CELL ORGANELLES

• Cell organelles include the cell membrane, cytoplasm, nucleus, nucleolus, endoplasmic reticulum, Golgi body, lysosomes, mitochondria, cilia, and flagella.
• The cell membrane is a thin layer with channels that allow molecules to pass in and out, and it is part of the fluid mosaic model which means the molecules are constantly changing position.
• The cytoplasm is a jelly-like or watery material where the organelles are located.
• The nucleus is the largest organelle of the cell and is separated from the cytoplasm by the nuclear membrane which contains nuclear pores that allow large molecules to pass through.
• DNA or deoxyribonucleic acid contains all inherited characteristics and is a thin thread when not dividing and thickened threads when dividing known as chromosomes.
• The DNA contains the information that determines what type of protein the cells can make.
• The nucleolus is an area inside the nucleus that is involved with protein manufacture.
• Ribosomes are small spherical organelles that join together and make amino acids into proteins.
• The endoplasmic reticulum consists of pairs of parallel membranes that provide an area for chemical reactions and store and transport molecules.
• The Golgi body or Golgi apparatus consists of flattened membranes stacked on each other and is located near the nucleus, it modifies proteins for secretion from the cell.
• Lysosomes are formed from the Golgi body and contain a digestive enzyme that allows them to breakdown large molecules, they breakdown worn out organelles and can combine with vesicles to break down things inside the vesicles.
• Mitochondria, singular mitochondrion, are spherical sausage shaped structures with an outer membrane and a folded inner membrane, some of the reactions of cellular respiration occur in the mitochondria.
• Cilia are projections that are short and numerous and resemble hair, while flagella have only one or two of them and are longer.
• The cytoskeleton consists of microtubules and microfilament that give the cell structure.
• Inclusions in cells can include haemoglobin and pigment and melanin.
• Cell size is typically 10 – 15 micrometres, 1 micrometer is one thousandth of a millimeter, a small size gives them a large surface area to volume ratio.