Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICB 3301 Lecture > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Basis of oxygen sensitivity

A

Oxygen can be reduced to toxic products (Reactive Oxygen Species (ROS)) such as O2 and hydrogen peroxide (H2O2)

Microbes that live in the presence of oxygen need enzymes to detoxify:
* Superoxide dismutase (SOD) - O2- + O2- + 2H+ –> H2O2 + O2
* Catalase - H2O2 + H2O2 –> 2H2O + O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Binary Fission Steps

A
  1. DNA replicates
  2. Cell elongaes, chromosomes segregate
  3. Septum forms (plasma membrane and cell wall synthesis)
  4. Cell divides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Central Dogma of Information Flow

A

Typical flow of information through DNA replication, transcription to RNA, and translation to proteins
* DNA viruses can hijack the replication process, the transcription process, or the translation process of a cell
* Some retroviruses can use their RNA to form DNA (against the current) via reverse transcriptase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Spontaneous Generation

A

The idea that living organisms could develop from nonliving matter

  • Challenged by Francisco Redi with his meat experiment that showed flies do not spontaneously form
  • Lazzaro Spallanzani demonstrated that microbes would not grow in sealed and boiled meat broth, positing that the air carried microbes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Transpeptidation

A

Cross-linking of peptidoglycan structure, forming a peptide interbridge and strengthening the cell (can occur as direct or indirect cross linking)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Chemotaxis

A

Sensory system of chemoreceptors in bacterial plasma membrane enables microbes to move toward or away from specific chemicals

For peritrichous E. coli, attractants cause long runs (biased random walk up gradient), whereas repellants cause tumbles

Runs + Tumbles = “random walk”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Viral Morphology

A

Icosahedral: 20-sided shape offers greatest stability, formed of hexamer and pentamer protomer subunits

Helical: Tube-shape, helical capsids are hollow tubes with protien walls (ex. influenza genome comprised of 8 plasmids forming its segmented RNA genome)

Binal: Has both icosahedral and helical shapes (ex. bacteriophages, burgeoning phage therapy to combat antibiotic resistance concerns)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Complex Symmetry

A

Ovoid, brick shape (ex. Poxvirus, largest of animal viruses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Viral Genomes

A

All the genetic material in an organism, can be:
* DNA or RNA
* Single stranded (ss) or double stranded (ds)
* Linear, circular, or segmented

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Borrelia burgdorferi

A

Spirochete bacterium, causative agent of Lyme disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Flagellum

A

Both Gram+/- bacteria have flagella, comprised of 3 parts:
1. Basal body: Comprised of a rod and series of rings, the motor of the flagellum (MS ring can spin the flagellum, L and P rings stabilize the rood)
2. Hook: Flexible protein structure connecting the basal body and filament
3. Hollow end of the flagella built in sequential addition outwards, stopped by the ruler protein

Source of energy for bacterial flagella is proton motive force across plasma membrane, not ATP!)

CCW rotation causes forward motion (run), CW rotation disrupts run (tumble)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Animal Virus Attachment

A

Viral surface proteins mediate attachment to host receptors (carbohydrates, proteins, and lipids)

Ex. Influenza = hemagglutinin, HIV gp120 = CD4 & CCR5, SARS-CoV-2 = spike protein binds to ACE2 (Angiotensin-Converting Enzyme 2) receptor, cleaves hormone angiotensin, regulates blood pressure before hijacking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Inclusions

A

Storage of carbon, phosphate, gas, and other substances; site of chemical reactions (microcompartments)

Also include magnetosomes, made up of magnetite crystals, allowing bacteria to orient themselves, used to feed on nutrient sediments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Viral Structure Components

A

Virion: Complete virus particle (different meanings depending on if virus is naked/enveloped)

Capsid: Protein coat around the viral genome, formed from protomers

Nucleocapsid: Nucleic acid + capsid

Protomer: Protein subunit of capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Major Groups of Microbes

A

Prokaryotic cells (cells that lack a membrane-bound nucleus, Bacteria and Archaea), eukaryotic members (have membrane-bound nucleus) include protists (algae) and fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Peptidoglycan

A

Important component in the cell walls of all bacteria
* Polysaccharides formed from two alternate subunit sugars (NAG and NAM), directly connected by a beta-1,4 glycosidic bond
* Chains of NAG and NAM sugars are cross-linked by peptides of alternating D- and L- amino acid forms (utilized to resist degradation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The Bacterial Growth Curve

A

Population growth is often studied by analyzing the growth curve, observed when microbes are cultivated in a batch culture (closed vessel, single batch of medium)

Made up of 4 phases:
1. Lag phase: No growth, cells synthesizing new components (variable in length)
2. Exponential (log) phase: Balanced growth, expressed as generation doubling time
3. Stationary phase: Population growth ceases due to buildup of toxins, reaching carrying capacity
4. Death phase: Many cells die off rapidly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Plasma membrane

A

Selectively permeable barrier, mechanical boundary of cell, nutrient and waste transport, location of many metabolic processes, detection of environmental cues for chemotaxis, and main site of energy generation (ETC)

  • Fluid mosaic protein structure
  • Amphipathic phospholipid bilayer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Cytoplasm

A

Viscous liquid within cell, the site of both transcription and translation

RNA polymerase transcribes DNA to mRNA in cytoplasm, ribosomes translate mRNA to protein - processes can occur simultaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Domain Archaea

A

Prokaryotic cells with plasma membranes (also cell walls and S layers sometimes), lack peptidoglycan

  • Asexual reproduction
  • Circular ds DNA chromosomes and plasmids
  • Gram+/-, diverse shapes (coccus and bacillus common)
  • Sizes similar to bacteria
  • Some are extremophiles (same classes as bacteria) (ex. Genus Haloquadratum - square tetrad, lives in high salt environments)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Domain Bacteria

A
  • Prokaryotic
  • Habitats: terreistrial and aquatic
  • Reproduce asexually via binary fission
  • Grows between 0.3um-100um, one of the largest is from genus Thiomargarita (>100um)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Bacterial Spores

A

Stress resistant, dormant cells that form within a “mother cell” under nutrient-limiting conditions
- Contains genetic information
- Multiple membranes and structures built
- Mother cell lyses and releases spore

Ex. Bacillus Genus and Clostridium tetani

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Layers Outside the Cell Wall

A

Capsules: Polysaccharides, organized and not easily removed
Slime layers: Polysaccharides, diffuse and organized, easily removed
S layers: Protein, organized

Outer layers function for attachment, protection from harsh environments, bacteriophages, and host immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Other Shapes/Arrangements

A

Bacillus - rod
Vibrio - curved rod (comma shaped)
Spirillum - rigid helix
Spirochete - flexible helix
Pleomorphic - variable shape (ex. Mycoplasma genus, has plasma membrane but no cell wall, causative agent of walking pneumonia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Gram+ vs. Gram- Cell Walls

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Biofilm Lifecycle

A
  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
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Viroids

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Flagella Distribution Patters

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Human Immunodeficiency Virus (HIV)

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Archaeal Membranes

A

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)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Viral Multiplication/Infectious Cycle

A
  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
32
Q

Flagella

A

Swimming and swarming motility

33
Q

Environmental factors influencing microbial growth

A
  • Oxygen concentration
  • Temperature
  • Solutes and water activity
34
Q

Membranous structures in some bacteria

A

Cyanobacteria contain thylakoids (photosynthetic membranes with chlorophyll)

35
Q

Viral Envelopes

A

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

36
Q

Animal Virus Entry

A

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

37
Q

Nucleoid

A

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

38
Q

Robert Koch

A

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

39
Q

Beijernick

A

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

40
Q

1600s Discovery of Microbes

A

Robert Hooke - First to describe microbes (eukaryotic fungi)

Antony van Leeuwenhoek - First to see prokaryotic bacteria, document their shapes and microbial movement

41
Q

Influenza Virus

A

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

42
Q

Animal Virus Synthesis and Assembly

A

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)

43
Q

Origins of the Universal Phylogenetic Tree

A

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

44
Q

Importance of Microbes

A
  • More photosynthesis than plants
  • Food/Goods production
  • Global ecosystem depends on microbes
  • <1% of earth’s microbes have been cultured
45
Q

Methanogenesis

A

Unique to Archaea, the biological production of methane

46
Q

Biofilms

A

Microbial communities attached to a surface covered with a protective matrix (formed of diverse group of species or just one)

Cells + Protective Film = Biofilm

47
Q

Viruses

A

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

48
Q

Biofilms on Teeth

A

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

49
Q

Winogradsky

A

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

Chemolithotrophs

50
Q

Microbial Growth

A

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

51
Q

How we cultivate and enumerate viruses

A

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))

52
Q

Periplasmic space

A

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

53
Q

Four Types of RNA Viruses

A
  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
54
Q

Coccus

A

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)

55
Q

N-actylglucosamine & N-acetylmuramic acid

A

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

56
Q

Pili (Fimbriae)

A

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)

57
Q

Measuring Microbial Growth

A
  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)
58
Q

Virus Taxonomy

A

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

59
Q

Jenner

A

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

60
Q

Temperature

A

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)

61
Q

Plasmids

A

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

62
Q

Gas vacuole

A

An inclusion that provides buoyancy for floating in aquatic environments

63
Q

Ribosomes

A

Involved in protein synthesis, located in the cytoplasm

64
Q

Cell wall

A

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 (+/-)

65
Q

Prions

A

Infectious protein
* Causes neurodegenerative diseases such as Scrapie (sheep) and Mad Cow (cow)

Ex. PrPC gene conformation changes to form the prion, which promotes conversion of other normal form genes into prion form (PrPSc), creating an aggregate which leads to disease

66
Q

Oxygen Concentration

A
  • Need oxygen - obligate aerobe
  • Require oxygen 2-10% - microaerophile
  • Prefer oxygen - facultative anaerobe
  • Ignore oxygen - aerotolerant anaerobe
  • Oxygen is toxic - strict anaerobe
67
Q

Microcompartments

A

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))

68
Q

Animal Virus Release

A

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

69
Q

Microbiology

A

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

70
Q

Koch’s Postulates

A
  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
71
Q

Advantages of a smaller cell

A

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

72
Q

FtsZ Protein

A

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)

73
Q

Louis Pasteur

A

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
74
Q

Fluid Mosaic Model of Membrane Structure

A

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

75
Q

Metchnikoff

A

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

76
Q

DNA vs. RNA Viruses

A

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

77
Q

Lipopolysaccharides (LPSs)

A

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

MICB 3301 Lecture (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions