Question

Each of the following means of physical control, describe the action on the cell, its effect on the cell (be very specific – what does it do to vital parts or chemicals within the cell), and give a detailed specific example of its use in controlling microbes. I want detail – do a good job or lose points.(5 points)

Autoclave

Boiling

Pasteurization

Radiation: both UV light and ionizing radiation

Cold    (Refrigeration and freezing)

Answer 1

-Autoclave :-autoclave machines are giant pressure cooker,which uses the power of steam to kill the germs in order to sterilize the cell

-In autoclave water boils at higher temperature than it`s boiling point,and the steam is generated which kills the undesired microbes.

-Autoclave lysis the microbe cell and thus causing it`s death, and thus heat kill the microbes.

-There are many uses of autoclave but recently the pre-disposal treatment of medical waste where waste from medical which contains microbes are autoclaved so that the microbes die and disposal became un pathogenic.

BOILING

- As we know that the cell membrane is made up of protein and lipid so if we apply high temperature on it than the protein denature and lipid will become too fluid so lysis of the membrane

-After that it will lead to disruption of the nucleic acid i.e. genetic material so the cell will totally destroy

-However in boiling some heat is lost as steam

-Example is egg boiling where the protein denature and changes its confirmation.

PASTEURIZATION

-Pasteurization is a process of heating at very high temperature of dairy food in order to kill bacteria

-due to high heat the enzymes(responsible for bacterial metabolism) in the bacteria are denatured means change there shape which cause there inability to metabolism i.e. they become useless so,the bacterial metabolism ceases and so their functioning

- Also due to high temperature the liquid inside the bacterial cell starts expending and a time will reach where the cell burst and so the death of bacteria.

-Pasteurization is frequently uses in milk in order to keep it free from microbes.

RADIATION

UV radiation:- At 260 nm - 270 nm the UV radiation is mutagenic to microbes.

-This radiation breaks the molecular bonds within micro-organismal DNA which produces Thymine dimers and thus kills the microbes or lessen it`s activity.

-It has also very uses but mostly in water purification where microbes which can not be killed by other processes are killed by exposure of UV radiation

IONIC radiation

-It is short wavelength , High intensity radiation which destroy the MOs

-this radiation come in the form of gamma or X radiation which reacts with DNA resulting in damaging of the cell

COLD

-Refrigeration and freezing ceases the enzymatic activity of the microbes and hence slow down the activity of the microbes which causes longer stay of the food

-Frozen bacteria`s are completely inactive because the enzymatic activity (responsible for metabolism)are ceased.

-It is done in every food we eat