Question

Sterility: sites with low or no microbes in nature and home, how to make things sterile (lab, home)

cell membranes and walls: differences in the structure of call walls and membranes between microbes - prokaryotic and eukaryotic, gram-positive and gram-negative, surface structures and their functions

Answer 1

There is no such sites with low or no microbes in nature and home because microbes can grow in all the good conditions and harsh conditions.

Sterilization of things of Lab and home

There are some important methods for sterilizing a lab. These include,

1. Steam Sterilization by autoclaving the equipment at high temperature between 121-134 ˚C and 15 psi pressure.

2. Dry heat sterilization at higher temperature.

3. Boiling, flaming and incineration of some materials.

4. By using some chemical disinfectants.

Difference in the structure of call walls and membranes between microbes

The presence of the cell membrane is seen in all cells whereas the cell wall is present in plants, algae, fungi and bacteria. The cell membrane is made up of lipid bilayer and proteins, whereas the cell wall is made up of cellulose. The cell membrane is living whereas the cell wall is non-living.

The cell wall of gram-positive are thicker than the gram-negative bacteria. The cell wall of gram-positive bacteria contains almost 95% of peptidoglycan whereas the cell wall in gram-negative bacteria contains only 5-10%.

Cell surface structures

The cell membrane consists of a layer of spontaneously arranged amphipathic phospholipids, which have the hydrophilic head regions interacting with the intracellular and extracellular medium of the bilayer while the hydrophobic tail regions remain isolated from the surrounding water. Thus a continuous and spherical lipid bilayer is formed. The major driving force in the formation of lipid bilayers is hydrophobic interactions.

Functions

The cell membrane is made up of lipid bilayer, proteins and some amount of cholesterols that helps to maintain their fluidity at different temperatures. The proteins present in the cell membrane act as transporters for transporting molecules to and from the cytoplasm. The cell membrane separates the cytoplasm of cells from the outer environment and protects the cell from its outer atmosphere.