week 3: Infectious Diseases, Viruses

Question 1

what are the two major types of infectious diseases?

Answer 1

Bacteria and Viruses

Question 2

what are the seven routes of transmission?

Answer 2

1. direct contact - touching, kissing, sexual relations
2. Indirect contact - touching an object that an infected person has been touching.
3. airborne contact - breathing in air that carries a pathogen.
4. Food-borne infection - eating something that is contaminated by microorganisms.
5. Animal borne pathogens - animals spreading through bites, feces
6. water borne diseases - coming into contact with contaminated water
7. perinatally - mothers can pass a disease to the child

Question 3

what are 4 UNCONTROLABLE risk factors when it comes to infectious diseases?

Answer 3

Heredity
Aging
Environmental Conditions
Organism Resistance

Question 4

what are 7 CONTROLABLE risk factors when it comes to infectious diseases?

Answer 4

stress
nutrition
physical fitness level
sleep
drug use
hygiene
high-risk behavior

Question 5

describe endemic

Answer 5

the constant presence of a disease in a given geographic area

Question 6

what is a hyperendemic

Answer 6

the disease is highly prevalent and effect all age groups equally.

Question 7

describe holoendemic

Answer 7

a high level of infection beginning early in life and affecting mostly children.

Question 8

is bacteria eukaryotic or prokaryotic

Answer 8

bacteria is a prokaryotic organism, lacing a nucleus.

Question 9

an important feature of bacteria is the cell wall. what does the cell wall contain

Answer 9

peptidoglycan

Question 10

gram stain is used to classify bacteria cell wall composition. what it:

gram-positive

gram-negative

Answer 10

gram-positive bacteria have simpler walls and contain a large amount of peptidoglycan

gram-negative bacteria have less peptidoglycan and an outer membrane that can be toxic

Question 10

give an example of a bacterial disease

Answer 10

tuberculosis

cholera

salmonella

plague

Question 11

what are the two ways a bacteria will produce a disease in humans

Answer 11

1. it will break down cells for food
2. release toxins that interfere with normal activity

Question 12

describe exotoxins
(3 points)

Answer 12

• soluble in body fluids
• mainly produced by gram-positive bacteria
• plasmids or phages carry most of the genes for toxins

Question 13

name two types of exotoxins

Answer 13

neurotoxin - targets nervous system

enterotoxin - targets cells lining gastrointestinal tract

Question 14

describe cholera
cause and symptoms

Answer 14

caused by the gram-negative bacteria VIBRIO CHOLERA enterotoxin

intestinal infection

symptoms of severe diarrhoea

Question 15

what is a staphylococcal infection?

Answer 15

bacteria that are usually always on our skin but cause an infection if it enters a cut or break in the skin

Question 16

give two examples of staphylococcal infections

Answer 16

scarlet fever
strep throat
pneumonia

Question 17

what bacterial organism causes tuberculosis and what are the symptoms?

Answer 17

mycobacterium tuberculosis

symptoms include fever, chills, fatigue and malaise, weight loss, and persistent cough

Question 18

describe endotoxins

Answer 18

part of outer membrane surrounding gram-negative bacteria. the effect is exerted when the bacteria dies and the cell walls undergo lysis and release the toxin.

Question 19

what are the symptoms of an endotoxins

Answer 19

chills, fever, weakness, general aches, blood clotting, tissue death, shock and death.

Question 20

what measures have been used to reduce the incidence of bacterial infections

Answer 20

improvements in public health
-better water supply
-sanitation
-food quality

vaccinations

treatments using antibiotics and anti-viral drugs

Question 21

what is a virus?

Answer 21

viruses are submicroscopic infectious agents that replicate only inside the living cells of other organisms

Question 22

what is composed of theses two principle parts:

the genome that is made of nucleic acid and a protective shell that is made of protein (capsid)

Answer 22

virus

Question 23

what are 3 structural characteristics of a virus

Answer 23

1. 10 to 300 nm in diameter
2. nucleic acid genome (DNA or RNA) surrounded by a protein coat called a capsid
3. many animal viruses are surrounded by a membranous envelope.

Question 24

what are 4 things a viral genome might encode for

Answer 24

* Replicases * Coat proteins * Movement proteins * Attachment proteins

Question 25

what is capsid made of

Answer 25

protein subunits called capsomeres

Question 26

what is a viral envelope?

Answer 26

derived from membranes of host cells. Viral glycoproteins on the envelope bind to specific receptor molecules on the surface of a host cell.

Question 27

how does a virus recognize a cell it can infect

Answer 27

it matches its surface marker with a receptor site on a cell

Question 28

what is a bacteriophage or phages

Answer 28

bacteriophages are viruses that infect bacteria

Question 29

how does a phage infect a host cell

Answer 29

a protein tail piece attaches the phage to the host cell and injects the phage DNA inside.

Question 30

what are the two reproductive mechanisms used by phages

Answer 30

lytic cycle and the lysogenic cycle.

Question 31

describe the lytic reproductive cycle used by phages (4 points)

Answer 31

cycle results in death of the host cell. produces more phages and breaks open the cell wall, releasing the progeny viruses. a virulent phage is one that only uses the lytic cycle. bacteria defend using restriction enzymes that cut up the phage.

Question 32

describe the lysogenic reproductive cycle used by phages (4 points)

Answer 32

replicates the phage genome without destroying the host cell. the viral DNA is incorporated into the host cell's chromosomes. the integrated viral DNA is knows as a prophage. the phage DNA is copied and passed on to all the daughter cells when the cell divides.

Question 33

explain norovirus (3 points)

Answer 33

1. a diverse group of viruses in the group caliciviridae. 2. causes inflammation of the stomach and intestines causing diarrhoea and vomiting. 3. it only takes a small amount to particles to infect someone.

Question 34

describe coronavirus

Answer 34

1. family of enveloped positive-sense single-stranded RNA viruses 2. one of the largest RNA 3. acts like mRNA and can be transcribed by the hosts ribosomes. this is due to the 5' and 3' ends.

Question 35

which virus attacks the cells in the body designed to protect us from infection (immune system cells)

Answer 35

HIV

Question 36

what cells specifically does HIV infect

Answer 36

infects white blood cells carrying the CD4 cell surface protein.

Question 37

what is the effect of genetic variation

Answer 37

give rise to new strains which increases virulence renders vaccines ineffective

Question 38

name 2 processes of genetic variation

Answer 38

1. mutation 2. Recombination - viruses exchange segments of the genome.

Question 39

what is a prion?

Answer 39

are slow-acting, virtually indestructible infectious proteins that cause brain diseases in mammals.