Exam 1 Flashcards

Question

Gram+ vs. Gram- [Cell Walls](https://www.technologynetworks.com/immunology/articles/gram-positive-vs-gram-negative-323007)

Answer 1

Gram+: Thick layer of peptidoglycan, **teichoic acids** are also present to increase structure Gram-: Comprised of a thin wall of peptidoglycan and an outer membrane, between the two is the periplasmic space, outer membrane contains **lipopolysaccharides** (hairlike structures) and porins **Both reside outside the plasma membrane of their respective cell**

Answer 2

1. Attachment: Preconditioning of suface by cells to help with attachment (involving proteins/carbohydrates), pili, adherence proteins 2. Colonization: Cells lose flagella, begin to form the matrix, cells utilize **quorum sensing** (cell-cell signaling that is density dependent) to activate gene expression, genes to make matrix of polysaccharide, protein, and DNA 3. Maturation: Forming mushrooms with channels for nutrients to enter and oxygen gradients to form 4. Dispersal

Answer 3

Circle of viral ssRNA with **no capsid** * Do not encode proteins * RNA may pair with plant RNA (causing RNA silencing)

Answer 4

Monotrichous: One flagellum Polar: Flagellum at the end of the cell Amphitrichous: One flagellum at each end of the cell Lophotrichous: A cluster of flagella at one or both ends of a bacteria Peritrichous: Flagella spread over the entire cell surface

Answer 5

Causative agent of Acquired Immune Deficiency Syndrome (AIDS) - enveloped * Viral spike protein gp(glycoprotein)120 binds host cell CD4 receptor and CCR5 coreceptor * Virus targetes helper T cells, which often have CD4 receptors

Answer 6

Provide enhanced stability for survival and growth at high temperature * Pyrococcus furiosus, means "rushing fireball", a hyperthermophile with over 50 flagella of unknown use, source of Pfu polymerase (sismilar use to bacteria Taq polymerase)

Answer 7

1. Attachment to host cell 2. Entry and uncoating 3. Synthesis of viral proteins and nucleic acids 4. Assembly of capsids 5. Release of virions

Answer 8

Swimming and swarming motility

Answer 9

* Oxygen concentration * Temperature * Solutes and water activity

Answer 10

Cyanobacteria contain thylakoids (photosynthetic membranes with chlorophyll)

Answer 11

Largely come from the viral host cell, within the envelope are spikes made by the virus * Space between envelope and capsid, **tegument** proteins are found * Not every virus has an envelope

Answer 12

Can occur via fusion or endocytosis, regardless of if the cell is enveloped * Fusion binds directly to the host cell membrane, releasing nucleocapsid into the host cell, followed shortly after by uncoating to release the nucleic acid * Endocytosis occurs by engaging a receptor, resulting in the virus being enclosed by a membrane-bound organelle

Answer 13

Localization of genetic material (DNA), can be closed circular or linear, the region "occupied" by the genetic material within the cytoplasm **not membrane-bound**

Answer 14

First direct evidence that bacteria cause disease * Studied *Bacillus anthracis* (anthrax) * Termed the word Pathogen (disease-causing microbe) * Developed general postulates designed to form a relationship between a microbe and a disease

Answer 15

Credited with isolating bacteria that are nitrogen-fixing (reduce atmospheric N₂ to ammonia NH₃ as a nitrogen source)

Answer 16

Robert Hooke - First to describe microbes (eukaryotic fungi) Antony van Leeuwenhoek - First to see prokaryotic bacteria, document their shapes and microbial movement

Answer 17

Enveloped virus, contains segmented RNA genome * Hemagglutinin spike **binds** to host sialic acid (like Rabies), Neuraminidase spike **cleaves** host lipids and proteins to release virus from infected host * RNA replicase is a viral enzyme using the RNA genome of the virus to form an RNA copy

Answer 18

Synthesis: All viruses make proteins using host ribosomes * Translation occurs in the cytoplasm Assembly: Capsid and genome, in the cytoplasm or nucleus, spike proteins insert into membrane to become viral envelope Some viruses stop reproducing, enter dormant state within the host called **latency**, which can be reactivated (ex. chicken pox and shingles)

Answer 19

Based on sequence analysis of small subunit ribosomal RNA (SSU rRNA), 16S rRNA for Bacteria & Archaea, 18S for Eukarya

Answer 20

* More photosynthesis than plants * Food/Goods production * Global ecosystem depends on microbes * <1% of earth's microbes have been cultured

Answer 21

*Unique to Archaea*, the biological production of methane

Answer 22

Microbial communities attached to a surface covered with a protective matrix (formed of diverse group of species or just one) Cells + Protective Film = Biofilm

Answer 23

Acellular (nonliving), infect living cells to replicate, depending on live host metabolism * Made up of protein and nucleic acid (virion) * Range from only 3 genes (Parvovirus) to 900 (Mimivirus) Considered to be **obligate, intracellular parasites**

Answer 24

Dental plaque is a form of biofilm Caries - tooth decay (bacterial fermentation produces acid which degrades enamel) Periodontal Disease: Microbial infection with inflammation and tissue destruction (ex. *Porphyomonas gingivalis*) Possible link to Alzheimer's

Answer 25

Isolated bacteria that oxidize inorganic compounds (iron and sulfur) for energy (H⁺ electrons) **Chemolithotrophs**

Answer 26

An increase in the number of cells in a population * Eukaryotic microbes exhibit both sexual and asexual reproduction * Prokaryotic microbes (Bacteria and Archaea) reproduce asexually through binary fission

Answer 27

Bacteriophages for bacteria/archaea cells, animal viruses for eukaryotes, begin with embryonated eggs for vaccines, or tissue cell cultures to view plaque assays (used to determine virion numbers, expressed ad plaque forming units (PFUs))

Answer 28

In Gram- bacteria, it contains hydrolytic enzymes and binding proteins for nutrient processing and uptake; in Gram+ bacteria, it may be smaller or absent

Answer 29

1. Double stranded RNA (ds RNA): Genomes act directly as mRNA (go directly to ribosomes for translation), translate viral +RNA into protein (ex. Polio, Zika) 2. Positive sense single stranded (+ss RNA): Genomes can also act as mRNA (ex. Influenza, Rabies) 3. Negative sense single stranded (-ss RNA): Genomes can't act as mRNA, virus must carry RNA replicase within the capsid, upon entry and uncoating replicase makes +RNA from -RNA genome, which is then translated 4. Retroviruses: Use reverse transcriptase to copy RNA genome into DNA (becomes **provirus**), which is then integrated using integrase enzymes and transcribed into mRNA and translated

Answer 30

Coccus - sphere Diplococcus - pairs Streptococcus - chians Staphylococcus - grapevine-like clusters Tetrads - 4 cocci in a square (ex. *Deinococcus* genus, survives extreme radiation via robust DNA repair mechanism)

Answer 31

NAM and NAG, polysaccharides which form peptidoglycan in bacterial cell walls

Answer 32

Thin, protein appendages, used for attachment * Sex pili: involved in the process of transferring genetic information between bacterial cells via conjugation (horizontal gene transfer) * Type IV pili: associated with "twitching" motility, can undergo repeated extensions-attachment-retraction movement to shift cells in a coordinated effort (Skerker and Berg, 2001)

Answer 33

1. Direct cell counts: Counting chambers (Petroff-Hausser) 2. Viable cell counts: Plating (colony forming units (CFUs)) 3. Turbidity measurements: Microbial cells scatter light striking them by laser, more turbid = more cells = more light scattered (measured via spectrophotometer)

Answer 34

Key defining properties are: * Nucleic acid type (DNA/RNA, ds/ss) * Capsid symmetry (binal, helical, icosahedral) * Presence/absence of an envelope

Answer 35

Credited with the development of the first vaccine * Material from cowpox lesions protects against smallpox

Answer 36

Hyperthermophiles: Grow between 85-113C Thermophiles: Grow between 45-85C (ex. *Thermus aquaticus*, source of Taq polymerase) Mesophiles: Grow between 20-45C (ex. *Escherichia coli*) Psychrophiles: Grow between 0-20C (ex. Genus *Chlamydomonas*, responsible for watermelon snow)

Answer 37

Small, closed circular DNA that exist and replicate independently of chromosome * May carry genes that confer advantage * Conjugative plasmid: can be transferred between bacteria * R plasmid: containes genes that encode **resistance** to antibiotics

Answer 38

An inclusion that provides buoyancy for floating in aquatic environments

Answer 39

Involved in protein synthesis, located in the cytoplasm

Answer 40

Rigid, lies just outisde of plasma membrane * Protection from osmotic stress, toxic substances * Helps maintain cell shape * Bacteria are grouped based on their Gram-stain characteristic (+/-)

Answer 41

Infectious protein * Causes neurodegenerative diseases such as Scrapie (sheep) and Mad Cow (cow) Ex. PrP^C gene conformation changes to form the prion, which promotes conversion of other normal form genes into prion form (PrP^Sc), creating an aggregate which leads to disease

Answer 42

* Need oxygen - obligate aerobe * Require oxygen 2-10% - microaerophile * Prefer oxygen - facultative anaerobe * Ignore oxygen - aerotolerant anaerobe * Oxygen is toxic - strict anaerobe

Answer 43

Inclusions with functions other than storage Carboxysomes: * Within CO₂ fixing bacteria * Polyhedral shape, protein shell * 2 enzymes within (carbonic anhydrase - converts carbonic acid to CO₂, RubisCO - adds CO₂ to Ribulose 1,5 bisphosphate (RuBP), 1st key reaction of Calvin Cycle (fixes CO₂ into carbohydrates in dark photosynthetic reactions))

Answer 44

Occurs either via cell lysis or budding (membrane lipids surroudn capsid to form envelope)

Answer 45

The study of organisms too small to be seen by the unaided eye (from um to nm in length)

Answer 46

1. A microbe must be found in all cases of disease and be absent from healthy 2. Microbe must be isolated and grown in pure culture 3. Same disease must result when isolated microbe (from postulate 2) is inoculated into a healthy host 4. The same microbe must then be isolated from the diseased host

Answer 47

Small cells have higher SA/V ratio, resulting in more efficient nutrient uptake, faster growth

Answer 48

A key cytoskeletal protein in Bacteria and Archaea * Highly-conserved protein present in every bacteria * Homologue of tubulin * Required for cell division and septum formation * Forms **contractile ring** at midcell * Energy from the hydrolysis of GTP (guanosine triphosphate)

Answer 49

Conducted swan-neck flask experiments to demonstrate that microbes can be trapped, only grew when the glass was broken off * Pasteur and Lister realized that microbes can causes disease and infection

Answer 50

Lipid bilayer with floating proteins * Lipids have flexible ester bonds * Amphipathic lipids form bilayer * Stabilized by sterol-like molecules (ex. hopanoids)

Answer 51

Discovered bacteria-engulfing human cells (macrophages) * Utilize phagocytosis to destroy them

Answer 52

The primary factor determining the life cycle of an animal virus is the form of its genome * DNA viruses typically replicate within the nucleus, use host DNA polymerase (**exception** being herpesviruses which use their own DNA polymerase) * RNA viruses typically replicate in the cytoplasm, use RNA replicases to convert their RNA to RNA

Answer 53

Helps form the outer membrane of Gram- bacteria cells, comprised of: * O Side Chain (O antigen) * Core Polysaccharide (unique to each bacteria) * Lipid A (embedded in outer membrane) Provides protection from host defenses (O antigens vary to evade immune response), helps with attachment and stability, Lipid A portion of LPS can act as a toxin (endotoxin), causing fever and septic shock