Photosynthesis

Photosynthesis

Photosynthesis - A process in which sunlight energy is used to make glucose.

This biochemical process is carried out by…

• Plants
• Algae
• Some types of bacteria

This process is meant to feed these organisms and give out air. Plants use light energy from the sun to transform CO2 from the air with water from the ground into glucose. This process happens in the chloroplast of the plant cell. Oxygen is created as a waste product and released into the air while this process occurs. This makes plants autotrophs because theyŕe making their own food.

• The plant gets water from the soil through its roots
• The plant collects carbon dioxide from the air
• Carbon dioxide enters the plant through the stomata

Stomata - Pores of plant leaves

• Also from organisms exhaling, factory smokestacks, car fumes
• Light energy is from photons

Photons - High energy particles released by the sun and travel towards earth.

During the Process:

1. Plant takes in carbon dioxide and water
2. (Within plant cell) water is oxidized and carbon dioxide is reduced
3. The water and carbon dioxide is transformed into glucose
4. The plant releases oxygen into the air and stores energy within the glucose molecules

Oxidized - Loses electrons

Reduced - Gains electrons

Photosynthesis formula:

CO2 + H2O + sunlight →C6H12O6+O2

Carbon dioxide, water, and sunlight are the inputs of photosynthesis. The outputs are glucose and oxygen. Although carbon dioxide and water are the reactants to this chemical reaction, they don't react to each other. Instead, they´re used in different parts of photosynthesis.

• The oxygen product is used by animals to breath

• Plants need oxygen when there is no sunlight

• Like animals, plants use cell respiration

  

Inside the Plant Cell

Chloroplasts - Small organelles inside the plant cell that store the energy of sunlight

• Chloroplasts are found in plants and algae
• Chloroplasts have chlorophyll
• Chloroplasts have grana

Grana

Grana - stacks of disk-like structures that are found inside of chloroplasts

Thylakoids - disk-like structures

• Each thylakoid has its own membrane

Thylakoid Membrane & Light Independent Reactions

At the thylakoid membrane, light energy is absorbed and converted into chemical energy.

• Water is needed
• Light energy is used to make the 2 molecules… ATP and NADPH
• The chlorophyll absorbs energy from light waves which converts to chemical energy

^The chemical energy in the form of ATP & NADPH

• These processes are called light-dependent reactions because they need light
• Plants use two photosystems for light-dependent reactions

Photosystems

• Photosystem I happens after photosystem II

-They were named in order of the discovery of them by scientists

• Key: Photosystem II (PSII) Photosystem I (PSI)
• Photosystem II makes ATP
• Photosystem I makes NADPH
• Photosystems need water to make ATP and NADPH

^This is one of the reasons why plants need water to survive

Photosystem II

1. An enzyme inside of PSII splits water into hydrogen ions, oxygen gas, and electrons
2. Hydrogen ions (H+)
3. The O2 is a waste product and diffuses out of the cell

• This is how plants make oxygen for animals

1. H+ moves through ATP synthase

Atp synthase - An enzyme that makes ATP

1. ATP synthase adds a phosphate to a molecule called ADP to make ATP

• ATP is an energy source to many chemical reactions in cells

1. The electrons from the water split are passed to the chlorophyll in PSII
2. Energy from the sunlight is added to the electrons which makes high energy electrons

High energy electrons - Electrons with energy from sunlight

1. The high energy electrons move through the electron transport chain

Electron transport chain - A chain of proteins

• As they move, some of their energy is used to move H+ into the thylakoid

^As H+ moves into the thylakoid, the H+ concentration in the thylakoid increases

^² The H+ ions make ATP

1. The transport chain moves the high energy electrons to PSI

Photosystem I

1. When the electrons arrive at PSI, they’re low energy electrons
2. Chlorophyll absorbs light energy and gives it to the electrons

• This makes them high energy electrons

1. An enzyme adds the high energy electrons and H+ to NADP+
2. NADP+ becomes NADPH

• PSII supplies PSI with electrons and if PSII doesn’t work then PSI won’t get the electrons to make NADPH

Calvin Cycle and Light Independent Reaction

• The calvin cycle takes place in the stroma.

Stroma - A space between the thylakoid membrane and the chloroplast membranes

• The calvin cycle is the synthesis part of photosynthesis
• The calvin cycle is a light independent reaction because it doesn’t require direct light
• The calvin cycle produces carbohydrate molecules
• Assembled from energy from ATP and NADPH molecules
• The carbohydrate molecules are from carbon dioxide
• The calvin cycle uses the chemical energy and CO2 to make sugars
• Chemical energy (ATP and NADPH)

1. Rubisco takes the carbon from CO2 and adds it to a carbohydrate molecule

Rubisco - An enzyme of the calvin cycle that makes carbon fixation occur

Carbon fixation - When the rubisco takes carbon from CO2 and adds it to a carbohydrate molecule

• Rubisco gives plants and algae the carbon they need to make sugars by fixing CO2

1. The other enzymes use chemical energy in ATP and NADPH to make sugars

• The calvin cycle needs ATP and NADPH to make sugar. Without them the calvin cycle can’t make sugar

Chlorophyll during Photosynthesis

Chlorophyll - Pigment responsible for giving plants their green color

1. Gets hit by blue- and red-light waves
2. Absorbs energy from blue- and red-light waves
3. Reflects green-light waves

^Makes plant appear green

• Chlorophyll is part of photosystems I and II to make light-dependent reactions

https://education.nationalgeographic.org/resource/photosynthesis

https://apps.explorelearning.com/gizmos/launch-gizmo/3054/2188613