Question

1. What factors limit the size of cells? Be sure to list at least two factors.
2. How do cells communicate with other cells? Be sure to detail at least one specific example in detail.
3. What are some examples of prokaryotic cells? What are some examples of eukaryotic cells?
4. In what specific ways to antibiotics affect bacteria?

Answer 1

Ans1)The size of a cell is limited by its surface area to volume ratio. A smaller cell is much more effective in transporting substances across it than a larger cell.

-Size of cell also depends on the structures necessary to hold the cell together, the nucleocytoplasmic ratio, and how much fragile the cell membrane is.

Ans2)Cells communicate with each other by the basic use of hormones. These hormones can be autocrine(secreted by cell itself), paracrine(by nearbycell)and endocrine(hormone in blood). Also the cells may contact each other directly using junctions which may be of three types-

Gap junction, tight junction, desmosomes.

For example during the conduction of electrical signal in a cell the signalling molecule is a neurotransmitter.It is secreted by the cell itself and helps in conduction of signal. This type of communication comes under autocrine because the signalling cells are responding to molecules produced by itself. Similarly growth hormones secreted by cells also come under the same autocrine hormones.

Ans3)Example of prokaryotic organisms are-

Escherechia coli

Streptococcus bacteria

Staphylococcus

Blue green algae

Mycoplasma

Examples of eukaryotes-

Algae, mushroom, tapeworm, protozoans

Ans4)

Antibiotics aim at altering or effecting the normal metabolism of cell so that it cannot survive.

They either kill the bacteria or suspend its growth.Antibiotics have different mode of action-

By affecting the Cell wall formation and linkages-Beta lactam ,vancomycin

Affecting DNA and RNA synthesis-Flouroquinolones,rifamycin

Inhibiting folate synthesis-sulfonamides

Affecting cell membrane-daptomycin

Protein synthesis-Linezolid

Inactivating enzymes-Aminoglycosides

Target modification-Vancomycin