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Biochemistry > Photosynthesis L10 > Flashcards

Photosynthesis L10 Flashcards

(98 cards)

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1
Q

what are animals

A

heterotrophic organisms

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2
Q

what do animals require

A

an input of energy and nutrients in order to function

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3
Q

how do animals get energy input

A

contained in food and much of an animal’s existence is taken up in the pursuit of food

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4
Q

can animals make their own energy

A

Animals can synthesise some organic molecules but cannot generate their own energy or most nutrients which are gained from eating food

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5
Q

what do food chains describe

A

interaction between animals which eat other animals but at the start of all food chains are plants

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6
Q

what are the primary producers

A

plants

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7
Q

what are the consumers

A

animals

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8
Q

why is photosynthesis important

A

arguably most important process that occurs on earth

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9
Q

what is the most fundamental to the existence of life on planet

A

plants have ability to synthesise their own “food” in form of large complex organic molecules from simple molecules

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10
Q

how do plants build biomass in their structure

A

complex carbon based molecules

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11
Q

where is the energy derived from for plants

A

energy to carry out these synthetic processes is derived from sunlight absorbed by plant tissues

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12
Q

examples of photosynthetic processes

A

flowering plants
algae
mosses

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13
Q

how is photosynthetically synthesised biomass accumulated

A

photosynthetic organisms capture carbon dioxide gas from the atmosphere, fix it into existing carbon-based molecules acquiring carbon - build new molecules

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14
Q

what do plants need to gain biomass

A

uptake of water and a few nutrients from the soil

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15
Q

what are plants like

A

autotrophic – self sufficient, make their own food, producers

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16
Q

what are animals dependant on

A

consuming organic carbon based molecules to drive metabolism, food

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17
Q

where does photosynthesis get energy from

A

electromagnetic radiation (light)

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18
Q

what is energy used for in photosynthesis

A

synthesise short term high energy molecules used to drive biosynthetic reactions - newly synthesised organic molecules that plant uses to grow

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19
Q

what are the short term high energy molecules

A

ATP

NADPH

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20
Q

what is the estimated biomass production in the world

A

100 petagrams (100 x 1015 g) of carbon per year about half in the ocean (mostly by algae/phytoplankton) and half on land

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21
Q

what is a major component of terrestrial biomass

A

wood

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22
Q

why is wood important

A

fuel source

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23
Q

what is wood composed of

A

basically cellulose and lignin (lignocellulose)

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24
Q

what is cellulose made of

A

many sugar

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25
cellulose structure
beta glucose molecules in a straight chain
26
what are cellulose fibres made into
folded into microfibrils
27
what is the major component of plant cell wall
microfibrils
28
what are microfibrils function
keep plant together e.g. leaves
29
what makes up the plant cell wall
Cellulose Lignin Hemicellulose
30
what is the structure of hemicellulose
branched beta glucose chain, cross links and side chains
31
what is the structure of lignin
different sugars linked and cross linked in different ways
32
what do algae form
Algae form phytoplankton in oceans and fresh water
33
what do the green plant leaves do
intercept light radiation from the sun
34
what is the structure of the leaf from the surface
``` Upper epidermis Palisade parenchyma Vascular bundles Spongy parenchyma Lower epidermis ```
35
Where is the air space in the leaf
Spongy parenchyma
36
Why is the air space in the leaf important
Photosynthesis takes up carbon dioxide and makes oxygen – need gas exchange Through stomata, regulates air movement
37
Why are the vascular bundles important
Transport highway of the plant, where sugar being made by photosynthesis is taken up and distributed to plant
38
Where are the chloroplasts
mesophyll cells | Upper part of leaf – where most sunlight
39
Where are chloroplasts derived from
Cyanobacteria
40
What is an organelle
Anything in the cell that is enclosed by a separate membrane
41
What is the function of the inner membranes
Separate specific entity from cytoplasm and provide a specific biochemical environment to carry out specific reaction e.g. photosynthesis
42
how long are chloroplasts
about 10 μm
43
What do the chloroplasts contain
starch granules
44
What is the function of the starch granules in chloroplasts
Starch being produced by photosynthesis stored here initially
45
Where does photosynthesis happen
Thylakoid of chloroplast
46
What is the function of stroma
Provides biochemical environment to carry out certain reactions
47
what does the stroma contain
e.g. enzymes, carriers, many molecules
48
what is the most inefficient enzyme
RUBISCO
49
what does RUBISCO enzyme catalyse
reaction of ribulose-biphosphate to two molecules of 3-phosphoglycerate Reaction uses a carbon dioxide molecule
50
what does the reaction of fixing carbon contain
complex with short-lived intermediate molecules
51
why is the fixing carbon reaction a C3 photosynthesis
result is two molecules of | 3-phosphoglycerate, each containing 3 atoms of carbon
52
what is the main reaction of photosynthesis
Fixing carbon - Main reaction that fixes carbon dioxide gas occurs in stroma of chloroplast, involves combining molecule of carbon dioxide gas with a simple phosphorylated sugar, ribulose 1,5 biphosphate
53
how does carbon dioxide reach chloroplasts
Plants must have a constant supply of carbon dioxide, taken up by the stomatal pores, diffuse into the leaf into cells then chloroplasts
54
what is RUBISCO enzyme built of
two types of subunits, each distinct proteins encoded by two different genes
55
what are the two RUBISCO enzyme subunits
small subunits (SSU) and large subunit (LSU)
56
how many kilodaltons is a small subunit of RUBISCO
14kD
57
how many kilodaltons is a large subunit of RUBISCO
55kD
58
why are functional enzymes huge molecules
Functional enzyme there are 8SSU and 8 LSU
59
how is large subunit active site need to be activated
magnesium ions carbon dioxide enzyme Rubisco activase
60
what do magnesium ions do
store electrons
61
how many active sites are there on each enzyme
8
62
are all the active sites on an enzyme the same activation state
8 active sites on each enzyme can be in different states of activation
63
when is RUBISCO activated
only activated in the light (only needed in photosynthesis)
64
what does RUBISCO do
transfer 5 carbon into two 3 carbon sugars metabolised into triose phosphate: use energy and electrons > ATP ADP > NADPH NADP+ + Pi
65
what does the calvin cycle regenerate
3 C into 5 C sugar
66
what is the main product of calvin cycle
Triose phosphate
67
what is triose phosphate used in
used in many ways can be exported from the chloroplast and used to make sucrose in cytosol
68
what is sucrose in calvin cycle used for
main metabolised sugar cells use for energy and metabolism
69
why is the calvin cycle important
Major synthesis pathway in many plants carrying out photosynthesis during day
70
what is exported from the calvin cycle
Sugar will be exported from leaf cells into plants plumbing system (phloem) and moved around plant to where it’s needed for growth (source/sink)
71
what can triose phosphate alternatively be made into
converted into fructose-6-phosphate which forms basis for making starch in chloroplast
72
what is starch
a polymer of glucose
73
what is starch made of
two slightly different glucose polymers
74
what are the two glucose polymers in starch
amylopectin | amylose
75
what do plants synthesis in day
Plants can synthesise starch
76
what does starch synthesis make
large starch granules within chloroplasts so by sunset, leaf’s chloroplasts full of starch grains
77
what is amylopectin
branched starch
78
what is amylose
one strain of starch
79
how does amylose and amylopectin differ
different chemical properties
80
what is starch broken down into
starch synthesized during the day is degraded into glucose and maltose and can be exported out of the chloroplast into the cytosol so that at dawn, no starch remains
81
what percentage of carbon exported during photosynthesis
Arabidopsis leaf about 40% of carbon assimilated during photosynthesis
82
what happens to the carbon exported during photosynthesis
used immediately by plant in metabolism and exported to make sucrose and other molecules
83
what and why is carbon stored as
stored in chloroplast as starch for use in night
84
what is the rate starch reserves are used
Starch reserves at night occurs at linear rate, and almost all reserves used up at dawn when photosynthesis starts again
85
what is vital for plant growth
Pattern of starch accumulation and breakdown during 24 hours is vital for normal growth of the plant
86
why is starch degradation under precise control
Flexibility and subtlety of this control is illustrated when plants are subjected to an unexpected early night
87
what is Erythrose 4- phosphate is used to initiate
complex biosynthetic pathway which gives rise to three amino acids, phenylalanine, tyrosine and tryptophan inside the chloroplast
88
where does Shikimate pathway occurs
chloroplasts
89
what Shikimate pathway starting point for
synthesis of many complex aromatic and alkaloid molecules including lignin
90
if amino acids not made what happens to plants
Amino acids not made, can’t form proteins, enzymes, cell walls – so die
91
what does chlorophyll absorb
two blue and red light wavelengths
92
why does chlorophyll absorb green wavelengths
because it is green
93
what causes a helium nucleus of slightly less mass
fusion of four protons in the sun results
94
what happens to the mass lost
converted to heat and electromagnetic radiation energy via the equation e=mc^2
95
what is the first step of light driven electron transport on thylakoid membrane
Light energy is captured by chlorophyll associated with two protein complexes in the photosystem II and photosystem I
96
what is the second step of light driven electron transport on thylakoid membrane
Flow of electrons between photosystems = generation of a proton gradient across thylakoid membrane, used to make ATP via the ATP synthase complex
97
what is the third step of light driven electron transport on thylakoid membrane
Electrons for this process come from water which is broken down using light energy into electrons, protons and oxygen gas
98
what causes plants to grow slower
pattern of starch accumulation and breakdown during 24 hours disrupted environmental changes grow less well than normal plants in predictable conditions carbon shortage at night leads to starvation symptoms and temporary slowing or growth stops

Biochemistry (13 decks)

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