extreme biology Flashcards
give some environmental factors that plants need to be able to cope with
drought cold heat light salinity flooding nitrogen poverty wind loneliness cold
what do plants rely on light for
photosynthesis
what are the advantages and disadvantages of having large leaves in warm climates
advantages
- more area for light capture and photosynthesis
disadvantages
- exposed to a lot of heat
- photosynthesis releases a lot of heat which can be damaging
what doe ordinary sunlight at the surface of the earth contain and what is the effect of each of these
UV light - causes sunburn and is damaging to RNA/DNA
visible light - plants use the blue and red end of the visible light and reflect green light
infrared light - not used in biochemical pathways and is damaging in terms of heat
which part of the leaves are most affected by heat and how can heat damage be reduced
leaves get hotter away from their edges. by increasing the amount of edge a leaf has, the more heat loss radiation can be carried out
how does leaf size adapt to get more light
make the leaf bigger to get more sunlight
how does leaf size adapt to evade high temperature damage
make the leaf smaller to increase heat loss by radiation
how can leaf shape help to protect against over heating
we can change the orientation of leaves to avoid direct sunlight
so leaves also change shape i.e. curl up
apart from radiation, what are other methods of heat loss form leaves
transpiration of water helps plants keep cool do that their biochemistry isn’t wounded
in what conditions are small leaves favourable
extremes of dryness, heat, draught and cold
in what conditions are large leaves favourable
where there is sufficient water for cooling and it is warm enough to avoid excessive radiative cooling
large leaves maximise light harvesting
what adaptations have desert plants undergone
they are overexposed to heat so they have small leaves so that they can effectively radiatively cool because they don’t have access to enough water to cool by transpiration
what kind of plants do we get in hot treeless deserts
ephemerals, adaptors, resistors
describe the plant growth cycle in hot treeless deserts
in the dry season almost no plants grow but when it rains there is a massive bloom
what are ephemerals
they are desert annuals
they have a short life time (weeks/months) but seeds are long lived
energy form photosynthesis in leaves allows them to produce flowers. insects then pollinate them
the plant dies and the seeds are left in the soil/sand and when it rains more plants grow
what are the 4 main steps of ephemeral life cycle
growth
flowering
seed setting
death
are ephemerals draught resistant
not particularly
what is cryptobiosis
a metabolic state entered by organisms in response to adverse environmental conditions
what are poikilohydric plants and give an examples
they are resurrection plants craterostigma plantagineum
what is the response of resurrection pants in draught
during draught the plants dehydrate, shrivel and become photosynthetically inactive
it then regrows from dormant roots and shoots when watered
describe a dehydration protection response of resurrection plants
- accumulation of sucrose and trehalose to protect membranes and proteins from denaturation
- when it is dry it allows all of the tissues to shrink nut they don’t die.
- as the water content goes down it starts to produce more sucrose which is a good cryo-preservative as the sugar acts against drying
how do poikilohydric (resurrection) plant and ephemerals differ
ephemerals die and leave their seeds
resurrection plants don’t die
what are phreatophytes
deep rooted large perennial plants that obtain a significant portion of water from the phreatic zone
what is the phreatic zone
the zone of saturation
what are the 2 roost formed by the phreatophytes
deep tier roots that get water from the deep water table
shallow tier roots that capture rainfall
describe the leaves of phreatophytes
they are tiny in order to reduce water loss and aid radiative heat loss
are stomata open or closed during the day in phreatophytes
they are closed to prevent water loss s
give a example of a phreatophyte
creosote bush
mesquite plant
what is the oldest plant
the larrea tridentata found in the death valley is thought to be the oldest creosote bush ring estimated at 11700 y/o reaching up to 20m in diameter
it is a phreatophye
what are xerophytes
- plants that can survive very dry conditions for long periods of time and are found in arid climates
- they usually have small leaves or needles
- they have thickened leaves or stems for water storage and to act as a heat buffer
what is an arid climate
climate with low water availability
describe the succulents of xerophytes
succulents contain storage of water in very sugary cores and they are found in leaves and stems
give examples of xerophytes and note the type of succulent they have
aloe vera and crassula - leaf succulents
cactus - stem succulents
describe cacti in terms of their leaves and stems
- cactus spines are their leaves but they are not for photosynthesis, instead they are for protection
- the entire stem of the cactus is photosynthetic
what are cacti areola
an area on the plant where a tuft of white hairs come out
give reasons why cacti are very good at retaining water
- because they have very waxy cuticles and water succulents
- they have reduced SA to volume ratio
- stomata are strategically concentrated inside the pleats (shaded most of the time) to reduce desiccation when they are open so that sunlight doesn’t drive off too much water
- cacti apex are generally covered in hairs - the hairs protect it from light and heat damage - no photosynthesis occurs here
what conditions are high altitude cacti adapted to
dry, cold air and intense light
what does it mean that high altitude cacti are very pubescent and how is this of benefit
they are very hairy
- this results in light being scattered to prevent damage but it can still be let through for photosynthesis
- when stomata are open they lose less water du to the microenvironment created by the hair
- the hairs also prevent heat loss at night
- protection from herbivores and pathogens
high altitude cacti are long/short lived and slow/fast growing
long
slow
what kind of conditions are euphorbias adapted to
dry conditions
how do euphorbias protect themselves against other animals and how are they different to cacti
they oose whit latex to protect themselves against grazing by insects and other animals but cacti can’t doe this
cacti have areola but euphorbias don’t
what are lithops and what is there nickname
they are called stone plants because they look like stones
- their outer leaves shed in the winter and are replaced by new ones (they need to get rid of old leaves because they are light damaged)
what is a compass plant
a plant that reduces heat and water loss native to new mexico
- it reduces the heating of planar faces
- they change leaf orientation so that they can still photosynthesise but prevent light and heat damage (this orientation increases water efficiency)
- they have large leaves which are held vertically
- new leaves grow in random orientation but within 2-3 weeks it twists on its petiole to a vertical position
are most plants C3 or C4
C3
what are the differences between C3 and C4 metabolism
C4 metabolism is a photosynthetic pathway that adapted from the C3 pathway in response to extreme heat and drought. It evolved independently in several lineages of vascular plants. The C4 pathway works most effectively in hot and dry climates with limited CO2. It is called C4 because instead of forming a 3-carbon compound (as in the C3 pathway), it makes a 4-carbon compound (malate).
what are the advantages of C4 metabolism in plants
- In hot, dry environments C4 metabolism is more efficient than C3 because it minimizes photorespiration, a counterproductive pathway to photosynthesis where rubisco incorporates oxygen instead of carbon dioxide. C4 plants minimize photorespiration by separating carbon fixation and the calvin cycle in space or in time. In both pathways, carbon dioxide is initially incorporated into the plant by an enzyme called PEP carboxylase which has no affinity for oxygen (avoiding photorespiration). The benefits of reduced photorespiration exceed the energy cost of C4 pathways
- C4 plants also reduce water loss by transpiration because they can keep their stomata closed more than C3 plants. The plants need to open their stomata in order to take in carbon dioxide and release oxygen into the atmosphere. During this time, water is lost by transpiration which is enhanced in hot and dry climates. The C4 pathway is more efficient at incorporating carbon dioxide compared to the C3 pathway so the stomata can be kept closed more, thus avoiding water loss.
what are the two main type of C4 metabolism
There are two main types of C4 metabolism – one that separates carbon dioxide fixation and the calvin cycle with space (C4 pathway) and one that separates them with time (CAM). In the C4 pathway, plants open their stomata during the day and carbon fixation occurs in the mesophyll cells where carbon dioxide is incorporated by PEP carboxylase forming malate. Malate is then transported to the bundle sheath cells via plasmodesmata and the carbon dioxide is released and incorporated into the calvin cycle by rubisco. In CAM plants, stomata are opened at night. Carbon dioxide is fixed to oxaloacetate by PEP carboxylase (the same as in the C4 pathway), then converted to malate or another type of organic acid which is stored inside vacuoles until the next day. In daylight, the CAM plants do not open their stomata, but still photosynthesize because the organic acids are transported out of the vacuole and broken down to release carbon dioxide which enters the Calvin cycle.
what are the differences between the 2 types of C4 metabolism
In the C4 pathway, plants open their stomata during the day and carbon fixation occurs in the mesophyll cells where carbon dioxide is incorporated by PEP carboxylase forming malate. Malate is then transported to the bundle sheath cells via plasmodesmata and the carbon dioxide is released and incorporated into the calvin cycle by rubisco. In CAM plants, stomata are opened at night. Carbon dioxide is fixed to oxaloacetate by PEP carboxylase (the same as in the C4 pathway), then converted to malate or another type of organic acid which is stored inside vacuoles until the next day. In daylight, the CAM plants do not open their stomata, but still photosynthesize because the organic acids are transported out of the vacuole and broken down to release carbon dioxide which enters the Calvin cycle.
what percentage of plants are C4
3% but 5% of biomass and 23% carbon fixation
how much less water do C4 plants lose compared to C3
C4 plants lose 1/2 as much water per unit CO2 compared to C3 plants
what is the most abundant protein on the planet
rubisco
what does rubisco do
it fixes CO2 into sugars in plants nut it is very sensitive to oxidation by pure oxygen and it evolved when oxygen levels in the atmosphere were much lower so there was less selection pressure at the time to discriminate
the fact that rubisco can’t easily discriminate between oxygen and carbon dioxide lead to photorespiration
what does spatial separation mean in C4
physical separation of where CO2 is brought into the plant and where rubisco is active
CO2 brought into the mesophyll
rubisco active in bundle sheaths (active everywhere in C3 plants)
what increases the internal CO2 concentration
CO2 pumps - so that we generate an environment high in CO2 conc in the bundle sheathes
where is malate synthesised
in the mesophyll cells
hoe does malate get from the mesophyll cells to the bundle sheath cells
it diffuses via plasmodesmata
why can’t C3 plants grow in very hot areas
because with increasing temp rubisco incorporates more oxygen than CO2
what is marram grass
it is found on sand dunes and curls when dry and opens when wet = opening controlled by hinge cells
stomata are in the grooves to reduce water loss
what is the C4 time separation reaction called
CAM
what are the stomatal differences between the 2 C4 pathways
spatial separation - stomata closed at night and open during the day time separation (CAM) - stomata open at night and closed during day
what are the steps in CAM
CO2 is incorporated by PEP carboxylase and converted to oxaloacetate which is converted to malate which is converted to malic acid which is stored in the vacuoles during the day
during the day malic acid is moved to the cytoplasm and converted back to malate which is then pumped into the chloroplasts
CO2 is released and reacts with rubisco in the calvin cycle and pyruvate is released which goes back to the mesophyll cells
in what type of climates can slat be problematic for plants
marine and brackish waters and arid land areas
give examples of halophytic plants and their specialised salt organs and adaptive metabolisms
mangroves - slat glands - salt is secreted from glands
atriplex - slat bladders - produce gritty silver layer when excreting salt
mesembryanthemum crystallinum - ice plant - facultative CAM - shifts to CAM metabolism in dry or saline conditions
not all halophytes have obvious morphological features - provide an example
thellungia halophylia (salt tolerant) - close relative of Arabidopsis (salt sensitive)
what is the mechanism that allows thellungia halophylia to be salt tolerant
- ion channels in thellungia roots are less permeable for Na than in Arabidopsis
- limitation of Na uptake is the main strategy for avoiding sodium toxicity in thellungia
- thellungi host a potential set of genes that could be used to make our crop plants more salt tolerant
what are adaptations in plants to avoid anoxia from water flooding
pneumatophores - specialised aerial roots that enable access to O2 in water logged habitats
hypoxic roots - if roots are often flooded e.g. lotus, they produce aerenchyma tissue in their roots. cells within the roots die to produce channels through which air can diffuse allowing the system to respire even when flooded
what is an angiosperm
a plant that has flowers and produces seeds enclosed within a carpel(usually a fruit)
what is a gymnosperm
no flowers or enclosed seeds, seeds often cones e.g. conifers
describe seagrass (zostera marina)
it is an angiosperm with submerged male and female parts
what has seagrass lost genes for
it has lost all genes for stomata, UV protection (UV light only penetrates mm), IR light (cooled by water instead) and volatile terpenes (defence mechanism against predators)
what has seagrass gained genes for
encoding cell wall components for osmotic control to prevent saltwater driving water out of the plant
how can nitrogen poverty be evaded by carnivory
when plants eat insects it provides them with a nitrogen source -this is useful if the soil is nutrient poor
give examples of carnivorous plants and their mechanisms
venus fly trap - reversibly depolarises cells to open and close. its hairs need to be triggered twice before it will close
bladderwart - if bladders are triggered by touch they spring opne then suck in the insect and close a digest it
pitcher plants - produce vessels, sometimes with a lid to prevent fluid dilution. the vessel fluid digests insects that land in it
give an example of how parenthood can help with nitrogen poverty
coco de mer
lodoicea maldavica is a monodominant palm producing the largest seeds.
the plant invest heavily in reproduction
coco de mer has large leaves that gather up bird droppings, petioles etc from other plants and their own pollen
the rain washes it all down tubes that feed to the ground producing a nutrient rich environment for their offspring
this mechanism improves phosphorus and nitrogen supplies which are needed to sustain costly reproctive functions
what doe monodominant mean
when more than 60% of the tree canopy is comprised by a species
how are coco de mer and coconuts different
the seeds of coco de mer are not salt tolerant so they die if they fall in the sea unlike coconuts
describe the arctic tundra environment
cold deserts, biodiversity is very low
little rainfall
high densities of the same species
7 months of snow cover in winter - limited light capture
what kind of plants do we find in the arctic tundra
plants that have short growing seasons and life cycles in summer then go into senescence in winter
plants have high nutrient efficiency and live in the shallow soil above the permafrost (frozen rock/soil)
some plants are able to grow in rocks, give an example
lichens and mosses - able to tease nutrients out of the rocks
describe the Antarctica plants
must grow quickly and in extremely cold conditions
metabolic activity is maximised at low temperatures
there are only 2 native vascular plant species
what are the 2 native vascular plant species of the Antarctica
hairgrass
pearlwort
both of these grow in small clumps
how do lichens grow in the antarctica
they find spaces where the sun melts the snow
growth season is less than 120 days per year
growth rate is 0.01-1mm per year
long life
how do mosses grow in Antarctica
they form colonies that collect and retain water
their photosynthetic enzymes have maximal activity at 5C
photosynthesis quickly activates after frost
describe the plant growth in taiga
mainly coniferous but some angiosperms
plants can deal with cold and warm temperatures due ti the continental climate
there is low species diversity but large bands of single species
what is taiga
huge bands of forest
what is earth’s largest terrestrial biome
taiga
what are the dangers of cold to plants
- biological thermodynamic processes come to a halt
- changes in biomolecule conformation, stability and function
- perturbation of normal cellular processes
- reduced fluidity of membranes
- perturbation in the balance between production and neutralisation of ROS
- extracellular ice crystal formation depletes water in and around cells and crystals can puncture cell wall/memb and may rupture the inside of the plant
what do plants induce to protect themselves from the cold
cold tolerant mechanisms and components
describe the preparation of taiga conifer trees for winter
- they sense changes in day length/temperature which causes cold tolerant mechanisms to be triggered
- large central vacuole is replaced by lots of small vesicles to limit ice crystal formation
- starch granules disappear and other sugars accumulate
- thylakoid membranes separate and become disorganised
- changes in membrane lipid composition
- high concentrations of oligosaccharides to promote high viscosity of the cytoplasm of freeze dehydrated cells
- changes in proteins expressed
how do membranes change in response to cold
unsaturation, increased phosphatidylethanolamine and decreased phosphatidylcholine, increased phospholipids, reduced galactolipids
which proteins are upregulated in response to cold
dehydrins - prevent membrane-membrane interactions
antioxidant systems - protection against oxygen damage
heat shock proteins
pathogenesis related proteins
describe the leaves of deciduous trees
they generally have large light gathering leaves which are shed in winter to prevent the tree from being blown over
what is an abscission layer
it is a barrier across the petiole
it forms between the leaf petiole and the stem
- the leaf remains attached by the abscission layer as long as auxin is being produced i.e. the plant is growing
- when the plant prepares for winter auxin stops being produced
- the cells in the abscission layer start to separate and form a protective barrier to pathogens for when the leaf falls and prevent sap loss
when does the abscission layer form
in spring with new leaf growth
why are new buds sticky
because they coat themselves in sugar as a cryoprotective mechanism
what are response of leaves in winter that aren’t shed
- flat surfaces radiate away heat but don’t absorb much so they supercool
- to get around this, plants curl and drop their leaves in response to cold as this changes the airflow
- they also often have dense hair under the leaves which protect the stomata
give an example of a plant that drops and curls its leaves
rhododendron
describe the origin of conifers
- large continental mass called the Pangea formed which had a very dry centre because it was far from the sea
- this lead to the extinction of giant tree ferns
- conifers evolved and began colonising the continent changing its habitat
- conifers were likely the major food source of adult sauropods
give an example of a large conifer that was thought to feed sauropods
monkey puzzle tree
what is meant by conifers being evergreen
they are spring ready - have green leaves throughout the year
what conditions are conifers best adapted to
dry, cold and high altitude
how are conifers designed for snow
snow can land on them and their branches will bend and shed the snow if they get too loaded
angiosperms would probably break under the weight of snow
what can happen to photosynthesis in conifers in winter
some shut down photosynthesis and increase the conc of carotenoid pigments to protect against light damage
photosynthesis resumes after winter dormancy in response to daylight
the oldest bristlecone pine was accidently burnt describe the plants soil and root system
- they grow slowly in dolomite soils and the root system is composed of highly branched shallow roots while a few large branching roots provide support
- they are extremely draught tolerant with waxy needles, thick needle cuticles to aid water retention
- wood is very dense evading invasion by predators
crown drag is greatest in trees with narrow/broad leaves and the advantage is to be deciduous/coniferous
broad
deciduous
describe an oak tree (angiosperm) (deciduous)
dense heavy trunk
limited sway
broad root base
describe and pine tree (conifer) (gymnosperm)
lighter trunk
more sway
deep tap root
what is a buttress root
- most rainforest soil is nutrient poor and nutrients are available largely at the soil surface
- rainforest trees tend to have very shallow roots which can often be seen above the soil
how do trees/leaves reduce crown drag
- leaves twist, curl or fold to resist wind so they aren’t ripped off the tree or cause the tree to fall over
what can plant loneliness be caused by
distant colonisation
devastated land
widespread separation
give an example of a plant that grows on devastated land
rosebay willowherb - grows in ash - doesn’t require soil fungi - they have feathery seeds so that they can colonise land rapidly
give examples of plant loneliness - how do cacti combat loneliness
cacti are often spread out so need to try hard to find a pollinator
they often have improved advertising to attract pollinators
give an example of loneliness in a tropical forest
some species are not hermaphrodites and have male and female parts on different plants so have to transfer pollen
plant species often use a pollinating insect instead of relying on wind
they synchronise their flowering using the solar analemma
why can’t temperate tropical rainforest plants or polar plants rely on temperature or daylight
because the environment is very stable
they use the solar analemma instead
what is the solar analemma
- a consequence of the earth’s rotational axis being at an angle of 23.5 to the plane of its orbital and earth’s orbital is elliptical
- plant detect tiny changes in when dawn occurs
- the analemma curve is bigger in the south because we have an elliptical orbit and we are tipped slightly towards the sun during the southern hemisphere’s summer
give some examples of common classes of extremophiles
acidophile alkaliphile halophile hyperthermophile oligotroph osmophile piezophile psychrophile thermophile
what is deinococcus radiodurans
a radiation surviving bacterium
- DNA organised into tightly packed choroids
- meat treated with radiation thought to kill all live nut meat still spoiled and DR was isolated
- radio-resistance of DR was a side effect of dealing with long term desiccation
how does DR repair DNA
it can repair single and double stranded DNA
- upon damage it brings its DNA into a compartmental ring like structure where it s repaired
- nucleoids then fuse from the outside of the compartment with the damaged DNA
what are the basic requirements for early life
carbon and nitrogen - they generate energy through cycles like the calvin cycle, krebs cycles and nitrogen cycle
what are the 3 domains of life
bacteria, archaea, eukaryotes
what are the different atmosphere states in its evolution
anaerobic, single cells
anaerobic, photosynthesis, single cells
aerobic, eukaryotes
multicellular life, Cambrian explosion, stability
what are the effects of oxygenation of the atmosphere
- oxygenation of the atmosphere by photosynthetic pigments is thought to have caused precipitation of iron from the seas that lead to the iron rich strata now used for iron ore
- oxygenation also resulted in a radiation of greenhouse gasses such as CO2 which lead to the great cooling leading to snowball earth
what are the origins of extremophile prokaryotes
archaea
what are the 2 main biochemical cycles of life
calvin cycle and the krebs cycle - both use carbon for energy storage and transfer
evolution of what process lead to the great oxygenation event
photosynthesis
what does photosynthesis require
a means by which photons are captured and their energy directed to the reaction centre where CO2 is fixed
what is the light harvesting complex
it sits embedded in a membrane and consists of proteins and pigments surrounding a reaction centre
(various pigment molecules bound to proteins)
where is the light harvesting complex of green plants found
the thylakoid membranes of chloroplasts
what are antenna pigments
chlorophyll b, xanthophylls, carotenes
why is it good that absorption spectra are not overlapping
because when you have more than one pigment you broaden the absorption range for photosynthesis
what is the other role of carotenoids
they act as an antioxidant to prevent photo-oxidative damage of chlorophyll
each antenna complex has between 250-400 pigment molecules and the energy they absorb is shuttled to the specialized chlorophyll a proteins complex known as the .……….. …………. of the photosystem
reaction centre
how is energy shuttled in photosynthesis
by resonance energy transfer
what is a photosystem
composed of a reaction centre surrounded by several light harvesting complexes
what is a reaction centre
association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor
nitrogen fixation by pants requires …………
microbes
what fixes atmospheric nitrogen into a more suable form such as ammonia
diazotrophsare bacteria and archae
what are the steps in the nitrogen cycle
- atmospheric nitrogen absorbed by nitrogen fixing bacteria in plant roots or taken into the grounf by decomposers
- nitrogen fixing soil bacteria result in ammonification giving ammonium
- nitrifying bacteria result in nitrification producing nitrites
- nitrates are produced form nitrites by nitrifying bacteria
- denitrifying bacteria convert nitrates int atmospheric nitrogen or nitrate assimilation occurs into plants which are eaten by animals
as far as we know all living systems derive(d) their energy from
electrons
electrons are used in chemiosmosis what is this
where electrons flow down their conc gradient and H are pumped against their conc gradient across the membrane
when H flow back down their conc gradient they pass through ATP synthase, generating ATP
give an example of another redox reaction which creates energy other than photosynthesis
NO2 reduction
archaea are more closely related to …….. than bacteria and where does this evidence come from
eukaryotes
evidence from genes sequencing - particularly rRNA
what are the different energy sources of archaea
organic resources
phototrophic
carbon dioxide fixation
archaea membranes are comprised of …… lipids not ……. lipids
ether not ester
how do archaea reproduce
asexually
have any pathogenic archaea been found
no - only mutualistic and commensals
what about archaea membranes stabilises them at high temperatures
their highly branched structure - they contain branched isoprene chains
what can isoprene chains of archaea membranes do
they can be joined together between phospholipids
they can form carbon rings which increase stability
what do methanogenic archaea do
they breakdown lignocellulose into simple sugars and methane (the by-product) - methanogens are key organisms in decomposition and they are obligate anaerobes
what are thermoacidophiles
can cope with extreme temp and pH e.g. picrophilustorridus
- thick extracellular protein mucilage
- they have an S layer
- they oxidise sugars via modified glycolysis (entner dudoroft)
- 12% of genes are transporters
what debate about archaea is ongoing
whether eukaryotes are derived from them
where are microbes that use sulphur oxidation for energy generation found e.g. paracoccus dentrificans bacterium
hot sulphurous springs
what is halotolerance
tolerance to high slat conc
what are halobacteria
photoautotrophs
what are lipids made from
glycerides: glycerol + FA
what is phosphatidycholine
a diglyceride which is a major phospholipid of membranes
the degree of ………. affect van der waal forces which can change lipid properties
saturation
weak attractive forces between FA chains are countered by ……..…. ……… …………
random thermal motion - bond rotation, stretching etc
what is the structure of membrane glycerides
they have a glycerol core with usually 2 of 3 of the OH groups linked to FA by ester linkages
the .…….. and degree of ……….. of FA determines the physical properties of the lipids
length
saturation
describe saturated fat and FA
the molecules of saturated fat are packed closely together forming a solid - e.g. butter
describe unsaturated fat and FA
the molecules of fat cannot pack closely together because they have kinks in their FA chains forming a liquid - e.g. olive oil
phospholipids have ……….. heads and …………….. tails
hydrophilic head
hydrophobic tails
different lipid classes confer different ……….. to membranes
shapes
the charged headgroups such as phosphatidylcholine are attached to the remaining OH groups of glycerol projected into the …….. phase. the …….., ………… and ……. of these groups plus the degree of …………. of FA tails controls the shape of the molecule and affects the curvature of the membrane
water
size, charge and shape
saturation
other lipids such as …………. and its derivatives can be embedded in the membrane further affecting the curvature and biophysical properties of the membrane
cholesterol - stiffens the membrane
when exposed to stress the heterogenous mixtures (……..) of different lipids can phase separate to form what and what is the effect of this
rafts
pools of a single class of lipids which can lead to physical change in the bilayer structure
inverted micelles and hexagonal II can form
what is an inverted micelle
polar head groups face inwards and non-polar tails face outwards
what are the effects of membrane lipids becoming more unsaturated
- introduction of kinks in the FA chains which reduces the van der waals between chains
- reduction of the temperature of the liquid crystalline –> gel phase transition (Tm) - melting temperature - membranes stay fluid for longer when temperature decreases
- membranes in the gel phase are not fluid and are functionally altered
- L-alpha and Hex II transitions are also important
increasing sterol content of membranes increases fluidity/rigidity
fluidity
melting point of FA decreases/increases as the proportion of unsaturated bonds increases
decreases
give 3 examples of saturated FA
steric, palmitic, lauric
give 3 examples of unsaturated FA
oleic, linoleic and linolenic
what is the structure of cholesterol
it has a rigid ring system and a short branched hydrocarbon tail
it is largely hydrophobic but has a polar OH group making it amphipathic
how does cholesterol affect membrane fluidity
interaction of membranes with relatively rigid cholesterol decreases the mobility of the hydrocarbon tails of phospholipids
cholesterol interferes with close packing of FA tails
membranes with more cholesterol have fluidity intermediate between the liquid crystal and crystal states
cholesterol stiffens the membrane
what is cholesterol on skin transformed to in sunlight
vitamin D
at low temp we increase/decrease the number of cis double bonds in FA
increase
at high temp we increase/decrease the number of cis double bonds in FA
decrease
freeze fracture electron microscopy of membranes can reveal ……………
Hex II structures and internal structure of membrane bilayers
what is freeze fracture electron microscopy
- specimen frozen
- frozen sample is fractured
- new exposed faces are coated in gold
- viewed under a scanning electron micrograph
what are the 2 appearances of Hex II structures
granular or tubular
………….. shocked proteins may also form Hex II structures
temperature
what are differences in osmotic water loss during freezing of cold acclimated and non-cold acclimated cells
non-acclimated - plasma memb produce intracellular vesicles when they dehydrate - material lost by endocytotic vesiculation - lysis
acclimated - plasma memb produce extracellular protrusions when they dehydrate - exocytotic extrusions and re-expansion
what organisms are particularly exposed to seasonal temperature changes
land plants
although mammals and birds can regulate their body temp they may not be able to control the temp of their …… ……… and ……… how do they get around this
body surfaces
extremities
they make their membranes more polyunsaturated at exposed sites
describe archaea membranes
- they have phospholipids
- they have a different stereoisomer of glycerol
- they have ether linkages instead of ester linkages
- they have isoprene chains instead of FA
- they have branching isoprene side chains which can join together between phospholipids and they can also form carbon rings - they increase the structural stability of the membrane
what are the different levels of protein structure
- primary - the order of amino acids in a polypeptide chain
- secondary - formation of alpha helices and beta sheets by H bonding in the polypeptide backbone
- tertiary - interaction between R groups - disulphide bridges, ionic interactions, hydrophobic/hydrophilic interactions - development of 3D structure
- quaternary - interactions of different polypeptide chains either by non-covalent interactions (as in collagen and haemoglobin) and/or cys-cys disulphide bonds (as in antibodies)
what kind of organisms produce heat shock proteins
prokaryotes and eukaryotes
are heat shock proteins only produced in response to heat
no they are produced in response to other stresses too
what are the 2 roles of heat shock proteins
1 - degrading or repairing misfolded proteins arising from heat shock
2 - act as molecular chaperones that bind to enzymes and prevent thermally induced misfolding - under normal conditions these chaperones assist the folding or some proteins when they emerge from the ribosome
smaller HSPs are ………….. ………..and larger ones are involved in …………. ……………….. ………. …… ………
molecular chaperones
refolding and degradation of proteins
what is a proteasome
the cells protein recycling plant
protein complexes which degrade unneeded or damaged proteins by proteolysis, a reaction that breaks peptide bonds
enzymes that help are called proteases
how are proteins tagged for degradation by the proteasome and what is the effect of this tagging
- they are tagged with ubiquitin which is catalysed by ubiquitin ligases
- once tagged, this is a signal to other ligases to attach additional ubiquitin molecules.
- the result is a polyubiquitin chain that is bound by the proteasome allowing it to degrade the tagged protein
- degradation yields peptides which are further broken down into amino acids and used to sequence new proteins
ER and Golgi play a key role in protein ………… and …………..
assembly and trafficking
denatured proteins are stick and aggregate in the …… what process has evolved to recover this situation
ER
UPR - unfolded protein response - eukaryotes only
what are the 3 key UPR pathways and what are they all regulated by
all regulated by binding of BiP-aHSP70
1. PERK - arrest of general translation but triggers transcription and translation of factor ATF4
2. degradation of misfolded proteins
3. active signalling pathways that lead to increased chaperones involved in protein folding
if these objectives are not achieved then the UPR triggers apoptosis
what diseases are caused by upregulation of UPR
huntington’s, alzhiemers, Parkinson’s, mad cow
name 2 thermostable enzymes
Taq DNA pol
Vent pol
describe vent pol
- used for PCR and isolated from Thermococcus litoralis archaean
- cell wall consists of S layer that doesn’t form hexagonal lattices
- found in deep hydrothermal vents, shallow submarine thermal springs or oil wells
- anaerobic organotrophhyperthermophile
- grows between 55-100 C
- non motile
- vent pol has lower error rate than Taq pol due to its proof reading abilities
describe Taq pol
- heat tolerant and active >75 C and can be used in PCR
- Taq pol has more intramolecular attractions than normal DNA pol so can hold together better
describe the cell structure and memb surface of an archaea
- S layer composed of 2 proteins - surface covering and memb anchoring
- gram positive - contains pseudomurein layer as well as S layer
- cytoplasmic memb composed of diether lipids
what is a hexagonal phase
formed by some amphiphilic molecules when they are mixed with polar solvent. the amphiphilic molecule aggregate into cylindrical structures and are disposed on a hexagonal axis - micelles fused together
what does H I mean
polar outside
what does H II mean
polar inside
animals need to shelter from the cold in subnivean habitats - what is a subnivean habitat
the habitat under dense snow pack using its protection from wind chill and the insulation that the snow can provide through the air it holds keeping the temperature higher than outside
which type of ecosystems change very little throughout the year
tropical rainforests near the equator
which ecosystems change dramatically throughout the year
polar regions - they change dramatically with seasons which the organisms must adapt to
why does earth have seasons
because it is orbitally inclined - the earths orbit around the sun is elliptical such that the earth is closer to the sun in the southern hemispheres summer
what are some reasons that organism migrate
to avoid conditions that would make them physiologically unable to survive or that would eliminate their food supply until spring
what are the greatest migrators in terms of distance
birds and cetaceans
what are some reasons why animals don’t migrate
the distance is too great
there are physical barriers
they have found ways to continue feeding and coping in their present environment
why is climate change causing an issue for animals that rely on subnivean habitats
climate change is causing unusual warm periods in winter which is causing the snow to be too thin, or thaw and refreeze to create an ice layer that is non-conductive to the survival of lemmings for example
give 2 examples of polar animals that are being affected by climate change
lemmings - subnivean habitats affected
reindeer - rely on being able to paw through the snow to get food but the icy layer formed prevents this and they starve
describe the success of Scottish voles in using subnivean habitats in winter
the snow provides thermal insulation maintaining a temperature of 2-3 C under the pack - the subnivean habitat also provides protection from predators
what caused the large increase in voles in 2011
prolonged snow cover
voles increased in number rapidly because they are protected from environmental conditions and predators
how do large mammals that cannot shelter cope with the cold
they rely heavily on insulation to reduce heat loss - this could be fur or adipose tissue (blubber)
why do fur and feathers reduce heat loss
they have an insulating effect because of the air they hold
layers of fur can be adjusted seasonally to make it denser in the winter
describe the structure of blubber
it has outer and inner layers
- outer layers have a high proportion of monounsaturated FA
- inner layers are enriched with saturated FA
what is the double benefit of blubber
food store and streamlining
what 3 ways can heat be lost from an animal surface
evaporation, conduction and radiation
reducing/increasing the SA:volume reduces heat loss
reducing
how do animals reduce heat loss from extremities
they may reduce the temperature of these structures while maintaining a high core body temperature
what is regional heterothermy
reduction in the temperature of peripheral structures whilst retaining temperature in cores and other structures that will fail at low temperatures
what problem can be presented with good insulation
overheating when the external temperature changes or when heat is produced during exercise
how can insulation layers be tuned
by reducing or increasing the depth of fur or feathers using erector muscles in the skin
give two ways that peripheral blood flow can be altered in response to external temperature
vasoconstriction - when cold - constrict vessels –> prevents heat loss
vasodilation - when hot - dilate vessels –> heat loss
what are counter current heat exchangers
the arteries leading to the peripheral structures are closely positioned with veins returning from that structure
heat is exchanged between them, warming the venous blood travelling to the heart and cooling the arterial blood going to the periphery such that heat loss is reduced
surfaces that are routinely cold have high levels of ……… in their membrane lipids to keep the membrane fluid enough to function correctly
PUFAs - polyunsaturated fatty acids
why are counter current heat exchangers useful in birds legs
birds have very thin legs which have high SA:volume ratio - they exhibit highly efficient counter current exchange systems to prevent excessive heat loss
describe the counter current exchangers of marine animals
marine mammals often live in waters that are cooler than their cores (they are endotherms) and have counter current heat exchangers in their limbs, flukes and dorsal fins
are counter current exchangers used in poikilothermic (cold blooded) animals
yes they are used to retain heat by muscles
describe the composition of tuna muscles
they have high levels of myoglobin
what is myoglobin
it is similar to haemoglobin but is highly enriched in highly active muscles
what is the rete mirabilia
complex interweaving of arteries and veins
how does counter current exchange allow ectotherms to effectively act as endotherms
the counter current exchange systems allow them to behave like endotherms by reducing the loss of heat that they generate metabolically
why are counter current exchangers special in leatherback turtles
they allow them to be the only reptile hunting in cold deep waters
the counter current exchange systems are at the base of their limbs and retain heat in their muscles
they also have thick layer of fat and oil insultation
what is the largest species of marine turtle
leatherback turtle
why are leatherback turtles referred to as gigantothermic
because they are very large which reduces their SA:volume reducing heat loss
what do bumblebees use counter current exchangers for
to retain heat in their flight muscles and not lose it via blood circulation to the abdomen
they can fly at cooler temperatures and higher altitudes as a result of this
how can ice affect plants and animals
ice crystals are sharp and can puncture cell membranes and damage tissues and dehydrate cells
how do animals and plants reduce their freezing point
they either produce certain sugars or anti freeze proteins
give 2 examples of lowering freezing point
- arctic beetle produces high levels of glycerol and sorbitol that are cryoprotective
- glucose is a cryoprotective for freezing and storing sperm
insects need to produce cryoprotectants in …….. of their need
advance
what do antifreeze proteins prevent
formation of sharp ended water crystals
how do teleost fish cope with living in waters cooler than their blood freezing temperature
they produce antifreeze proteins which inhibit growth of ice crystals and also accumulate to prevent growth of sharp pointed crystals
describe the general structure of antifreeze proteins
they tend to have faces enriched in serine and threonine amino acids, the hydroxyls of which interact directly with ice
what is hibernation
prolonged period of reduction in body temperature and metabolism
give 3 examples of hibernating animals
squirrels, bats and hedgehogs
what is torpor
period of inactivity often with reduced temperature and metabolism for a short term
it is usually overnight/diurnal and in response to temperature or food supply fluctuations
what is aestivation
period of torpor to avoid heat and draught
give an example of an animal that undergoes torpor
lemurs
what are some adaptations of squirrels for winter
- heartrate decreased by 90%
- cellular lipid composition altered
- extra types of lipid transporter proteins in heart muscle cells
- head and brown fat receive more blood than other organs
how do animals arouse from hibernation
organs in the thorax and head warm first followed by other tissues
heat is produced by two main mechanisms
1 - shivering to produce heat from muscle activity
2 - activation of brown fat which generates heat through activation of mitochondria
large animals have less/more energy requirement per unit mass so less/more expenditure of body mass is required to maintain body temperature
less
less
large animals have small/large SA:volume so lose more/less heat so can survive on fat stores
small
less
arousing energetically is too ………. for large animals
costly
do bear enter full hibernation and why are they considered hibernators
no their temperature isn’t as low but breathing and heart rate drop significantly
bears maintain a higher temperature to keep their organs active
they are considered hibernators because metabolic activity is lowered
how do polar bears survive the winter
- fat storage
- black skin - UV absorbance
- compact ears and tail
- PUFAs on cold contact areas
- hollow hairs for insulation and buoyancy
list some facts about polar bear reproduction and adaptations
- they are polygamous and mate in spring
- fertilized ovum undergoes delayed implantation - cubs born soon after implantation
- gestation period of 8 months
- mother inhabits 2 chamber cave deep in snow
- females nurse young for 2.5 years
- sexual maturity at 3-4 years
- milk contains 33% fat
- lactating females go into dormancy during denning
what are the effects of climate change on polar bears
- triplets becoming rare when previously common
- % cubs reaching 12 months decreased
- fewer cubs weaned by 18 month than previously
what other animals other than polar bears are affected by loss of ice
walrus - cannot feed without ice and need to come up and rest to prevent excess heat loss in water
they now have to rest on land and juveniles get crushed
what are the 3 options to cope with heat for animals
evade - shelter
evaporate - sweat
endure
why do some spider role down sand dunes
to avoid contact with the hot surface
how do lizards minimise contact with hot surfaces
they raise their body off the ground to minimise contact and alternate the legs that they stand on
how do sidewinder rattle snakes avoid heat contact
they move sideways up sand slopes helping them survive in deserts - sideways movement reduces heat contact because the point of contact is smaller and alternates
up too what temperature can the antelope ground squirrel tolerate and above this temperature what does it do
can cope with up to 42.3 C
they hide in burrows to evade heat above this temperature
how do great gerbils evade heat
they seek refuge in burrows
patches of bare earth form above and around the burrow which reflect light keeping the burrow cool
what is the Bernoulli effect
burrows show this effect
it reduces CO2 conc in the burrow and cools it
give 2 examples of animals which seek refuge in burrows showing the Bernoulli effect
leaf cutting ants
praire dogs
the larger the body mass the more/less insulation needed
less - elephants have very thin pelts
what is spatially confined insulation
having thick pelts in some places and thin in others e.g. guanaco
large animals don’t lose so much heat due to their ………………..
small SA:volume
smaller animals lose a lot of heat ………. due too high SA:volume so they need to be well insulated
radiatively
why do elephants and rabbits have high SA:volume in ears
so that they can lose heat but radiation
how is heat loss from ears adjustable
increased temp - temp ears rises because they open up blood vessels in the ears to allow for radiative cooling
which 3 mammals sweat
horses, humans, patas monkeys
how do horses dissipate heat when exercising
- they sweat heavily
- horse sweat is low in slat and high in protein
- latherin is a detergent like protein present in horse sweat and causes the foaming of a sweating horse
- the function of latherin is to wet the hair to facilitate translocation of sweat to the surface o the pelt from the skin to allow for evaporative cooling
- horses have a thick oily pelt and latherin opens up and exposes the hydrophobic core and binds to oily hairs
what type of protein is latherin
it is part of the PLUNCs protein family that are produced in various forms in the oral and upper respiratory tract of humans
in horses latherin may have originally been a salivary protein that adapted to facilitate sweating
latherin decreases/increases the surface tension of sweat, facilitating evaporative cooling at the hair tips
decreases
why doe zebras have stripes
- flies can’t settle easily in the stripes
- thermoregulation
- confuse predators
describe the thermoregulating effect of zebra stripes
- black stripes get hotter because they absorb IR better
- the hairs on the black stripes erect more often for more efficient radiative cooling
- the black stripes also produce more latherin
how do birds cool since they don’t sweat
- they do gular flapping which increases airflow over the wet surfaces in order to evaporatively lose heat
how do dogs lose heat
they pant and extend their tongues to increase the amount of wet surface (watery mucosal surface) exposed to the air
what is the difference between dog and human panting
humans increase frequency of breathing which is energetically costly - usually due to exhaustion
dogs increase the depth of each pant not the frequency- they do it for heat loss
why do camels have insulation in the summer and winter
winter - toe prevent heat loss
summer - protect against solar irradiation
what happens if you shave a camel in summer
it would lose 50% more water due to having to cool more
how do camels save on the expense of water cooling
they allow their temperatures to go up and their temperature becomes stable when they get water again
can humans tolerate fluctuating body temperatures like large desert animals
no - our organs would be damaged with temperature fluctuation
how is the temperature of the human brain maintained
it has a counter current system that prevents heating and cooling
the veins at the nasal are very cool due to evaporation on nasal membranes when we inhale - this also humidifies air going into the lungs
veins integrate with the arteries coming for the heart which maintains the blood temperature going to the brain
what is the brian counter current exchange system called
the rete mirabilia - extensive breaking up of veins and arteries to increase heat exchange
why don’t rats or dogs need counter current exchangers
rats are evaders
dogs have efficient evaporative cooling
how are the kidneys adapted in desert animals
kidneys are almost spherical
the loop of henle is much longer so they can withdraw much more water from their urine
does the increase in length of the loop of henle in desert animals change the plasma conc
no the plasma conc stays the same
what is the thermoregulation effect of desert snakes not hissing
hissing causes water loss so desert snakes use sonic rattle instead or rub their scales together
how do beetles in the desert acquire rainfall
they rely on mist for water
the beetles posture themselves in the direction of mist and they have an elytra surface on their back
the mist condenses on their back and they absorb it
how do sangrouse transport water to their chicks
they fly to a water source, soak up the water into their feathers and take it to their chicks to avoid predation and travel to watering areas
what are the 2 species of camel
dromedary and Bactrian
why do camels have humps
for localised fat storage - it reduces the amount of insulation by compartmentalising it on their backs
how are camels adapted in terms of their lipids and cytoskeleton
they have altered lipids
they have a strengthened cytoskeleton
they have a high protein to lipid ratio
what is one of the hottest terrestrial environments on earth
the Saharan desert
describe the Saharan silver ant
they are thermophilic scavengers meaning that they feed on animals that die from overheating
the silver effect means they can reflect IR light
they must keep their temperature below 53.6 C
they need to reduce heat absorption and dissipate excess heat to minimize the amount of time spent in refuge
in what 3 ways do the silver hairs of the Saharan silver ant protect against overheating
- total internal reflection - hairs enhance reflectivity in the visible and near IR
- where solar radiation becomes negligible, hairs act as an anti-reflection layer enhancing emissivity and increasing the ability to offload excess heat
- the ants bare undersides reflect IR from the desert floor more efficiently than if covered by hairs
brine shrimp are found in salt lakes what are their cryoprotective adaptations
- they tolerate varying levels of salinity
- their eggs are metabolically inactive
- they remain in stasis for 2 years in dry oxygen free conditions
- they are cryptobiotic
- while in cryptobiosis they can survive extreme temperature
what is cryptobiosis
a metabolic state of life entered when adverse environmental conditions occur. metabolic activity is reduced to an undetectable level. when preferable conditions return organisms return to normal metabolic levels
give 2 examples of deep diving cetaceans
sperm whale
fin whale
give 2 examples of deep diving pinnipeds
elephant seal
California sea lion
give an examples of a deep diving reptile
leatherback turtle
give an example of a deep diving sirenian
west indian manatee
give an example of a deep diving mustelid
sea otter
what is biofluorescence
emission of light
what are some problems faced by deep diving mammals
increased pressure gas filled spaces are crushed gasses are absorbed/dissolved in the blood at high pressure high risk of embolism challenges with temperature regulation need different sensory perception need to adapt metabolism
for every 10m of depth in the ocean how many atmospheres do we increase by
1atm = 10m
give examples of gas filled spaces which are crushed in deep diving and why this is bad
the trachea and lungs can be crushed which can result in tissue damage
at high pressures why is it dangerous for gases to be absorbed by the blood
oxygen becomes toxic and nitrogen becomes narcotic
why is there a high risk of embolism with deep diving
bubbles of gas come out when the pressure decreases going towards the surface and these gases coming out of solution can cause embolisms
what is an embolism
obstruction of an artery, typically by a clot of blood or an air bubble
why are there thermoregulation challenges with deep diving
it gets colder the deeper you go because there is no warm solar irradiation
what is the diving response
the physiological changes during diving
give some examples of diving responses
bradycardia anaerobic metabolism vasoconstriction changes in organ perfusion patterns changes in pH of blood, partial pressure and oxygen content
what is bradycardia
slow heart rate
why do animals revert to anaerobic metabolism when diving and what is the consequence of this
they don’t have sufficient oxygen
the anaerobic metabolism results in a build up of lactate in the body due to muscles entering anaerobic metabolism
what is vasoconstriction and why does it occur when diving
when the blood vessels narrow
prevents excess heat loss by reducing the blood flow to the periphery
what is meant by changes in organ perfusion
changes in the amount of blood going to different organs
what are some diving responses in humans
apnoea bradycardia reduced cardiac output reduced blood supple to extremities gradual increase in mean arterial blood pressure
what is the aerobic dive limit
the dive duration after which there is an increase in post-dive conc of lactate in the blood - the point where anaerobic respiration comes in
why do weddell seals only dive for short periods for the majority of their dives
so they don’t reach their aerobic dive limit - during short dives they remain aerobic with little lactate accumulation
how can ADL be calculated
from the size of the oxygen stores and the animals metabolic rate - this can approximately indicate the animals maximum dive duration
longer dives need longer surface recovery time to repay ……..… …………
oxygen debt
carrying oxygen in the blood while diving makes the blood more ……………… which can cause a range of vascular issues
viscous
compare renewal of air in the lungs in a single breath in humans vs. manatees and cetaceans
manatees and cetaceans can renew 90% in one breath but humans can only renew 10%
distribution of oxygen stores is different/the same in different species
different
where are the 3 main places that oxygen is stored
blood, muscle and lungs
how do the oxygen stores of humans and weddell seal differ
seals store more oxygen in the blood and muscle than humans
humans strore more oxygen in the lungs than seals
why is myoglobin highly concentrated in muscle in deep divers
myoglobin has a higher affinity for oxygen than haemoglobin so would strip oxygen from blood
muscle is tolerant to hypoxia so we get withdrawal of oxygen from the muscle which protects other organs form damage
why is it best to have little air in the lungs when deep diving
they get crushed
when air in the lungs is compressed this delivers huge amounts of nitrogen to the blood which has narcotic effects
the nitrogen bubbles out and can cause the bends which increases embolism risk
which cetacean has the most rete mirabilia
sperm whales
where are rete mirabilia found in cetaceans
inner dorsal wall of the thoracic cavity and in the periphery
are rete mirabilia in sperm whales counter current exchange systems
no - in this case it is a blood storage system - the complex array of blood vessels allow more blood storage and so the ability to store more oxygen - the volume of blood increases but its conc doesn’t - this is the same in spotted dolphins
how are blood stores in cetaceans used in diving
they have stores of rbcs that are compressed when they dive and the blood cells go into the blood increasing its volume
how is blood storage maximised in pinnipeds
the venous systems are enlarged and increased in complexity
they have a sinus (inflation of the vena cava) and blood is stored there
they also store blood in the spleen - diving capacity is correlated with spleen size - the spleen is contracted when blood is required in the circulatory system
what causes a stitch
contraction of the spleen to release its blood storage
do deep diving animals have larger lungs than land animals
no - diving lungs are generally less lobes and have increased cartilage support with very small residual volumes
what does the diaphragm oblique in cetaceans allow for
allows the viscera (guts) to move forward under compression
describe the trachea of diving animals
short with well reinforced rings
which whales collapses its trachea
baleen whales
which whales keep their trachea open
toothed whales
how is pressure difference decreased in the trachea
by pushing air into the trachea
why do cetacean ribs need to be modified
to allow their lungs to collapse - air is then expelled in to the bronchioles and the trachea
whales/pinnipeds dive with full lugs
whales/pinnipeds exhale before diving
whales
pinnipeds
what is the bends
gas coming out of solution on decompression
what can the bends cause in certain bones
dysbaric osteonecrosis
what is dysbaric osteonecrosis
bone death caused by nitrogen embolism (the bends) - they get cavities in their bones and spongy bones
what evidence indicates that leatherback turtles are deep divers
bone cavities
why don’t leatherback turtles have scutes/scales
so their bodies are much more flexible which allows them to dive to great depths
why do leatherback turtles have extensive brown fat
because that’s where mitochondria are concentration
as well as brown fat what other type of fat is concentrated in leatherback turtles
adipose tissue
why do leatherback turtles have counter current exchangers
to increase blood volume
which gene results in increased spleen size in humans
PDEIOA - provides people with larger reservoir of oxygenated blood cells
which genes affects the human diving reflex
BDKRB2
name 2 high altitude birds
bar headed goose
rippell’s griffon vulture
amphibians are negative/positive pressure breathers
positive
most non avian reptiles, birds and mammals are positive/negative pressure breathers
negative pressure breather using rib ventilation
mammals have elaborate alveolated lungs to increase ………. for gas exchange
SA
the oxygenated/deoxygenated air in humans/birds mixes
the oxygenated/deoxygenated air in humans/birds doesn’t mix
humans mix - don’t evacuate all the air from the previous breath
birds no mix - air goes into sacs then moves through a one way system
why do birds lungs need to be more efficient than human lungs
so they can gather more oxygen for flight and high altitudes
what are some notable aspects of the bar headed goose
- larger wing area for weight than other geese
- breath more efficiently under low oxygen and are able to reduce heat loss
- haemoglobin has higher oxygen affinity than other geese to fuel flapping flight
- flight muscle undergoes an increase in bulk prior to migration
- they have high proportion of oxidative fibres and capillaries per muscle fibre than expected
all these differences exist without prior exercise or hypoxia exposure
describe the mitochondria of bar headed goose
no special features in terms of respiratory capacities, oxygen kinetics or phosphorylation efficiencies but are distributed towards the subsarcolema and adjacent to capillaries
what are the 3 high altitude human communities
Tibetans (60)
Andeans (60)
Ethiopians (64)
what are the adaptations of high altitude humans
- larger hearts and lungs
- altered cerebrovascular responses
- no change in amino acid sequence of haemoglobins or myoglobins
- higher oxygen level in placental blood
which high altitude human community uses erythrocytosis
Andeans
which high altitude human communities exhibit arterial hypoxaemia
Tibetan
Andeans
what is erythrocytosis
increase in the total rbc mass secondary to a number of non-hematogenic systemic disorders in response to a known stimulus
what is arterial hypoxemia
low level of oxygen in the arterial blood which can cause tissue hypoxia
what are the differences between Tibetans and Andeans
Tibetans have different physiological traits
- decreased arterial oxygen content
- increased resting ventilation, lack of hypoxic pulmonary vasoconstriction
- lower incidence of reduced birth rate
- reduced haemoglobin concentration
what do lowland humans develop when they go to high altitude
they develop increased haemoglobin concentration to compensate for the hypoxic high altitude environment
Andeans and Tibetans can saturate there blood more easily with oxygen than ……………….
Ethiopians or sea level people
Andeans and Tibetans have the same problems but they solves them in different ways, explain
- Andeans have more haemoglobin than Tibetans
- Tibetans use smaller amounts of oxygen more efficiently
- they both have genes advantageous for high altitudes but Tibetans have other advantageous genes that Andeans don’t
