life at extremes

Question 1

how are cells dynamic

Answer 1

not static
active
can respond to their environments

Question 2

define robustness

Answer 2

the ability of a cell to maintain performance and function in the face of internal and external disruptions

Question 3

how does fever during infection help the mmune system?

Answer 3

increased white blood cell movement
increased proliferation of T cells/WBC
enhanced rate of phagocytosis

Question 4

what happens to cells at high tempertures eg above 37

Answer 4

they get stressed
enzymes cant work properly.denatured
proteins dont fold properly
membrane more fluid

Question 5

what is the consequence of an ill-folded protein?

Answer 5

faulty protein
loss of regulatory component
loss of control of the protein

Question 6

what happens to membranes as they become too hot?

Answer 6

hard to control movement

too fluid

Question 7

what does the membrane do if it becomes too hot?

Answer 7

change the lipid composition to being fully saturated

cholestrol added

Question 8

what does a fully saturated lipid membrane mean>

Answer 8

single bonds only
most viscous
compact
less permeable

Question 9

what does cholesterol do to membranes?

Answer 9

adds strength and stabilises the membrane

Question 10

how is the issue of proteins not folding properly fixed?

Answer 10

heat shock proteins

Question 11

what is a heat shock proteins?

Answer 11

produced when the cell is exposed to elevated, sub-lethal temperatures

Question 12

what is the function of a heat shock protein?

Answer 12

help proteins fold properly

they bind to proteins that are newly synthesied and hold them in place for binding

Question 13

what issues are caused by low temperatures

Answer 13

slow enzyme reactions
rigid and viscous membranes
ice crystals making holes in membranes

Question 14

how does the membrane respond to being too cold

Answer 14

unsaturate the lipids making them have double bonds
this makes the membrane more fluid
cholesterol is removed and the membrane made less stable and more fluid

Question 15

what is the function of glycoproteins and glycolipids

Answer 15

protect the cell
stablise protein structures in ECM
buffer

Question 16

how are glycolipids and gycoproteins produced?

Answer 16

carbohydrates are added to proteins in the RER
glycosidic bonds link these to the side chains of amino acids
flags the protein to be moved to membrane

Question 17

how can ice crystals be bad?

Answer 17

kill the cell by punching holes in the membrane

Question 18

How do artic fish prevent ice crystals forming?

Answer 18

glycoproteins in blood arrange the formation of the crystals so they form along protein making them harmless to cells

Question 19

what’s special about the wood frog?

Answer 19

can freeze solid and thaw out multiple times and be fine

antifreeze glycopoteins and high gluose levels help them

Question 20

how can bacteria survive extreme temperatures

Answer 20

proteins and metabolism in some mean they can be optimised for cold temps
their proteins are flexible and only work at the certain temperature ranges

Question 21

what is chitin

Answer 21

structural carbohydrate used with other substances to create a harder material

Question 22

whats wrong with low oxygen?

Answer 22

essential in ATP synthesis
low oxygen is toxic
death via necrosis

Question 23

what oxygen do cells like?

Answer 23

low oxygen

as you get further from blood vessels, nutrients and oxygen decrease anyway

Question 24

what is hypoxia

Answer 24

and environment low in oxygen
high altitude
aquatic

Question 25

when can hypoxia occur?

Answer 25

premature babies poisoning anaemia

Question 26

what is local hypoxia

Answer 26

ischaemiea strokes | cancer and vessels collapse

Question 27

how do cells sense hypoxia?

Answer 27

special oxygen sensing enzymes

Question 28

how do oxygen sensing enzymes work?

Answer 28

they activate a range of transcriptional factors stop cell cycle after G1 stop things that arent essential switch to anaerobic respiration

Question 29

what is angiogenesis?

Answer 29

making new blood vessels

Question 30

how does angiogenesis occur?

Answer 30

in response to hypoxia cells activate genes | cells are stimulated in vessles to branch off, proliferate and move towards hypoxic cells

Question 31

what causes the cells to proliferate in angiogenesis?

Answer 31

genes involved in growth factors such as VEGF and FGF

Question 32

what is VEGF?

Answer 32

vascular endothelial growth factor

Question 33

how do cancer cells exploit angiogenesis?

Answer 33

they are high demand cells and use energy quickly they send out growth signals that act on nearby vessels the vessels send off shoots towards the tumour in all directions and the tumour ends up with an extensive blood supply helping it grow

Question 34

what is quiescence?

Answer 34

state of reversible cell cycle arrest

Question 35

what happens in quiescence?

Answer 35

stay in G0 phase starvation of the cell low metabolic rates non-essential things are shutdown

Question 36

what is irreversible cell cycle arrest called?

Answer 36

senescent

Question 37

what is autophagy

Answer 37

Self-eating | protective mechanism

Question 38

how does autophagy work?

Answer 38

cells form membrane vesicles called autophagosomes | to digest organelles and proteins with enzymes

Question 39

why is autophagy used?

Answer 39

efficient method to recycle building blocks in times of nutrient deprivation

Question 40

example of a small scale autophagy?

Answer 40

proteasome

Question 41

what does a proteasome do?

Answer 41

recycle individual proteins and amino acids for more protein synthesis

Question 42

examples of toxic environments for cells

Answer 42

raidation, UV light free radicals and oxidative stress toxins and posions

Question 43

how is a reactive oxygen species made

Answer 43

last step in transferring electrons to oxygen doesnt happen creates highly reactive oxygen species made in cells as side effect of normal metabolism

Question 44

what can reactive oxygen species do to cells?

Answer 44

react with biological molecules chain reaction of macromolecules creating more radicals modify proteins

Question 45

what effect can ROS have on proteins?

Answer 45

modify structure and function crosslink or fragment them modify nucleotides

Question 46

how can you prevent ROS damage?

Answer 46

antioxidants

Question 47

how do antioxidants prevent reactive oxygen species damage

Answer 47

react with them and neutralise them

Question 48

an example of natural antioxidant in the body

Answer 48

glutathione found in the liver donates electrons to ROS to make them more stable

Question 49

what is superoxide?

Answer 49

converts superoxide to hydrogen peroxide then catlase converts that to water line of defence to help

Question 50

whats a drug transporter?

Answer 50

transmembrane protien using ATP to transport drugs and substances across membranes

Question 51

the purpose of drug transporters?

Answer 51

stops exposure to chemicals gets things out of cells before they cause damage transports small dangerous chemicals they dont like

Question 52

what is the DNA damage response mechanism?

Answer 52

detection cell cycle stops repair initiated, genes turned on if damage extensive cell undergoes apoptosis

Question 53

list some things damaging dna

Answer 53

``` cellular metabolism UV light ionising radiation chemical exposure replication errors ```

Question 54

what is the integrated stress response?

Answer 54

series of mechanisms to protect the cell and fluctuations in the environment

Question 55

what are the cells defences?

Answer 55

antioxidants DNA repair apoptosis ECM