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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
three basic shapes of a bacteria
Spiral (spirilli), Rod (bacilli), and Round (cocci)
26
Bacterial Metabolism
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
27
vectors
suitcases of holding genetic info to other places and spread
28
Autotrophic Bacteria
Photoautotrophs | Chemoautotrophs
29
Photoautotrophs
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
Chemoautotrophs
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
Heterotrophic Bacteria
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
Heterotrophic Bacteria may be
free-living or symbiotic (two different species live together in an intimate way)
33
Commensalism
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
Mutualism
Both species benefit from association. | Mutualistic bacteria live in human intestines and release vitamins K and B12 which help produce blood components.
35
produce blood components. | Parasitism
Parasite benefits at host expense; disease-causing bacteria are called pathogens Many form endospores
36
Cyanobacteria!
(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
Cyanobacteria charcteristics
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
Antibiotic compounds fall into two classes
Compounds that inhibit protein biosynthesis | Compounds that inhibit cell wall biosynthesis
39
Compounds that inhibit protein biosynthesis
Erythromycin | Tetracycline
40
Compounds that inhibit cell wall biosynthesis
These affect bacterial but not animal cells Penicillin Ampicillin Fluroquinolone
41
Bacterial resistance to antibiotics is increasing.
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
Carl Woese and George Fox
discovered that the base sequence of their rRNA differs from bacteria.
43
archea Other differences
Archaea do not have peptidoglycan in their cell walls like the bacteria. Archaea are biochemically more like eukarya than bacteria.
44
Archaea are now thought to be more closely related to
eukarya than to bacteria.
45
Many live in harsh conditions:
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
Viral Structure and Classification
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
Capsid
outer layer composed of protein subunits
48
Capsid or no capsid
Some are enveloped by membrane | Others “naked”
49
obligate intracellular parasites`
Cannot reproduce outside a living cell | Are either active or inactive, instead of living or non-living
50
Hypotheses about viral origin and evolution
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
Bacteriophages
Viruses that infect bacterial cells | There are two types of bacteriophage life cycles.
52
lytic cycle
Viral reproduction occurs The host cell undergoes lysis Hundreds of virus particles are released
53
lysogenic cycle
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
Reproduction of Animal Viruses
``` Animal virus enters the host cell Uncoating releases viral DNA or RNA Budding: Viral particles released in a bud Acquires a membranous envelope ```
55
Retroviruses
(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
A flu virus has an
H (hemagglutinin) spike and an N (neuraminidase) spike
57
H spike
allows the virus to bind to the receptor | 16 different types
58
N spike
attacks host plasma membranes Allows mature viruses to exit the cell 9 different types
59
characteristics of spikes
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
Emerging viruses are new or previously uncommon illnesses.
Examples are AIDS, West Nile encephalitis, hantavirus pulmonary syndrome (HPS), severe acute respiratory syndrome (SARS), Ebola, hemorrhagic fever, and avian influenza
61
Several types of events can cause emergence of viruses
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
Viruses are best known for
causing infectious diseases in plants and animals.
63
Herpes, HIV, cancer
Viruses lack metabolism; thus, antibiotics have no effect
64
Viroids
Naked strands of RNA | Many crop diseases
65
Prions
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
nitrogen fixing
convert gaseous nitrogen into usable forms
67
who could have brought oxygen to the earth first?
bacteria (cynobacteria)
68
size and color of cynobacteria pigments
many different colors and large in size
69
mutualistic relationships for bacteria
fungi to form lichens
70
symbiotic relationships`
Intimate relationships between two different species are called
71
commensalistic relationships
that exist in the intestines of humans.

Biology 1201: Organisms and Diversity (20 decks)

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