Bacterial Cell Structure

Question 1

Functions of the cell wall:

Answer 1

1.Determines the cell shape
2.Prevent osmotic lysis
3.part of cell envelope

Question 2

Cell wall structure

Answer 2

1- Made up of peptidoglycans
2- linked by polypeptides
3-Polymer of disaccharides

Question 3

Q. What are the two types of cell wall

Answer 3

Gram+ve
Gram -ve

Question 4

Q. Why does a gram -ve cell wall turn colourless once we add alcohol

Answer 4

Because the peptidoglycan layer is thinner than in gram+ve cell wall.

Question 5

Gram Positive Cell walls

Answer 5

1.Thick peptidoglycan
2.No periplasm
3. No outer cell membrane
4. Teichoic acids

Question 6

Gram Negative Cell Wall

Answer 6

1.Thin peptidoglycan
2. Periplasm
3.Outer cell membrane
4. No Teichoic acid

Question 7

Q. We can’t do a gram test on mycoplasmas ?

Answer 7

as it contains sterols and a complete cell wall

Question 8

Q. What is the clinical importance of cell wall?

Answer 8

lipopolysaccharides secretes endotoxins in gram negative bacteria

Question 9

Lipopolysacchrides

Answer 9

Lipid A

Question 10

The rigidity and shape of the bacterial cell is due to:

Answer 10

lipopolysacchride

Question 11

Which substance of the membrane of gram-negative bacteria is a potent endotoxin?

Answer 11

Lipopolysacchride

Question 12

Glycocalyx

Answer 12

A network of polysacchrides that project from cellular surfaces

Question 13

Glycocalyx consists of :

Answer 13

1-A gelatinous capsule
2-A slimy layer

Question 14

Function of GLycocalx

Answer 14

protects bacterium from harmful pathogens

Question 15

Which of the following is the most important structure related to microbial attachment to
cells?

Answer 15

Glycocalyx

Question 16

Structure of Bacterial Flagella

Answer 16

outside cell wall made up of flagellin attached by a protein hook anchored to the wall of the membrane by the basal body

Question 17

Function of Flagella

Answer 17

motility

Question 18

Pili and Fimbirae

Answer 18

Filamentous appendages that are shorter, straighter and more numerous than flagella

Question 19

Pili and Fimbriae are found in

Answer 19

Gram -ve Bacteria

Question 20

Fimbriae function

Answer 20

allow attachment

Question 21

Pili Function

Answer 21

Transfer DNA from one cell to another

Question 22

Prokaryotic cells have:

Answer 22

no true nuclei

Question 23

Endospores are only found in two shapes

Answer 23

1-Bacillus
2-Clostiridium

Question 24

Germination of endospores

Answer 24

Return to vegetative state

Question 25

Endospores are resistant to :

Answer 25

1-Dissection
2-heat
3-chemicals

Question 26

Endospores are:

Answer 26

Resting cells

Question 27

Main difference between Flagella and Cilia:

Answer 27

Flagella : Taller
Cilia : Shorter

Question 28

80S ribosomes

Answer 28

1-Membrane bound
2-Free
3- Attached to the ER in cytoplasm

Question 29

70S Ribosomes

Answer 29

Found in chloroplasts and mitochondria

Question 30

Prokaryotes

Answer 30

1-1 circular chromosome
2- No histones
3- Reproduce by BInary Fission
4- No organelles
5- Peptidoglycan cell walls
6- chromosomes not in a membrane

Question 31

Eukaryotes

Answer 31

1- Paired chromosomes
2- chromosomes are in nuclear membrane
3- organelles
4-histones
5- Mitotic spindle
6- polysacchraide cell walls