CSEC: CELLS - simple but important.......LEARN IT!

Parts of the UNSPECIALISED cell

"It is important that you learn to DRAW & EXPLAIN the function of these cell organelles" 
Circles and dots will not work when you are representing cell organelles...... 

DIAGRAM OF AN UNSPECIALISED PLANT CELL

Cell Membrane This is a thin, flexible layer round the outside of all cells made of phospholipids and proteins. The function of the cell membrane is to allow waste material to exit the cell. The cell membrane forms a barrier between the inside of the cell and the outside, so that the chemical environments on both sides can be different. It regulates the movement of materials into and out of the cell.

Cell Wall The function of the cell wall is to provide structural support. It gives rigid support due to its strong cellulose component. It has plasmodesmata which are small breaks in the wall itself. They allow substances to enter and leave the cell.

Golgi Body The Golgi body stores, packages, and distributes the lipids and proteins made in the endoplasmic reticulum. It puts proteins into packages, called vesicles.

Rough Endoplasmic Reticulum (RER) The RER is generally a series of connected flattened sacs, studded with numerous ribosomes, which give it its rough appearance. The ribosomes synthesise proteins, which are processed in the RER 

Smooth Endoplasmic Reticulum (SER) Makes lipids and steroids and package proteins for transport.

Lysosomes These are small membrane-bound vesicles formed from the RER containing a mixture of digestive enzymes. They are used to break down unwanted chemicals, toxins, organelles or even whole cells, so that the materials may be recycled. They can also fuse with a feeding vacuole to digest its contents. Lysosomes are the cell’s garbage disposal system. They clean up while patrolling the cell. This organelle breaks down large molecules into many smaller molecules by using their special proteins. Lysosomes also kill and digest invading organisms.

Cytoplasm The function of the cytoplasm is to distribute oxygen and food (nutrients) to other parts of the cell and it supports all parts inside the cell. It has three main functions: storage, energy, and manufacturing. The cytoplasm contains nutrients that have been dissolved which help for the dissolving of waste products.

DIAGRAM OF AN UNSPECIALISED ANIMAL CELL

Vacuole These are membrane-bound sacs containing water or dilute solutions of salts and other solutes. Most cells can have small vacuoles that are formed as required, but plant cells usually have one very large permanent vacuole that fills most of the cell, so that the cytoplasm (and everything else) forms a thin layer round the outside. Plant cell vacuoles are filled with cell sap, and are very important in keeping the cell rigid, or turgid. Some unicellular protoctists have feeding vacuoles for digesting food, or contractile vacuoles for expelling water.

Ribosomes - Ribosomes are the protein builders or protein synthesizers of the cell.

Chloroplast Chloroplasts are the food producers of the cell. They contain chlorophyll, the green pigment that is needed for photosynthesis. Through the process of photosynthesis, green plants use the energy from the sun to convert it into sugar. The main purpose of this organelle is to produce sugars and starches.

Nucleus This is the largest organelle. Surrounded by a nuclear envelope, which is a double membrane with nuclear pores - large holes containing proteins that control the exit of genetic substances and ribosomes from the nucleus. The interior is called the nucleoplasm, which is full of chromatin- a DNA/protein complex. During cell division the chromatin becomes condensed into discrete observable chromosomes.

Nuclear Envelope The nuclear envelope (double membrane) surrounds the nucleus and all of its contents. It is similar to the cell membrane around the whole cell. There are pores and spaces for RNA (genetic materials) and proteins to pass through while the nuclear envelope keeps all of the chromatin and the nucleolus inside.

Nucleolus The nucleolus is where ribosomes are made. The nucleolus disappears during cell reproduction. This is because ribosomes are not needed when cells reproduce.

Mitochondria The function of the mitochondria is to provide the cell with energy. Through the process of respiration, the mitochondria uses oxygen to change sugar into energy. It gives out energy by combining sugar molecules with oxygen to make carbon dioxide and water.