Lecture 6 Flashcards
The scientific name of an organism consist of two words. What are they?
Genus and species.
True or false. The species name is capitalized
False. The genus name is capitalized.
True or false. Both the genus and species name should be italicized, but only the genus name can be abbreviated.
True
In Escherichia coli, which is the genus and which is the species?
Escerichia is the genus and coli is the species.
What three distinct shapes are recognized in bacteria.
1- Sperical or ellipsoidal termed cocci
2-Cylindral or rod-shaped termed bacilli
3-Spiral shaped shaped subdivided into
-Vibros are curved rods resembling commas.
-Spirilla have a corkscrew shape and rigid bodies
-Spirochetes are like spirilla but are flexible
Explain the 5 arrangements of the cocci cell.
1-Diplococci-pairs of cocci (Neisseria gonorrhoeae)
2-Streptococci- chains of cocci (Streptococcus pyogenes)
3-Staphylococci-clusters of cocci (Staphylococci aureus)
4-Tetrads- four cocci arranged in a square (Micrococcus luteus)
5-Sarcinae- cubical of eight cocci (Sarcina ventriculi)
Explain the 4 arrangements of the bacilli cell.
1-Diplobacilli- pairs of bacilli (Pseudomonas aeruginosa)
2-Streptobacilli- chains of bacilli (Bacillus cereus)
3-Palisade arrangement- bacilli stacked on top of each other (Corynebacterium diphtheriae)
4-Letter arrangement - bacilli forming letters X,Y or Z (Corynebacterium diphtheriae)
What does this unit (um) represent in measurable amount? What is it’s name and other known names.
1 um= 10-6 m = 1/25,400 in. um= nanometer
What size are most bacteria?
0.2 um - 4 um in width x 0.3 um- 10um in length.
What size is E. coli?
1.1 x 2.0 um
List the following organism from smallest to largest- bacteria, (fungi, algae, protozoa) and viruses.
Virus, bacteria and (fungi, algae, protozoa).
What factors contribute to the size of bacteria?
The age of the culture and medium which it’s isolated from.
Name four characteristic of the cell wall.
- The cell wall is rigid and not flexible.
- Is responsible for the shape of the cell.
- Protects the cytoplasm, which is the center of vital activities.
- Plays a part in cell division.
What is the thickness of a cell wall?
10-25 nm
From Gram-positive and Gram-negative bacteria, which of them has a thinner cell wall?
Gram-negative.
Define a hypotonic medium.
Lower solute medium relative to the cell.
What is lysozyme?
An enzyme that degrades the cell wall.
Describe osmotic lysis.
When Gram-positive cells are exposed to lysozyme in a hypotonic medium, they undergo rapid lysis referred to lysis osmosis.
True or false. If lysozyme treatment is conducted in a isotonic medium, destruction of the cell wall is followed by the formation of protoplast.
True
Peptidoglycan is present in the cell wall of which types of cell? What is their function?
Procaryotic. Responsible for the strength and shape of the cell.
True or false. Cell wall can account for 15% of the dry weight of bacterium.
False, they account for 20%
Peptidoglycan accounts for how much % of the dry wights of the Gram-positive cell?
50-80%
Peptidoglycan accounts for how much % of the dry weight of the Gram-negative cells?
1-10%
Name the four amino acids that create a polypeptide chain which result in cross linking, chain and lastly a sheet to occur.
1- L-alanine
2-D-glutamate
3-L-lysine
4-D-alanine
