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Cellular organelles and their functions (Mitochondria (Description - they…
Cellular organelles and their functions
Mitochondria
Description
- they are usually oval-shaped and have a double membrane. The inner membrane is folded in structures called cristae. Inside the cristae in the matrix. The matrix contains enzymes involved in respiration.
Function
- the mitochondria is the site of aerobic respiration. This process produces ATP which is an energy supply in the cell. Cells that are very active and require a lot of energy contain a lot of mitochondria.
Plasma membrane
Function
- the cell surface membrane controls the movement of substances going in and out the cell. It also contains receptors that can respond to chemicals such as hormones.
Description
- found on the surface of animal cells and just inside the cell wall of other cells. It is mostly made up of lipids and proteins.
Nucleus
Description
- It is a large organelle surrounded by a double membrane that contains a lot of pores. This membrane is called a nuclear envelope. The nucleus also contains chromosomes and a nucleolus.
Function
- the nucleus controls the transcription of DNA which controls the cell's activities. DNA contains the instructions needed to make proteins. The nuclear pores allow substances such as RNA to pass between the nucleus and the cytoplasm. The nucleus is also responsible for making ribosomes.
Chloroplast
Description
- small flattened structures found in plant and algal cells. It is surrounded by a double membrane. Inside, there are structures called thylakoid membranes. The thylakoid membranes are stacked up to form structures called grana. The grana are linked by thin flat pieces called lamellae.
Function
- the chloroplast is the site of photosynthesis in the cell. Some of the processes involved in photosynthesis occur in the grana and some occur in the stroma.
Golgi apparatus
Description
- a group of fluid-filled flattened sacs. Vesicles are often seen to the side of this.
Function
- Processes and packages new lipids and proteins. They also make lysosomes.
Golgi vesicle
Description
- A small fluid-filled sac found in the cytoplasm. It is surrounded by a membrane and produced by the golgi apparatus.
Function
- Stores the lipids and proteins that are made by the golgi apparatus. It also transports them out of the cell.
Ribosomes
Description
- Ribosomes are very small organelles that can float freely in the cytoplasm. It can also be attached to the REM. It is made up of RNA and proteins and is not surrounded by a membrane. There are two types of ribosomes: 80s and 70s.
80s
can be found in Eukaryotic cells.
70s
can be found in prokaryotic cells, mitochondria and chloroplasts. They are also bigger than
80s
Function
- The site where proteins are made
Lysosome
Description
- A round organelle with no clear internal structure. It is surrounded by a membrane. Lysosomes are a type of golgi vesicle.
Function
- Contains lysozymes. Lysozymes are digestive enzymes. They are kept separate from the cytoplasm by surrounding membranes. They can be used to digest worn down components if the cell and also any invading cells.
RER (Rough Endoplasmic reticulum)
Description
- A system of membranes enclosing a fluid-filled space. The surface of the RER is covered with ribosomes.
Function
- The RER folds and processes proteins that have been made at the ribosomes.
SER (Smooth Endoplasmic Reticulum)
Function
- Synthesises and processes lipids
Description
- Similar to the RER except there are no ribosomes on its surface)
Cell wall
Description
- A rigid structure surrounding cells in plants, algae and fungi. It is mainly made up of carbohydrate cellulose in plants and algae. In fungi, it is made up of chitin.
Function
- The cell wall supports the cell and prevents them from changing their shape.
Flagellum
Description
- A long hair like structure found on some bacteria cells.
Function
- Rotates to allow the cell to move
Cell vacuole
Description
- The cell vacuole in plants is an organelle bound by a membrane called the tonoplast. It contains cell sap. Cell sap is a weak solution of sugar and salts.
Function
- Helps to maintain the pressure inside the cell and keep the cell rigid by becoming turgid. The vacuole can isolate unwanted chemicals inside the cell. It can also act as a source of energy when needed.
Plasmids
Description
- Small loops of DNA. It is separate from the main nucleoid. This makes it ideal for passing between prokaryotes.
Function
- Can carry information such as antibiotic resistance
Nucleoid
Function
- Carries genetic information that controls the cell's activities.
Description
- Nucleoid means nucleus like. It is a tightly coiled loop of DNA that floats freely in the cytoplasm
Mesosomes
Description
- Mesosomes are similar to mitochondria. They are folded and clumped together to maximise the surface area. They are found lining the walls of prokaryotic cells.
Function
- The site of respiration