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Biology 1201: Organisms and Diversity > chapter 20 > Flashcards

chapter 20 Flashcards

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1
Q

what are two microscopic, single celled organisms

A

bacteria and archea

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2
Q

what does prokarytoes mean

A

before a nucleus

no membrane bond organelles

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3
Q

who discovered prokaryotes, what is referred as?

A

Dutch microscopist Antonie van Leeuwenhoek

father of microbiology

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4
Q

what did Antonie van Leeuwenhoek study?

what did he also do?

A

green charophyte alga Spirogyra, Dental Plaque

made microscopes

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5
Q

Prokaryote Structure

A

Lack a membrane-bounded nucleus (DNA in nucleoid region)
Outer cell wall
Some move by means of flagella
Lack membranous organelles
May have accessory rings of DNA (plasmids)

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6
Q

capsule

A

gel-like coating outside the cell wall
made up of a polysaccharide layer
called glycocalyx.

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7
Q

fimbriae

A

hairlike bristles that allow

adhesion to surfaces

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8
Q

nucleoid

A

location of the

bacterial chromosome

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9
Q

conjugation pilus

A

elongated, hollow appendage

used to transfer DNA to other cells

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10
Q

flagellum

A

rotating filament that propels the cell

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11
Q

what kind of DNA do prokaryotic cells have?

A

have a circular DNA`

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12
Q

Louis Pasteur

A

devised an experiment that showed that a previously sterilized broth cannot become cloudy with microorganism growth unless it is exposed directly to the air where bacteria are abundant.
Disproved the theory of spontaneous generation of microbes by performing these types of experiments.

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13
Q

Pasteur’s Experiment

A

HYPOTHESIS A: Bacteria arise spontaneously in a broth

HYPOTHESIS B: Bacteria in the air contaminate a broth

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14
Q

Reproduction in Prokaryotes

A

Asexual
Prokaryotes reproduce asexually by means of binary fission.
Generation time is as short as 12 minutes

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15
Q

mutations in prokaryotes

A

are generated rapidly and passed on to offspring more quickly than eukaryotes

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16
Q

are Prokaryotes haploid or diploid

A

Mutations are immediately subjected to natural selection

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17
Q

Conjugation

A

Conjugation pilus forms between two cells

Donor cell passes DNA to recipient cell through the pilus

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18
Q

Transformation

A

Occurs when bacterium picks up free pieces of DNA from other prokaryotes
Becomes incorporated into genome

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19
Q

Transduction

A

Occurs when bacteriophages carry portions of bacterial DNA from one cell to another
Serve as vectors

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20
Q

most common type of prokaryote

how many

A

bacteria

Over 9,000 different bacteria have been named (more are being named)

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21
Q

how do bacteria arise

A

from the division of preexisting bacteria—not by spontaneous generation

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22
Q

what do the cell wall of the bacteria contain?

A

peptidoglycan

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23
Q

how are bacteria commonly differentiated

A

through a gram stain procedure

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24
Q

Gram-negative bacteria

A

have a second plasma membrane which blocks antibiotic drugs, making infections difficult to treat

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25
Q

three basic shapes of a bacteria

A

Spiral (spirilli),
Rod (bacilli), and
Round (cocci)

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26
Q

Bacterial Metabolism

A

Obligate aerobes – unable to grow in the absence of free oxygen (need oxygen)
Obligate anaerobes – unable to grow in the presence of free oxygen
Examples: Botulism, gas gangrene, and tetanus
Facultative anaerobes – able to grow in either the presence or absence of free oxygen

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27
Q

vectors

A

suitcases of holding genetic info to other places and spread

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28
Q

Autotrophic Bacteria

A

Photoautotrophs

Chemoautotrophs

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29
Q

Photoautotrophs

A

Use solar energy to reduce carbon dioxide to organic compounds
Photosynthetic
Anoxygenic – Green sulfur and some purple bacteria living in oxygen-poor conditions
Oxygenic

30
Q

Chemoautotrophs

A

Oxidize inorganic compounds to obtain energy
Energy is used to reduce CO2 to an organic compound
Chemosynthetic
Live in environments such as deep sea vents 2.5 km below sea level

31
Q

Heterotrophic Bacteria

A

Most prokaryotes are chemoheterotrophs that take in organic nutrients.
Aerobic saprotrophs decompose most large organic molecules to smaller molecules.
Essential components of a healthy ecosystem

32
Q

Heterotrophic Bacteria may be

A

free-living or symbiotic (two different species live together in an intimate way)

33
Q

Commensalism

A

One population modifies the environment in such a way that a second population benefits.
Obligate anaerobes live in our intestine because bacterium E. coli uses up oxygen.

34
Q

Mutualism

A

Both species benefit from association.

Mutualistic bacteria live in human intestines and release vitamins K and B12 which help produce blood components.

35
Q

produce blood components.

Parasitism

A

Parasite benefits at host expense; disease-causing bacteria are called pathogens
Many form endospores

36
Q

Cyanobacteria!

A

(Formerly called the blue-green algae (Cyanophyta))
are Gram-negative bacteria that are photoautotrophic
Believed to be responsible for introducing oxygen into the primitive atmosphere

37
Q

Cyanobacteria charcteristics

A

Lack visible means of locomotion
Can live in extreme environments
In association with fungi, form lichens
They possess heterocysts, cells without nuclei, where nitrogen fixation occurs.
Cyanobacterial “blooms” result from pollution in lakes and ponds

38
Q

Antibiotic compounds fall into two classes

A

Compounds that inhibit protein biosynthesis

Compounds that inhibit cell wall biosynthesis

39
Q

Compounds that inhibit protein biosynthesis

A

Erythromycin

Tetracycline

40
Q

Compounds that inhibit cell wall biosynthesis

A

These affect bacterial but not animal cells
Penicillin
Ampicillin
Fluroquinolone

41
Q

Bacterial resistance to antibiotics is increasing.

A

Genes conferring resistance can be transferred among bacteria by transformation, conjugation, or transduction.
Now 90% of Staphlococcus aureus are resistant to penicillin and increasingly to methicillin (MRSA).
MRSA is common in hospitals and nursing facilities.

42
Q

Carl Woese and George Fox

A

discovered that the base sequence of their rRNA differs from bacteria.

43
Q

archea Other differences

A

Archaea do not have peptidoglycan in their cell walls like the bacteria.
Archaea are biochemically more like eukarya than bacteria.

44
Q

Archaea are now thought to be more closely related to

A

eukarya than to bacteria.

45
Q

Many live in harsh conditions:

A

Anaerobic marshes
Methanogens
Produce methane from hydrogen gas and carbon dioxide
Salty lakes
Halophiles
Require high salt concentrations for growth
Hot sulfur springs
Thermoacidophiles
Reduce sulfides and survive best at temperatures above 80ºC
Plasma membranes contain unusual lipids that confer tolerance of high temperatures

46
Q

Viral Structure and Classification

A

Each type has at least two parts (capsid and core)
Viruses are characterized by
Size and shape
10–400 nm in diameter
Type of nucleic acid core
Single stranded or double stranded? DNA or RNA?`

47
Q

Capsid

A

outer layer composed of protein subunits

48
Q

Capsid or no capsid

A

Some are enveloped by membrane

Others “naked”

49
Q

obligate intracellular parasites`

A

Cannot reproduce outside a living cell

Are either active or inactive, instead of living or non-living

50
Q

Hypotheses about viral origin and evolution

A

Proteins and nucleic acids, organic molecules in viruses, evolved and
viruses may have arisen from these two basic polymers when cells did.
Viruses may have been derived from pieces of cell genomes.
Viruses may have evolved backwards from living cells.
Viruses degenerated from living cells.

51
Q

Bacteriophages

A

Viruses that infect bacterial cells

There are two types of bacteriophage life cycles.

52
Q

lytic cycle

A

Viral reproduction occurs
The host cell undergoes lysis
Hundreds of virus particles are released

53
Q

lysogenic cycle

A

Virus becomes integrated into the host genome and may reenter lytic cycle.
This is known as latency and the latent viral DNA is called a prophage.

54
Q

Reproduction of Animal Viruses

A 
Animal virus enters the host cell
Uncoating releases viral DNA or RNA
Budding:
Viral particles released in a bud
Acquires a membranous envelope
55
Q

Retroviruses

A

(HIV, the virus that causes AIDS)
Contain reverse transcriptase
Carries out RNA  cDNA reverse transcription
cDNA becomes integrated into host DNA
Replicated as host DNA replicates
HIV may remain latent for years
Viral DNA is transcribed; new viruses are produced

56
Q

A flu virus has an

A

H (hemagglutinin) spike and an N (neuraminidase) spike

57
Q

H spike

A

allows the virus to bind to the receptor

16 different types

58
Q

N spike

A

attacks host plasma membranes
Allows mature viruses to exit the cell
9 different types

59
Q

characteristics of spikes

A

Each type of spike can occur in different varieties.
Our immune system only recognizes H spikes and N spikes it has been exposed to.
Currently the H7N9 and H5N1 subtypes of flu virus are of great concern because they can potentially become pandemics (global outbreaks).

60
Q

Emerging viruses are new or previously uncommon illnesses.

A

Examples are AIDS, West Nile encephalitis, hantavirus pulmonary syndrome (HPS), severe acute respiratory syndrome (SARS), Ebola, hemorrhagic fever, and avian influenza

61
Q

Several types of events can cause emergence of viruses

A

A virus may extend its range.
Example: West Nile was transported to US and took hold in birds and mosquitoes
A genetic mutation may occur.
Example: Influenza strains H5N1, H1N1, and H7N9 were created through mutation of flu viruses which only infected animals
It is necessary to obtain flu vaccine each year due to the rapidly mutating flu virus

62
Q

Viruses are best known for

A

causing infectious diseases in plants and animals.

63
Q

Herpes, HIV, cancer

A

Viruses lack metabolism; thus, antibiotics have no effect

64
Q

Viroids

A

Naked strands of RNA

Many crop diseases

65
Q

Prions

A

Protein molecules with contagious tertiary structure
TSEs are neurodegenerative diseases which destroy nerve tissue in the brain
They are untreatable and fatal
Some human and other animal diseases: Mad cow disease
Some practices, including eating brains of cattle, transmitted the cattle disease (BSE or bovine spongiform encephalopathy) to humans.

66
Q

nitrogen fixing

A

convert gaseous nitrogen into usable forms

67
Q

who could have brought oxygen to the earth first?

A

bacteria (cynobacteria)

68
Q

size and color of cynobacteria pigments

A

many different colors and large in size

69
Q

mutualistic relationships for bacteria

A

fungi to form lichens

70
Q

symbiotic relationships`

A

Intimate relationships between two different species are called

71
Q

commensalistic relationships

A

that exist in the intestines of humans.

Biology 1201: Organisms and Diversity (20 decks)

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