Anatomy and Physiology How Does It Work? Menu “ Learning is mmm, mmm good”Active Transporto “pumps”o Endocytosiso ExocytosisCell Metabolismo Catabolismo Anabolismo Enzymes Growtho Cell growtho Cell reproduction
Active TransportCalcium PumpAllows the cells to force nearly all the of the intra-cellular calcium ions (Ca++) into special compart- Active transport is when a sub-ments or out of the cell entirely. A muscle cell can- stance moves from an area of lownot operate properly unless the intracellular Ca++ concentration to an area of highlevels are low. concentration.Sodium-Potassium PumpTransports sodium ions out of cells and potassiumions into cells. The sodium –potassium pump maintains lowersodium concentration in intracellular fluid than surroundingextracellular fluid. It maintains higher potassium concen-tration in the intracellular fluid than surrounding extra-cellular fluid.EndocytosisThe plasma membrane traps some extracellular materialand brings it into the cell. Phagocytosis: microorganismsare engulfed by the plasma membrane and enter the cells inin vesicles that have been pinched off from the membrane.Pinocytosis: “condition of the cell drinking” is a similar pro-cess in which fluid and the substances dissolved in it enter thecell.ExocytosisIs the process by which large molecules can leave the celleven though they are too large to move out through the plas-ma membrane.(1)(page 9-98)
Cell MetabolismMetabolic PathwayCell metabolism involves many different chemicals reactions that usually happen in a sequence of reac-tions. This can be described as Catabolic- Catabolism is the kind of metabolism that breaks down mole-cules, usually nutrient molecules, and thus releases energy rom the broken molecules. (require net out-put energy)Some metabolic pathways build larger molecules from smaller ones and are called anabolic pathways–anabolism is where pathways build large, complex molecules from smaller ones. (require net input en-ergy)EnzymesAre classified as functional proteins. Chemical reactions that make up the metabolic pathway can’t hap-pen on their own. the activation energy needed to start a chemical reaction is too great for a significantnumber of chemicals to react by themselves. What is needed to make a reaction happen is a catalyst. Acatalyst is a chemical that reduces the amount of activation energy needed to start a chemical reaction.They participate in chemical reactions but are not they are not changed by the reaction. This is how en-zymes contribute to cell metabolism.CoenzymesUsually enzyme molecules contain a non-protein part called cofactor which can be made up of inorganicions or vitamins may make up part of a cofactor. A coenzyme is a cofactor that is an organic non-proteinmolecule.Active siteThis is a part of the enzyme molecule that chemically “fits” the substrate molecules. A substrate is themolecules acted on by an enzyme molecule.Classification and Naming of EnzymesOxidation– reduction enzymes: these are known as oxidases, hydrogenates, and dehydrogenases. Ener-gy release for muscular contraction and all physiological work depends on these enzymes.Hydrolyzing, or hydrolases: Digestive enzymes belong to this group. The hydrolyzing enzymes arenamed after the substrate acted on, for example, lipase, sucrose, and maltase.Phosphorylating: these add or remove phosphate groups and are known as phosphorylates or phospha-tase.Enzymes that add or remove carbon dioxide: These are known as carboxylases or decarboxylases.Enzymes that rearrange atoms within a molecule: These are known as mutates or isomerizes.Hydrases: These add water to a molecule without splitting it, as do hydrolases.
General Functions of EnzymesAllosteric Effector: A molecule or other agent that alters enzyme function by changing itsshape.End– product inhibition: A chemical product at the end of a metabolic pathway binds to theallosteric site of one or more enzymes along the pathway that produced it and thereby in-hibits synthesis of more product. This type of negative feedback mechanism in the cell thatprevents the accumulation of an extreme amount of a metabolic product.Proenzymes: Substances that convert proenzymes to active enzymes are often called kinas-es. They usually do their job of activating enzymes by means of allosteric effect.CatabolismCellular respiration is a process in which the cell breaks down glucose (C6H12O6), or a nutri-ent that has been converted to glucose or on of its simpler products, into carbon dioxide(CO2) and water. Potential energy is released as the molecules break down.3 smaller pathways that are chemically linked together to form larger catabolic pathway(cellular respiration) are shown below:1. Glycolysis2. Citric acid cycle3. Electron Transport SystemAnabolismMany anabolic or “building” pathways occur in human cells. The process of protein synthe-sis is very important because it begins with reading the genetic “master code” in the cell’sDNA. This influences all cell structures and functions.Obligatory base– pairing: Adenine pairs with thymine and Guanine pairs with cytosine (orvise versa).Process of transcription and translation is shown below: (1)(pages 98-107)
GrowthCell GrowthGrowth depends on using genetic information in DNA to makestructural functional proteins needed for cell survival. Duringthis phase of growth newly formed cells produce newmolecules in addition to cell membrane, fibers, and otherstructures necessary in the development process. Theproduction of cytoplasm and plasma membrane is producedas protein synthesis. Also DNA replication , the process inwhich nucleic acid (RNA) is directly synthesized on the DNAmolecule to help enzymes. The replication of the entire set ofDNA molecule will prepare it for cell reproduction.Cell ReproductionReproduction of the cells is the splitting of two separate cells.One the parent cell, which becomes a split into the nowdaughter cell. The genetic information is needed of each cellto run them properly. Cell division also known as mitosis, the processin which cell are organized to replication of DNA into two identical setsthat will then make one complete daughter cell. Mitosis has fourphases which include Prophase, Metaphase, Anaphase, and Telophase.Meiosis the type of cell division that occurs only in primitive sex cellsduring the becoming of mature sex cells. The primitive sex cellsbecome mature sex cells called gametes. Each cell receives 23chromosomes from each parent cell making 46 total for the offspring.(1) (pages 109-114)