Photosynthesis and Chloroplast Structure

Study Notes

Photosynthesis

Photosynthesis is the process where organisms use light energy, carbon dioxide and water to create food.
This process occurs within chloroplasts of plant cells.
Chloroplasts are specialized organelles that contain chlorophyll, a pigment which gives plants their green color.
Each plant cell contains one to hundreds of chloroplasts.
Plant cells are eukaryotic meaning they have a unique membrane surrounding them and a nucleus that regulates cell functions.
The cell wall provides structure and protects the cell.
The plasma membrane regulates chemicals and supplies going in and out of the cell, also used for communication.
Plasmodesmata allows communication and flow between cells.

Chloroplast Structure

Chloroplasts have an outer membrane, inner membrane, stroma, granum, thylakoid, lamella, and lumen.
Chlorophyll is found within the thylakoid membranes of the chloroplast.
Chlorophyll absorbs light into the chloroplast cell.
Chlorophyll Type A, the green-colored chlorophyll, is mainly responsible for photosynthesis.
The outer and inner membranes regulate the movement of molecules in and out of the chloroplast.
The stroma is a fluid found in the chloroplast cavity.
The light-independent reaction process of photosynthesis takes place in the stroma.
Granum are stacks of thylakoids.
Thylakoids, or grana, are the sites of the light-dependent reaction process of photosynthesis and contain chlorophyll.
The lamella acts as a filter for chemicals entering or leaving the chloroplast.
The lumen is inside the thylakoids and is where oxygen is produced during photosynthesis by removing hydrogen atoms from water.
Chloroplast DNA contains instructions for photosynthesis.
Chloroplasts also have ribosomes that are responsible for energy conversion during photosynthesis and carbon fixation during the Calvin cycle.
The endosymbiotic theory suggests that chloroplasts evolved from prokaryotic single-celled organisms.

Photosynthesis Processes

There are two main processes involved in photosynthesis: the light-dependent reaction and the Calvin cycle.
The light-dependent reaction occurs in the thylakoid membranes.
Sunlight energizes electrons in chlorophyll molecules, creating an electron transport chain.
Energy is released from the electron transport chain to create ATP and NADPH.
As electrons lose energy, chlorophyll molecules replace them with hydrogen (H+) protons from water (H2O).
Oxygen (O2) is released as a byproduct.
The Calvin cycle, or light-independent reaction, takes place in the stroma.
Energy from ATP and NADPH is used to create glucose (a type of sugar).
The Calvin cycle has three main stages: carbon fixation, reduction, and regeneration.
Carbon fixation involves enzymes creating new compound elements.
Reduction converts one compound into another and recycles certain molecules.
Regeneration sends some molecules back to the light-dependent reaction while others form glucose.

Thylakoids

Thylakoids are small, oval-shaped structures composed of membranes containing chlorophyll.
Stacks of thylakoids are called granum.
Chlorophyll A is located in the thylakoids and is essential for photosynthesis as it absorbs specific wavelengths of light energy.
The thylakoids are the site of the light-dependent reaction.

Stroma

Stroma is the liquid material found throughout the chloroplast cavity.
It provides volume and protection for different structures inside the chloroplast.
The Calvin cycle takes place in the stroma.
Glucose produced by the Calvin cycle remains in the stroma until needed.

Description

Explore the fascinating process of photosynthesis and the intricate structure of chloroplasts in plant cells. This quiz covers the role of chlorophyll, the components of chloroplasts, and how plant cells function. Test your knowledge of these essential biological concepts!