3A_Biomolecules

25/3/2010

Macroconcept : Systems and change Definition: Homeostasis is the tendency of an organism to maintain equilibrium between internal and external environments to ensure stability. Despite the change in the external environment, the living system of an organism maintains an equilibrium in its internal environment.
 * Homeostasis**

Processes to maintain equilibrium in an organism: -osmosis -diffusion -active transport in order to understand this, we must understand the plasma membrane

Define, explain, give an example.

**ENERGY, MATTER & ORGANISATION -** BIOMOLECULES //** Living systems are complex and highly organized, and they require matter and energy to maintain this organization. **//
 * **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.

This balance is achieved through various biogeochemical cycles and the processes of photosynthesis and cellular respiration - //focus is on ENERGY//

Living organisms obtain and process matter and energy e.g. In the human body, we eat food, and the digestive system processes this food to give us energy for our daily activities.
 * Biomolecules**

Note: The mitochondria generates energy, it does not store energy. Energy is stored in the form of fats. Mitochondria generates ATP from glucose.

Living things use matter and energy to build and maintain body structures. e.g. Milk: Calcium builds bones, Protein builds muscles.

Communities of organisms depend on the cycling of matter and the flow of energy. Note: The food chain is not a good example, because it is not a cycle. It's a one-way thing.

Energy can be lost - wastage during conversion. Usually comes in the form of heat energy. But energy cannot be destroyed. Energy can flow from one system to another. Matter has energy.

The constant flow of energy and cycling of matter in the biosphere leads to a balanced or steady state. e.g. Carbon and water cycles.

Why is the carbon molecule suitable for life as we know it? -can be converted into many different types of structures and forms -one of the most abundant elements on earth -has a valency of 4, has 4 free valence electrons to bind with 4 other atoms, thus can form a macromolecule with different properties and functions -very stable, with double covalent bonds, difficult to break down -has the ability to combine with itself (carbon backbone)

Why is the chemistry of water suitable for life? -exists in 3 states -when it drops temp to below 0 degrees, it expands in volume, thus density is reduced and it floats in its own state -basically all of water's properties