Sameness and Variety (Mitosis and Meiosis) 161 Example Expressed using apples, DNA replication looks like this. Observe Go look at the model of DNA on the demonstration table. We have been presenting DNA as a straight ladder, but actually it is twisted on itself like a spiral staircase. This shape is called a helix. The Chromosome Normally DNA exists as loose strands (chromatin) in the nucleus of a cell. This nuclear DNA sends a message (RNA) to the ribosomes where protein and enzymes are synthesized. When stretched out, the length of one DNA molecule in a human cell is almost 4 cm. However, the cell itself is but a tiny fraction of that size. During cell reproduction the DNA must be able to move around. So it shortens its length by tightly coiling up. In doing so, the DNA strands become wider and are visible under a microscope. Visible DNA is called a chromosome. Coiling Coiled DNA Normal DNA (chromosomes) DNA. 1. A chromosome is made up of tightly ? QUESTION 2. Explain the reason for this shape. 3. When not reproducing, DNA is found in the of a cell and exists in the form called
Electron Transport Chain
The electron transport chain, also known as the electron transport system, is a group of proteins that transfer electrons through a membrane within mitochondria to create a gradient of protons that drives adenosine triphosphate (ATP)synthesis. The cell uses ATP as an energy source for metabolic processes and cellular functions. ETC involves series of reactions that convert redox energy from NADH (nicotinamide adenine dinucleotide (NAD) + hydrogen (H)) and FADH2(flavin adenine dinucleotide (FAD)) oxidation into proton-motive force(PMF), which is then used to synthesize ATP through conformational changes in the ATP synthase complex, a process known as oxidative phosphorylation.
Metabolism
Picture a campfire. It keeps the body warm on a cold night and provides light. To ensure that the fire keeps burning, fuel needs to be added(pieces of wood in this case). When a small piece is added, the fire burns bright for a bit and then dies down unless more wood is added. But, if too many pieces are placed at a time, the fire escalates and burns for a longer time, without actually burning away all the pieces that have been added. Many of them, especially the larger chunks or damp pieces, remain unburnt.
Cellular Respiration
Cellular respiration is the cellular process involved in the generation of adenosine triphosphate (ATP) molecules from the organic nutritional source obtained from the diet. It is a universal process observed in all types of life forms. The glucose (chemical formula C6H12O6) molecules are the preferred raw material for cell respiration as it possesses a simple structure and is highly efficient in nature.
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