Metabolic processes Flashcards
Differences between chloro-a and b
chloro- A contains a methyl group (CH3)
chloro- B contains a aldehyde group (COH)
what is the primary pigment?
Chloro-A (blue and green)
what are the accessory pigments?
Carotenoids (gives orange colour to carrots)
Chloro- b (yellow-green)
What is a pigment?
Pigments absorb light energy
What are prokaryotic autotrophs?
eg. cyanobacteria
no nucleus or membrane bound organelles
Form algae blooms —> can produce toxins harmful to humans and animals
What are Eukaryotic Autotrophs?
eg. Algae, photosynthetic plants, protists and plants
chlorophyll is contained in membranes of chloroplasts
What is the equation for photosynthesis?
6CO2(g) + 6H2O(l) + light energy ——> C6H1206(aq) + 6O2(g)
What is the basic structure of a plant? (5 things)
1) Leaves - provide max surface area exposed to sunlight, limiting the distance gases need to travel to the chloroplast.
2) Epidermis layer - transparent, colourless layer of cells below the cuticle of the leaf, stem and root which allows light to travel through to the next layer
3) Mesophyll layer - spongy and palisade, photosynthetic cells that form the bulk of the plant leaf
4) Guard cells - epidermal cells of a leaf or stem that for and regulate the size of the stomata
5) Stomata - microscopic openings on the surface of the leaf that allow for gas exchange between air spaces inside the leaf and the atmosphere
What are the transportation networks and the difference between the two veins
Xylem - dead vascular veins that transport water from the roots UP to the leaves
Phloem - living vascular bundles that carry carbs produced by photosynthesis from the leaves to where ever it is needed or where it is stored (i.e. roots)
Roots - absorb water and minerals from the soil, anchor the plant
what is transpiration?
Transpiration is completely passive, and is loss of water vapour from the plant tissue through the stomata that helps draw water (and dissolved minerals) up from the roots through the xylem.
Basically the plant is sweating
—> cools plant to prevent overheating and denaturing of enzymes that catalyze photosythesis.
What controls the rate of gas exchange and transpiration?
the shape of the guard cells
What are chloroplasts ?
- Photosynthesis takes place here
- Contain their own DNA and ribosomes
- Membrane reticulation fill the inner space to increase surface area.
What is the inner thylakoid space called?
Lumen
What is the protein rich interior material called?
Stroma
What is a thylakoid?
membrane bound organelles that contain light absorbing pigments and electron transport chains (ETC)
–>inside stroma
What are stacks of thylakoid called?
Grana
What is lamella(e)
unstacked thylakoids that connect individual granum
Where are light dependant reactions held and what is involved
“photo” reactions happen in the thylakoid membrane
involving –> chlorophyll, H2O, light, oxygen, NADP, ADP. e-, H
where do “synthesis” reactions take place and what is involved?
occurs in the stroma
involves NADPH, ATP, RuBP, CO2 and G3P (PGAL)
Go through the 4 light stories
What is blue light and red light
blue light is light with =—>
- high energy
- high frequency
- Short wavelengths
red light is light with—>
- low energy
- low frequency
- long wavelengths
What happens when molecules are struck by a photon of light? (2 things)
1) fluoresce - when the perfect wavelength matches, the photon excites the electron (ground state) which jump to another energy level (excited state). The electron doesn’t stay excited forever so once it jumps back to ground state it lets go of the energy it got from the light, releases it as light or heat. Ground state. (non-photosynthetic)
2) Redox reaction - photon excited electron and when electron jumps instead of returning to ground state it gets stolen by another molecule right next door (MAJOR DIFFERENCE)
What is photolysis and what does it produce?
photolysis is the breaking up of water through light
h20 —–> 1/2 O2 +2H +2e-
How do carotenoids help? (2 ways)
—> some absorb light that would damage the chlorophyll and fluoresce it as heat
—>channel the light energy to the reaction centre (always chlorophyll a)
How do carotenoids help? (2 ways)
—> some absorb light that would damage the chlorophyll and fluoresce it as heat
—>channel the light energy to the reaction centre (always chlorophyll a)
Role of the photocenter
network of chlorophyll and carotenoid pigment molecules (held together in a protein matrix)
the pigments’ arrangement permits channelling of excitation energy to a central point called the reaction centre
overall balanced equation of photosynthesis
6CO2(g) + 6H2O(l)——-> C6H12O6(aq) +6O2(g)
What three factors affect the rate of photosynthesis?
Light –> as light intensity increases, photosynthesis increases (limited by Co2 and temp)
CO2 levels —> as C02 levels increase photosynthesis increases (limited by light and temp)
Temperature —> as temp increases so does rate of photosynthesis UNTIL ENZYMES DENATURE.
what are the three stages of light dependant reactions?
1) PHOTOEXCITATION of chlorophyll electrons –> spike in potential energy (photoexcitation) lasts a fraction of a second before returning to ground state
2) ELECTRON TRANSPORT through membrane bound carriers —-> must transfer to primary electron acceptor (NADP+) to form NADPH or the energy will fluoresce (as heat or light)
3) CHEMIOSMOSIS —> protons move through ATPase to drive the formation of ATP from ADP + Pi
What are the two photosystems and which chlorophyll do they contain?
Photosystem I, contains chlorophyll P700
Photosystem II, contain chlorophyll P680
what does NADP stand for?
Nicotinomide Adenine Dinucleotide Phosphate
what are the three differences between Cyclic and non-cyclic phosphorylation
1) Products —> cyclic only produces ATP, non-cyclic produces ATP and NADPH
2) e- lost or recycled? —> cyclic the electron is recycled. non- cyclic the electron is lost (goes to the Calvin Cycle)
3) Photosystems involved —> Cyclic only involves PS 1 700 (photosystem 1),
non-cyclic uses both PS 2 680 (photosystem 2) and PS 1 700 (photosystem 1)
What are the three phases of the Calvin Cycle ?
- ) Carbon fixation - Co2 is fixed to RuBP through enzyme called Rubisco creating
- —> 3-PGA (3 phosphoglycerate)
2) Reduction reactions -
3) Regeneration of RuBP
List the 3 main stages in the photosynthetic reaction pathway
(1) Light Reactions
– chemiosmotic generation of ATP via cytochromes electron transport chain
- reduction of NADP+ produced NADPH
(2) Dark Reactions
- use of ATP and NADPH to synthesize organic compounds from atmospheric CO2
(3) Regeneration of Pigment Molecules
- photolysis of water replaces electrons to return oxidized chlorophyll to its ground state
Identify two ways plants in warmer climates have adapted to deal with
photorespiration
C4 plant adaptations:
(1) leaf structure with bundle sheath cells next to veins to maximize availability of CO2
(2) uses PEP carboxylase instead of RuBP carboxylase so photorespiration is less likely to occur
(since PEP is less likely to bind to O2 than CO2);
(3) use a 4-carbon (hence, C4) oxaloacetate to deliver CO2 to cells; keeps
the CO2 to O2 ratio high so no photorespiration occurs when the stomata are closed to conserve
water and the O2 is building up in the leaf
CAM plants:
- CO2 only taken up at night and stored in vacuoles as oxaloacetate; stored carbon can run out
which means little production of sugars and explains slow growth in desert plants
List and briefly describe the three stages in the dark reactions.
(1) Carbon Fixation → Rubisco adds CO2 onto ribulose bisphosphate (RuBP) producing 2
molecules of phosphoglyceric acid (PGA)
(2) Production of Carbohydrate (Reduction) → series of reactions which use ATP and NADPH to
convert PGA → DPGA → PGAL
- PGAL is then used to form glucose (in reverse of glycolytic pathway)
(3) Regeneration of RuBP → series of reactions which use ATP to convert PGAl back into RuBP
to complete cycle
What is the pigment molecule in photosystem I
P 700
fluid matrix of the chloroplast
Stroma
yellow-orange pigment (like in carrots!!)
beta-carotene
site of the photosynthetic reactions
photosynthetic membrane
primary photosynthetic pigment that absorbs primarily
violet-blue light
Chloro-b
pigment that is able to absorb photons that chlorophyll a
cannot
accessory pigments
pigment molecule within photosystem II
P 680
cells in C4 plants that hold CO2
bundle sheath cells
dark reactions of photosynthesis
Calvin Cycle
Distinguish between the two different photosystems found in higher plants
(1) P680 – maximum energy absorption at 680nm
- reaction center of Photosystem II
- first photocenter in light reactions and passes electrons to cytochromes for ATP
synthesis
- electron replaced by photolysis of water
2) P700 – maximum energy absorption at 700nm
- reaction center of Photosystem I
- second photocenter in light reactions and passes electron to ferredoxin for NADPH
synthesis
- electron replaced by passage from photosystem II
- used in cyclic photophosphorylation in bacterial cells
5-carbon sugar to which CO2 is added during the dark reaction
Ribulose 1,5 Bisphosphate (RuBP)
What is the produce of Carbon fixation?
3-PGA (3 phosphoglycerates)
Explain what happens in the reduction phase of the Calvin Cycle
Part A of Reduction phase
- ATP undergoes hydrolysis (which breaks off a phosphate creating ADP)
- SIX PGA (phosphoglycerate) molecules are phosphorylated (phosphate is added) into SIX 1,3 BPG (1,3-bisphosphateglycerate) using SIX ATP molecules
Part B of Reduction Phase
-SIX NADPH molecules reduce SIX 1,3 BPG (1,3 - diphosphoglycerate) to form SIX G3P (PGAL) molecules
ONE G3P molecule leaves the cycle to form sugar (1/2 sugar, need two G3P to form ONE sugar)
FIVE G3P molecules (3C) are used to regenerate THREE molecules of RuBP (5C)
What happens in the regeneration phase of the Calvin Cycle
The carbon skeleton of the five G3P molecules are rearranged into 3 RuBP molecules
What are photocenters?
Photocenters are just a part of the photosystem that contains the carotenoids and the chlorophyll pigments. Imagine that little antenna array built in to the top of the photosystem. (pg 10)
What are bundle sheath cells impermeable to?
Co2
What is photophosphorylation?
the process of utilizing light energy from photosynthesis to convert ADP to ATP (phosphorylation of ADP produces high energy pyrophosphate bond)
series of membrane bound electron carriers in cellular respiration
cytochromes
the ketone which is an isomer of G3P
DHAP
respiratory proteins that transport protons into the mitochondrial ETC
Matrix
ETC (electron transport chain)
metabolism in the absence of oxygen
anaerobic respiration
what is the end product of glycolysis?
Pyruvate
cyclic series of reactions in which pyruvate is oxidized to CO2 & H2O
Citric acid cycle (Krebs cycle)
the location in the cell for glycolysis
Cytoplasm
location in the mitochondria for the citric acid cycle
matrix
reactions in which a molecule gains electrons
reduction reactions
large enzyme that removes carbon dioxide from pyruvate
Pyruvate dehydrogenase
the location of the electron transport chain
Cristae
enzyme that regulates respiration in muscle cells
Phosphofructokinase
What are the two ways organisms make ATP ?
and briefly describe the 2 ways that organisms make ATP.
1) Substrate level – enzyme used to strip P from one molecule and add it to
another (ADP, creates ATP)
2) Chemiosmosis – H+ pumped to intermembranous space of mitochondrion by
active transport, diffuses back into matrix through STP synthetase complex
and phosphorylates ADP (pg. 106)
Why does glycolysis cost the cell 2 molecules of ATP initially?
Glucose must be “activated” by the addition of the 2 phosphate groups to destabilize bonds and break apart the stable ring structure.
Two examples of structural isomer conversions during the glycolytic pathway
Glucose 6-phosphate and fructose 6-phosphate
DHAP and G3P (glyceraldehyde 3-phosphate)
What are the 4 stages of cellular respiration and their locations?
What is the goal of oxidation of pyruvate ?
convert pyruvate to
Acetyl-CoA + produce NADH
Difference between cyclic and non-cyclic photophosphorylation?
