Lent Flashcards
How much of the BMR is used by the CNS and how much by ion transport?
CNS= 30-40%
Ion transport= 40-60%
What 3 components of food (groups) make up a healthy diet?
Sugars/Starch
Fats/Oils
Proteins
Why are proteins an inefficient energy storage?
1) Lots of E is required to make the peptide bond in the first place, so overall not much energy is being released
2) Also only half of the protein is actually available, a large proportion is essential for body function and can’t be broken down
Where is fat stored in humans?
Muscle, liver, heart and adipose tissue
Describe the structure of adipose tissue
White Adipose tissue contains 1 lipid droplet
Brown Adipose tissue contains multiple lipid droplets
Why are carbohydrates vital?
Brain only uses glucose for energy
Fat is unable to pass blood brain barrier
Fats cannot be converted back into carbs
Carb also required by RBC and parts of the kidney
Why is muscle glycogen only for muscle?
Unable to transport Glucose-6-phosphate
G-6-phosphotase not present
Unable to form glucose to be transported
What types of fuel storage are present in plants?
Starch= Amylopectin + Amylose
Can convert triglycerides into carbs
Movement of sucrose around instead of as glucose
Where are fats stored in plants?
Oleosomes- commonly in seeds
What are endosperms?
Tissue surrounding seed of an angiosperm
is an energy store, technically a separate organism
Activated by Gibberellins
e.g. coconut water
What is the use of Phosphocreatine?
Buffer to keep ATP concentration constant
Converted from creatine to phosphocreatine by creatine kinase
How can levels of ATP and Pcr be measured?
Using NMR spectroscopy and P31
- Only shows relative conc changes
-Only shows molecules with ‘spin’
What energy stores are used to stay alive overnight?
Glycogen
Then protein
What is the order of energy store usage during long starvation?
Glycogen
Protein breakdown- then conserved
Fat breakdown- until fully exhausted
Then protein breakdown
Until death
Why is protein broken down when glycogen runs out?
Protein can be broken down to produce carbs to feed the brain. The body takes a while to switch to ketone bodies which can be produced from fats to feed the brain
What are the difference between the muscle of a marathon runner and that of a sprinter?
Marathon- aerobic respiration so Type I, high glycogen storage
Sprinter- Anaerobic respiration Type II, many mitochondria, less glycogen storage
Why is fat not immediately used as a fuel source?
Production of ATP from fat is slow
Requires more O2
Brain requires carbs to stay alive
How efficient are we?
20%
What processes decreases muscle efficiency?
Heat loss
Loss in the conversion process in mitochondria
Define homeotherms
Able to maintain internal temperature
Define Poikilotherms
Don’t actively regulate internal temperatures
Define Ectotherms
Dependent on external sources of heat to regulate temperature (fish, reptile, invertebrates)
Define Endotherms
Control body temperature by metabolic processes (mammals, birds, tuna)
Positives and negatives for being an endotherm
Can operate at many temperatures
Require extra food to carry out metabolic processes
How are fluctuations in temperatures created in humans?
External environment- causing redirection of blood
Hormones- progesterone increases body temp
Circadian rhythms- body colder at night
Ways in which heat can be retained?
Redistribution of blood to core
Counter current exchange- warming of cold returning blood so heat contrast when moved to extremities is less (dolphins)
Define heat capacity
1kcal raises the temp of 1kg of water by 1 degree celcius
What are the 3 processes to increase heat production?
1) Shivering
2) Changes in BMR (futile cycles)
3) Brown adipose tissue
Activation of sympathetic pathway
How does changes in BMR increase heat production?
Decreases efficiency of processes, leading to heat production
Controlled by the hypothalamus and thyroid gland
T4 conversion to T3 increases amount of ineffciency
1) Uncoupling proteins- less ATP made (UCP1)
2) Increase Na/K activity- large energy cost
3) Promotion of futile cycles
Why are uncoupling proteins present in plants?
For generation of heat
- attract pollinators
- help melt ice (skunk cabbage)
What is a dangerous example of uncoupling proteins?
DNP- weight loss drug
Mitochondrial uncoupler bypassing ATP-synthase and diffusing the H+ gradient
Side effects
- Nausea, Headaches, Death, Dehydration
What are the 4 ways of losing heat?
Radiation
Conduction
Convection
Evaporation
What is heat loss dependent on?
Surface area
Temperature difference
Evaporation rate also dependent on humidity
How is heat lost by radiation?
Loss of IR heat
How is heat lost by conduction?
Depends on the surface that is in contact
Water is much more conductive than air or fat
Adipose tissue can act as an insulator, but can be bypassed to increase heat loss
How is heat lost by convection?
Movement of air and water maintaining temperature gradient
How is heat lost by evaporation?
Sweating @ sweat glands
Acted on by sudomotor nerves
Sympathetic NS, with cholinergic receptors (muscarinic)
Similar to salivary secretion, undergoes primary and secondary modification
NOTE: it’s an active process so does produce heat itself
What are behavioural responses to control heat loss/gain?
- Movement into the sun/shade
- Removal/addition of layers
What autonomic controls for heat control are present?
Cholinergic= shivering, sweating
Noradrenergic= BAT, piloerection, vasoconstriction
What part of the hypothalamus controls the satiety signal?
Ventro- medial nucleus (VMN)
What part of the hypothalamus is responsible for hunger centre?
Lateral hypothalamus
What area of the hypothalamus is responsible for body temperature control?
Preoptic area
What type of mechanism is used to control heat and why is it important?
Feed-forward mechanism
Anticipate future events, to maintain a stable internal temperature, and ensure that overcorrection doesn’t occur
Important for homeostasis
How can metabolic rate be increased?
Exercise
Digestion
Illness
Pregnancy
Change in temp
How does body size effect BMR and SMR?
Body size does increase BMR however doesn’t increase SMR. SMR being specific metabolic rate, which is greater in small animals due to the SA:Vol
What is allometry?
Study of scaling relationships
What is the Bergmann Rule?
Endotherms living in colder environments are larger than their warmer environment counterparts
What is Allen’s Rule?
Endotherms living in cold environments they have smaller/shorter limbs
What is Kleiber’s 3/4 rule?
Shows that BMR does not increase in proportion to body mass
Endotherms have a greater BMR compared to poikilotherms
- Not very accurate
What are the implications of metabolic scaling?
Biochemistry for smaller life occurs faster
They have faster HR and BR
What is the free radical theory of ageing?
- Quicker metabolism quicker ageins
- Due to more production of harmful chemicals
- This can damage cells and DNA, leading to mutations
However: some tortoises and birds live very long despite their size
What is the bird anomaly?
Birds have a longer lifespan
e.g. comparison between rodents of similar sizes and bats
Perhaps due to wing evolution, meaning more likely to survive
So reproductively active later in life
Slower life cycle = Live longer
What are the main differences between plants and animals?
1) Plants are sessile
2) Individual plant cells have controls
3)Plants are autotrophs
4) Plant cells have cell walls
What are the key similarities between plants and animals?
1) Both carry out gas exchange
2) Both are multicellular organisms
3) Both require nutrients
4) Have structural support
What are the differences between monocots and dicots?
Monocot- one cotyledon, SAM at soil level, parallel vasculature, fibrous root system
Dicot- two cotyledon, SAM in top of plant, tree-like vein vasculature, form lateral roots
What are differences in animal and plant development?
Plant development not restricted to young plants
Fast response
Animal- homeostasis
Plants- guard cell
What are the two types of division in plant cells?
Anticlinal (within the layer) (L1 and L2
Periclinal (forms new layer) L3
What are the 3 zones in the SAM
1) Central zone- dividing cells
2) Peripheral zone- divide and differentiate
3) Rib zone- provides cells for stem
What 3 key hormones regulate growth in plants?
Auxin
Gibberellins
Cytokinins
What is apical dominance and how is it achieved?
AM stops control of axillary meristem.
Production of IAA, stops lateral root growth. Use of sucrose by AM means not enough for axillary meristem
Where is the root apical meristem located?
In the tip of the root, protected by the root cap
What are the zones present in the RAM?
Quiescent zone- for dividing cells
Root cap- mechanical protection, and gravity sensor
Where are lateral roots formed, and what controls the growth?
Lateral roots are formed from the perricycle
They are controlled by pulses of auxin which prime the areas for growth, however actual growth is controlled by NRT1.1 channels
What is the vascular cambium?
Secondary growth, where phloem and xylem are made depending on their location, within the stem
What 2 hormones control the expression of the vessels (phloem and xylem)
Cytokinin
Auxin
What does a phytochrome consist of?
Protein and Chromophore
Which phytochrome is active Pr or Pfr?
Pfr- when in trans state
How does Pfr work?
Moves into the nucleus
Acts as a transcription factor
Some remain in the cytoplasm to control ion concs
What two complexes detect blue light?
Cryptochrome
Phototropin
What complex detects UV light, specifically the residues?
UVR8, specifically tryptophan residues
What can a plant ‘hear’?
Buzzing, e.g. buzz pollination by bees
What can a plant ‘smell’?
Ethylene- causing colour development and ripening
Warning signals released by other plants
How are plant defences coordinated between plants?
Jasmonic acid
-to deter herbivores
- warn other plants (HexVic)
How can caterpillars overcome plant defences?
Cause stomatal closure
Prevents release of signalling chemicals
Stop plant from controlling water content also
What are 2 examples of plants that use smell to attract pollinators?
Skunk cabbage
TItan Arum
How do plants tell the time?
Circadian rhythm present in cells
Also effected by environment
How does reaction to stress vary between types of plants?
Perennial (many season)- focus on growth
Annual (1 season)- focus on reproduction
What is an example of plant acclimation?
Yorkshire fog grass- adapt to reduce arsenic intake
acclimate to arsenic by incorporating it into building molecules
What are the 3 main abiotic stresses and their effect on plants?
Temp- denaturation of proteins, change in DNA/RNA
Drought- Plasma membrane contraction
ROS- denaturation of proteins
What does PGR stand for?
Plant growth regulators
What are the names of the 9 plant signalling chemicals?
Auxin
Cytokinin
Gibberellins
Ethylene
ABA
Jasmonic acid
Salicylic acid
Brassinosteroids
Strigolactone
What does auxin do?
Controls growth and plant development
e.g. lateral root formation
What does cytokinin do?
Stimulates cytokinesis, or senescence
What does Gibberellins do?
Present in chloroplast, controls cell elongation
Upregulated by auxin
Binds to DELLA and breaks it down
What does ABA do?
Prevent growth and germination
Found when conditions are bad e.qg. drought
What does Ethylene do?
Cause fruit ripening
Is a gas hormone
What does strigolactone do?
Allows for symbiosis with fungi
What does brassinosteroids do?
Cell growth, development, everything
What does jasmonic acid do?
Responds to herbivores
What does salicylic acid do?
Responds to pathogens
How does the DELLA- Gibberellins signalling work?
Signal transduction by degradation
DELLA usually bound to TF, doesn’t allow transcription
Gibberellins binds to DELLA, breaks it apart
TF able to bind and cause transcription
How does phosphorelay signalling occur?
Phosphorylation cascade
Usually for hormones ethylene and cytokinin
How can signalling occur inside plant cells?
Symplastically- Signalling via plasmodesmata
Via movement of phytochromes and steroid hormones
How and why does Ca2+ signalling occur in plants?
Occurs by movement of Ca2+ via plasmodesmata
Occurs in response to wounding, salt stress
What type of signalling can lead to systemic acquired acclimation?
ROS communication
What is the evidence for long distance communication via nucleic acids?
GFP (green fluorescent protein) used to tag RNA.
Shows movement of RNA all around the plant
What is the difference between tropic and nastic movement?
Tropic- in a certain direction
Nastic- in any direction (non-directional)
How does gravitropism work in the roots?
Statoliths in statocytes relocate to the bottom
PIN-3 relocate to the bottom
PIN-2 and AUX1 relocate auxin to bottom
Auxin INHIBITS growth of bottom side
How does gravitropism work in the shoots?
Statoliths in endodermis relocate
PIN-3 relocate to bottom
Auxin redistributed
Auxin CAUSES growth of bottom side
What channel proteins are involved in phototropism?
PHOT1 and 2 temporarily stop auxin transport
PIN-3 resumes movement
What is thigmonasty and an example?
Response to touch
e.g. Mimosa Pudica contraction due to changes in turgor pressure
What is nyctinasty?
Movement associated to circadian clock
How does movement in a venus fly trap occur?
Cl- efflux causing Ca2+ signalling
Causes movement of K+ out
Changing elastic potential
Causing it to snap shut
What is circumnutation?
Swinging motion
Both nastic and tropic
e.g. vines growing
What are the responses in growth of shoots and roots to changes in environment (water and Pi)?
Shoots continue to grow until roots can’t provide more water
Roots grow until shoot can’t provide more phosphate
What are the effects of light stress?
Too high energy light can cause photobleaching
What are the effects of temperature stress?
Too high- denature enzymes, water evaporation, effect membrane fluidity
Too low- ice crystals form (can pierce mem)
What are 4 metabolic changes that can occur to maintain protein integrity in plants?
Metabolic
1) Dehydrins- form shield around protein
2) Chaperones- stabilize and repair
3) Desaturase enzymes- increase no of unsaturated to control mem fluidity
4) Anti-freeze- stop ice crystals from growing, by binding to them
What are 3 physiological changes that can occur to maintain protein integrity in plants?
1) Abscission- leaf loss
2) Change leaf shape/angle
3) Modify leaf surface (waxy cuticle)