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Organelles (Nucleus (The Nuclear Envelope and Nuclear Pores:
-The…
Organelles (Nucleus, Lysosomes, Mitochondria, The Golgi Apparatus (body), Cell Wall, Vacuole, Cytoplasm:
-Suspended in the cytoplasm are a number of specialised cells., The Rough Endoplasmic Reticulum (RER)
-It extends out from the nuclear envelope and continues with it .
-The RER is covered in ribosome which are the sites of protein synthesis (making protein)
-The RER helps transport proteins which have been made in the ribosomes to where they are needed.
-Some proteins may be secreted from the cell.
-Some proteins may be placed on the plasma membrane. , Ribosomes:
-They are made of protein and ribosomal RNA (ribonucleic acid)
-Ribosomes translate the instructions carried on MRNA into protein (making protein)
-Ribosomes can be attached to membrane (RER) or free in the cytoplasm.
-Ribosomes consist of one large and one small sub unit with a total size nm. , The Smooth Endoplasmic Reticulum (SER)
-It is a second type of endoplasmic rectulum which also occurs in the cytoplasm.
-SER is important in synthesising (making) and transporting lipids, steroids and hormones.
-Example:In the Ovaries and testes it is a site of production of hormones such as oestrogen,steroids, insulin,glycogen and testosterone.
-Unlike the RER, there are no ribosomes associated with SER., Cytoskeleton:
-Is a network of fibres made of protein.
What does the cytoskeleton do?
-It keeps the cells shape stable by providing an internal framework called the cytoskeleton.
The 2 main types of fibres are:
Microtubules-Help move organelles and other cell contents e.g:chromosomes.
Microfilaments-These are smaller than microtubules and act as a 'skeleton' helping to support the cell and are also responsible for cell movement.
Some of the Overall roles of the cytoskeleton:
-It determines the shape of the cell.
-Is involved in the movement of organelles in place.
-It makes up centrioles or spindle fibre.
-It helps hold organelles in place. , Centriores:
-Are only ever found in animal cells not plant cells.
-These are small tubes of protein fibres (microtububules) there is a pair of them next to the nucleus in animal cells.
-Centrioles are involved in cell division when they generate spinale fibres which are responsible for the separation of chromosomes., Flagella and Cilla:
-They are structurally the smae.
-They are hair like extensions that stick out from the surface of cells and are often involved in movement.
Cilla: It is used for relatively short structures, e.g:cilliated epithelial cells.
Flagella or undulopodia: may be used for relatively long structures which are often found in ones or twos, e.g:sperm cells, in eukaryotic cells flagella is called undulopodia.
-Some bacteria have flaella , they look simular but are very different in structure from undulipodia in ekaryotic cells., Chloroplast:
-They are only found in plant cells
-They are surrounded by a double membrane or envelope.
-Flatterened sacs or thylakoids run through the internal solution or stroma.
-The sacs are stacked in places. Here they are called grana(singular granum).
-They are the site of photosynthesis. Grand traps light energy which is used to fix carbon dioxide stroma.
-Chloroplast is an organelle where photosynthesis takes place in producing sugars and other organic nutrients for the cell.
-They are the site of photosynthesis. Grand traps light energy which is used to fix carbon dioxide stroma.
-Flatterened sacs or thylakoids run through the internal solution or stroma.
-They are surrounded by a double membrane or envelope which is permeable to many small ions.
-The sacs are stacked in places. Here they are called grana(singular granum).
Thylakiods:Are fluid-filled sacs which are stacked up in the chloroplast into structures called granum (singular).)