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Biology > Chapter 20: Viruses and Prokaryotes > Flashcards

Chapter 20: Viruses and Prokaryotes Flashcards

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1
Q

How complex are viruses?

A

Viruses are the simplest life-like structures.

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2
Q

True or False: It’s easier to change a simple structure, rather than complex.

A

True

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3
Q

Why aren’t viruses living?

A

Viruses are not living because they only reproduce they only reproduce (and they need a host to do so).

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4
Q

How do viruses reproduce?

A

Viruses reproduce only by infecting living cells.

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5
Q

Who demonstrated that the cause of tobacco mosaic disease was found in the liquid extracted from infected plants?

A

Dmitri Ivanovsky

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6
Q

Ivanovsky found that viruses are _______ than bacteria, and they can stay in a ____________ form.

A

Ivanovsky found that viruses are smaller than bacteria, and they can stay in a crystalline form.

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7
Q

What are viruses made of?

A

proteins, nucleic acids, and sometimes lipids

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8
Q

True or False: Viruses differ widely in terms of size and structure.

A

True

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9
Q

The protein coat surrounding a virus is called a what?

A

capsid

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10
Q

Can viruses have an additional membrane surrounding the capsid?

A

Yes

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11
Q

The simplest viruses contain only a few _____, whereas the most complex may have more than a hundred _____.

A

genes

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12
Q

What do most proteins on the capsid do?

A

Bind to receptor proteins on the host cell

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13
Q

When are the viral genes expressed?

A

Once the viral genes are inside the host the cell- this is also when the virus can destroy the host cell.

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14
Q

Viruses that infect bacteria are called what?

A

bacteriophages

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15
Q

What do bacteriophages have for protection?

A

A tail sheath

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16
Q

What happens in a lytic infection?

A

In a lytic infection, a virus enters a bacterial cell, makes copies of itself, and causes the cell to burst (lyse).

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17
Q

What is an example bacteriophage that causes a lytic infection?

A

Bacteriophage T4

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18
Q

Bacteriophage T4 has a ___ ____ inside a protein capsid that bonds to the surface of a host cell.

A

Bacteriophage T4 has a DNA core inside a protein capsid that bonds to the surface of a host cell.

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19
Q

What does the virus do once it bonds to the cell surface?

A

It injects its DNA into the cell.

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20
Q

What type of RNA does the cell make from the viral genes?

A

messenger RNA

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21
Q

The viral mRNA is translated into viral _______ that chop up the cell’s DNA.

A

proteins

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22
Q

Copies are made of _______ ____ once the viral genes control the cell.

A

Copies are made of nucleic acid once the viral genes control the cell.

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23
Q

The host cell’s metabolic system makes copies of ______ ____ and ______ ________.

A

The host cell’s metabolic system makes copies of nucleic acid and capsid proteins.

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24
Q

The viral nucleic acid and proteins are then assembled into what?

A

new virus particles

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25
Q

The virus particles are released to infect other cells when the host cell _____.

A

lyses

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26
Q

What are the names of the two cycles that the virus can go through (depending on environmental conditions)?

A

Lytic Cycle and the Lysogenic Cylcle

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27
Q

What does “lysis” mean (from the word lytic)?

A

destroy

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28
Q

True or False: Chromosomes are made of genetic material.

A

True

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29
Q

A virus that attacks bacteria is called a _____.

A

phage

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30
Q

What are the steps to the Lytic Cycle?

A
  1. virus attaches to cell and injects DNA
  2. viral DNA circulizes
    (if continuing with lytic)
  3. new viruses (viroids) are made
  4. cell lyses (releases virus)
    repeat
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31
Q

What are the new viruses made in the Lytic Cycle called?

A

viroids

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32
Q

What are the two classifications of prokaryotes?

A

Bacteria and Archaea

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33
Q

What is the main difference between bacteria and archaea?

A

Materials

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34
Q

Prokaryotes are ___-________.

A

Prokaryotes are sub-cellular.

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35
Q

The smallest and most abundant microorganisms on Earth are ___________.

A

prokaryotes

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36
Q

Do prokaryotes have DNA?

A

Yes

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37
Q

Where is a prokaryote’s DNA found?

A

In the cytoplasm (it free floats)

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38
Q

A primitive cell (like a prokaryote) is more sophisticated than a ____, but less than a _________.

A

A primitive cell (like a prokaryote) is more sophisticated than a virus, but less than a eukaryote.

39
Q

True or False: Prokaryotes have cell walls.

A

True

40
Q

What are in the cell wall of a prokaryote?

A

Sugars and amino acids

41
Q

So prokaryotes have an additional layer of protection for resistance called a what?

A

slime capsule

42
Q

The _____________ describes the bacterial cell wall made of part sugar and part amino acid .

A

peptidoglycan

43
Q

Are bacteria a larger group than archaea?

A

Yes

44
Q

Some prokaryotes have ________ that they use for movement.

A

flagella

45
Q

____ mainly serve to anchor the bacterium to a surface or to other bacteria.

A

pili

46
Q

Archaea look very _______ to bacteria.

A

similar

47
Q

Both archaea and bacteria ____ nuclei.

A

Both archaea and bacteria lack nuclei.

48
Q

Do archaea have peptidoglycan?

A

No, the archaea membranes contain different lipids.

49
Q

Archaea DNA sequences are more like those of what than those of bacteria?

A

eukaryotes

50
Q

_____ and _________ are related more closely to each other than to ________.

A

Archaea and eukaryotes are related more closely to each other than to bacteria.

51
Q

True or False: Many archaea live in extremely harsh environments.

A

True

52
Q

Archaea and bacteria both are equally small, ____ _______, and have cell walls.

A

Archaea and bacteria both are equally small, lack nuclei, and have cell walls.

53
Q

Prokaryotes are much ________ than most eukaryotic cells.

A

smaller

54
Q

Rod-shaped prokaryotes are called what?

A

bacilli

55
Q

Spherical prokaryotes are called what?

A

cocci

56
Q

Spiral and corkscrew-shaped prokaryotes are called ____.

A

spirilla

57
Q

How do prokaryotes move?

A

Some do not move at all.
Some are propelled by flagella.
Some glide slowly along a layer of slime-like secreted material.

58
Q

Can bacteria adapt by changing shape to survive?

A

Yes

59
Q

How do prokaryotes store the chemical energy they need?

A

by storing it in the form of food molecules such as sugar

60
Q

True or False: Some species are able to change their method of energy capture or release depending on the conditions of their environments.

A

True

61
Q

When a prokaryote has grown so that it has nearly doubled in size, it _________ its DNA and divides in half.

A

When a prokaryote has grown so that it has nearly doubled in size, it replicates its DNA and divides in half.

62
Q

After the division, there are now two identical cells. What type of reproduction is this?

A

binary fission

63
Q

What form of reproduction is binary fission?

A

asexual

64
Q

When growth conditions become unfavorable, many prokaryotic cells form an _________.

A

endospore

65
Q

An endospore is a a thick internal wall that encloses the what?

A

DNA and a portion of the cytoplasm

66
Q

Can endospore remain dormant for a long period of time?

A

Yes

67
Q

What is one of the main ways prokaryotes evolve?

A

Mutations

68
Q

In prokaryotes, mutations are _________ by daughter cells produced by binary fission.

A

In prokaryotes, mutations are inherited by daughter cells produced by binary fission.

69
Q

The process of prokaryotes exchanging genetic information is called what?

A

conjugation

70
Q

During conjugation, a hollow bridge forms between two _________ _____.

A

bacterial cells

71
Q

The genetic material, usually in the form of a ______, moves from one cell to the other.

A

plasmid

72
Q

Many plasmids carry genes that enable bacteria to what?

A

survive in new environments or to resist antibiotics that might otherwise prove fatal

73
Q

What does this transfer of genetic information increase?

A

It increases the genetic diversity in populations of prokaryotes.

74
Q

_____________ bacteria are present in soil and in rotting plant material decompose complex organic molecules into simpler molecules.

A

Actinomycetes

75
Q

How do prokaryotes supply raw materials, and thus help to maintain equilibrium in the environment?

A

By decomposing dead organisms

76
Q

What is a type of pond bacteria that performs photosynthesis?

A

cyanobacteria

77
Q

Food chains are dependent upon ___________ as producers of food and biomass.

A

prokaryotes

78
Q

What do all organisms need to make protein and other molecules?

A

Nitrogen

79
Q

Only a few kind of organisms, all of which are what, can convert N2 into useful forms?

A

Prokaryotes

80
Q

What process converts nitrogen gas into ammonia?

A

Nitrogen fixation

81
Q

Nitrogen-fixing bacteria and archaea provide __% of the nitrogen used by other organisms.

A

90

82
Q

The prophage is a combination of the _____ and _________ DNA.

A

The prophage is a combination of the viral and bacterial DNA.

83
Q

Once combined, can the two types of DNA separate?

A

No

84
Q

In the lysogenic cycle, when the viral DNA is replicated and the host cell divides, the DNA makes a what?

A

copy of itself

85
Q

For both daughter cells, the genetic makeup is what?

A

the genetic makeup is identical at the end of mitosis

86
Q

If the environmental conditions allow for it, the viral DNA circularizes and then goes into the _________ ____.

A

lysogenic cycle

87
Q

What are the steps to the lysogenic cycle?

A
  1. viral DNA integrates into host DNA
  2. viral DNA is replicated (host replicates own DNA)
    host cell divides (mitoses)
  3. prophage may leave host DNA to enter lytic cycle
88
Q

What is the difference between the lysogenic cycle and the lytic cycle?

A

The lytic cycle destroys the host cell, once it uses it. The lysogenic cycle takes advantage of the host cell, but lets it live.

89
Q

True or False: Both cycles are a survival mechanism, so the virus can stay “alive.”

A

True

90
Q

In the lysogenic cycle, when the host cell divides, what part of mitosis is it?

A

Cytokinesis

91
Q

How many times does the DNA make a copy of itself?

A

Each time the host cell divides

92
Q

What is the difference between HIV and AIDS?

A

HIV is the infection. AIDS is when the patient starts showing symptoms.

93
Q

An illness that can transfer from each species is called what?

A

zoonosis

94
Q

An example of zoonosis is what?

A

Rabies

Biology (7 decks)

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