LEC 4 ACELL/PROKAR MICROBES

Question 1

complete viruses are called

Answer 1

virions

Question 2

most viruses range from ______ in diameter

Answer 2

10 to 300 NM

Question 3

some viruses, called ________ cause specific types of cancers

Answer 3

oncogenic viruses or oncoviruses

Question 4

surrounded by _____ which is composed of protein units called CAPSOMERES

Answer 4

capsid (protein coat)

Question 5

have an outer _______. hence the name envelope

Answer 5

envelope (lipids and polysaccharides)

Question 6

viruses originated in the primordial soup and coevolved with bacteria and archaea

Answer 6

COEVOLUTION THEORY

Question 7

viruses evolved from FREE LIVIMG PROKARYOTES that invaded other living organisms, and gradually lost functions which were provided by the host cell

Answer 7

retrograde evolution theory

Question 8

viruses are pieces of host cell RNA or DNA that have escaped from living cells and are no longer under cellular control. of the three theories, this is currently the most widely acellular explanation for the origin of viruses

Answer 8

escaped gene theory

Question 9

Viruses have FIVE PROPERTIES that distinguish them from living cells:

Answer 9

1. They possess either DNA or RNA.
2. They are unable to replicate on their own.
3. Unlike cells, they do not divide by binary fission, mitosis, or meiosis.
4. They lack the genes and enzymes necessary for energy production.
5. They depend on the ribosomes, enzymes, and metabolites of the host cell for
   protein and nucleic acid production

Question 10

most VIRAL GENOMES ARE THE FIRST two types

Answer 10

double stranded DNA VIRUSES and single stranded RNA viruses

Question 11

most viral genomes are CIRCULAR molecules, but some are

Answer 11

LINEAR

Question 12

viruses that infect bacteria are known as _________ or simply PHAGES

Answer 12

bacteriophages

Question 13

who is the 2 people who create G. phagein “TO DEVOUR”?

Answer 13

frederick twort and felix d’herelle

Question 14

2 types of bacteriophages

Answer 14

VIRULENT AND TEMPERATE

Question 15

virulent bacteriophages always causes what is known as the ____ cycle.

Answer 15

lytic

Question 16

3 categories of bacteriophages based on their SHAPE

Answer 16

1. Icosahedron
2. filamentous
3. complex

Question 17

the five steps in the lytic cycle

Answer 17

1. attachment
2. penetration
3. biosynthesis
4. assemnly
5. release

Question 18

______ escape from their host cells either by lysis of the cell or by budding. viruses that escaped by budding become enveloped viruses

Answer 18

animal viruses

Question 19

viral infections in which the virus is able to hide from the host’s immune system by entering cells and remaining dormant

(ex: herpes viral infections)

Answer 19

latent virus infections

Question 20

chickenpox may be followed, years later, by _____ — both the result of the same birus because those chickenpox/____ never completely go away

Answer 20

shingles

Question 21

• what is not effective against viral infections — this is very important to remembers.

Answer 21

antibiotics

Question 22

are drugs that are used to treat viral infections .These agents interfere with virus-specific enzymes and virus production by disrupting critical phases in viral multiplication or inhibiting synthesis of viral DNA, RNA, or proteins

Answer 22

ANTIVIRAL AGENTS

Question 23

• These viruses cause cancer.
• Examples include Epstein–Barr virus,
human papillomaviruses, and human T-
lymphotrophic virus type 1 (HTLV-1)

Answer 23

oncogenic viruses or oncoviruses

Question 24

• This virus causes acquired
immunodeficiency syndrome (AIDS).
• It is an enveloped, single-stranded RNA
virus.
• The primary targets for HIV are CD4+ cells

Answer 24

UNODEFICIENCY VIRUS (HIV)

Question 25

viroids and priors are

Answer 25

SMALLER AND LESS COMPLEX INFECTIOUS PARTICLES THAN VIRUSES

Question 26

___ are short, naked fragments of single-stranded RNA, which can interfere with the metabolism of PLANT CELLS - are transmitted between plants in the same manner as viruses - ex are potato spindle tuber and citrus exocortis

Answer 26

viroids

Question 27

are small infectious proteins that cause fatal neurologic diseases in animals and humans (e.g., Scrapie, Bovine spongiform encephalopathy [mad cow disease], and Creutzfeldt– Jacob disease). • Of all pathogens, _____ are the most resistant to disinfectants. • The mechanism by which prions cause disease remains a mystery. • “Kuru” – laughing death

Answer 27

prions

Question 28

bacteria are divided into three major phenotypic categories

Answer 28

gram negative, gram positive, mycoplasma spp.

Question 29

three basic categories of bacteria used on SHAPE

Answer 29

COCCI, BACILLI, CURVEE AND SPIRAL SHAPED BACTERIAL

Question 30

- in singly or in pairs (diplococci) - chains (streptococci) - clusters (staphylococci) - packets of 4 (tetrads) or packets of 8 (octads) about 1 um in diameter and some of it have “coccus in their name”

Answer 30

cocci

Question 31

• They are often referred to as rods; they may be short or long, thick or thin, and pointed or with curved or blunt ends. • They may occur singly, in pairs (diplobacilli), in chains (streptobacilli), in long filaments, or branched. • An average sized bacillus is 1 x 3 μm. • Extremely short bacilli are called coccobacilli. • Examples of medically important bacilli: Escherichia, Klebsiella, Proteus

Answer 31

BACILLI

Question 32

Examples of curved bacteria

Answer 32

Vibrio spp. Campylobacter spp. Helicobacter spp.

Question 33

• Examples of spiral-shaped bacteria

Answer 33

Treponema spp. Borrelia spp.

Question 34

Staining Procedures Three major categories of staining procedures

Answer 34

1. Simple staining procedure 2. Structural staining procedures 3. Differential staining procedures

Question 35

two common techniques of fixation

Answer 35

heat fixation and methanol fixatiln

Question 36

gram positive

Answer 36

blue to purple (thick peptigolycan lauer)

Question 37

gram negative

Answer 37

pink to red (outer cell membrane washed off)

Question 38

who developed the staining procedure

Answer 38

hans christian gram

Question 39

is the red dye that is driven through the bacterial cell wall using heat

Answer 39

carbon fuchsin

Question 40

because mycobacteria are not decolorized by the acid-control mixture, ______

Answer 40

they are said to be ACID-FAST

Question 41

some are motile

Answer 41

rods

Question 42

all are motile

Answer 42

spirilla

Question 43

• If a bacterium is able to “swim,” it is said to be motile. • Bacterial ______ is most often associated with flagella and less often with axial filaments. • Most spiral-shaped bacteria and about 50% of bacilli are motile; cocci are generally nonmotile. • Motility can be demonstrated by stabbing the bacteria into a tube of semisolid medium or by using the hanging-drop technique

Answer 43

motility

Question 44

• A bacterial colony contains millions of organisms. • _____ (appearance of the colony) varies from one species to another. • ______ includes size, color, overall shape, elevation, and the appearance of the edge or margin of the colony. • ________ can also include the results of enzymatic activity on various types of media. • As is true for cell morphology and staining characteristics, colony morphology is an important “clue” to the identification (speciation) of bacteria

Answer 44

colony morphology

Question 45

Size of colonies is determined by the organism’s generation time and is another important characteristic of a particular bacterial species. Here, the generation time is assumed to be ________

Answer 45

30minutes

Question 46

capnophilic organisms grow best in the presence of increased concentrations of CO2 usually

Answer 46

5-10%

Question 47

• All bacteria require some form of the elements such as carbon, hydrogen, oxygen, sulfur, phosphorus, and nitrogen for growth. • Some bacteria require special elements (e.g., calcium, iron, or zinc). • Organisms with especially demanding nutritional requirements are said to be fastidious (“fussy”). • The nutritional needs of a particular organism are usually characteristic for that species and are sometimes important clues to its identity

Answer 47

true

Question 48

• As bacteria grow, they produce many waste products and secretions, some of which are enzymes. • Pathogenic strains of many bacteria, such as staphylococci and streptococci, can be tentatively identified by the enzymes they secrete. • In particular environments, some bacteria produce gases such as carbon dioxide or hydrogen sulfide. • To identify bacteria in the laboratory, they are inoculated into various substrates (i.e., carbohydrates and amino acids) to determine whether they possess the enzymes necessary to break down those substances

Answer 48

biochemical and metabolic activities

Question 49

• Many pathogens are able to cause disease because they possess capsules, pili, or endotoxins, or because they secrete exotoxins and exoenzymes that damage cells and tissues. • Frequently, pathogenicity is tested by injecting the organism into mice or cell cultures. • Examples of some common pathogenic bacteria: Neisseria meningitidis, Salmonella typhi, Shigella spp., Vibrio cholerae, Yersina pestis, and treponema

Answer 49

pathogenicy

Question 50

• Laboratory identification of bacteria is moving toward analyzing the organism’s DNA or RNA--techniques collectively referred to as molecular diagnostic procedures. • The composition of the genetic material (DNA) of an organism is unique to each species. • DNA probes make it possible to identify an isolate without relying on phenotypic characteristics. • Through the use of 16S rRNA sequencing, the degree of relatedness between two different bacteria can be determined

Answer 50

genetic composition

Question 51

are bacteria, but they do not possess all the attributes of typical bacterial cells

Answer 51

rikkettsias, chlamydias and mycoplasma

Question 52

have a gram negative type of cell wall and are obligate intercellular pathogens (they must live within a host cell; they cannot grow on artificial culture media)

Answer 52

obligate intracellular pathogens

Question 53

have “leaky membranes” is _______ are “energy parasites” meaning they prefer to hse ATP molecules produced by their host cell

Answer 53

1. ricketttsias 2. chlamydias

Question 54

• They are the smallest of the cellular microbes. • They lack a cell wall and therefore assume many shapes (i.e., pleomorphic). • In humans, pathogenic mycoplasmas cause primary atypical pneumonia and genitourinary infections. • Because they have no cell wall, they are resistant to drugs like penicillin that attack cell walls. • They produce tiny “fried egg” colonies on artificial media.

Answer 54

mycoplasma

Question 55

Photosynthetic Bacteria Photosynthetic bacteria include purple bacteria, green bacteria, and cyanobacteria; they all use light as an energy source, but not in the same way. • Purple and green bacteria do not produce oxygen, whereas cyanobacteria do. • Photosynthesis that produces oxygen is called oxygenic photosynthesis. • Photosynthesis that does not produce oxygen is called anoxygenic photosynthesi

Answer 55

true

Question 56

discovered in 1977; they are prokaryotic organisms. • Genetically, archaea are more closely related to eukaryotes than they are to bacteria. • Archaea vary widely in shape. • Many archaea are extremophiles, meaning that they live in extreme environments; e.g., environments that are extremely hot, dry, or salty. • Archaea possess cell walls, but their cell walls do not contain peptidoglycan (in contrast, all bacterial cell walls contain

Answer 56

the domain archaea true