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Biology > Lecture 3 - Microbiology > Flashcards

Lecture 3 - Microbiology Flashcards

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0
Q

Basic Form of Virus

A
  • consists of protein coat called a capsid w/ one to several hundred genes in the form of DNA or RNA inside the capsid
  • no virus contains both DNA & RNA
  • Most animal, some plant, and very few bacterial viruses surround themselves with a lipid-rich envelope either borrowed from membrane of host cell or synthesized in host cell cytoplasm
  • Envelope typically contains some virus-specific proteins
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1
Q

Viruses

A
  • Tiny infectious agents, much smaller than bacteria

- comparable in size to large proteins

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2
Q

Virion

A

mature virus outside the host cell

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3
Q

What organisms experience viral infections?

A

all organisms

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4
Q

Bacteriophage

A
  • virus that infects bacteria
  • viruses adsorbs to a specific glycoprotein on host cell membrane
  • when a virus infects bacteria is nucleic acid penetrates into the cell through the tail
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5
Q

Endocytotic Process

A
  • Most viruses that infect eukaryotes are engulfed by an endocytotic process
  • Once inside the cell, there are two possible paths: a lysogenic infection or a lytic infection
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6
Q

Lytic Infection

A
  • The virus commandeers the cell’s reproductive machinery & begins reproducing new viruses
  • The cell may fill w/ new viruses until it lyses, or it may release the new viruses one at a time in a reverse endocytotic process
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7
Q

Latent Period

A
  • Period from infection to lysis

- Encompasses the eclipse period

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8
Q

Virulent Virus

A

Virus following a lytic cycle

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9
Q

Lysogenic Infection

A
  • The viral DNA is incorporated into the host genome
  • If the virus is an RNA virus & it possesses reverse transcriptase, DNA is reverse transcribed from RNA & incorporated into host cell genome
  • When host cell replicates its DNA, the viral DNA is replicated as well
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10
Q

Temperate Virus

A
  • Virus in a lysogenic cycle

- Host cell infected w/ this may show no symptoms of infection

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11
Q

Provirus

A
  • When the viral DNA remains incorporated in the host DNA, & the virus is said to be dominant or latent
  • AKA prophage if the host cell is a bacterium
  • Virus may be activated when host cell is under stress, UV light, or carcinogens
  • When virus becomes active, it becomes virulent
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12
Q

Classification of Viruses

A

One way is by the type of nucleic acid they possess

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13
Q

Unenveloped Plus-Strand RNA

A
  • Responsible for the common cold
  • Not all animal viruses are enveloped
  • “plus-strand” indicates that proteins can be directly translated from the RNA
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14
Q

Enveloped Plus-Strand RNA

A
  • Retroviruses such as virus that causes AIDS

- Retrovirus carries reverse transcriptase

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15
Q

Minus-Strand RNA

A
  • Measles, rabies, & the flu

- The complement to mRNA & must be transcribed to plus-RNA before being translated

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16
Q

What type of RNA and DNA viruses are there?

A
  • Double stranded RNA viruses & single and double stranded DNA viruses
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17
Q

Viroid

A
  • Related form of infectious agent
  • small rings of naked RNA w/o capsids
  • only infect plants
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18
Q

Prions

A
  • naked proteins that cause infection in animals

- capable of reproducing themselves w/o DNA or RNA

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19
Q

Antibodies

A
  • How the human body fights viral infections

- Bind to viral protein & w/ cytotoxic T cells, which destroy infected cells

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20
Q

Spike Proteins

A
  • Protrude from envelope & bind to receptors on new host cell, causing virus to be infectious
  • What antibodies recognize
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21
Q

Vaccine

A

Injection of antibodies or of a nonpathogenic virus w/ the same capsid or envelope

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22
Q

Carrier Population

A

More than one animal may act as carrier population

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23
Q

Structure of Virus

A

Capsid, nucleic acid, & lipid-rich protein envelope

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24
Q

Structure of Bacteriophages

A

Tail, base plate, & tail fibers

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25
Q

Prokaryotes

A
  • no membrane bound organelles

- split into 2 domains: Bacteria & archaea

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26
Q

Archaea

A
  • Have similarities to eukaryotes as well as bacteria
  • found in extreme environments: salty lakes & boiling springs
  • cell walls not made from peptidoglycan like bacteria
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27
Q

Bacteria

A

most prokaryotes

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28
Q

Kingdom Monera

A

contains all prokaryotes

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29
Q

What do organisms require in order to grow?

A

the ability to acquire carbon, energy, and electrons

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30
Q

Carbon Sources

A
  • can be organic or inorganic
  • most contribute oxygen and hydrogen as well
  • carbon dioxide is a unique inorganic carbon source b/c it has no hydrogens
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31
Q

Fixing Carbon Dioxide

A
  • Reducing it & using the carbon to create organic molecules usually through the Calvin cycle
  • All microorganisms are capable of it to some degree
  • Reduction of carbon dioxide requires lots of energy & most microorganisms can’t use it exclusively as their carbon source
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32
Q

Autotrophs

A
  • supply one’s own food

- capable of using carbon dioxide as sole source of carbon

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33
Q

Heterotrophs

A
  • use preformed, organic molecules as their carbon source

- organic molecules come from other organisms both living and dead

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34
Q

Where do all organisms acquire energy from?

A
  1. Light : Phototrophs

2. Oxidation of organic or inorganic matter : Chemotrophs

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35
Q

Lithotrophs

A

Acquire electrons or hydrogens from inorganic matter

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36
Q

Organotrophs

A

Acquire electrons or hydrogens from organic matter

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37
Q

Fixing Nitrogen

A
  • Some bacteria are capable of it
  • Atmospheric N is abundant but in strongly bound form that’s useless to plants
  • Process by which N2 is converted to ammonia
  • Most plants unable to use ammonia & must wait for other bacteria to further process the N in a process called nitrification
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38
Q

Nitrification

A
  • Two step process that creates nitrates from ammonia, which are useful to plants
  • Requires two genera of chemoautotrophic prokaryotes
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39
Q

Chemoautotrophy

A
  • Inefficient mechanism for acquiring energy, so chemoautotrophs require large amounts of substrate
  • All known chemoautotrophs are prokaryotes
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40
Q

Structure of Prokaryotes

A
  • have organelles just not membrane bound
  • instead of nucleus, have single, circular double stranded molecule of DNA
  • Have DNA & RNA
  • Molecule of DNA is twisted into supercoils & is associated with histones in Archaea & diff proteins in bacteria
41
Q

Nucleoid

A
  • The DNA, RNA, & protein complex in prokaryotes
  • AKA chromatin body, nuclear region, or nuclear body
  • Not enclosed by a membrane
42
Q

Major Shapes of Bacteria

A
  1. Cocci : Round

2. Bacilli : Rod

43
Q

Other Shapes of Bacteria

A
  1. Spirilla: Rigid Helical

2. Spirochetes: Helical

44
Q

Mesosome

A
  • Invaginations of the plasma membrane

- Prokaryotes may or may not contain them

45
Q

Inclusion Bodies

A
  • Prokaryotes have them

- Granules of organic or inorganic matter

46
Q

Plasma Membrane of Prokaryotes

A

Phospholipid bilayer that surrounds cytosol

47
Q

Phospholipid

A
  • Phosphate group, two fatty acid chains, and a glycerol backbone
  • Phosphate group is polar & fatty acid chains are nonpolar = amphipathic
48
Q

Micelle

A

Spherical structure formed when amphipathic molecules spontaneously aggregate, turning polar ends toward solution & nonpolar ends toward each other when placed in aqueous solution

49
Q

Liposome

A
  • Form from ultrasonic vibrations

- Vesicle surrounded and filled by aqueous solution

50
Q

Haponoids

A

Steroid-like molecules embedded in plasma membrane of prokaryotes

51
Q

Proteins Embedded in Membranes

A
  • Responsible for functional aspects of membranes

- Act as transporters, receptors, attachment sites, and enzymes

52
Q

Integral or Intrinsic Proteins

A

Amphipathic proteins that traverse the membrane from the inside of the cell to the outside

53
Q

Peripheral or Extrinsic Proteins

A
  • Situated entirely on the surfaces of the membrane

- Ionically bonded to integral proteins or the polar group of a lipid

54
Q

Fluid Mosaic Model of the Membrane

A
  • Forces holding the entire membrane together are intermolecular, therefore the membrane is fluid
  • Its parts can move laterally but cannot separate
  • The mosaic aspect is reflected in the asymmetrical layers of its proteins
55
Q

Membrane Fluidity

A
  • Cholesterol moderates membrane fluidity in eukaryotes

- hopanoids reduce fluidity in prokaryotes

56
Q

Brownian Motion

A

Random movement of molecules

57
Q

Diffusion

A

Movement from high to low (w/ no electrical charge)

58
Q

Chemical Concentration Gradient

A

A gradual change in concentration of a compound over a distance (points in direction of lower concentration)

59
Q

Electrical Gradient

A

For molecules with charge (points in direction positive charge molecule will tend to move)

60
Q

Electrochemical Gradient

A

The electrical and chemical concentration gradient added

61
Q

Semipermeability

A
  • Slows diffusion of molecule but doesn’t stop it

- Size & polarity of the molecule affect its semipermeability

62
Q

Size & Semipermeability

A

The larger the molecule, the less permeable the membrane to that molecule

63
Q

Polarity & Semipermeability

A

The greater the polarity of a molecule the less permeable the membrane to it

64
Q

Polar molecules with molecular weight greater than 100 and Permeability

A

A natural membrane is impermeable to them w/o assistance

65
Q

Transport or Carrier Proteins

A

Facilitate diffusion of specific molecules across the membrane

66
Q

Facilitated Diffusion

A
  • Diffusion must occur down the electro-chemical gradient of all species involved
  • Most human cells rely on it for their glucose supply
  • Makes the membrane selectively permeable
  • Transport Proteins
67
Q

Active Transport

A
  • Movement of compound against electrochemical gradient
  • Requires energy
  • Direct or indirect use of ATP
68
Q

Passive Diffusion

A
  • Depends on lipid solubility - Are you nonpolar enough to slide through?
  • Depends on size too
69
Q

Protoplast

A

The bacterial plasma membrane and everything in it

70
Q

Bacterial Envelope

A
  • Surrounds protoplast
  • Cell wall is a component & is adjacent to plasma membrane
  • Cell wall functions to prevent protoplast from bursting
71
Q

Hypertonic

A
  • Most bacteria are hypertonic to their environment

- The aqueous solution of their cytosol contains more particles than the aqueous solution surrounding them

72
Q

Isotonic

A

Cytosol contains same amount of particles

73
Q

Hypotonic

A

Cytosol contains less particles

74
Q

Hydrostatic Pressure & Osmotic Pressure

A

As cell fills with water and the hydrostatic pressure builds, it eventually equals the osmotic pressure & the filling stops

75
Q

Cell Wall of Bacteria

A

Made of peptidoglycan

76
Q

Peptidoglycan

A
  • Series of disaccharide polymer chains w/ amino acids, 3 of which are not found in proteins
  • More elastic than cellulose & porous
77
Q

Lysozyme

A

Enzyme produced naturally by humans - attacks disaccharide linkage in peptidoglycan

78
Q

Classification of Bacteria by Type of Cell Wall

A

gram staining

79
Q

Gram-Positive Bacteria

A
  • Thick peptidoglycan cell wall
  • Prevents gram stain from leaking out
  • Purple
  • Have cell wall 4x thicker than plasma membrane
80
Q

Gram-Negative Bacteria

A
  • Thin peptidoglycan cell wall - allows most of stain to wash off
  • Pink
  • Have a phospholipid bilayer outside the cell wall
81
Q

Bacterial Flagella

A
  • Long, hollow, rigid, helical cylinders made from globular protein called flagellin
  • Rotate counterclockwise to propel bacteria in single direction
  • When they are rotated clockwise, bacteria tumbles
  • Flagellum is propelled using energy from proton gradient rather than ATP
82
Q

Bacterial Reproduction

A
  • Three forms of genetic recombination: Conjugation, transformation, & transduction
  • Cell division: binary fission - asexual reproduction
83
Q

Binary Fission

A
  • Circular DNA is replicated
  • Two DNA polymerases begin at same point on circle (origin of rep) & move in opposite directions making complementary single strands that combine with their template strands to form 2 complete DNA double stranded circles
  • The cell then divides, leaving 1 circular chromosome in each daughter cell. The 2 daughter cells are genetically identical
84
Q

Conjugation

A
  • Requires that one bacterium have a plasmid w/ the gene that codes for the sex pilus
85
Q

Plasmid

A

Small circles of DNA that exist & replicate independently of the bacterial chromosome

86
Q

Sex Pilus

A

Hollow, protein tube that connects 2 bacteria to allow the passage of DNA

87
Q

F Plasmid (Conjugative Plasmid)

A

Donates resistance to certain antibiotics

88
Q

Transformation

A

Process by which bacteria may incorporate DNA from their external environment into their genome

89
Q

Transduction

A

When capsid of a bacteriophage mistakenly encapsulates a DNA fragment of host cell, and then when they infect a new bacteria they inject the harmless bacterial DNA fragment instead of a virulent viral DNA fragment

90
Q

Endospores

A
  • some gram + bacteria can form them
  • can lie dormant for hundreds of years
  • Resistant to heat, UV radiation, chemical disinfectants and desiccation
  • can survive in boiling water for over an hour
  • Formation is triggered by lack of nutrients
  • Formed when bacterium divides within its cell wall & one side then engulfs the other
91
Q

Kingdom Fungi

A
  • Lots of diversity
  • Three divisions w/in kingdom: Zygomycota, Ascomycota, & Basidiomycota
  • Separated into divisions, not phyla, like plants
92
Q

Fungi

A
  • All are eukaryotic heterotrophs - obtain food by absorption rather than ingestion
  • Most considered saprophytic
  • Most possess cell walls called septa, made of the polysaccharide chitin
  • With exception of yeast, they are multicellular
  • cell may contain one or more nuclei
  • Nuclei w/in single cell may or may not be identical
  • Lack centrioles
  • Mitosis takes place entirely in the nucleus
  • The nuclear envelope never breaks down
93
Q

Fungi - Absorption of Food

A

They secrete digestive enzymes outside their bodies & then absorb the products of digestion

94
Q

Saprophytic

A

Live off dead organic matter, but many fungi don’t distinguish between living and dead matter & thus can be potent pathogens

95
Q

Fungi’s Growth State

A

They consist of a tangled mass called a mycellium of multiple branched thread-like structures called hyphae

96
Q

Chitin

A
  • More resistant to microbial attack than is cellulose

- Same substance the exoskeleton of arthropods is made

97
Q

Septa

A
  • Usually perforated to allow exchange of cytoplasm between cells called cytoplasmic streaming
  • cytoplasmic streaming allows for very rapid growth
98
Q

Fungi Reproduction

A
  • Alternate between haploid & diploid stages, but haploid stage predominates & is their growth stage
  • Hyphae are haploid
  • Can reproduce sexually or asexually
99
Q

Fungi Asexual Reproduction

A
  • Occurs by producing spores or budding (cell fission)

- Occurs when conditions are good

100
Q

Fungi Sexual Reproduction

A
  • Occurs between hyphae from 2 mycelia of different mating types + and -
  • Occurs when conditions are tough

Biology (4 decks)

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