Membrane+Structure+and+Respiration+Questions+SLS

September 15, 2008 Science-Human Bio**
 * Shelby Smith

The structure of a phospholipids is they are constructed like fats, but in the place of the third fatty acid, there is a phosphate group or a grouping that contains both nitrogen and phosphate. The heads are hydrophilic and the tails are hydrophobic. When in water, the hydrophilic heads face towards the water, while the hydrophobic face away to form the tails.
 * (1) p. 31 Describe the structure of a phospholipids (insert an image). Indicate the parts that are hydrophilic and the parts that are hydrophobic.**
 * (2) p. 31 How do phospholipids arrange themselves in water? **

The fluid-mosaic model of the membrane says that protein molecules form a shifting pattern within the fluid phostpholipid layer. Cholesterol lends support to the membrane. The components that are fluid are the phospholipids bilayer which is fluid at body temperature. The components of the mosaic are the proteins which are able to change position by moving laterally.
 * (3) p. 46 Describe the fluid-mosaic model of a membrane. (insert an image) Which components are the fluid, and why? Which components are the mosaic, and why?**

The plasma membrane marks the boundaries between the inside and the outside of the cell. The structure of the membrane suits this structure because it is necessary for the proper function and life of the cell by holding it together and controlling what comes in and what is able to get out.
 * (4) p. 46 What is the function of the membrane? How does the structure of the membrane suit that structure?**

The membrane is considered to be selectively permeable because it allows only certain molecules and ions to enter and exit the cytoplasm freely.
 * (5) p. 46 Why is the membrane considered selectively permeable?**

Diffusion is the random movement of molecules from the area of higher concentration to the area of lower concentration, until they are equally distributed. In other words, it allows cells to passively enter and exit the cells. An example of diffusion is molecules enter into the plasma membrane, such as a scent reaching the nose and binding to the plasma receptors in the nose signaling the brain of the scent.
 * (6) p. 46 What is diffusion? Give an example.**

(**7) p. 46 What is osmosis?** Osmosis is when the diffusion of water across the plasma membrane happens.

Isotonic: The same concentration of nondiffusible solutes and water on both sides of the plasma membrane. Cells maintain their usual shape and size. Hypotonic: Solutions that cause cells to swell or even burst, lysis refers to the disrupted cells; hemolysis refers to disrupted red blood cells. Hypertonic: Loss of water in the cell, causing them to shrink and shrivel.
 * (8) p.46 How do isotonic, hyptonic, and hypertonic solutions differ and how does each affect cells? (insert an image)**

Passive transport is when a molecule is transported at a rate higher than usual across the plasma membrane from the side of higher concentration to the side of lower concentration. Active transport is when a molecule is moving contrary to the normal direction – from lower concentration to higher concentration.
 * (9) pp. 46-47 What is the difference between passive and active transport?**

The various ways that substances can enter cells are diffusion, facilitated transport, active transport, endocytosis and exocytosis. Passive ways of crossing into the cell are facilitated transport, diffusion and exocytosis, and Active ways on the other hand include: active transport and endocytosis.
 * (10) pp. 46-47 What are the various ways substances can enter and exit cells? (diffusion, facilitated transport, active transport, endocytosis, exocytosis) Which are passive and which are active ways of crossing the cell?**

Large substances exit the cell by exocytosis and the phagocytosis is when some white blood cells are able to take up pathogens by endocytosis.
 * (11) p. 47 What is the difference between exocytosis and phagocytosis?**

The overall formula for cellular respiration is the blood transports glucose into oxygen for the cells, which breaks down glucose to carbon dioxide and water. The reactants are glucose and oxygen and the products are water and CO2.
 * (12) p. 54 What is the overall formula of cellular respiration? What are the reactants and what are the products?**

Hydrogen and Carbon Dioxide. Two ATP molecules are produced per glucose.
 * (13) pp. 54-55 Which molecule captures the energy released from glucose? How many molecules are produced per glucose?**

The roll of Oxygen in cellular respiration is that it serves as the final collector at the end of the chain. It also makes the citric acid cycle aerobic, but it doesn’t combine anything in cellular respiration.
 * (14) p. 55 What is the role of oxygen in cellular respiration?**

Carbon dioxide comes from the break down of glucose into water and CO2.
 * (15) p. 55 Where does carbon dioxide come from in cellular respiration?**

Fermentation is an anaerobic process that breaks down glucose that results in a gain of two ATP and end products such as alcohol and lactate. Carbon Dioxide.
 * (16) p. 56 What is fermentation? How many ATP are produced per glucose molecule?**
 * (17) p.56 What is the waste product of yeast fermentation?**