DNA Into Protein

DNA into protein. The nucleus contains the genome. In humans the genome is split between 23 pairs of chromosomes. Each chromosome contains a long strand of DNA tightly packaged around proteins called histones. Within the DNA there are sections called genes. These genes contain the instructions for making of proteins. When a gene is switched on, an enzyme called RNA polymerase attaches to the start of the gene. It moves along the DNA making a strand of messenger RNA out of bases in the nucleus. The DNA code determines the order in which the free bases are added to the messenger RNA. This process is called transcription. Before the messenger RNA can be used as a template for the production of proteins, it needs to be processed. This involves removing and adding sections of the RNA. The messenger RNA then moves out of the nucleus into the cytoplasm. Protein factories in the cytoplasm called ribosomes, bind to the messenger RNA. The ribosome reads the code I the messenger RNA to produce a chain made up of amino acids. There are 20 different types of amino acids. Transfer RNA molecules carry the amino acids to the ribosome. The mRNA is read three bases at a time. As each triplet is read a transfer RNA delivers the corresponding amino acid. This is added to a growing chain of amino acids. Once the last amino acid has been added, the chain folds into a complex 3D shape to form the protein. Endoplasmic Reticulum • • • • • • • • • Largest membranous system in the cell Primarily, it is involved in protein translation. There are some proteins that are attached to the endoplasmic reticulum. Thus, ER have a large role in protein synthesis. Also, there are some ribosomes thar are free floating in the float around in the cytosol. Ribosomes are attached to the cytosolic side of the ER. Connects about 30% of the membranes within the cell. Involved in synthesis, storage, and transport of macromolecules and detoxification of drugs Two regions: - Rough ER - Smooth ER (does not have ribosomes. Rather it is involved in the synthesis, storage and transport of micro molecules as well as the detoxification of drugs) Rough - Rough - ribosomes on cytosolic surface - Proteins are formed within the Cisternae. - Ribosomes synthesize proteins which pass through to Cisternae - In cisternae original structure is altered - Proteins are then packaged into transport vesicles, where they will bud off and go to the Golgi Apparatus. - Transport vesicles travel to Golgi Apparatus. Smooth - • It is not involved in protein synthesis because it does not have ribosomes attached to it. Continuous with RER No Ribosomes Functions in: ➢ Synthesis storage and transport of lipids ➢ Calcium storage, which can be very important, especially in neurons. Calcium can change signalling within the cell, depending on how much calcium is inside the cytosol. Golgi Complex - - - Synthesized proteins in RER – transport vesicles- proteins will bud off to the Golgi Apparatus. This is where the proteins will undergo post-translational modifications. Proteins can be modified and folded into the ultimate protein that we want. Once they go to into the Golgi and the proteins have been made into their final form, they will bud off again and go to into where they are needed. If it is something that we want to secrete, such as insulin they will be trafficked to the plasma membrane and they will be released. However, if it is something that is needed for a lysosome, it will be trafficked to the location where it is needed. So, it has something like a postcode on the vesicle to tell it where to go. Transport vesicles fuse Proteins are modified as they move from the receiving to shipping region Packaged into secretory vesicles Convert glucose to ATP. • Mitochondria - The “powerhouse” of the cell. It is main function Is to produce ATP Double membrane organelle. ATP produced mainly via oxidative phosphorylation ✓ Possess their own DNA, because it was like a symbiotic relationship. ✓ Self-replicate Replicate • • Microtubules – blue DNA – yellow Removal of waste products • • Lysosomes contain an array of enzymes capable of breaking down: proteins, nucleic acids, carbohydrates and lipids. Cells are very pragmatic, and they will recycle as much as they can, so anything that is not =-needed anymore, say that the mitochondria gets old and needs to be recycled, lysosomes will engulf that - mitochondria, break it down into its constituent parts and use it to make new things, such as new and more mitochondria. • Mutations in these enzymes can cause genetic diseases called lysosomal storage diseases, and these can be catastrophic. • If waste products cannot be broken down within the cell, these waste products will build up and can cause terrible diseases. • Digest material taken up by the cell in endocytosis. • Involved in both autophagy and phagocytosis Autophagy: destruction of internal organelles/proteins. Phagocytosis: destruction of external components. Storage - inclusions are not metabolically active • • • • • Not necessarily organelles of the cell, but cells can store things. Glycogen – the storage form of glucose. - Often stored in liver cells - Stored very close to the mitochondria, ready to use for energy. Lipids – storage of triglycerides Efficient form of energy store - Stored in the form of lipid droplets. Pigments – melanin Inclusions are not normally membrane bound