1.1 Aseptic techniques and cell culture

Question 1

Aseptic techniques

Answer 1

Aseptic techniques eliminates unwanted microbial contaminants when culturing micro-organisms or cells. It involves the sterilisation of equipment and culture media by heat or chemical means and subsequent exclusion of microbial contaminants.

Question 2

Starting a microbial culture

Answer 2

A microbial culture can be started using an inoculum of microbial cells on an agar medium, or in a broth with suitable nutrients.

Question 3

Growth factors

Answer 3

Animal cells are grown in medium containing growth factors from serum. Many culture media exist that promote the growth of specific types of cell and microbes.

Growth factors are proteins that promote cell growth and proliferation. Growth factors are essential for the culture of most animal cells.

Question 4

Cell division

Answer 4

In culture, primary cells can divide a limited number of times, whereas tumour cells lines can perform limited divisions.

Question 5

Plating out

Answer 5

Plating out of a liquid microbial culture on solid media allows the number of colony-forming units to be counted and the density of cells in the culture estimated.

Question 6

Serial dilution

Answer 6

Serial dilution is often needed to achieve a suitable colony count.

Question 7

Vital staining

Answer 7

Is required to identify and count the number of viable cells.

Question 8

Haemocytometer