3A_Biomolecules

25th March 2010

- Definition: Despite changes in the outer environment, the living system will maintain equilibrium ** -Example of **processes** involved: Osmosis, Diffusion, Active transport, Passive Transport -Osmosis is when particles move from a region of higher water potential to a region with lower water potential across a cell membrane.
 * Homeostasis

-Define terms -Explain terms -Illustrate terms with an example to explain and support the statement
 * Revision for Exams**

> -In cells, energy is stored in the form of fats. We get fatty acids from the food we eat, forming lipids and hence fats. > -Mitochondria produces/generates energy by producing using glucose. It does //not// store energy. > -Growth and repair of damaged cells require energy obtained from food eaten by organisms > -Cells get 'food', process the food, and convert it into protein, fats, glucose etc. > -Young mammals feed on mother's milk to grow. Milk contains calcium which is used by mammals to build bones. It also contains proteins which helps to build muscles (structure of the body) > -Food chain is **not** a cycle: it is a one-way flow that does not repeat itself > -Energy can be lost (converts to mechanical energy, especially heat energy) but cannot be destroyed. It can flow from one organism to another organism (e.g. Eating beef—taking energy from the meat of the cow muscles and use it to build own muscle). Hoof of animals are wasted because they are chemical energy which cannot be digested (cows are not eaten whole. Only a part (the meat) is eaten. > -Water cycle > -Carbon cycle > -Earth is in trouble because the cycle is disrupted. Water is no longer cycled and is locked away somewhere as pollutants. Also, too much carbon dioxide is produced
 * **Energy** is stored in the organization of matter:
 * Living organisms use matter and energy to build and maintain body structures:
 * Living organisms obtain and process matter and energy
 * The structure of a molecule always dictates its function.
 * The structure and function of biological living systems obeys the laws of thermodynamics.
 * Communities of organisms depend on the cycling of matter and the flow of energy
 * The constant flow of energy and cycling of matter in the biosphere leads to a balanced or steady state

1. Are we just chemicals? 2. Are we what we eat? 3. Why is carbon molecule suitable for life as we know it? -Carbon molecules have a valency of four so they can bond with four other atoms, hence they can form a different macro-molecule with different property and function due to their different structure. Function is related to structure. -Double bonds: difficult to break down -Carbon atoms can bond with itself -Important because virtually all molecules in the body (excluding water) contain carbons. Examples include sugar, DNA, proteins, fats. -Carbon is capable of making diverse compounds because carbon can bond with four other groups around it and to other carbon molecules. It can form long chains of molecules, each with different properties. Even at 30 carbon molecules, there are millions of ways in which molecule can be arranged.

Also, carbon can readily form bonds with many other molecules: hydrogen, oxygen, halogens, and even some metals. 4. Why is the chemistry of water suitable for life? -Three states -Abnormal behavior: expands instead of contracting when frozen—ice float instead of sink -Get answer from PPT on water