SCB 260 CHAPTER 15 MICROBIAL
VIRULENCE FACTORS FINAL PAPER 2026
COMPLETE ANSWERS GRADED A+
⩥ Virulence. Answer: The degree or extent of pathogenicity
⩥ Portals of Entry. Answer: The avenue by which a pathogen gains
access to the body. The portals of entry for pathogens are mucous
membranes, skin, and direct deposition beneath the skin or membranes
(the parenteral route).
a) Many microorganisms can penetrate mucous membranes of the
conjunctiva and the respiratory, gastrointestinal, and genitourinary tracts.
b) Most microorganisms cannot penetrate intact skin; they enter hair
follicles and sweat ducts.
c) Some microorganisms can gain access to tissues by inoculation
through the skin and mucous membranes in bites, injections, and other
wounds. This route of penetration is called the parenteral route
⩥ Portals of Entry - Parenteral Route. Answer: Portal of entry for
pathogens by deposition directly into tissues beneath the skin and
mucous membranes
,⩥ Portals of Entry - Mucous Membranes. Answer: Many bacteria and
viruses gain access to the body by penetrating mucous membranes lining
the respiratory tract, gastrointestinal tract, genitourinary tract, and
conjunctiva, a delicate membrane that covers the eyeballs and lines the
eyelids. Most pathogens enter through the mucous membranes of the
gastrointestinal and respiratory tracts
⩥ Portals of Entry - Skin. Answer: The skin is the largest organ of the
body in terms of surface area and weight and is an important defense
against disease. Unbroken skin is impenetrable by most microorganisms.
Some microbes gain access to the body through openings in the skin,
such as hair follicles and sweat gland ducts. Larvae of the hookworm
actually bore through intact skin, and some fungi grow on the keratin in
skin or infect the skin itself
⩥ Portals of entry for the Pathogens of Some Common Diseases.
Answer:
⩥ ID50. Answer: The number of microorganisms required to produce a
demonstrable infection in 50% of the test host population
⩥ LD50. Answer: The lethal dose for 50% of the inoculated hosts within
a given period
⩥ Adherence. Answer: Attachment of a microbe or phagocyte to
another's plasma membrane or other surface. The attachment between
, pathogen and host is accomplished by means of surface molecules on the
pathogen called adhesins or ligands that bind specifically to
complementary surface receptors on the cells of certain host tissues.
a). Surface projections on a pathogen called adhesins (ligands) adhere to
complementary receptors on the host cells.
b). Adhesins can be glycoproteins or lipoproteins and are frequently
associated with fimbriae.
c). Mannose is the most common receptor.
d). Biofilms provide attachment and resistance to antimicrobial agents.
⩥ Biofilm. Answer: A microbial community that usually forms as a
slimy layer on a surface
⩥ Adhesin. Answer: A carbohydrate-specific binding protein that
projects from prokaryotic cells; used for adherence, also called a Ligand
⩥ Ligand. Answer: A carbohydrate-specific binding protein that projects
from prokaryotic cells; used for adherence, also called an Adhesin
⩥ How Bacterial Pathogens Penetrate Host Defenses. Answer: Capsules
Cell Wall Components
Enzymes
Antigenic Variation
VIRULENCE FACTORS FINAL PAPER 2026
COMPLETE ANSWERS GRADED A+
⩥ Virulence. Answer: The degree or extent of pathogenicity
⩥ Portals of Entry. Answer: The avenue by which a pathogen gains
access to the body. The portals of entry for pathogens are mucous
membranes, skin, and direct deposition beneath the skin or membranes
(the parenteral route).
a) Many microorganisms can penetrate mucous membranes of the
conjunctiva and the respiratory, gastrointestinal, and genitourinary tracts.
b) Most microorganisms cannot penetrate intact skin; they enter hair
follicles and sweat ducts.
c) Some microorganisms can gain access to tissues by inoculation
through the skin and mucous membranes in bites, injections, and other
wounds. This route of penetration is called the parenteral route
⩥ Portals of Entry - Parenteral Route. Answer: Portal of entry for
pathogens by deposition directly into tissues beneath the skin and
mucous membranes
,⩥ Portals of Entry - Mucous Membranes. Answer: Many bacteria and
viruses gain access to the body by penetrating mucous membranes lining
the respiratory tract, gastrointestinal tract, genitourinary tract, and
conjunctiva, a delicate membrane that covers the eyeballs and lines the
eyelids. Most pathogens enter through the mucous membranes of the
gastrointestinal and respiratory tracts
⩥ Portals of Entry - Skin. Answer: The skin is the largest organ of the
body in terms of surface area and weight and is an important defense
against disease. Unbroken skin is impenetrable by most microorganisms.
Some microbes gain access to the body through openings in the skin,
such as hair follicles and sweat gland ducts. Larvae of the hookworm
actually bore through intact skin, and some fungi grow on the keratin in
skin or infect the skin itself
⩥ Portals of entry for the Pathogens of Some Common Diseases.
Answer:
⩥ ID50. Answer: The number of microorganisms required to produce a
demonstrable infection in 50% of the test host population
⩥ LD50. Answer: The lethal dose for 50% of the inoculated hosts within
a given period
⩥ Adherence. Answer: Attachment of a microbe or phagocyte to
another's plasma membrane or other surface. The attachment between
, pathogen and host is accomplished by means of surface molecules on the
pathogen called adhesins or ligands that bind specifically to
complementary surface receptors on the cells of certain host tissues.
a). Surface projections on a pathogen called adhesins (ligands) adhere to
complementary receptors on the host cells.
b). Adhesins can be glycoproteins or lipoproteins and are frequently
associated with fimbriae.
c). Mannose is the most common receptor.
d). Biofilms provide attachment and resistance to antimicrobial agents.
⩥ Biofilm. Answer: A microbial community that usually forms as a
slimy layer on a surface
⩥ Adhesin. Answer: A carbohydrate-specific binding protein that
projects from prokaryotic cells; used for adherence, also called a Ligand
⩥ Ligand. Answer: A carbohydrate-specific binding protein that projects
from prokaryotic cells; used for adherence, also called an Adhesin
⩥ How Bacterial Pathogens Penetrate Host Defenses. Answer: Capsules
Cell Wall Components
Enzymes
Antigenic Variation
