Question

Why do the phycobilins found in red algae trap more light energy than chlorophyll in deep water?

Which of the green algae are motile? How do these organisms move?

How are the pseudopodia of these amoebas different than the pseudopodia of Foramens and Radiolarians?

Can you see any internal structures in the bacteria? Why or why not?

Given the differences between bacterial and animal cells as previously discussesed, what aspects of abcterial structure might be good targets for antimicrobial agents?

If you were looking at eukaryotic cells using the same magnification, what structures might you see?

Do all antibiotics work the same way? Explain

What are some of the ways antibiotics work to kill bacteria?

How do Cyanobacteria get their sugars and organic matter?

Answer 1

Phycobilins are light capturing bilins which are found in cyanobacteria and in the chloroplast of red algae. They consists of a molecule called chromophore which makes them coloured. They are unique in nature and bound to certain water soluble proteins called phycobiliproteins. These proteins pass the light energy to chlorophylls for photosynthesis. The phycobilins are efficient in absorbing red, orange, yellow wavelengths of light which cannot be absorbed by chlorophyll a. Organisms living in shallow water contain more phycobilins which can capture red and yellow light, while those at living in greater depth contain phycobilins which absorb green light.

The Chlamydomonas reinhardtii is a motile alga, that contains two flagella. Green algae moves according to the beat. The beating of flagella is the basic principle in their movement. The movement of two flagella are synchronised by mechanical forces.

Foraminiferans, radiolarians and amoeba belongs to subphylum Sarcodina. These three have pseudopodia, which is also known as cytoplasm extensions. Amoebas have soft bodies while radiolarians have skeleton from opaline silica. Moreover, foraminiferans create shells that are known as test.

When compared with eukaryotes, intracellular features of bacterial cell are quite simple. They do contain organelles as that of eukaryotes. Chromosomes and ribosomes are the only easily observable intracellular structures in bacteria.

Bacteria cell is a prokaryotic cell	Animal cell is eukaryotic
Size is 0.2 to 2 micrometer	Size is 10 to 100 micrometer
Cell wall made up of murein	No cell wall
Have different shape like coccus, bacillus etc	Irregular shape due to the lack of cell wall
No nucleus	Membrane bound nucleus
No mitochondria	Mitochondria is present in the cytoplasm
70S, small ribosome	80S, large ribosome
Heterotrophs or autotrophs	Autotrophs
Reproduce asexually by binary fission and sexually by conjugation	Reproduce asexually by mitosis and sexually by meiosis
No centrioles	Contain centrioles

There are five main antimicrobial drug targets in bacteria. They are:

1. Cell wall synthesis
2. DNA gyrase
3. Metabolic enzymes
4. DNA directed RNA polymerase
5. Protein synthesis

Eukaryotic cells contain membrane-bound organelles, such as nucleus, while prokaryotic cells do not. Differences in cellular structure of prokaryotes and eukaryotes include the presence of mitochondria and chloroplasts, the cell wall, and the structure of chromosomal DNA.

No, all antibiotics does not work in the same way. Antibiotics work against bacteria either by killing or by slowing or suspending its growth. Each anitibiotic is classified as per the coverage of the bacteria(gram positive, gram negative, aneraboes). The five classes of antibiotics mentioned above works in five different ways.

Antibiotics must selectively target bacterial cells for eradication not human cells. Here are the some examples how antibiotics kills bacteria:

1. Bacteria produce a cell wall made up f peptidoglycan and human does not produce it. The antibiotic pencillin can prevent the final cross linking or transpetidation step in the asse,mbly of this macromolecule thereby inhibiting cell wall synthesis. The result is the cell wall bursts killing the bacterium.
2. Antibiotics can also target the metabloic pathways of bacteria. The drugs such as sulfonamides inhibit a criical enzyme called dihydropteroate synthase which is included in pathway of folic acid synthesis and thus bacteria cannot grow longer.
3. Another antibiotic tetracycline kills bacteria by inhibiting protein synthesis. Tetracycline binds to a specfic site in ribosome inhibiting a key RNA interaction.

Most cyanobacterias are photoautotrophic organisms that fix CO2 and release O2. In cyanobacteria RUBISCO is an enzyme which converts CO2 into sugars.