Cell biology with all content Flashcards
1.1 Required practical activity 2: investigate the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition 1.2 cell division
what are uncontaminated cultures of microorganisms needed for
investigating disinfectant and antibiotic action
describe the preparation of an uncontaminated culture using aseptic technique 7
use pre-sterilized plastic petri dish or glass petri dish and agar gel before with an autoclave
pour sterile agar gel into petri dish and allow tie to set
sterilize the inoculating loop by passing it through the Bunsen burner flame
dip inoculating loop into the solution of microorganisms and make streaks with the loop on the surface of agar
put the lid on the perti dish and secure it with tape
label accordingly and turn and store upside down
incubate the culture at 25oc in laboratories
Why must inoculating loops be sterilised by passing
them through Bunsen burner flame?
To kill any bacteria present on the
inoculating loop
Why must the Petri dish lid be secured with adhesive
tape and the whole dish stored upside down? 3
Stops bacteria in the air contaminating the culture.
Lid is not fully sealed to stop growth of
anaerobic bacteria in a lack of oxygen.
Upside down to prevent condensation from forming
and dripping down onto the colonies
How is the number of bacteria in a population after a
certain time calculated from the mean division time?
Number of bacteria in population at end of time period =
number of bacteria at
the beginning of the time period x 2^number of divisions in the time period
In hours
Why are cultures incubated at 25oC in
school laboratories?
Harmful pathogens are less likely to to
grow at this temperature.
What are chromosomes made up of?
Chromosomes consist of DNA molecules combined with proteins They contain genes which provide the instructions for protein synthesis
What is a gene?
A section of DNA which codes for a
protein
What are the three main stages of the cell
cycle?
- Replication of DNA and synthesis of
organelles - Mitosis
- Division of cell
Why is mitosis important?
● Produces identical cells with the same genetic information.
● Produces additional cells for growth and
repair
first stage of the cell cycle 4
-Longest stage cells grow and increase in mass, replicate DNA and synthesise more organelles (eg. mitochondria, ribosomes)
Describe the second stage of the cell cycle
2
Each chromosome in a pair is pulled to
opposite poles of the cell
then the nucleus
divides.
Describe the third stage of the cell cycle
The cytoplasm and cell membrane divide -
two identical daughter cells are produced.
What is a stem cell?
An unspecialised cell which is capable of
differentiating into other cell types and of
self-renewal.
What is the function of stem cells in embryos? 2
Embryonic stem cells can replicate, differentiate themselves into other types of cells.
may be able to treat conditions
such as paralysis and diabetes by dividing to replace
damaged cells
