week 18 Flashcards
what is the first law of thermodynamics
no energy can be lost within the universe. energy can be converted from one form to another.
what is the second law of thermodynamics
every energy transfer increases the entropy (chaos) of the universe. takes the environment into account.
what is cellular respiration by definition
the metabolic process by which an organism obtains nutrients by oxidising them and releasing waste products.
what is the difference between exergonic and endergonic reactions?
exergonic= energy is released
endergonic= energy is required
describe the difference between anabolism and catabolism
anabolism= use of energy to build complex molecules e.g. protein synthesis
catabolism= release of energy through molecule breakdown, e.g. breakdown of glucose
how does ATP release energy
releases energy when the outermost inorganic phosphate is removed. energy is stored in the outermost phosphate because the negative charges repel each other.
name two ways ATP is formed
- substrate level phosphorylation (transfer of phosphate group)
- oxidative phosphorylation (chemiosmosis)
what is chemiosmosis
movement of ions down their electrochemical gradient across a semipermeable membrane.
what is the role of the enzyme kinase
adds a phosphate
what is metabolism
the totality of an organism’s chemical reactions
what is photosynthesis
a process that converts atmospheric CO2 and H2O into carbohydrates
what are phototrophs
photosynthetic organisms
what is involved in the light reaction of photosynthesis
they are membrane-bound, releasing O2 from splitting 2H2O. the hydride ion from H2O reduces NADP+ to NADPH.
what is involved in the dark reaction of photosynthesis
occurs in solution, CO2 is reduced to carbohydrate, this required energy from NADPH and ATP
what is an antenna pigment
they extend the range of light capture especially in green wavelength. Carotenoids
what is photophosphorylation
synthesis on ATP, which is dependent on light energy
how are dark reactions identified
fast CO2 injection, rapid ‘quench’ (perchloric acid) to stop reactions, 2D chromatography improves separation of intermediates
what is the composition of RuBisCos subunists
8 small subunits and 8 large subunits. large subunits are nuclear-encoded and small subunits are chloroplast encoded
what does photorespiration do
recycles toxic products of the oxygenation reaction. Consuming NADH, ATP and giving glyoxylate, serine, glycine and CO2
what do the dark reactions do
uses NADPH and ATP with RuBisCo to fix CO2 and regenerate RuBP
what types of photosynthesis are well suited to growth under high light and reduced water availability
C4 and CAM
what are purines and pyrimidines
Purines have two fused rings (A and G) while pyrimidines have got one ring (C and T)
what does a nucleotide consist of
a base, the sugar deoxyribose and a phosphate.
what does DNA ligase do
joins fragments of new DNA from the lagging strand
In what direction does DNA replication occur
5’ -> 3’
define the difference between catabolic and anabolic reactions
catabolic= breakdown of molecules into smaller ones, energy released
anabolic= build-up of molecules requiring energy
what are antenna pigments
they extend the range of light capture, especially in the green wavelength
how is light absorbtion organised
between two photosystems (PSI and PSII)
what is the cytochrome b6f complex and its role in photosynthesis
a protein in the thylakoid membrane involved in transporting electrons between photosystem I and II
what light (nm) are the photosystems PSI and PSII paired to capture
PSI= P700 (absorbs light maximally at 700nm)
PSII= P800 (absorbs light maximally at 680nm)
what is the z scheme
the path of electron flow and reduction potentials.
absorbing light energy converts P680 and P700 into excited molecules (better reducing agents).
light energy drives electron flow uphill, NADP+ is reduced to NADPH. antenna pigments capture light.
what is the chloroplast structure
4-8mm diameter with two membranes, internal membrane (thykaloid membrane) stacking
what is the cyclic electron flow
an alternative electron transport pathway which produces ATP without generating NADPH
what is photophosphorylisation
process where light energy is used to generate ATP in photosynthetic organisms
what is chloorplast ATP synthase
an enzyme which synthesises ATP in chloroplasts consisting of two major particles, CF0 and CF1.
what is chemiosmosis
a process where the movement of ions across a membrane down their electrochemical gradient is used to generate ATP
what are pyrenoids
membrane-bound structures found in the chloroplast of some algae. some (like carboxysomes) include rubisco and concentrate co2
what is C4 photosynthesis
an alternative photosynthetic strategy to get around limited rubisco. four carbons, hatch-slack pathway
what is CAM photosynthesis
saves water use, using an inverted stomatal opening/ closing to save water and concentrate co2 in the leaf. stomata are closed during the day and open at night.
whats the difference between C3 and C4 photosynthesis
C3- most common pathway, produces a 3 carbon molecule. more common in cooler more humid environments.
C4- produces a four carbon molecule. more effiecient in hot/ dry enviroments
what end of the DNA strand are nucleotides added
3’
