Chapter 4

Question 1

Flagella

Answer 1

3 parts:
–Filament – long, thin, helical structure composed of protein flagellin
–Hook – curved sheath
–Basal body – stack of rings firmly anchored in cell wall

Question 2

Monotrichous

Answer 2

single flagellum at one end

Question 3

Lophotrichous

Answer 3

small bunches emerging from the same site

Question 4

Amphitrichous

Answer 4

flagella at both ends of cell

Question 5

Peritrichous

Answer 5

flagella dispersed over surface of cell

Question 6

Periplasmic Flagella

Answer 6

Internal flagella, enclosed in the space between the outer sheath and the cell wall peptidoglycan
•Produce cellular motility by contracting and imparting twisting or flexing motion

Question 7

Fimbriae

Answer 7

Fine, proteinaceous, hairlike bristles emerging from the cell surface
•Function in adhesion to other cells and surfaces

Question 8

Pili

Answer 8

Rigid tubular structure made of pilin protein
•Found only in gram-negative cells
•Function to join bacterial cells for partial DNA transfer called conjugation

Question 9

Glycocalyx

Answer 9

Coating of molecules external to the cell wall, made of sugars and/or proteins
•Two types:
–Slime layer - loosely organized and attached
–Capsule - highly organized, tightly attached

Question 10

Functions of the Glycocalyx

Answer 10

Protect cells from dehydration and nutrient loss
•Inhibit killing by white blood cells by phagocytosis, contributing to pathogenicity
•Attachment - formation of biofilms

Question 11

The Cell Envelope

Answer 11

External covering outside the cytoplasm
•Composed of two basic layers:
–Cell wall and cell membrane
•Maintains cell integrity
•Two different groups of bacteria 
demonstrated by Gram stain

Question 12

Gram-positive bacteria

Answer 12

thick cell wall composed primarily of peptidoglycan and cell membrane

Question 13

Gram-negative bacteria

Answer 13

outer cell membrane, thin peptidoglycan layer, and cell

Question 14

Coccus

Answer 14

spherical

Question 15

Bacillus

Answer 15

rod

Question 16

Coccobacillus

Answer 16

very short and plump

Question 17

Vibrio

Answer 17

gently curved

Question 18

Spirillum

Answer 18

helical, comma, twisted rod,

Question 19

Spirochete

Answer 19

spring-like

Question 20

Structure of Cell Walls

Answer 20

Determines cell shape, prevents lysis due to changing osmotic pressures
•Peptidoglycan is the primary component:
–Unique macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments

Question 21

Gram-Positive Cell Wall

Answer 21

20-80 nm thick peptidoglycan
•Includes teichoic acid and lipoteichoic acid: function in cell wall maintenance and enlargement during cell division; move cations across the cell envelope; stimulate a specific immune response
•Some cells have a periplasmic space, between the cell membrane and cell wall

Question 22

Gram-Negative Cell Wall

Answer 22

Inner and outer membranes and periplasmic space between them contains a thin peptidoglycan layer
•Outer membrane contains

Question 23

lipopolysaccharides

Answer 23

Lipid portion (endotoxin) may become toxic when released during infections
–May function as receptors and blocking immune response
–Contain porin proteins in upper layer – regulate molecules entering and leaving cell

Question 24

Gram-positive turns what color

Answer 24

retain crystal violet and stain purple

Question 25

Gram-negative turns what color

Answer 25

lose crystal violet and stain red from safranin counterstain

Question 26

Steps to do gram stain

Answer 26

Crystal Violet Gram’ siodine Alcohol Safranin