exam 1 Flashcards

Question

John Needham

Answer 1

Proponent of spontaneous generation 1745 He heated nutrient fluids (chicken broth and corn broth), cooled it, and then poured it into covered flasks, the solutions were teeming with microorganisms. Needham claimed that the microbes developed spontaneously from the fluids.

Answer 2

1765 disproved Needham conclusion * suggested that microorganisms from the air probably entered the solutions from the air after they were boiled. * showed that nutrient fluids heated after being sealed did not develop microbial growth.

Answer 3

1858 Theory of biogenesis: living cells can arise only from preexisting living cells

Answer 4

living cells can arise only from preexisting living cells

Answer 5

1861 demonstrated that microorganisms are present in the air and that they can contaminate sterile solutions, but air itself does not create microbial life. During a job on understanding why wine and beer sour, discovered that microorganisms called yeasts convert sugars to alcohol in the absence of air. This is called FERMENTATION (1857). Discovered pasteurization (1864)...process of heating to kill bacteria to reduce/prevent spoilage This was the first link that microorganisms can cause changes in organic materials. that microorganisms might cause disease introduced germ theory of disease

Answer 6

is the process of conferring immunity using a vaccine which is a preparation of killed, inactivated, or attenuated microorganisms or toxoids to induce artificially acquired active immunity

Answer 7

1798 **developed the first vaccine for smallpox** milkmaid couldn't get smallpox because she had already been sick with cowpox, a much milder disease Jenner decided to test this story: collected scrapings from cowpox blisters and made inoculations with this material by scratching the arm of a healthy volunteer with the cowpox contaminated needle. The person became mildly sick but recovered and never contracted either cowpox or smallpox

Answer 8

is an aqueous or alcohol solution of a single basic dye - is used to highlight the entire microorganism so that cellular shapes and structures are visible. - A mordant may be added to the simple stain to: increase the affinity of a stain for the specimen coat a structure (such as a flagellum) to make it thicker. - Examples of simple stains: 1. methylene blue (blue) 2. carbolfuchsin (red) 3. crystal violet (purple) 4. safranin (pink)

Answer 9

may be added to the simple stain to: increase the affinity of a stain for the specimen coat a structure (such as a flagellum) to make it thicker.

Answer 10

react differently with different bacteriacan be used to distinguish them - 2 types of differential stains 1. Gram Stain 2. Acid-Fast Stain

Answer 11

was developed in 1884 by the Danish microbiologist Hans Christian Gram - differentiates/classify bacteria into 2 large groups a. gram positive (+) purple b. gram negative (-) pink

Answer 12

1. Apply crystal violet which colors all bacteria purple (primary stain) • Wash off w/ddH O. 2 2. Apply iodine, a mordant, all bacteria still purple. 3. Wash with ethanol or ethanol- acetone solution, a decolorizing agent - Gram + bacteria will be purple; Gram - bacteria will be colorless - wash off w/ddH2O 4. stain with safranin, a counterstain. - Gram (-) will be pink; Gram (+) will be purple - wash off w/ddH2O - blot dry 19 - examine microscopically

Answer 13

no membrane covering peptidoglycan wall Gram (+) bacteria have a thicker cell wall composed of peptidoglycan than gram (-) bacteria

Answer 14

outer membrane covers peptidoglycan wall Gram (-) bacteria have a thin layer of peptidoglycan and outside of that, a layer of lipopolysaccharide

Answer 15

rystal violet and iodine can go through the thick cell wall, but once inside form a complex (CV-I) which can not go out of the cell. - gram (+) bacteria stain purple because of the trapped CV-I complex - gram (-) bacteria will be colorless because the alcohol wash disrupts the lipopolysaccharide and allow the CV-I complex to be washed out of the cell - gram (-) bacteria are pink because of the counterstain with safranin - Gram stain is most consistent when used on young, growing bacteria. result of gram staining provide information for proper treatment of disease - Generally, gram (+) bacteria are easily killed by penicillin and sulfonamide drugs. - Gram (-) bacteria are resistant to these drugs, but are more susceptible to streptomycin, chloramphenicol, and tetracycline.

Answer 16

stain binds to bacteria that have a waxy materia(mycolic acid and evades immune system and phagocytosis happens) l in their cell walls - used to identify all bacteria in the genus Mycobacterium Ex. **Mycobacterium** **tuberculosis** causes tuberculosis. Ex. **Mycobacterium leprae** causes leprosy. - used to identify the disease-producing strains of the **genus Nocardia**

Answer 17

**a. Apply carbolfuchsin** to heat-fixed smear and gently heat to enhance penetration and retention of the dye. (All organisms will be red.) b. Wash c. Decolorize with **acid-alcohol**. - Acid-fast organisms will be red since carbolfuchsin is soluble in the waxy material of the cell wall - Non-acid-fast organisms will be colorless since these organisms do not have the waxy material in their cell walls to retain the carbolfuchsin d. **Counterstain with methylene blue.** - Acid-fast organisms will be red. - Non-acid-fast organisms will be blue.

Answer 18

- capsule: a gelatinous covering of some microbes; confers virulence(polysacharide or polysacharide protine) - is more difficult than other types of staining procedures because capsules are soluble in water and may be removed during washing.

Answer 19

a. Mix bacteria with Nigrosine, an acidic dye which provides a dark purple background. b. Spread dye as in negative staining. c. Stain slide with crystal violet, basic dye to stain bacteria (purple) d. Capsules will appear as colorless halos surrounding purple bacterial cells against a dark purple background.

Answer 20

Endospores are resistant, **dormant** structures within a cell which protects the microbe from adverse environmental conditions. - are formed by 7 genera of bacteria (including **_Bacillus_** and **_Clostridium_**) - do not stain with ordinary stains because the dyes do not penetrate the wall of the endospore. - 2 methods used: - A. Schaeffer-Fulton endospore stain - B. Dorner endospore stain

Answer 21

a. Apply malachite green to heat-fix smear on slide and steam heat for 5 minutes. Spores will stain green and cells will be colorless. b. Wash c. Counterstain with safranin, which will stain ***_the cells_*** ***_pink. Spores will be green_***. d. Wash

Answer 22

a. Put carbolfuchsin, red, in a test tube b. Add several loopfuls of organism c. Boil in a beaker of water for 10 minutes * *Spores will be red, cells colorless.** d. Add several loopfuls of the carbolfuchsin- bacteria mixture to a drop of **nigrosine on a slide** e. Smear mixture **- Bacterial cells will be colorless against dark purple background (Negative Staining).** **- Endospores inside the cells will be red.**

Answer 23

Flagella are structures of locomotion. - Staining flagella involves using a mordant and carbolfuchsin to build up the diameters of the flagella until they become visible under the light microscope. - It is a tedious and delicate staining procedure.

Answer 24

1857- 1914 A period of explosion of discoveries in microbiology which led to the establishment of microbiology as a science.

Answer 25

English surgeon initiates aseptic surgical techniques. **He began soaking surgical dressings in a mild solution of carbolic acid (phenol) which kills bacteria**. This reduced the incidence of infections and deaths in surgical patients. Founder of aseptic surgery

Answer 26

proved the germ theory of disease discovered a rod-shaped bacteria now known as Bacillus anthracis in the blood of cattle that had died of anthrax. He cultured the bacteria and injected samples of the culture into healthy animals which became sick and died. Koch isolated the bacteria in the blood and found it to be the same as the original bacteria isolated. Experimental procedure used to relate specific microbe to a specific disease is known as Koch’s postulate 1881 - developed pure culture and staining techniques. • 1882 - discovered Mycobacterium tuberculosis, the causative agent of tuberculosis. • 1883 - discovered Vibrio cholerae, the causative agent of cholera.

Answer 27

**developed immunization techniques based on Edward** Jenner’s work with smallpox (vaccination) • Avirulent form of bacterium causing fowl cholera can induce immunity against subsequent infections by virulent counterpart. Vaccine: cultures of avirulent microorganism used for preventative inoculations also discovered Streptococcus pneumoniae (1881), the causative agent of pneumococcal pneumonia.

Answer 28

developed a differential staining technique called the Gram stain which differentiates bacteria into 2 groups, gram (-) and gram (+).

Answer 29

of Germany discovered Escherichia coli, the causative agent of urinary tract infections and traveler's diarrhea.

Answer 30

of Germany introduced a covered dish for growing microorganisms on a solid medium. **(petri dish)**

Answer 31

of Germany proposed a theory of immunity in which antibodies are responsible for immunity. * Discovery of chemotherapy—treatment of disease by use of chemical substances (i.e. synthetic drugs & antibodies) * Magic bullet — substance that could target and destroy the pathogen without harming the host * Salvarsan (arsenic derivative; 1910)— chemotherapeutic agent against syphillis

Answer 32

of Russia discovered a filterable organism (virus) caused tobacco mosaic disease.

Answer 33

Scottish physician and bacteriologist discovered the antibiotic, **_penicillin_**, by accident Thus he discovered a mold (fungus), Penicillium chrysogenum which could inhibit the growth of bacteria.

Answer 34

established the system of nomenclature (naming) for organisms which assigns each organism 2 names... A. Genus is the 1st name and is always Capitalized and underlined or italicized. B. Specific epithet or species is the 2nd name and is not capitalized, but is underlined or italicized. Example: 1. S**_taphylococcus aureus_** or * Staphylococcus aureus* 2. **_Escherichia col_**i or *Escherichia coli*

Answer 35

**1. Microorganisms degrade dead plants and animals and recycle chemical elements such as nitrogen, carbon, oxygen, sulfur, and phosphorus.** Example - bacteria and fungi return carbon dioxide to the atmosphere when decomposing organic matter...carbon cycle Example - Nitrogen fixation - converting nitrogen gas into ammonia (i.e. Rhizobium species) **2. Microorganisms are used to decompose** **organic matter in sewage...recycle water and prevent pollution (bioremediation) of rivers and oceans** Bioremediation: use of microorganisms to remove environmental pollutant (Zoogloea ramigera). **3. Microorganisms (i.e. Bacillus thuringiensis) cause disease in insects and thus can be used as a biological control in insect pests (instead of pesticides which harm the environment)**. 4. **Microorganisms can be used to produce food such a**s: a. soy sauce (Aspergillus oryzae (fungi) b. yogurt (Streptococcus thermophilus) for acid production, Lactobacillus bulgaricus for flavor and aroma). 5. **Using biotechnology and recombinant DNA technology, bacteria, can be used to produce human proteins:** a. insulin b. factor VIII c. tissue plasminogen activator d. growth hormone e. use in gene therapy

Answer 36

1. T**he body has a normal flora of microorganisms** inside and on its surface that usually are a benefit to the body. 2. The important factors which determine whether a person will contract a disease include: **a. the disease producing properties of the microorganism** **b. the resistance of the body.** 3. **Only a minority of microorganisms are pathogenic (disease producing).** Biofilms: community/aggregate of microorganisms that are usually attached to a surface through secretion of a matrix. Ex. dental plaque Emerging Infectious Diseases (EID): diseases that are new or changing and are increasing or have potential to increase in the near future i.e. H1N1 influenza, S. aureus – MRSA, VISA, Ebola virus, Zika virus

Answer 37

smallest particle of an element that still retains its distinctive chemical properties

Answer 38

Atoms that contain the same number of protons and electrons but different number of neutronsdifferent atomic mass.

Answer 39

sotopes that can decay and emit electromagnetic radiation, which can damage DNA/protein. – It can be detected by X-ray film or other methods. – Is widely used in molecular biology studies to label molecules. – Can be detected by: * a Geiger counter (monitor) * exposure to X-ray film (autoradiography)

Answer 40

made up of two or more atoms joined together by covalent chemical bonds

Answer 41

– Involves the sharing of electrons between two atoms – Bond strength is ~12- kcal/mol (the energy needed to break a bond) – Single bond: 2 atoms sharing 1 pair of electrons – Double bond: 2 atoms sharing two pairs of electrons

Answer 42

electrons are shared unequally by bonded atoms

Answer 43

Electrons are shared equally by bonded atoms

Answer 44

the power of an atom to draw electrons to itself

Answer 45

– Interaction between atoms that do not involve sharing of electrons – Weak bonds, but many non-covalent bonds working together can stabilize the 3D structure of a large molecule (intra- molecular interactions) – Important for biomolecules; help molecules bind to other molecules (intermolecular interactions)

Answer 46

Ionic interaction Hydrogen bonds Van der Waals interaction Hydrophobic interaction

Answer 47

“water-fearing” Non-polar molecules do not form hydrogen bonds with water. Hydrophobic interaction is formed because all parties that “hate” water are pushed together.

Answer 48

Individually, they are weak Together, they are strong Confers stability of a molecule Confers specificity of binding

Answer 49

Small organic molecules combine to form large molecules macromolecules are usually polymers (made of repetitive monomers)

Answer 50

molecules produced by the cell All cells produce similar biomolecules...

Answer 51

“small” molecules Nucleotides Simple sugar Amino acids Fatty acids

Answer 52

“Large” molecules Nucleic acids Polysaccharides Proteins Lipids

Answer 53

dehydration synthesis reaction) water producing reaction

Answer 54

water obsorbing reaction

Answer 55

- Are sugars and starches (chain of glucose) - Basic building block = Monosaccharide (simple sugars) - General composition: (CH2O)n - 3 major groups: 1. monosaccharides: contains 3-7 C atoms; i. e. glucose, fructose, galatose, deoxyribose, ribose 2. disaccharides: formed by the bonding of 2 monosaccharides in a dehydration synthesis reaction i. e. glucose + fructosesucrose glucose + galactoselactose glucose + glucosemaltose

Answer 56

contains 3-7 C atoms; i.e. glucose, fructose, galatose, deoxyribose, ribose

Answer 57

Formed by the bonding of 2 monosaccharides in a dehydration synthesis reaction i.e. glucose + fructosesucrose glucose + galactoselactose glucose + glucosemaltose

Answer 58

consist of three or more monosaccharides; can have side chains branching from main structure i. e. glycogen, starch, & cellulose are composed of many glucose molecules - glycogen: found in animal cells and some bacteria. - starch: found in plant cells and is used as food by some animals. - cellulose: is component of plant and most algae cell walls

Answer 59

found in animal cells and some bacteria.

Answer 60

found in plant cells and is used as food by some animals.

Answer 61

is component of plant and most algae cell walls

Answer 62

a. provide a source to produce energy, mainly ATP, for the cell. b. function as food reserves c. Deoxyribose sugar is backbone of DNA (deoxyribose nucleic acid). d. are components of cell walls of bacterial cells

Answer 63

Are “fat” 2. Lipids - Are composed of C, H, O - Are nonpolar molecules; can’t dissolve in water - F(x)s: energy source - constituent of plasma membranes and cell walls Types of lipids: Triglycerides = simple lipids or fats Complex lipids 3. Steroids

Answer 64

are formed by the dehydration reaction of one **glycerol with 3 fatty acids.** - glycerol have 3 hydroxyl (-OH) groups attached to 3 C atoms - fatty acids are composed of long hydrocarbon (H-C) chains ending with carboxyl (-COOH) group.

Answer 65

have no double bonds between the carbon atoms; thus, the carbons have the maximum number of hydrogens attached (saturated with hydrogens). - Most animal fats are saturated fats.

Answer 66

have at least one double or triple bond between the carbons. - Most plant fats are unsaturated fats.

Answer 67

- contains elements (i.e. phosphorus, nitrogen, sulfur) in addition to C, H, O - Examples are waxes and glycolipids. - cell walls of bacteria belonging to the genus Mycobacterium contain waxes & glycolipids; provides distinguishing staining characteristic (acid-fast stain) - example: phospholipids (glycerol, 2 fatty acid, phosphate group) has polar and non-polar ends - is major constituent of cell membranes—phospholipid bilayer

Answer 68

(glycerol, 2 fatty acid, phosphate group) - has polar and non-polar ends - is major constituent of cell membranes—phospholipid bilayer

Answer 69

Steroids: has 4-ring structure - 3 six carbon rings and 1 five carbon ring - the addition of an -OH group makes the steroid a sterol (alcohol; cholesterol). - sterols are found in plasma membranes of animal, fungi, and plant cells and one group of bacteria (mycoplasmas) - Examples: cholesterol and hormones and Vitamin D in animals

Answer 70

nitrogen fixation

Answer 71

produce soy sauce

Answer 72

holes in swiss cheese by producing corbon dioxide

Answer 73

sourdough bread

Answer 74

protect us against dis- ease by preventing the overgrowth of harmful microbes, and others produce useful substances such as vitamin K and some B vitamin

Answer 75

a. the disease producing properties of the microorganism b. the resistance of the body.

Answer 76

Only a minority of microorganisms are pathogenic (disease producing). about 1%

Answer 77

a. soy sauce (Aspergillus oryzae (fungi) b. yogurt (Streptococcus thermophilus) for acid production, Lactobacillus bulgaricus for flavor and aroma). c. cheese (Propionibacterium species produce holes in Swiss cheese by producing carbon dioxide. ) d. bread (San Francisco sourdough bread requires Saccharomyces exiquus and Lactobacillus sanfrancisco) . e. alcoholic beverages (wine requires the yeast Saccharomyces cervisiae ). 43

Answer 78

Nucleotides are the basic building blocks of nucleic acids (DNA and RNA molecules—genetic material) • Are composed of – Phosphate group – Pentose: 5-carbon sugar molecule -deoxyribose vs ribose – Nitrogenous Base Deoxyriboucleic Ribonucleic Acid Acid

Answer 79

acquired data, some not so “available,” from rosalind franklin to construct a model for the DNA structure: double helix They won the Nobel Prize in 1962.

Answer 80

howed that DNA is helical from X-ray diffraction

Answer 81

Right-handed double helix DNA molecule has two strands; run anti- parallel direction The 2 DNA strands are complementary Has polarity: 5’3’ Purines and pyrimidines of opposite strands form H-bonds C-G (3 H-bonds); A-T (2 H-bonds) * Double stranded (ds) DNA can denature (melt) to single stranded (ss) DNA at high temperature, lower salt, or extreme pH conditions * These conditions breakup the H-bonds between complementary bases. 48 • DNA can also renature (anneal) under the reverse conditions Major groove is major binding site for DNA-binding proteins Bases are stacked perpendicular to axis of helix Bases face inside; sugar-phosphate backbone on the outside of helix Helix also held together by: hydrophobic & van der Waals

Answer 82

Consists of 1 strand of nucleotides Primary structure: the sequence of nucleotides in RNA Secondary structure: RNA is usually single stranded; some regions may form double stranded within the molecule. Tertiary structure: three- dimensional structure of a single RNA molecule

Answer 83

All cellular RNAs are synthesized by the transcription process. Type of RNA mRNAs messenger RNAs, code for proteins rRNAs ribosomal RNAs, form the basic structure of the ribosome and catalyze protein synthesis tRNAs transfer RNAs, central to protein synthesis as adaptors between mRNA and amino acids

Answer 84

is the principal energy-carrying molecule (potential form of energy). - is composed of adenine, ribose, and 3 phosphate groups - energy is released when a phosphate is removed ATP-----------\>ADP + Pi + Energy

Answer 85

are the monomeric building blocks of proteins There are 20 different aa. All organisms on earth have the same 20 aa. Each protein being synthesized are made from the different arrangements of the aa. Each aa monomer has 4 different groups attached to the central carbon atom (C) The nature of an aa is based on the composition of its side chain. * 20 different aa20 different side chains * Each side chain differ in: – Size Hydrogen – Shape – Charge – Hydrophobicity

Answer 86

* Alanine (ala) * valine (val) * Isolucine (ile) * Lucine (leu) * Methinonine (met) * Phenylalanine (phe) * Tryptophan (Trp)

Answer 87

1. basic * lysine (lys) * argininine (arg) * Histidine (his) 1. acidic * asparate (asp) * glutamate (glu) 1. polar amino acids * serine (ser) * threonine (thr) * asparagine (asn) * Glutamine(gln) * thyrosine (tyr)

Answer 88

cysteine (cys) glycine (gly) proline (pro)

Answer 89

is formed by amino acid monomers joined together by covalent peptide bonds

Answer 90

joins the amino end of one aa to the carboxyl end of another aa

Answer 91

Primary (1o) structure: – The linear sequence of amino acid – Also known as the protein sequence 2. Secondary (2o)structure: – It is the regularly repeating conformation of the peptide backbone –  Helix;  Strands sheets; turns – A polypeptide usually has different secondary structures at different regions – Is dependent on the amino acid sequence of the different regions. – Structure is stabilized by H-bonds 3. Tertiary (3o) structure: – Is the 3D arrangement of all the polypeptide’s amino acid residues – Is formed by packing various combinations of 2o structures – Structure is stabilized by a variety of non- covalent bonds between aa side chains (i.e. hydrophobic) 4. Quaternary structure: – The overall structure and organization of more than one polypeptide chain – Each polypeptide chain in this protein is referred to as a subunit.

Answer 92

modified protines ex 1. glycoproteins contain sugars 2. nucleoproteins contain nucleic acids 3. metalloproteins contain metal atoms 4. lipoproteins contain lipids

Answer 93

1. Structural proteins - microfilaments for movement of cells - cell membranes or cell walls - carrier proteinstransport molecules into and out of cells 2. Enzymes: catalyze chemical reactions 3. signaling molecules 4. Toxins are produced by certain bacteria; Bacteriocins: proteins produced by some bacteria that kill other bacteria. 5. Hormones for regulatory function (i.e. insulin) 6. Antibodies for immune function

Answer 94

(Proteinaceous infectious particles) infectious proteins. Unlike bacteria or viruses, prions do not require any DNA or RNA infectious. A prion is a misfolded protein has lost its normal conformation and function while acquiring the ability to convert other molecules of the same protein from the conformation into the abnormal prion form. This form of self propagation explains the infectious nature of prions. In all of the prion proteins studied, the transformation between the normal and prion forms occurs through a dramatic change in the protein’s three-dimensional structure. Prions cause diseases such as Creutzfeldt-Jakob disease (CJD; Kuru) in humans, in sheep (scrapie), and bovine spongiform encephalopathy (BSE or mad-cow disease).

Answer 95

proteins produced by some bacteria that kill other bacteria.

Answer 96

catalyze chemical reactions

Answer 97

- can resolve objects as close as 2.5 nm - Magnification is from 10,000X to 100,000X. - Only a very thin section (about 100 nm) of a specimen can be studied effectively - can’t obtain 3D image - Specimens must be fixed, dehydrated, and viewed under vacuum; therefore, shrinkage and distortion may occur; may get artifacts

Answer 98

- cannot resolve structures smaller than 0.2 um, therefore, cannot be used to observe viruses. - commonly used to observe various stained (killed) specimens and to count microbes. - Specimen appears colored against a bright background. - Maximum magnification is about 2000X (200x oil immersion)

Answer 99

used for examining live microorganisms that do not stain easily, or are distorted by staining, or are invisible in brightfield microscopy - uses a special condenser with an opaque disc that blocks light from entering the objective directly. - Specimen appears light against a black background. - can be used to detect Treponema pallidum, causative agent for syphilis

Answer 100

- uses an ultraviolet source of illumination that causes fluorescent compounds to emit light. - Some organisms fluoresce naturally. - Other organisms can be stained with fluorescent dyes called fluorochromes. - Specimens appear as luminescent objects against a dark background Combine a fluorochrome to a specific antibody for a specific antigen. Allow the antibody to combine with the specific antigen Wash to remove non-specific binding Thefluorochrome-antibody- antigen fluoresces under UV light 4. is useful in diagnosing syphilis and rabies or detecting specific cell types, tissues, or structures (Fig. 3.6a) 7

Answer 101

- uses beam of electrons (shorter wave length) instead of light - Structures smaller than 0.2 um can be resolved (viruses, cellular structures) - There are 2 types: 1. Transmission electron microscope (TEM) 2. Scanning electron microscope (SEM)

Answer 102

- Image is 3-dimensional - It can study surface structures of intact cells & viruses - resolves objects as close as 20 nm - Magnification is 1000X to 10,000X

Answer 103

Greek for “prenucleus” - Includes unicellular bacteria and archaea - DNA is not enclosed within a nuclear membrane; usually have single circular chromosome. - DNA is not associated with histone proteins - Lack membrane-bound organelles and cytoskeleton - Cell walls almost always contain peptidoglycan - Usually divide via binary fission

Answer 104

- Diplococci = two cocci - Streptococci = cocci in chains - Tetrads = cocci that divide in two planes and remain in groups of four - Sarcinae are cocci that divide in 3 regular planes and produce a cube- like group of 8 - Staphylococci are those that divide at random planes and form grape like clusters or broad sheets

Answer 105

- divide only across their short axis. - Diplobacilli appear in pairs after division. - Streptobacilli occur in chains. - Some have tapered ends like cigars. - Coccobacilli are oval and may look like cocci. - Most appear as single rods. - bacillus means: a. bacterial shape b. genus (i.e. Bacillus anthracis)

Answer 106

- have one or more twists; are never straight - Vibrios are curved rods that look like commas. - Spirilla have a distinctive helical shape like a corkscrew, fairly rigid bodies, and move by means of a flagella. - Spirochetes are helical, flexible, and move by means of an axial filament - Other spiral bacteria have more complex shapes and arrangements.

Answer 107

- Glycocalyx: general term used to describe substances that surround bacterial cells - are also called extracellular polymeric substances (EPS) - It is a gelatinous polymer composed of polysaccharide, polypeptide, or both - is viscous (sticky). - is referred as a slime layer if glycocalyx is unorganized & loosely attached to cell wall - is referred as a capsule if glycocalyx is organized and firmly attached to cell wall - Capsules confer bacterial virulence (the degree to which a pathogen causes disease) - capsules prevent from phagocytosis & dehydration & allow for substrate attachment

Answer 108

- are long filamentous appendages that move bacteria - There are 4 arrangements of flagella: a. monotrichous - single polar flagellum b. amphitrichous - single flagellum at both ends of cell c. lophotrichous - 2 or more flagella at one or both poles of the cell d. peritrichous - flagella distributed over the entire cell

Answer 109

single polar flagellum

Answer 110

single flagellum at both ends of cell

Answer 111

2 or more flagella at one or both poles of the cell

Answer 112

flagella distributed over the entire cell

Answer 113

- Three basic parts: a. Filament is the long outermost region which is constant in diameter and contains the globular protein flagellin - not covered by membrane or sheath b. Hook is the structure to which the filament is attached c. Basal body anchors the flagellum to the cell wall and the plasma membrane. (Fig. 4.8) - It is composed of a central rod inserted into a series of rings.

Answer 114

aused by rotation of basal body. - rotation is either clockwise or counter-clockwise around its long axis - Eucaryotic flagella undulate in a wave-like motion - Patterns of motility: a. "Run" or "Swim" - when a bacterium moves in one direction for a period of time. b. "Tumble" - abrupt, random changes in direction caused by a reversal of flagellar rotation - Taxis: the movement of a bacterium towards or away from a particular stimulus. a. If the stimulus is lightphototaxis b. If the stimulus is chemicalChemotaxis - positive chemotactic stimulus = attractant - negative chemotactic stimulus = repellent - ex. Light: a. if attractant → + phototaxis b. if repellent → - phototaxis

Answer 115

the movement of a bacterium towards or away from a particular stimulus. a. If the stimulus is lightphototaxis b. If the stimulus is chemicalChemotaxis - positive chemotactic stimulus = attractant - negative chemotactic stimulus = repellent - ex. Light: a. if attractant → + phototaxis b. if repellent → - phototaxis

Answer 116

- are bundles of fibrils that arise at the ends of the cell beneath the outer sheath and spiral around the cell. - used as a form of locomotion by spirochetes such as Treponema pallidum, the causative agent of syphilis. 3. Rotation of filament causes spiral motion that resembles the movement of a corkscrew

Answer 117

- are hair like appendages attached to bacterial cells - are shorter and thinner than flagella - consist of a protein called pilin - can occur at the poles of the bacterial cell or evenly distributed over the entire surface of the cell - many gram (-) bacteria have pili - 2 types of pili a. common pili (aka fimbriae) allows a cell to adhere to surfaces b. sex pili join bacterial cells to allow transfer of DNA from one cell to anotherconjugation (“bacterial sex”)

Answer 118

- The cell wall is a complex, semi rigid structure that surrounds the plasma membrane. - Almost all prokaryotes have cell walls - is the site of action of some antibiotics - Functions: 1. to prevent rupture of bacterial cells 2. to maintain the shape of the bacterium 3. to serve as a point of anchorage for flagella 4. to produce symptoms of disease in some species

Answer 119

- is composed of called peptidoglycan (disaccharide + polypeptide) - The disaccharide is composed of: 1. N-acetylglucosamine (NAG) 2. N-acetylmuramic acid (NAM) - alternating NAG and NAM form the carbohydrate backbone - tetrapeptide side chain (4 amino acids) attach to each NAM - Parallel tetrapeptide side chains may be linked by a peptide cross-bridge

Answer 120

- Gram (+) bacterial cell walls consists of several layers of peptidoglycan while gram (-) bacteria contain 1 thin layer 1.

Answer 121

- contain teichoic acids, which consists of an alcohol (glycerol) and phosphate - Have negative charge due to phosphate - F(x)s: regulates cation (+) movement in and out of cell - Preventing extensive wall breakdown and cell lysis - Provide antigenic specificity

Answer 122

- consist of an outer membrane, very few layer of peptidoglycan, and a periplasmic space (gel-like fluid) - peptidoglycan interacts with lipoprotein in the outer membrane - does not contain teichoic acids a. The outer membrane consists of: 1. lipoproteins 2. lipopolysaccharides (LPS) = lipid + polysaccharide - polysaccharide: O polysaccharides that function as antigens which can identify species of bacteria - lipid: lipid A (endotoxin) is toxic in host blood, causes fever and shock 3. phospholipids: strong (-) charge help evade phagocytosis

Answer 123

1. Evade phagocytosis 2. Provides a barrier to: a. certain antibiotics (penicillin) b. lysozyme (enzyme which breaks down cell walls of gram (+) bacteria) c. detergents d. heavy metals e. bile salts f. digestive enzymes (i.e. lysozyme) g. certain dyes - Outer membrane is semi-permeable: 1. Porin proteins form nonspecific channels (\< M.W. 800 can enter) 2. Specific channel proteins: a. permit passage of specific molecules only (i.e. Vit B12, iron, nucleotides, maltose) b. function as attachment sites for viruses and bacteriocins (proteins produced by some bacteria to kill closely related species).

Answer 124

Atypical Cell Walls a. Members of the genus Mycoplasma have no cell walls; they have unique plasma membranes which contain lipid sterols (probably protect the cells from osmotic lysis). b. Archaebacteria have cell walls composed of polysaccharide and proteins; NO peptidoglycan! c. L forms are tiny mutant bacteria with defective cell walls.

Answer 125

- Lysozyme: digestive enzyme that occurs naturally in eucaryotic cells; found in tears, mucus, and saliva. • Gram (+) cell walls: lysozyme catalyzes the hydrolysis of the bonds between the NAM and NAG sugars of the peptidoglycan layers, destroying the cell wall. - protoplast: resulting wall-less gram (+) cell 2. Gram (-) cell walls: not completely destroyed; some of the outer membrane remains. - spheroplast: outer membrane and the remaining cell 3. Protoplasts and spheroplasts are very susceptible to changes in the osmotic environment.

Answer 126

a. Phospholipids - 45-50% - bilayer: polar head vs. hydrophobic tail b. Proteins - Peripheral proteins: located at the inner and outer surface of the membrane - may function as enzymes that catalyze chemical reactions - may mediate changes in membrane shape during movement - Integral proteins: penetrate the membrane; some may form channels for passage of ions and molecules - Plasma membrane is a fluid mosaic model (dynamic and move) - Functions of plasma membrane: a. selectively permeable or semi-permeable: selective barrier for passage of molecules and ions b. contains enzymes which break down nutrients c. is involved in ATP production d. in some bacteria, pigments and enzymes for photosynthesis are found in the thylakoids of the plasma membrane

Answer 127

a. certain alcohols b. quartenary ammonium compounds c. Antibiotics, such as polymyxins, disrupt the phospholipids

Answer 128

a. Passive processes: movement of molecules from an area of high concentration to an area of low concentration - does not require energy (no ATP) - simple diffusion - facilitated diffusion - osmosis b. Active Process: use energy to move molecules from an area of low concentration to an area of high concentration (against the concentration gradient). - active transport - group translocation

Answer 129

- simple diffusion: movement of lipid soluble substances such as oxygen, carbon dioxide, and nonpolar organic molecules from area of high concentration to low concentration - facilitated diffusion: require the help of carrier protein to transport molecule across the membrane (i.e. glucose) - osmosis: net movement of water from an area of high water to low water concentration • A bacterial cell may be exposed to 3 kinds of osmotic solutions: a. Isotonic solution: the same solute concentration as the cell b. Hypotonic solution: less solute and more water than the cell therefore water will move into the cell which is hypertonic c. Hypertonic solution: more solute and less water than the cell so that water will move out of the cell and the cell will shrink (plasmolysis).

Answer 130

movement of lipid soluble substances such as oxygen, carbon dioxide, and nonpolar organic molecules from area of high concentration to low concentration

Answer 131

require the help of carrier protein to transport molecule across the membrane (i.e. glucose)

Answer 132

net movement of water from an area of high water to low water concentration • A bacterial cell may be exposed to 3 kinds of osmotic solutions: a. Isotonic solution: the same solute concentration as the cell b. Hypotonic solution: less solute and more water than the cell therefore water will move into the cell which is hypertonic c. Hypertonic solution: more solute and less water than the cell so that water will move out of the cell and the cell will shrink (plasmolysis).

Answer 133

like active transport but the substance is chemically altered while being transported across the membrane a. is a special form of active transport b. occurs exclusively in prokaryotes Ex.: glucose transported across the membrane gets phosphorylated, making it not able to move back across the cell membrane.

Answer 134

depends on a carrier protein to move substances against the [gradient] across a membrane

Answer 135

substance of cell inside plasma membrane - composed of 80% water - 20% = proteins, carbohydrates, lipids, and inorganic ions - cellular structures within cytoplasm: - nucleoid - ribosomes - inclusions - protein filaments - no cytoskeleton, nucleus, and membrane bound organelles

Answer 136

nuclear area - contains a single long circular molecule of double-stranded (ds) DNA, “chromosome". - No histone proteins associate with chromosome

Answer 137

extra small circular, dsDNA molecules - replicate independently of chromosome - usually contain 5 to 100 genes which are usually not essential for survival of the bacteria - may carry genes for antibiotic resistance, tolerance to toxic metals, production of toxins, synthesis of enzymes - horizontal gene transfer via conjugation

Answer 138

Resolution is the ability of lenses to distinguish between two points at a specific distance apart.

Answer 139

BF ## Footnote cannot resolve structures smaller than 0.2 um, therefore, cannot be used to observe viruses. TEM - can resolve objects as close as 2.5 nm SEM- - resolves objects as close as 20 nm

Answer 140

Treponema pallidum

Answer 141

Crystal violet and iodine can go through the thick cell wall, but once inside form a complex (CV-I) which can not go out of the cell.

Answer 142

- Generally, gram (+) bacteria are easily killed by penicillin and sulfonamide drugs. - Gram (-) bacteria are resistant to these drugs, but are more susceptible to streptomycin, chloramphenicol, and tetracycline.

Answer 143

1. is one of the most important molecules for living organisms 2. is the medium for most chemical reactions 3. is the most abundant molecule of most ``` living cells (~65-75%) 4. is a polar molecule, can form H-bonds ```

Answer 144

Proteins. Carbohydrates. Lipids. Nucleic Acids

Answer 145

Double stranded (ds) DNA can denature (melt) to single stranded (ss) DNA at high temperature, lower salt, or extreme pH conditions

Answer 146

modified protien 1. glycoproteins contain sugars 2. nucleoproteins contain nucleic acids 3. metalloproteins contain metal atoms 4. lipoproteins contain lipids

Answer 147

1. Structural proteins - microfilaments for movement of cells - cell membranes or cell walls - carrier proteinstransport molecules into and out of cells 2. Enzymes: catalyze chemical reactions 3. signaling molecules 4. Toxins are produced by certain bacteria; Bacteriocins: proteins produced by some bacteria that kill other bacteria. 5. Hormones for regulatory function (i.e. insulin) 6. Antibodies for immune function

Answer 148

Purines and Pyrimidines are nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA. The two-carbon nitrogen ring bases (adenine and guanine) are purines, while the one-carbon nitrogen ring bases (thymine and cytosine) are pyrimidines.

Answer 149

- is the principal energy-carrying molecule (potential form of energy). - is composed of adenine, ribose, and 3 phosphate groups - energy is released when a phosphate is removed ATP-----------\>ADP + Pi + Energy