Cell Ultrastructure

Description:

• Surrounded by a double membrane.
• Pores in the nuclear envolope.
• Dark staining area, nucleolus, within the nuclear envolope.
• Contains most genetic material.
• Largest organelle, aprox. 5 micrometers.

Function:

• Contains DNA organised into chromosomes.
• Pores allow ribosomes (synthesised by the nucleolus) to pass into the rest of the cell.

Desciption:

• Quantity depends on the activity of the cell.
• Bound by a double membrane.
• Inner membrane folded into finger like projections, called cristae.
• Central area contains a jelly, called matrix.
• Ribosomes and DNA (loop) float in the matrix.
• 0.5 micrometres in length.

Function:

• Cristae provide a large surface area for attaching enzymes.
• Matrix contains enzymes involved in cellular respiration.
• Inner membrane contains enzymes and proteins involved in respiration.

Description:

• Enclosed by a single membrane.
• Containing digestive enzymes.
• Spherical shape.
• Up to 1 micrometer in diameter.

Function:

• Enzymes used to recycle cell organic material or cell suicide.
• Membrane allows enzymes to be seperated from rest of cell. 

Description:

• Two hollow cylinders.
• Arranged at right angles to each other.
• Forming a ring of microtubules.
• Near the nucleus in animal cells.

Function:

• Used to organise spindle fibres used in nuclear division (mitosis).
• Only in animal cells.

Desciption:

• A series of single, flattened sacs enclosed by a membrane.
• Ribosomes on surface.
• The tubules forming ReR are up to 7.0x10-7m in diameter.
• Polypetide chains from bound ribosomes are threaded through into the eR space.
• Contains small membrane bound sacs called vesicles, containg the eR protein bud from the eR.

Function:

• Bound ribosomes which are threaded into eR space have their polypeptide chains folded into proteins.
• Glycoproteins may be formed by attatching carbohydrates to proteins.
• Vesicles containing eR protein buds are transported to other parts of the cell.

Description:

• No ribosomes.
• Sacs surrounded by membranes.
• Network of interconnected sacs in the cytoplasm.
• Continous with the outer membrane of the nuclear envolope.

Function:

• Synthesis of lipids.
• Carbohydrate metabolism.
• Detoxification of drugs and poisons.

Desciption:

• Stack of flattened sacs.

Function:

• Productions from the eR are modifed and stored before being packed into vesicles for transport.
• One side recieved vesicles from rest of cell.

Description:

• Attatched to the ReR and produced in the nucleolus.
• Can also be free floating in the cytoplasm.
• Both prokaryotic cells and eukaryotic cells have ribosomes but prokaryotic cells are smaller.
• Made of RNA and protein.

Function:

• Site of protein synthesis.

Desciption:

• Formed from 2 layers of phospholipid with proteins immersed inside.
• Phospholipids have a hydrophilic head facing cytoplasm and a hydrophobic tail facing towards the centre of the biolayer.

Function:

• Proteins in the membrane may be for structural support, enzymes, or in the assistance of molecule transportation across te membrane. 

Description:

• Fluid sac bound by a single membrane, called a tonoplast.
• Containing a solution of sugars, amino acids, waste product and mineral salts.
• Large vacuole in plant cells and a small non-permenant vacuole in animal cells.

Function:

• Temporary store of waste but can also contain hydrolytic enzymes.
• Supportive structure to keep cell rigid.

Description:

• Rigid and made of celulose fibres running through a mixture of other polysaccharides (complex sugars) such as pectins and hemiculluloses.

Function:

• Supportive structure.

Description:

• Large organelle only found in photosynthesising cells.
• At high magnifications grana can be seen.
• Have an envoloped membrane called a thylakid.
• Stack arrangements called grana.
• Surrounding the outer membrane is a stroma.

Function:

• To photosynthesise.

Description:

• Pectin layer joining 2 cells.
• Sticky to allow 2 cells to connect.

Function:

• Cements walls of 2 adjoining cells.
• Cell plate develops the middle lamella.

Description:

• Microscopic channels in the plant cell wall and membrane.

Function:

• Allows communication between cells and the transport of substances.

Description:

• Regions where the secondary cell wall is absent but primary wall is present.aka. Thinning of the cell wall.

Function:

• A simple pit isn't bordered and may be round or a slit shape.
• A circular bordered pit is round with a thickened margin.

Description:

• Non-pigmented organelle in a plant cell.
• Are plastids (cells that carry out photosynthesis).

Function:

• Synthesising and the production of starch granules using the polymerisation of glucose molecules.
• Also able to convert starch back to glucose if needed by the cell.
• Starch made is stored as it is insoluble.