#calvin cycle

[studyblr-of-a-biomed-student]

I had my Biochemistry Final

[biostudyblog]

Photosynthesis

While cell respiration produces CO2 and water as byproducts, photosynthesis uses CO2 and water. It produces sugar and oxygen as byproducts (along with water) which is necessary for cell respiration. 

The Chloroplast

Photosynthesis occurs within the chloroplast. The chloroplast is an organelle enclosed by a double membrane. It contains grana (containing layers of membranes called thylakoids). This is where the light-dependent reactions occur, and the stroma, where the Calvin Cycle (light-independent reactions) occur.

Light and Photosynthetic Pigments

When light hits an object, it is either reflected, transmitted, or absorbs. If you look at a yellow lemon, that yellow lemon absorbs all other colours, other than yellow, which it reflects, causing you to perceive it as yellow. If you shine green light on a green plant, all the light would be reflected, and the plant would die.

Photosynthetic pigments absorb light energy and use it for photosynthesis. Substances that absorb light in the visible spectrum are pigments. 

Chlorophyll a, the green photosynthetic pigment participates directly in light-dependent reactions. Other pigments, also called antennae, or accessory pigments assist in photosynthesis by capturing and passing photons of light to chlorophyll a, expanding the range of light that can be absorbed.

Chlorophyll b, carotenoids, and phycobilins are all examples of accessory pigments. Chlorophyll b is green, carotenoids are yellow, orange and red, and phycobilins are red. (Red algae in the deep ocean have these pigments

Light-Dependent and Light-Independent Reactions

Light-Independent reactions used to be called dark reactions, however, we now know that both reactions only can occur in the light.

Light-Dependent Reactions

Light-dependent reactions occur in the grana, within the thylakoid membranes. Thylakoid membranes are filled with light-absorbing complexes called photosystems. They contain chlorophyll a, chlorophyll b, and carotenoids. It is during this stage of photosynthesis that huge amounts of ATP are produced.

ATP is produced in chloroplasts the same way as in mitochondria, through ETC’s and chemiosmosis. When chlorophyll absorbs light, the electrons become energized, escape from the chlorophyll and enter the ETC. The energy from these electrons pumps protons across the thylakoid membrane, creating the protein gradient. The potential energy created by this is used to make ATP as protons flow through ATP synthetase channels. 

Water is necessary to replace the lost electrons. Water breaks down via photolysis into its components: electrons, protons, and oxygen atoms.

The electrons replace what the chlorophyll lost. The protons pass through ATP synthetase channels and are carried by NADP to the stroma to participate in light-independent reactions. Oxygen is released as a waste product.

Light-Independent Reactions

While light-dependent reactions make energy, light-independent reactions make the sugar PGAL. It occurs in the stroma. CO2 combines with protons and electrons from the light-dependent reactions, carried by NADP to make PGAL.

When CO2 is incorporated into a sugar molecule, it is called carbon fixation. This takes place during the Calvin cycle, which requires a lot of ATP. It also requires the enzyme rubisco in order to take place.

Structure of the Leaf

The palisade layer consists of tightly packed cells containing chloroplasts. This is where the majority of photosynthesis occurs. The spongy mesophyll also contains chloroplasts, however, they are less tightly packed, as they are surrounded by air spaces which allow the exchange of oxygen, carbon dioxide, and water vapour. The epidermis does not carry out photosynthesis. Above the epidermis is the waxy cutin called cutin, minimizing water loss. Guard cells open and close stomates which are necessary for gas exchange. Guard cells can photosynthesise.

[er-cryptid]

Light-Independent Reactions

-- Calvin cycle

-- occurs in stroma of chloroplast

-- inputs      -- NADPH      -- ATP      -- CO2

-- first step is carbon fixation

-- this is catalyzed by the enzyme rubisco

-- a series of reactions occur

-- produce      -- NADP+      -- ADP      -- sugar

-- more ATP is used than NADPH

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[faeinting]

3.1.19

Wow look at me being a regular poster!

I really love how this set of notes came out, they simplify everything yayyy

I'm thinking of starting my first bujo after exams on a grid notebook. Anyone got some tips?

[studymaias]

|2.28.18| studying the Calvin cycle for my exam on Friday with a fun little drawing I enjoyed making 😊

[delusionalcabbage]

Summer revision vibes 🍡🍡🍡 I wish I was at the beach (T ^ T) but the pastel highlighters make everything better... by the way there's a really good TedEd video on the Calvin cycle if anyone needs to revise it, it's on YouTube

[teachersource]

Melvin Calvin was born on April 8, 1911. An American biochemist known for discovering the Calvin cycle of photosynthesis along with Andrew Benson and James Bassham, for which he was awarded the 1961 Nobel Prize in Chemistry. The Calvin cycle is present in all photosynthetic eukaryotes and also many photosynthetic bacteria. Calvin spent most of his five-decade career at the University of California, Berkeley.

[ryuu-from-the-grave]

Me @ the botanist/biologist whomst the fuck ever decided that they should name reactions that don’t work in the dark, “dark reactions:” WHY