CH 4 Prokaryotes EXAM 1

Question 1

Describe the structure of prokaryotic flagella.

Answer 1

Prokaryotic flagella consist of three main parts: the hook, filament, and basal body.

Question 2

Explain the function of prokaryotic flagella.

Answer 2

Prokaryotic flagella rotate rapidly and respond to external stimuli, such as chemotaxis (chemical movement) and phototaxis (light movement).

Question 3

Define the protein that makes up prokaryotic flagella.

Answer 3

The protein that makes up prokaryotic flagella is called flagellin, which is a motor-protein only found in prokaryotic cells.

Question 4

How is the movement of prokaryotic flagella powered?

Answer 4

Prokaryotic flagella are powered by a proton-driven mechanism, utilizing hydrogen ions from the electron transport chain.

Question 5

Identify the different types of flagellar arrangements in prokaryotes.

Answer 5

The different types of flagellar arrangements are monotrichous (1 flagellum), lophotrichous (many flagella at one end), amphitrichous (flagella at both ends), and peritrichous (flagella evenly distributed around the cell).

Question 6

What is chemotaxis in prokaryotes?

Answer 6

Chemotaxis is the movement of prokaryotes in response to chemical stimuli, where they can move towards (+) or away from (-) a chemical source.

Question 7

What is phototaxis in prokaryotes?

Answer 7

Phototaxis is the movement of prokaryotes in response to light stimuli, where they can move towards (+) or away from (-) a light source.

Question 8

Where are the flagella of spirochetes located?

Answer 8

The flagella of spirochetes are located enclosed between the cell wall and the cell membrane.

Question 9

What is the purpose of flagella in spirochetes?

Answer 9

The purpose of flagella in spirochetes is to enable corkscrew motion, allowing the bacteria to twist and flex.

Question 10

Describe the structure and function of fimbriae in prokaryotes.

Answer 10

Fimbriae are hair-like structures on the surface of prokaryotic cells that help in adhesion to surfaces and other cells.

Question 11

Describe the structure of fimbriae.

Answer 11

Fimbriae are fine proteinaceous bristles found only in prokaryotes.

Question 12

Explain the function of fimbriae.

Answer 12

Fimbriae help bacteria attach to surfaces, forming biofilms and aggregates, which is useful for pathogens.

Question 13

Define the structure of pili.

Answer 13

Pili are rigid tubular structures made of a protein called pilin.

Question 14

What is the function of pili in bacteria?

Answer 14

Pili facilitate mating through conjugation, allowing two cells to come into contact and transfer DNA.

Question 15

Identify the types of bacteria that have pili.

Answer 15

Pili are found in gram-negative bacteria.

Question 16

Describe the composition of the prokaryotic glycocalyx.

Answer 16

The prokaryotic glycocalyx is made up of sugars and/or proteins.

Question 17

What is the purpose of the prokaryotic glycocalyx?

Answer 17

The glycocalyx serves as a protective barrier and aids in adhesion to surfaces.

Question 18

List the two types of prokaryotic glycocalyx.

Answer 18

The two types are the slime layer, which is loose, and the capsule, which is highly organized.

Question 19

Explain the structure of bacterial capsules.

Answer 19

Bacterial capsules, also known as K antigens, are mostly made up of polysaccharides and some amino acids.

Question 20

What is the function of bacterial capsules?

Answer 20

Bacterial capsules help adhere to surfaces, protect against phagocytosis, and prevent nutrient and water loss.

Question 21

Describe the basic structure of the prokaryotic cell wall.

Answer 21

The prokaryotic cell wall provides structural support and protection to the cell.

Question 22

Describe the structure of a prokaryotic cell wall.

Answer 22

The prokaryotic cell wall is made of peptidoglycan, which consists of protein and sugar.

Question 23

Explain the purpose of the prokaryotic cell wall.

Answer 23

The prokaryotic cell wall provides structural support, resists changes in osmotic pressure, determines cell shape, and prevents lysis.

Question 24

How does penicillin affect the prokaryotic cell wall?

Answer 24

Penicillin disrupts the cross-links forming peptidoglycans, primarily targeting gram-positive bacteria.

Question 25

What role does lysozyme play in relation to the prokaryotic cell wall?

Answer 25

Lysozyme hydrolyzes bonds in glycan chains, helping to kill bacteria and is found in substances like skin, sweat, tears, and saliva.

Question 26

Define the differences between gram-positive and gram-negative cell walls.

Answer 26

Gram-positive cell walls are thick (20-80 nm) and contain teichoic and lipoteichoic acids, while gram-negative cell walls are thin (1-3 nm) and more flexible, making them sensitive to lysis.

Question 27

What is the function of teichoic and lipoteichoic acids in gram-positive cell walls?

Answer 27

Teichoic and lipoteichoic acids contribute to the thickness of gram-positive cell walls.

Question 28

Describe the general structure of the gram-negative outer membrane.

Answer 28

The gram-negative outer membrane contains specialized polysaccharides and proteins, consisting of an inner and outer layer.

Question 29

What is the function of the gram-negative outer membrane?

Answer 29

The gram-negative outer membrane serves as a selective permeability layer, with porin proteins allowing access only to relatively small molecules.

Question 30

Explain what LPS is in the context of the outer membrane.

Answer 30

LPS, or lipopolysaccharide, is a component of the outer membrane of gram-negative bacteria, playing a role in immune response and structural integrity.

Question 31

Describe the structure and characteristics of lipopolysaccharides (LPS).

Answer 31

LPS are components of the outer membrane of gram-negative cell walls, consisting of a lipid portion (endotoxin) that may become toxic when released.

Question 32

Define the genus Mycoplasma and its unique features.

Answer 32

The genus Mycoplasma is characterized by the absence of a cell wall, having only a plasma membrane, and is stabilized by sterols, making them resistant to lysis.

Question 33

How does the structure of Mycoplasma contribute to its resistance to lysis?

Answer 33

The cell membrane of Mycoplasma is stabilized by sterols, which provide structural integrity and resistance to lysis.

Question 34

Identify an important medical species of Mycoplasma and its associated disease.

Answer 34

Mycoplasma pneumonia is an important medical species that causes pneumonia.

Question 35

Explain the unique characteristics of Acid-Fast bacteria like Mycobacteria.

Answer 35

Acid-Fast bacteria, such as Mycobacteria, have a modified Gram-positive structure with a thick cell wall containing mycolic acid, which provides resistance to acids, detergents, lysis, and many antibiotics.

Question 36

What is the role of mycolic acid in Acid-Fast bacteria?

Answer 36

Mycolic acid forms a waxy layer in the cell wall, providing a protective barrier against chemicals and the host immune system, contributing to resistance to staining and antibiotics.

Question 37

Describe the basic structure of mycolic acid found in Acid-Fast bacteria.

Answer 37

Mycolic acid is a long-chain, branched fatty acid that forms a waxy layer in the cell wall of Acid-Fast bacteria.

Question 38

Define protoplast and its significance in bacterial cells.

Answer 38

A protoplast is a bacterial cell that ordinarily has a cell wall but loses it, making gram-positive cells highly susceptible to lysis.

Question 39

What is a spheroplast and how does it differ from a protoplast?

Answer 39

A spheroplast is a bacterial cell that retains part of its cell wall, unlike a protoplast, which has completely lost its cell wall.

Question 40

Describe the process of spheroplast formation in gram-negative cells.

Answer 40

Spheroplast formation occurs when gram-negative cells lose their peptidoglycan layer but retain their outer membrane.

Question 41

Define the structure of the prokaryotic cell membrane.

Answer 41

The prokaryotic cell membrane follows the fluid mosaic model, is selectively permeable, and consists of 30-40% phospholipids and 60-70% proteins.

Question 42

How does the prokaryotic cell membrane function in cellular processes?

Answer 42

The prokaryotic cell membrane serves as the site for energy reactions, nutrient processing, synthesis, and transport.

Question 43

Describe the composition of the prokaryotic cytoskeleton.

Answer 43

The prokaryotic cytoskeleton is made up of long polymers of actin.

Question 44

Define the general structure of prokaryotic chromosomes.

Answer 44

Prokaryotic chromosomes are typically single or few in number, circular, and located in the cytoplasm.

Question 45

How do prokaryotic ribosomes differ from eukaryotic ribosomes?

Answer 45

Prokaryotic ribosomes are composed of 60% ribosomal RNA and 40% protein, differing from eukaryotic ribosomes in size and the number of proteins.

Question 46

Explain the function of prokaryotic ribosomes.

Answer 46

Prokaryotic ribosomes synthesize proteins by translating messenger RNA (mRNA) into an amino acid chain.

Question 47

What is the purpose of prokaryotic inclusion bodies?

Answer 47

Prokaryotic inclusion bodies serve as storage for nutrients, as prokaryotes do not have non-membrane bound granules.

Question 48

Describe the structure of bacterial plasmids.

Answer 48

Bacterial plasmids are non-essential, extrachromosomal, double-stranded DNA.

Question 49

How do bacterial plasmids contribute to bacterial survival?

Answer 49

Bacterial plasmids often carry protective traits such as drug resistance and the production of toxins, and they can pass between cells.