Eukaryotic Organelles
- Created by: VittoriaAnna
- Created on: 13-10-15 19:33
Nucleus:
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
.
Nucleolus:
- 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.
Endoplasmic Rectilium:
They are found near the nucleus and are made of flattened sacs called cisternae, which are continuous with the nuclear envelope.
Rough ER:
- 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.
Smooth ER:
- Involved in making lipids and the production of steroids.
Golgi Apparatus:
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:
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:
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:
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:
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.
Vacuoles:
- 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:
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:
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:
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.
Cell Wall:
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.
Cytoskeleton:
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.
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