The nucleus is the largest organelle found in animal and plant cells, at around 7-10 micrometres. Its main function is to control the cell.
- Contains chromatin
- Surounds the nucleolous and is surrounded by two membranes with a small gap between, called the nuclear envelope.
- Nuclear envelope contains nuclear pores that allow molecules through.
- It is found in almost all cells, apart from red blood cells and phloem sieve tubes in plants.
- Houses genetic material
- Creates ribonucleic acid and ribosomes.
- These travel out of the nucleus, through the nuclear pores, to the cytoplasm where they are involved in protein synthesis.
They are found near the nucleus and are made of flattened sacs called cisternae, which are continuous with the nuclear envelope.
- Studded with ribosomes.
- Transports proteins which are made on the attached ribosomes.
- Some of these proteins may be secreted.
- Some of these proteins may be placed on the cell surface membrane.
- Involved in making lipids and the production of steroids.
The golgi apparatus is found in both plant and animal cells and the main function is to 'package and process' proteins.
- Variable in size.
- A stack of membrane bound, fluid filled sacs, often found near the nucleus.
- Receives proteins from the ER and modifies them, eg- it may add a sugar molecule.
- Packages modified proteins into vesicles for transport.
- Some proteins may be secreted.
- Some proteins may go to the cell surface membrane.
Lysosomes are only found in animal cells. Their main function is to break down worn out components of cells.
- Contain extremely powerful digestive enzymes.
- Break down foreign substances like pathogens.
- Specialised lysosomes (acrosomes) in the head of a sperm cell contain enzymes to help penetrate the egg by breaking down the material surrounding it.
- Variable in size.
- Spherical sacs surrounded by a single membrane.
Mitochondria are found in animal and plant cells and are the site of respiration where ATP is produced.
- 2-5 micrometers.
- Called the universal energy carrier because ATP provides energy for almost all cellular activities.
- Has a sausage shape structure and 2 membranes.
- Inner membrane folded inside to form cristae, which are folded in the matrix (central part of mitochondrion).
Chloroplasts are only found in plant cells and are the largest organelle in plant cells, besides the nucleus.
- 5 micrometers.
- Used for photosynthesis.
- Contains chlorophyll.
- Membrane bound disk shaped organelle containing stacks of membranes.
- This forms the surface for reactions of photosynthesis.
- Contain 2 fluid separated membranes.
- Inner membrane folded into a netwrk of flattened sacs called Thylakoids, that are stacked into grana (one granum, two grana).
Vesicles are found in animal cells and are used to transport many different substances around the cell.
- The size is variable but usually around a few micrometers.
- Regulates pressure and water in cells.
- membrane bound sacs.
- Various functions and are common in secretory cells.
- Hydrophilic head and hydrophobic tail.
- Consists of fluid enclosed by a lipid bilayer membrane.
- Can form naturally.
- Large vesicles formed by smaller vesicles joining.
- Membrane bound.
- Have no specific shape.
- Contain water with many compounds in it.
- Function depends on cell- eg turgor pressure in plants.
Ribosomes are found in animal cells and provide a surface for protein synthesis.
- Act as an assembly line where coded information (mRNA) from the nucleus is used to assemble protens from amino acids.
- Small spherical organelle composed of 2 subunits which can be found on the rough ER, cytoplasm and other places.
- Translate genetic information in the form of mRNA into proteins.
Centrioles are small tubes of protein fibres that are usually 500 nm long.
- Small hollow cylinders containing a ring of microtubules.
- Take part in cell division and move chromosomes around.
- Tubular structure containing 9 microtubules.
- When two are next to eachother, they are usually at right angles.
- Absence of centrioles causes divisional errors.
- Usually in pairs next to the nucleus.
Flagellae/ cilia are found in animal cells, and are used for movement in cells such as sperm and aquatic bacteria.
- Nine micotubules surrounding.
- Called undulipodia in eukaryotes.
- Clilia are short versions and are less than 10 micrometres long.
The cell wall is found in plant cells and can be anywhere from 5-100 nm thick.
- permeable, tough, flexible and sometimes rigid layer that surrounds plant and bacterial cells.
- Located outside the cell membrane and provides support and protection, as well as acting as a filtering mechanism.
- Made of cellulose (in plants).
- Only present in plants and prokaryotes like bacterial cells.
The cytoskeleton provides a stable internal framework for the cell.
- Made up of microtubules.
- The microtubules have a diameter of 25nm but join tgether to make the size of a cell.