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Biology 202 > Chp 19, 27 > Flashcards

Chp 19, 27 Flashcards

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1
Q

Viral Genomes consist of __ or __ and are classified as __ viruses or __ viruses.

A

ds/ss DNA, ds/ss RNA; DNA, RNA

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2
Q

What is a Capsid?

A

The protein shell that encloses the viral genome. Capsids are built from protein subunits called capsomeres.

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3
Q

What are viral envelopes?

A

Viral envelopes surround the capsids of influenza viruses and many animal viruses. They are derived from membranes of host cells and therefore contain host cell phospholipids and membrane proteins.

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4
Q

What are phages?

A

Phages are viruses that infect bacteria. They are composed of an elongated capsid head and a protein tail piece that injects the phage DNA inside.

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5
Q

What occurs after the viral genome enters the host cell?

A

The cell begins to make viral proteins. The virus makes use of host machinary. Viral nucleic acid molecules and capsomeres self-assemble into new viruses.

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6
Q

What are the two alternative reproductive mechanisms found in phages?

A

The lytic cycle and the lysogenic cycle.

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7
Q

What is a virulent phage?

A

A phage that reproduces only by the lytic cycle.

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8
Q

Describe the Lysogenic cycle.

A

This cycle replicates the phage genome without destroying the host. The viral DNA molecule is incorporated into the host cell’s chromosome.

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9
Q

What are Temperate phages?

A

Phages that use both the lytic and lysogenic cycles.

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10
Q

What are the three ways in which bacteria defend themselves against phages?

A

Natural selection, restriction enzymes, and the Crispr-Cas system.

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11
Q

Explain how Natural selection aids in combat against phages for bacteria.

A

Natural selection favors bacterial mutants with surface proteins that cannot be recognized as receptors by a particular type of phage.

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12
Q

What is the role of restriction enzymes?

A

Restriction enzymes restrict a phage’s ability to replicate within the bacterium. Foreign DNA can be identified as such and cut up by these cellular enzymes.

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13
Q

Both bacteria and archaea can protect themselves from viral infection with the Crispr-Cas system. What does this acronym stand for?

A

Clustered regularly interspaced short palindromic repeats.

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14
Q

What is the role of each “spacer” sequence between the repeats?

A

Each “spacer” sequence corresponds to DNA from a phage that had previously infected the cell.

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15
Q

What are the two key variables used to classify viruses that infect animals?

A

ss or ds DNA/RNA and the presence or absence of a membranous envelope.

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16
Q

What role does the Viral envelope play?

A

Viral glycoproteins on the envelope bind to specific receptor molecules on the surface of a host cell. The viral envelope is usually derived from the host cell’s plasma membrane as the viral capsids exit.

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17
Q

What make retroviruses unique?

A

Retroviruses use reverse transcriptase to copy their RNA genome into DNA.

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18
Q

What is an example of a retrovirus?

A

HIV, a retrovirus that causes AIDS.

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19
Q

Unlike a prophage, a provirus…

A

remains a permanent resident of the host cell.

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20
Q

What is a provirus?

A

Viral DNA integrated into the host genome.

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21
Q

What transcribes the proviral DNA into RNA molecules?

A

RNA polymerase.

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22
Q

What two roles does the RNA molecules play in viral infection?

A

RNA molecules function both as mRNA for synthesis of viral proteins and as genomes for new virus particles released from the cell.

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23
Q

List 3 ways viral diseases affect animals.

A

Viruses may damage or kill cells by causing the release of hydrolytic enzymes from lysosomes. Some viruses cause infected cells to release toxins and others have molecular components such as envelope proteins that are toxic.

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24
Q

Viral infections cannot be treated by

A

antibiotics.

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25
Q

What epidemic of a flu-like illness appeared in Mexico and the US in 2009?

A

H1N1.

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26
Q

Viruses with RNA genomes are more prevalent in

A

Plants.

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27
Q

Plant viruses spread disease by two major routes:

A

Horizontal transmission, entering through damaged cell walls, and Vertical transmission, parent to offspring.

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28
Q

What are Prions?

A

Infections proteins that appear to cause degenerative brain diseases in animals. Prions are misfolded proteins that are able to convert more proteins into prions.

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29
Q

What are three diseased caused by Prions?

A

Scrapie in sheep, mad cow disease, and Creutzfeldt-Jakob disease in humans.

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30
Q

Why are Prokaryotes the most abundant organisms on earth?

A

Prokaryotes have the ability to adapt to diverse habitats and thrive almost everywhere.

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31
Q

What are the three most common shapes of Prokaryotes?

A

Spheres (cocci), rods (bacilli), and spirals.

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32
Q

What is the role of the cell wall? What do most bacterial cell walls contain?

A

The cell wall maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment. Most bacterial cell walls contain peptidoglycan, a network of sugar polymers cross-linked by polypeptides.

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33
Q

What is peptidoglycans?

A

A network of sugar polymers cross-linked by polypeptides.

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34
Q

Which domain lacks peptidoglycan?

A

Domain archaea.

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35
Q

Why do scientists use the Gram stain technique?

A

To classify bacteria by cell wall composition.

36
Q

Gram-positive bacteria have

A

simpler walls with a large amount of peptidoglycan.

37
Q

Gram-negative bacteria have

A

less peptidoglycan and an outer membrane that contains lipopolysaccharides.

38
Q

Many antibiotics target peptidoglycan and damage bacterial cell walls. Which type of bacteria is more susceptible to this type of antibiotics?

A

Gram-positive bacteria.

39
Q

__ are longer than fimbriae and allow prokaryotes to exchange DNA.

A

Pili

40
Q

__ are hairlike appendages that allow prokaryotes to stick to their substrate or individuals in a colony.

A

Fimbriae

41
Q

Explain the term Taxis.

A

The ability to move toward or away from a stimulus.

42
Q

What is exaptation? What is an example of exaptation?

A

Where structures adapted for one function take on new functions through descent with modification. An example of this is the flagella, which likely evolved as existing proteins were added to an ancestral secretory system.

43
Q

Although prokaryotic cells lack complex compartmentalization, they contain

A

specialized membranes that perform metabolic functions. These are usually infoldings of the plasma membrane.

44
Q

What are two examples of infoldings of the plasma membrane in prokaryotic cells?

A

The respiratory membrane in an aerobic prokaryote, and the thylakoid membrane in a photosynthetic prokaryote.

45
Q

Plasmids are

A

smaller rings of independently replicating DNA.

46
Q

Why are antibiotics able to inhibit bacterial growth without harming humans?

A

Differences between prokaryotes and eukaryotes in DNA replication, transcription, and translation.

47
Q

Prokaryotes reproduce quickly by a means of asexual reproduction known as

A

binary fission.

48
Q

What are the three features of prokaryote biology?

A

Prokaryotes are small, reproduce by binary fission, and they have short generation times.

49
Q

What are three factors that contribute to the considerable genetic variation of prokaryotes?

A

Rapid reproduction, mutation, and genetic recombination.

50
Q

What is genetic recombination?

A

The combining of DNA from two sources.

51
Q

What are three ways in which prokaryotic DNA from different individuals can be brought together?

A

Transformation, transduction, and conjugation.

52
Q

Describe the process of “Transformation”.

A

A prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment.

53
Q

What is Transduction?

A

The movement of genes between bacteria by phages. Transduction is considered accidental.

54
Q

What is Conjugation?

A

The process where genetic material is transferred from one prokaryotic cell to another.

55
Q

What are plasmids?

A

Small, circular DNA molecules found in most bacterial cells. Plasmids replicate independently of the cell’s main DNA molecule.

56
Q

What are R plasmids?

A

A type of plasmid that carry genes for antibiotic resistance.

57
Q

What is the F factor?

A

A piece of DNA required for the production of the Sex Pili, or a hollow protein tube used to transfer genetic information from the F+ cell to another cell.

58
Q

What are Episome?

A

Types of plasmid that can combine with the main DNA molecule.

59
Q

In conjugation, the recipient cell becomes a ____ ____ cell.

A

Recombinant F+ cell.

60
Q

How are High Freq. of Recombination (HFR) cells formed.

A

HFR cells are formed when only a fraction of the plasmid is transferred and incorporated into the bacterial cell’s DNA.

61
Q

____ cells are used in bacterial chromosomal mapping.

A

HFR.

62
Q

Prokaryotes are categorized by how they obtain ____ and ____.

A

Energy; Carbon.

63
Q

Autotrophs require ________ as a carbon source.

A

CO2 or related compounds.

64
Q

____ require an organic nutrient to make organic compounds.

A

Heterotrophs.

65
Q

What is the energy and carbon source for photoautotrophs?

A

CO2; HCO3- or related compound.

66
Q

What is the energy and carbon source for chemoautotrophs?

A

Inorganic chemicals; HCO3- or related compound.

67
Q

What is the energy and carbon source for photoheterotrophs?

A

Light; Organic compounds.

68
Q

What is the energy and carbon source for Chemoheterotrophs?

A

Organic compounds.

69
Q

The primary role of O2 in cellular respiration is to act as an __ acceptor.

A

Electron, e-.

70
Q

What can some obligate anaerobes use as an e- acceptor?

A

Nitrogen ions.

71
Q

Nitrogen is essential for the production of ____ and ____ in all organisms.

A

Amino acids; Nucleic acids.

72
Q

What are biofilms?

A

Biofilms are a form of metabolic cooperation that occur between different prokaryotic species in surface coating colonies.

73
Q

What are the 5 subgroups of Proteobacteria?

A

Alpha, Beta, Gamma, Delta, and Epsilon.

74
Q

Proteobacteria are gram-negative bacteria that include ____

A

photo/chemoautotrophs, and heterotrophs.

75
Q

What are Chlamydias?

A

Chlamydias are parasites that live within animal cells.

76
Q

Extreme halophiles live in

A

highly salty environments.

77
Q

Extreme thermophiles thrive in

A

very hot environments.

78
Q

Methanogens live in

A

swamps and marshes and produce methane as a waste product.

79
Q

In ____, both symbiotic organisms benefit.

A

Mutualism.

80
Q

In ____, one organism benefits while neither harming nor helping the other in any significant way.

A

Commensalism.

81
Q

In ____, an organism called a ____ harms but does not kill its host.

A

Parasitism; parasite.

82
Q

Parasites that cause disease are called

A

pathogens.

83
Q

Pathogenic prokaryotes typically cause disease by

releasing exotoxins or endotoxins. ____ are released only when bacteria die and their cell walls break down.

A

Endotoxins.

84
Q

Pathogenic prokaryotes typically cause disease by
releasing exotoxins or endotoxins. ____ are secreted and cause disease even if the prokaryotes that produce them are not present.

A

Exotoxins.

85
Q

Prokaryotes can be used in ____, or the use of organisms to remove pollutants from the environment.

A

Bioremediation.

86
Q

Why is Euglena called a mixtotroph?

A

They can undergo photosynthesis and can feed.

87
Q

Describe the form of diatoms.

A

Diatoms possess a test, or shell, made up of two halves. The test is mostly made of silica.

Biology 202 (8 decks)

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