Week 5 Flashcards
What is Photosynthesis?
An anabolic process by which the energy of sunlight is harvested and used to convert CO2 into more comples molecules
Photosynthesis is endoergonic or esoergonic?
Endoergonic (It requires energy from the sun)
A compound that lose an electron become:
Oxydized
A compound that gain an electron become:
Reduced
Where does Photosynthesis take place?
Inside Thylakoids which are located inside the chloroplasts
What happen during Light reactions?
Light reactions convert energy from the sun into chemical energy in the form of ATP and the reduced electron carrier NADPH
What happen during light-independent reactions?
Don’t use light directly, instead they use ATP, NADPH and CO2 to produce carbohydrates
What are pigments?
Molecules that absorb wavelenghts in the visible spectrum
What does chlorophyll drives?
Chlorophyll drives the production of ATP and NADPH
What are ATP and NADPH used for in the Calvin Cycle?
They’re used to fix CO2 and produce sugar
When a photon meets a molecule it can interact in 3 ways:
- Scattered
- Transmitted
- Absorbed
What happen when a photon is absorbed?
Absorption transfers the energy from the photon to the molecule and the molecule become excited
Why are the plants green?
When a photon of a particular wavelenght it a plant it will be absorbed but green photons are reflected
List the different types of Photosynthetic pigments:
- Chlorophyll a
- Chlorophyll b
- Accessory pigments
What’s the role of accessory pigments?
Absorb different light spectrum and transfer their energy to chlorophyll
What can happen when a pigment absorb a photon?
The energy can be:
- Released as heat/light
- Transferred to another molecule
- Used to drive a chemical reaction
What’s the structure of chlorophyll?
It has got a magnesium ion that coordinates the flat structure and a long carbon tail which attach it to a protein structure
What do photosystems do?
They harvest photon to excite chlorophyll which will pass the nergy to another chlorophyll molecule until it reaches the reaction center.
What happen when the energy is passed to a reaction center in the photosystem?
The last excited chlorophyll will pass its electron to an electron acceptor
Describe the features of Photosystem II
It’s primary donor is P680, a photon reaches the chlorophyll, it will absorb its energy an pass it to P680 (The reaction center).
How does the reaction center get an electron back?
By oxydizing water
Describe the features of Photosystem I
It’s primary donor is P700, which mean that it’s activated by less energy. It will cause the electron to move up and consequently 2 electron will reach NADP+ reductase
What’s NADP+ reductase
It’s an enzyme that will cause the reduction of NADP+ to NADPH
What’s the name of the process that link the 2 photosystem?
The Z scheme
Describe the cyclic electron transport
In this electron transport the electron goes back into the same photosystem causing production of ATP.
What’s chemiosmotic production of ATP?
It’s a process that occurs as the electron is passed down the transport chain it causes protons (H+) to be bumped in the lumen (against osmotic gradient so it requires energy). At the end all these electron pass through a special molecul called ATP synthase which produce ATP as protons pass through it.
Why is the production of ATP called chemi-osmotic?
Because it involves two gradients: One of ion/charges and one of concentration.
What are the 3 phases of Calvin Cycle?
Carbon fixation
Reduction and sugar production
Regeneration of the CO2 acceptor
What’s the role of riboluse bisphospate?
It’s a five carbon acceptor
When did photosynthesis first appeared?
2.7 billion years ago
What was used for photosynthesis instead of water?
Hydrogne Sulfide (H2S)
How may photosynthesis have evolved?
The depending on sulfide limited the process so photosynthetic organisms started using H2O which required a stronger oxidizing agent. Therefore it required the evolution of photsystem II.
What are the advantages of multicellularity?
- Avoidance of predation
- Overgrowth of unicellular competitors
- Expanded feeding opportunities
- Creation of protected internal environments
- Novel metabolic opportunities
- Enhanced motility and dispersal
What’s avoidance of predation:
Unicellular organisms have only engulfment as a way of predation, but as the prey become bigger it become difficult to eat it. However become bigger it’s a problem so by combining with other cell you overcome the problem and you can enlarge.
What’s overgrowth of unicellular competitors?
When you’re an individual you’ll grow at your own rate but when you’re multicellular you can make some cell specialize in growing faster so you outcompte unicellular organisms.
What are the 3 criteria of multicellular organisms and not the colonies?
- Their cells must be held together by a multicellular matrix
- Their cells must be able to comunicate with eacht other and respond to signals in a coordinated way
- They must have to include different type of cells, each specialise in a particular role.
What are the basic requirements for a multicellular organism?
- Cell adhesion
- Cell signaling and coordination
- Programmed cell death (apoptosis)
- Capacity for cellular differentiation
In which two ways could the first multicellular organism have arisen?
1) Clonal development by division of a single cell
2) Aggregation of individual cells
