exam 1 final 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

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 4

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 5

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 6

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

Answer 7

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

Answer 8

(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 9

(“prenucleus”)Its genetic material is not enclosed in a nuclear membrane

Answer 10

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

Answer 11

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 12

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 13

- unicellular eukaryotes - are members of the kingdom Protista - are classified according to their means of locomotion 1. cytoplasmic streaming (amoebas) 2. flagella 3. cilia - shapes vary - can live free or as parasites. - reproduction is sexual or asexual. (Fig. 1.1c)

Answer 14

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

Answer 15

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

Answer 16

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

Answer 17

living cells can arise only from preexisting living cells

Answer 18

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 19

- are so small that they can only be seen with an electron microscope. - are not cellular. - are parasites which require a host cell to replicate itself. - simple structure: - Core contains the nucleic acid (DNA or RNA) - Protein coat surrounds core - Lipid envelope may surround coat

Answer 20

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 21

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

Answer 22

- 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 23

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 24

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 25

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

Answer 26

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 27

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 28

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

Answer 29

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

Answer 30

- 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 31

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 32

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 33

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 34

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 35

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 36

- 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 37

**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 38

- 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 39

- 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 40

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 41

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 42

- 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 43

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 44

- 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 45

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

Answer 46

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 47

Treponema pallidum

Answer 48

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 49

- 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 50

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 51

Proteins. Carbohydrates. Lipids. Nucleic Acids

Answer 52

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

Answer 53

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

Answer 54

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 55

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 56

- 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 57

are cocci that divide in 3 regular planes and produce a **cube**- like group of 8

Answer 58

“exteme-ophile” - are prokaryotes - cell walls lack peptidoglycan - are found in extreme environments - There are 3 main groups of Archaea 1. Methanogens: produce methane gas as waste product 2. Extreme halophiles: salt-loving 3. Extreme thermophiles: heat-loving; live in hot sulfurous water such as hot springs in Yellowstone National Park.

Answer 59

- 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 60

- 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 61

- 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 62

- 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 63

- 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 64

single polar flagellum

Answer 65

single flagellum at both ends of cell

Answer 66

- 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 67

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

Answer 68

flagella distributed over the entire cell

Answer 69

- 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 70

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 71

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 72

- 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 73

- 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 74

- 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