Anatomy Fall 2009 Unit 1: Biology Review Cells, Cellular Respiration & Homeostasis Cell Structure & Function: - Cells are the most basic unit of living things. - The nucleus serves to contain and protect the cell’s DNA. Because it houses the DNA it is also often said to control processes in the rest of the cell. - The cell membrane covers the outside of the cell, and functions to not only provide some support and structure, but also controls what enters and exits the cell. - Mitochondria are the powerhouses of the cell. Mitochondria complete cell respiration, and so produce ATP for the cell. - Ribosomes are like little protein factories. They work together with RNA to produce protein from the DNA code. - The endoplasmic reticulum works with ribosomes to add final “structure” touches to proteins. The endoplasmic reticulum also packages them up to be sent where needed. - The golgi apparatus functions mainly to ship things throughout the cell, into and out. - Peroxisomes and lysosomes are like little digestive enzyme sacs that engulf foreign matter, toxic substances and dead cell parts, and break them down to be exported. - Centrioles are essential in cell division (mitosis and meiosis). - Cytoplasm is everything else in the cell (not organelles). Cell Respiration: - C6H12O6 + 6O2 6CO2 + 6H2O + Energy - The energy is stored in the phosphate bonds of ATP (adenosine triphosphate). - Cellular respiration involves combining sugar (glucose) and oxygen, to produce carbon dioxide—water—and energy. - The glucose comes from food you consume, and oxygen from respiration. Some of the carbon dioxide and water is expelled through exhalation, however some is kept in the body for blood pH (carbon dioxide) and hydrolysis reactions (water). - The most important product of respiration is the production of ATP (stored chemical potential energy). - Cell respiration occurs in your mitochondria (remember). - There are actually three stages to respiration: glycolysis, krebs/citric acid cycle, and the electron transport chain. - During glycolysis glucose is broken down into pyruvate molecules. - During the krebs/citric acid cycle those pyruvate molecules are used to make a bunch of NADH compounds. - During the electron transport chain the H+ ions from NADH are used to create an energy gradient, which can be used to push together ADP and P to form ATP! Anatomy Fall 2009 - At the conclusion of respiration, 36 molecules of ATP are made. Homeostasis: - Internal balance within living organisms. - Organisms are constantly surrounded by changes, and as a result their internal conditions are constantly changing. - To maintain balance, and bring your internal conditions back to their “original setting”, your body completes a variety of mechanisms to keep things stable. - When your body is imbalanced, you often notice physiological disabilities and conditions affecting your health.