what occurs during the depolarisation phase?

-voltage gated Na+ channels open, Na+ enters cell

voltage gated K+ ion channels slowly open

Na+ channels can be closed but capable of opening, open, or closed and incapable of opening (inactivated)

what occurs during the repolarisation phase?

Na+ channels close slowly

voltage gated K+ channels continue to open (K+ leaves the cell)

K+ can be closed or open (no inactivation)

what occurs during the hyperpolarisation phase?

K+ continues to enter the cell, K+ channels close slowly

what occurs during the after polarisation phase?

K+ and Na+ AT, return to resting potential

how much faster is an unmyelinated axon vs a myelinated?

unmyelinated: 0.5-2.0m/s

myelinated: 80-120m/s

where are sodium channels concentrated?

within nodes