Cell Biol

Question 1

What is the organization of the body?

Answer 1

Cells > Tissues > Organs > Systems > Body

Question 2

What is the significance of having Fe on haem group in haemoglobin? (2)

Answer 2

Fe serves as an electron carrier & helps maintain structural integrity

Question 3

What are some features that define prokaryotes from eukaryotes?

Answer 3

Prokaryotes:
- has circular DNA & nucleoid

Eukaryotes:
- has double membrane organelles (Golgi, ER)
- has nucleus

Question 4

What are the structures of a cell nucleus?

Answer 4

Nucleolus - site of ribosome synthesis (transcription) within nucleus

Nuclear membrane - pored & double

Question 5

What is the function of a peroxisome?

Answer 5

converts hydrogen peroxide into H2O

Question 6

How do prokaryotes and eukaryotes reproduce?

Answer 6

Prokaryotes:
Binary fission

Eukaryotes:
Mitosis / Meiosis

binary fission - asexual reprod. (one divides into two)

Question 7

What types of molecules are able to pass through a membrane bilayer?

Answer 7

Gases, small & non-polar molecules
e.g. CO2, O2, N2, ethanol

Question 8

How and why does the composition differ between lipid bilayers on different cells/orgnanelles?

Answer 8

There is different lipid proportions & lipid anchored proteins

It differs depending on the cell/organelle’s function

Question 9

What are 5 main lipids in a membrane?

Answer 9

4 phospholipids:
PC - phosphatidylcholine
PE - phosphatidylethanolamine
PS - phosphatidylserine
SM - sphingomyelin

& Cholesterol

Question 10

What does exoplasmic / cytosolic mean? Which category do the phospholipids belong to?

Answer 10

Exoplasmic - facing extracellular envir.
> PC, SM
Cytosolic - facing cytoplasm
> PE, PS

Question 11

Name a sterol present in lipid membranes and what are sterol’s functions?

Answer 11

Cholesterol

Adds viscosity (thickens membranes)
Makes membrane “fluid”

Question 12

What 2 parts of the phospholipid membrane can change?

Answer 12

Phosphat-x head groups
Cholesterol

Question 13

What does heat do to the membrane?

Answer 13

Changes consistency
More heat = more fluid

Question 14

How does cholesterol affect the phospholipids PC and SM?

Answer 14

PC tails - disordered –> ordered (elongated)

SM tails - unchanged (alr ordered)

Question 15

What makes a membrane curved / linear?

Answer 15

Curved - when heads are smaller than tails

Linear - when head & tails are same width

Question 16

What type of microscopy do we use to look at living cells? What are the procedures?

Answer 16

Light microscopy
Using H&E stain or florescent dyes

Question 17

Why do we use H&E stain for light microscopy?

Answer 17

Haemotoxylin binds to acidic molecules:
DNA & acidic amino acids

Eosin binds to basic amino acids

Question 18

How do we make cells florescent to observe under the microscope?

Answer 18

Incubate fixed & permeabilized cultured cells with the proteins