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Chapter 27 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

History of Microbiology

A

The size of prokaryotic cells led to their being undiscovered for most of human history​

In 1546, Italian physician Girolamo Fracastoro suggested that disease was caused by unseen organisms​

Antony van Leeuwenhoek was first to observe and accurately describe microbial life​

Modern electron microscopes allows the study of cell substructure.​

Louis Pasteur refutes idea of spontaneous generation (idea that living things arise spontaneously from other living things)

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2
Q

Two lines of technology

A

Microscopy for visualization.​

Infectious disease investigations.

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3
Q

Robert Koch studied anthrax; proposed four postulates

A

The microorganism must be present in every case of the disease and absent from healthy individuals.​

The putative causative agent must be isolated and grown in pure culture.​

The same disease must result when the cultured microorganism is used to infect a healthy host.​

The same microorganism must be isolated again from the diseased host.

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4
Q

Prokaryotic Diversity

A

Oldest, structurally simplest, and most abundant forms of life​

Abundant for over a billion years before eukaryotes appeared​

90-99% unknown and undescribed​

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5
Q

Prokaryote Domains

A

Bacteria.​

Archaea.​

Many archaea are extremophiles.

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6
Q

Unicellularity

A

Most are single-celled.​

May stick together to form associations and biofilms.

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7
Q

Cell size

A

Size varies tremendously.​

Most are less than 1 μm in diameter.

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8
Q

Nucleoid

A

Chromosome is single circular double-stranded D N A.​

Found in the nucleoid region of cell.​

Often have plasmids.

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9
Q

Cell division and genetic recombination

A

Most divide by binary fission.​

Exchange genes through horizontal gene transfer; not a form of reproduction.

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10
Q

Internal compartmentalization

A

No membrane-bounded organelles.​

No internal compartment.​

Plasma membrane can be extensively infolded.

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11
Q

Flagella

A

Simple in structure.​

Different from eukaryotic flagella.

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12
Q

Pili

A

Protein filaments extending from the surface

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13
Q

Metabolic diversity

A

Oxygenic and anoxygenic photosynthesis.​

Chemolithotrophic.

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14
Q

Bacteria and archaea differ

A

They differ in four key areas:​

-Plasma membranes​

-Cell walls​

-D N A replication​

-Gene expression

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15
Q

Plasma membrane

A

All prokaryotes have a plasma membrane.​

Membranes of archaea differ from bacteria and eukaryotes.​

Archaean membranes are formed of glycerol linked to hydrocarbon chains by ether linkages (not ester like bacteria & eukaryotes).​

Hydrocarbons may be branched.​

Tetraethers form a monolayer instead of a bilayer; allows extremophiles to withstand high temperatures.

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16
Q

Cell wall

A

All prokaryotes have cell walls.​

Bacteria have peptidoglycan.​

Archaea lack peptidoglycan.

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17
Q

D N A replication​

A

Both have single replication origin; nature of origin and proteins used are different.​

Archaeal D N A replication is more similar to that of eukaryotes.

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18
Q

Gene Expression

A

Archaeal transcription and translation are more similar to those of eukaryotes.

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19
Q

Early systems relied on staining characteristics and observable phenotypes

A

Photosynthetic ability​

Cell wall structure​

Motility​

Unicellular, colony-forming, or filamentous​

Spore-forming ability​

Importance as human pathogens or not

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20
Q

Molecular Classification

A

Amino acid sequences of key proteins​

Percent guanine–cytosine content​

Nucleic acid hybridization​

Closely related species will have more base pairing.​

Gene and R N A sequencing​

Especially rR N A.​

Whole-genome sequencing

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21
Q

Molecular Classification

A

Based on these molecular data, several prokaryotic groupings have been proposed​

Bergey’s Manual of Systematic Bacteriology, 2nd edition​

Large scale sequencing of random samples indicates vast majority of bacteria have never been cultured or studied in detail

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22
Q

Prokaryotic Cell Structure

A

3 basic shapes​

-Bacillus – rod-shaped​

-Coccus – spherical​

-Spirillum – helical-shaped

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23
Q

Prokaryotic Cell Characteristics

A

Cell wall​

Peptidoglycan forms a rigid network.​

Maintains shape.​

Withstands hypotonic environments.​

Archaea have a similar molecule (pseudomurein).​

Gram stain.​

Gram-positive bacteria have a thicker peptidoglycan wall and stain a purple color.​

Gram-negative bacteria contain less peptidoglycan and do not retain the purple-colored dye – retain counterstain and look pink.

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24
Q

Prokaryotic cell walls

A

Gram positive bacteria​

Thick, complex network of peptidoglycan.​

Also contains lipoteichoic and teichoic acid.​

Gram negative bacteria​

Thin layer of peptidoglycan.​

Second outer membrane with lipopolysaccharide.​

Resistant to many antibiotics.

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25
Q

Prokaryotic cell walls 2

A

S-layer​

Rigid paracrystalline layer found in some bacteria and archaea.​

Outside of peptidoglycan or outer membrane layers in gram-negative and gram-positive bacteria.​

Diverse functions – often involves adhesion.​

Capsule​

Gelatinous layer found in some bacteria.​

Aids in attachment.​

Protects from the immune system.

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26
Q

Flagella

A

Slender, rigid, helical structures.​

Composed of the protein flagellin.​

Involved in locomotion – spin like propeller.

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27
Q

Pili

A

Short, hairlike structures.​

Found in gram-negative bacteria.​

Aid in attachment and conjugation.

28
Q

Endospores

A

Develop a thick wall around their genome and some of the cytoplasm when exposed to environmental stress​

Highly resistant to environmental stress​

Especially heat.​

When conditions improve can germinate and return to normal cell division​

Bacteria causing tetanus, botulism, and anthrax

29
Q

Prokaryotic cells often have complex internal membranes

A

Invaginated regions of plasma membrane​

Function in respiration or photosynthesis

30
Q

Nucleoid region

A

Contains the single, circular chromosome.​

May also contain plasmids.

31
Q

Ribosomes

A

Smaller than those of eukaryotes.​

Differ in protein and R N A content.​

Targeted by some antibiotics.

32
Q

Prokaryotic cell organization

A

Internal compartments​

Small number of membrane-bounded structures seen​

Magnetosome in magnetotactic bacteria​

Protein shells called bacterial microcompartments (B M C)​

They isolate specific metabolic processes. ​

Increase concentration of reactants.​

Protect the cell from toxic metabolic intermediates.

33
Q

Prokaryotic Genetics

A

3 types of horizontal gene transfer​

-Conjugation – cell-to-cell contact.​

-Transduction – by viruses.​

-Transformation – from the environment.

34
Q

Natural transformation

A

Occurs in many bacterial species.​

D N A from a dead cell picked up by a live cell.​

Proteins for it are on the bacterial chromosome.​

Evolved, not an accident of plasmid or phage biology.

35
Q

Artificial transformation

A

Some species do not naturally undergo transformation.​

Accomplished in the lab.​

Used to transform E. coli for molecular cloning.

36
Q

Generalized transduction

A

Virtually any gene can be transferred.​

Occurs via accidents in the lytic cycle.​

Viruses package bacterial D N A and transfer it in a subsequent infection.

37
Q

Specialized transduction

A

Occurs via accidents in the lysogenic cycle.​

Imprecise excision of prophage D N A.​

These phage carry both phage genes and chromosomal genes.

38
Q

Conjugation

A

Plasmids may encode functions not necessary to the organism, but may provide a selective advantage​

In E. coli, conjugation is based on the presence of the F plasmid (fertility factor)
F+ contain plasmid, F- cells do not (recipient)

39
Q

F plasmid transfer

A

F+ produces F pilus that connects it to F- cell. Occurs through conjugation bridge. F plasmid copied through rolling replication. Results in two F+ cells.

40
Q

The F plasmid can integrate into the bacterial chromosome

A

Events similar to crossing over in eukaryotes.​

Homologous recombination.​

41
Q

Hfr cell (high frequency of recombination)

A

F plasmid integrated into chromosome.​

Replicated every time host divides.

42
Q

The F plasmid can also excise itself by reversing the integration process

A

An inaccurate excision may occur picking up some chromosomal D N A – F′ plasmid.

43
Q

During conjugation in Hfr strains, the transfer of genes is linear and progressive

A

Genes farther from the origin of transfer will be transferred later.​

Different marker genes appear in the recipient cell at specific times.​

Gene order can be mapped based on entry time

44
Q

R (resistance) plasmids

A

Encode antibiotic resistance genes.​

Acquire genes through transposable elements.

45
Q

Genes from pathogenic species transferred by plasmids or transduction

A

Encode genes for pathogenic traits.​

Enterobacteriaceae.​

E. coli O157:H7 strain evolved by acquiring genes for pathogenic traits.

46
Q

Mutations in bacteria

A

Mutations can arise spontaneously in bacteria as with any organism

47
Q

Screens of prokaryotic genomes revealed repeated sequences with spacer regions called CRISPR

A

Clustered Regularly Interspaced Short Palindromic Repeats

Adaptive immunity to viral infection

Useful for gene editing in the lab

48
Q

Nutritional strategy

A

how prokaryotes get carbon, get electrons for redox chemistry, and perform energy transformation.

49
Q

Prokaryotes can be classified into five nutritional types

A

Chemoorganoheterotrophs​

Chemolithoheterotrophs​

Chemolithoautotrophs​

Photolithoautotrophs​

Photoorganoheterotrophs

50
Q

Prokaryotic Metabolism

A

Organisms require carbon for building, a source of electrons to use in redox chemistry, and energy for anabolic processes. ​

Nutritional strategy = how they get carbon, get electrons for redox chemistry, and perform energy transformation. ​

How they get carbon:​

Heterotrophs get carbon in reduced forms.​

Autotrophs get carbon in oxidized forms (CO2). ​

How they get electrons for redox chemistry:​

Lithotrophs get electrons from reduced inorganic substances. ​

Organotrophs get electrons from reduced carbon sources. ​

How they perform energy transformation:​

Chemotrophs oxidize reduced chemicals from the environment.​

Phototrophs transform energy by harvesting light.

51
Q

Respirations and fermentations

A

Prokaryotes have greater diversity to perform respirations and fermentations

Eukaryotes - restricted to organic electron donors and oxygen as a terminal electron acceptor (aerobic).

Prokaryotic fermentations can metabolize pyruvate and other compounds to recycle electron donors​

Fermentation by-products are industrially and commercially valuable

52
Q

Beneficial Prokaryotes

A

Decomposers release a dead organism’s atoms to the environment

Nitrogen fixers reduce N2 to NH3 (ammonia).

53
Q

Fixation

A

Photosynthesizers fix carbon into sugars

54
Q

Plants as microbial ecosystems

A

Mutually beneficial association between plants and bacteria​

Nitrogen-fixing bacteria on plant roots.

55
Q

Parasitic relationships

A

Parasitic relationships

Can harm important crops.​

Example: Crown gall disease

56
Q

Animals as microbial ecosystems

A

Mutually beneficial association between animals and bacteria​

Cellulase-producing bacteria in ruminants.​

Human microbiome protects against pathogens and aids in digestion.

57
Q

Bacteria in bioremediation

A

Bacteria are used for bioremediation​

Remove pollutants from water, air, and soil.

58
Q

Biostimulation

A

adds nutrients to encourage growth of naturally occurring microbes

59
Q

Halorespiration

A

bacteria remove halogenated compounds from toxic waste

60
Q

Human Bacterial Disease

A

In the early 20th century, infectious diseases killed 20% of children before the age of five​

Sanitation and antibiotics considerably improved the situation.​

In recent years, however, many bacterial diseases have appeared and reappeared

61
Q

How bacteria cause disease

A

To cause disease, pathogenic bacteria​

Gain entry to the body.​

Colonize at the site of infection.​

Evade the immune system.​

Spread to other sites in the body.​

Cause damage by the production of toxins or by triggering inflammatory responses.

62
Q

Helicobacter pylori

A

Can cause stomach ulcers​

Treated by reducing stomach acid.​

Can cause gastritis​

Treated with antibiotics.​

This pathogen can also cause stomach cancer and a type of lymphoma

63
Q

Gonorrhea

A

One of the most prevalent communicable diseases in North America.

64
Q

Chlamydia

A

Can cause pelvic inflammatory disease and heart disease

65
Q

Syphilis

A

Four distinct stages.​

-Chancre – highly infectious​

-Rash – infectious​

-Latency – no longer infectious but attacking internal organs​

-Damage now evident – heart disease, mental deficiency, nerve damage

Biology (18 decks)

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