Organelle Structures and Funtions.

Nucleus * Largest organelle * Houses the majority of the cells genetic information. * Has instructions for making proteins - * Some of which regulate cell activity
Within the nucleus- Structure - | Function - | * Dark patches shown when stained are called Chromatin(s) | * Chromatins consist of DNA and proteins. In mitosis condense and become visible chromosomes. | * Surrounded by Nuclear envelope | * Phospholipid bi-layer with fluid between them with pores allowing molecules to pass through | * Dense spherical structure within the nucleus called the Nucleolus | * Makes RNA and ribosomes which pass into the cytoplasm for use in protein synthesis |

Nuclear envelope * Encloses genetic materials in eukaryotic cells * Allows free movement of ATP, oxygen and small ions i.e. water, Co2 Structure - | Function - | * Phospholipid bi-layer | * Physical barrier between the contents of the nucleus and the cytoplasm | * Nuclear pores | * Facilitate and regulate exchange of materials i.e. RNA & Proteins between the nucleus and cytoplasm |

Endoplasmic reticulum * Flattened membrane-bound sacs called cisternae * Continuous with the outer nuclear membrane Structure | Function | Rough ER – Studded with ribosomes | To transport proteins made on the ribosomes for secretion from the cell or use on the cell surface membrane | Smooth ER – No ribosomes | Involved in making lipids required by the cell |

Golgi complex * Processes proteins & lipids destined for the plasma membrane, lysosomes or endosomes * Combines simple molecules to make more complex molecules before compressing and sorting them for either storage or transportation. Structure | Function | CIS face | Substances enter from the endoplasmic reticulum (ER) for processing | Cisternae | Flattened membrane disks that make up the Golgi body | Lumen | Site where sulfation of substances passing through the Golgi body happens | }
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Newly forming vesicle | Complex molecules which have been compressed for sorting & transportation through trans face | Trans face Exocytotic vesicles Secretory vesicles Lysosomal vesicles | Proteins are sorted and transported to their destination via 1 or more of these vesicles depending on the molecular marker. |
Ribosomes
* Tiny organelle * Some in the cytoplasm and some bound to the rough ER * Each ribosome consists of 2 sub units * No membrane

Function * Site of protein synthesis * Act as an assembly line where coded information (mRNA) from the nucleus is used to assemble proteins from amino acids

Mitochondria

Structure * 2 membranes * fluid inside is called the matrix * Spherical or ‘sausage shaped’
Function
* Site of ATP production during RSP * Almost all energy needed by cells comes from ATP Structure | Function | Outer membrane | Covers the organelle and contains it | Inner membrane highly folded to form a Cristae | Increases the surface area to allow more reactions and work to be done |

Lysosomes

Structure * Spherical sacs surrounded by a single membrane

Function * Contain powerful digestive enzymes * Breakdown materials i.e. White blood cell lysosomes help breakdown foreign microorganisms * Specialised in a sperms acrosome to breakdown the eggs outter membrane allowing the sperm to penetrate it.

Chloroplasts Structure * Only found in plant cells and some protoctist cells * Have 2 membranes separated by fluid filled space * Inner membrane is continuous with a network of flattened membrane sacs called thylakoids. * A stack of thylakoids is called a Granum / Grana * Chlorophyll molecules are found on the surface of the thylakoid membrane and intergranal membranes.

Function * Site of PHS in plant cells * Light energy is used to drive the reactions of PHS * Carbohydrate molecules are made from Carbon dioxide and water during PHS.

Plasma membrane

Structure * Made up of proteins and phospholipids - Fluid mosaic model * Phospholipid bi-layer approx. 7nm thick * Phospholipids consist of a hydrophilic head and 2 hydrophobic tails * The heads face out of the cell / surface and the tails are inside the cell – tail to tail O-- --O * Proteins are embedded into the membrane

Function

* Partially permeable barrier to water soluble molecules, charged molecules, polar substances * Allows – Lipid soluble, non-polar, uncharged molecules and tiny molecules i.e. Water & Co2 to cross the barrier

Centrioles

Structure * Small tubes of proteins fibres (microtubules) * Found in pairs next to the nucleus in animal cells and some protoctist cells

Function * Take part in cell division * Known as spindles which move chromosomes during nuclear division – * When the centrioles start to divide they move to opposite ends of the cell leaving a trail of microtubules / spindle fibres