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Question 1

thread-like appendages composed entirely of protein, 12–30 nm in diameter.

Answer 1

Bacterial flagella

Question 2

is a whip-like filament, long, thin, helical structure composed of protein flagellin.

Answer 2

Flagella

Question 3

Three types of Flagella arrangement are known:

Answer 3

(1) Monotrichous (single polar flagellum).
(2) Amphitrichous (flagella @ both ends).
(3) Lophotrichous (cluster at one end).
(4) Peritrichous (flagella covering the cell).
(5) Atichous (with no flagella).

Question 4

Bacterial flagella are composed of three parts:

Answer 4

a- Filament
b- Hook
c- Basal body

Question 5

Flagella function:

Answer 5

a- Rotation propels bacterium through environment.

b- The movement of bacterium toward or away from a particular stimulus is called taxis.

Question 6

• Guide bacteria in a direction in response to external
environment stimulus:

Answer 6

1) chemical stimuli – chemotaxis; positive and negative

2) light stimuli – phototaxis

Question 7

rod like, protein extensions, these projections adhere to one another and to substances in the environment or to their host

Answer 7

Fimbriae

Question 8

Some fimbriae carry

Answer 8

enzymes that render soluble, toxic ions into insoluble, nontoxic form.

Question 9

Fimbriae function

Answer 9

a- Sticky, bristle-like projections.
b- Used by bacteria to adhere to one another and to substances in environment.
c- Used by bacteria to move across a surface.
d- Save an important function in biofilm.

Question 10

is a type of fimbria,
longer than fimbria but shorter than flagella.
Typically only one to a few pili are present per cell.

Answer 10

Pili

Question 11

How are pili different from bacterial flagella?

Answer 11

Bacterial flagella are flexible structures that rotate to propel (push) the cell,
pili are hollow tubes used to transfer DNA from one cell to another.

Question 12

Function of bacterial cell wall:

Answer 12

1- Provide structure and shape and protect cell from osmotic force.
2- Assist some cells in attaching to other cells or in resisting antimicrobial drugs. 3- They provide ligands for adherence
4- Have receptor sites for drugs or viruses.
5- Composed of peptidoglycan (polysaccharide).
6- In addition, bacterial cell wall fragments can have immune stimulatory and cytotoxic properties and thus play important roles in pathogenesis and disease.

Question 13

Scientists describe two basic types of bacterial cell wall;

Answer 13

Gram-positive &
Gram- negative

Question 14

Gram-positive bacterial cell wall:

Answer 14

1- Relatively thick layer of peptidoglycan.

2- Contain unique polyalcohols called teichoic acid.

3- Appear purple following Gram staining procedure.

4- Presence of up to 60% mycolic acid in acid-fast bacteria (T.B)

Question 15

Gram-negative bacterial cell wall:

Answer 15

1- Have only a thin layer of peptidoglycan.

2- Bilayer membrane outside the peptidoglycan contain phospholipids, proteins, and lipopolysaccharide (LPS)

3- Appear pink following Gram staining procedure.

Question 16

Lipids in LPS can cause

Answer 16

fever, vasodilation, inflammation, shock, and blood clotting.

Question 17

It’s about 8nm thick and composed of phospholipid bilayer and associated proteins.

Answer 17

cytoplasmic membrane

Question 18

Structure of cytoplasmic membrane

Answer 18

1- Referred to as phospholipid bilayer.

2- Composed of lipids and associated proteins (integral proteins and peripheral proteins).

3- Fluid mosaic model describes current understanding of membrane structure.

Question 19

Function of cytoplasmic membrane

Answer 19

1- Control passage of substances into and out of the cell.
2- Energy storage.
3- Harvest light energy in photosynthetic bacteria.
4- Selectively permeable.
5- Naturally impermeable to most substances.
6- Proteins allow substances to cross membrane.
7- Maintain concentration and electrical gradient.

Question 20

is enclosed by the cytoplasmic membrane, is essentially an aqueous fluid containing the nuclear material, ribosomes, nutrients, enzymes

Answer 20

Cytoplasm

Question 21

The bacterial genome is composed of

Answer 21

a single circular chromosome containing double-stranded DNA (bacterial chromosome),

which carry all the information required for the cell structure and function.

Question 22

Bacterial chromosome are not surrounded by

Answer 22

nuclear envelope and don’t contain histones.

Question 23

Small circular pieces of double-stranded DNA which are separated from the genome.

Answer 23

Plasmid – Extrachromosomal DNA

Question 24

Copies of plasmids can be transferred from cell to cell during

Answer 24

binary fission
or through conjugation.

Question 25

Plasmid DNA may code for characteristics such as

Answer 25

antibiotic resistance and exotoxin production.

Question 26

Vegetative cells transform into endospores when nutrients are limited and the process of endospore formation called

Answer 26

sporulation

Question 27

Endospores Only made by certain bacteria (Bacillus and Clostridium) called

Answer 27

endospore– forming bacteria

Question 28

endospore– forming bacteria that produce deadly toxins that cause such fatal diseases as

Answer 28

anthrax, tetanus and gangrene.

Question 29

Because spores are thermostable they can be destroyed only by moist heat at

Answer 29

121°C for 15 minutes.

Question 30

What is the process of sporulation?

Answer 30

It is the production of spores. The one vegetative cell forms a single spore, which, after germination, develops into a new cell

Question 31

What is germination in microbiology?

Answer 31

In bacteria, germination is the process in which a spore begins to grow vegetative cells.

Question 32

Sites of protein synthesis.

Answer 32

Ribosomes

Question 33

Ribosomes Composed of

Answer 33

polypeptides and ribosomal RNA.

Question 34

70S ribosome composed of smaller

Answer 34

30S and 50S subunits.

Question 35

Cytoskeleton Play different roles in the cell:

Answer 35

Cell division Cell shape Segregation of DNA molecules Movement through the environment

Question 36

Cytoskeleton Composed of

Answer 36

three or four types of protein fibers.