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BIO 111 > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Cell Envelope

A

The layers surrounding the contents of the cell:

  • Glycocalyx
  • Cell Wall
  • Cell Membrane
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2
Q

Glycocalyx

A

A slimy substance that adheres to the outside of the cell wall:

  • Protects the cell from dehydration
  • Allows bacteria to attach to tissue, which can then be invaded
  • Protection against phagocytosis by white blood cells, increasing survival rate
  • Retards the staining process
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3
Q

Capsule

A

A distinct thick gelatinous material that surrounds some types of microorganisms; sometimes required for an organism to cause disease; type of glycocalyx

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4
Q

Slime Layer

A

Type of glycocalyx that is diffuse (thin) and irregular

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5
Q

Mycoplasma

A

Genus of bacteria that lack cell walls; pump ions (Na+) out of the cell to keep turgor pressure equal inside and outside - prevents lysis; cell membranes strengthened by cholesterol

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6
Q

Cell Wall

A

A rigid structure that maintains cell shape and provides protection from the environment (e.g., low levels of heat, chemicals); provides protection from osmotic pressure

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7
Q

Lysis

A

The swelling and bursting of a cell

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8
Q

Penicillin

A

Antibiotic that interferes with the synthesis of the peptidoglycan portion of bacterial cell walls; binds to and inactivates the enzymes responsible for resealing breaks in the cell wall, causing lysis

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9
Q

Lysozyme

A

An enzyme found in tears that digests (breaks down) peptidoglycan

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10
Q

Gram-Positive Cell Wall

A

Thick, homogenous sheath of petidoglycan (20-80 nm thick) that forms about 90% of the cell wall; retain crystal violet stain (purple)

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11
Q

Peptidoglycan

A

Macromolecule found only in bacteria that provides strength to the bacterial cell wall; composed of alternating glycan molecules and tetrapeptide chains (4 amino acids long); contains teichoic acid

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12
Q

Glycan Molecules

A

A simple sugar (glucose) connected to an amino acid (amino sugar)

  • NAG (N-acetylglucosamine)
  • NAM (N-acetylmuramic acid)
  • Forms a mesh-like structure
  • Alternating sugars form numerous layers (up to 30 layers thick)
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13
Q

Tetrapeptide Chain

A

Each layer of carbohydrates are connected by amino acids or peptides (NAM); exact amino acids vary between species (Gram+ cells)

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14
Q

Teichoic Acid

A

A complex molecule that contains amino acids, sugars, glycerol, and phosphate molecules; used as structural material; travels from the cell membrane through the cell wall, connecting them (Gram+ cells)

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15
Q

Gram-Negative Cell Wall

A

Thin layer of peptidoglycan (1 layer thick, 5-20% of cell wall) surrounded by an outer membrane; 2 layers - periplasmic space and outer membrane; stain pink

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16
Q

Periplasmic Space

A

A region between the cell membrane (inner) and the outer membrane in Gram-negative bacterial cells

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17
Q

Periplasm

A

Gel-like material that fills the periplasmic space

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18
Q

Outer Membrane

A

Bilayer of Gram-negative cells that surrounds the peptidoglycan layer:

  • Layer of phospholipids and macromolecules which serves as a selective barrier for some small molecules to pass
  • Layer of Lipopolysaccharides (LPS) which forms the outer sheath of the membrane
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19
Q

Lipopolysaccharide (LPS) or Endotoxins

A

A molecule formed by bonding lipid to polysaccharide; can be toxic to the human body; different types can be used to identify different strains or species of bacteria

20
Q

Porin Proteins

A

Proteins embedded in the outer membrane that allow specific molecules to pass and will shut off when the cell is threatened; makes antimicrobial agents less effective against Gram-negative bacteria

21
Q

Cell Membrane

A

Serves as a barrier to molecules (selectively permeable); composed of a phospholipid bilayer (40%) with proteins (60%) embedded in the bilayer; hydrophobic fatty acid tails and hydrophillic phosphate heads

22
Q

Carrier Protein

A

Bind to specific substances and transport them across the cell membrane

23
Q

Channel Protein

A

Opening which allows small, water soluble substances to go across the cell membrane

24
Q

Selectively Permeable Membrane

A

Prevents the entrance or exit of certain molecules (large molecules, molecules not soluble in fat, except for water)

25
Q

Enzymes Embedded Within the Cell Membrane

A

Help with:

  • Anabolic chemical reactions, including the synthesis of cell wall and appendages
  • Catabolic pathways, such as electron transport chain (produces ATP)
26
Q

Flagella

A

Long (1-70 nm), thin (20 nm), rigid hair-like appendages composed of protein that must be specifically stained to be seen with a light microscope; rotate 360 degrees at nearly 2000 rpm, causing the cell to slowly spin in the opposite direction providing movement (10X length in a second); important in causing disease

27
Q

Composition of Flagella

A
  • Filament: the long, tube-like structure
  • Hook: where the filament is inserted into
  • Two rings: Hook inserted here, provides the anchor for the filament and the hook has one ring attached to the cell membrane and the other to the cell wall
28
Q

Flagella Arrangements

A
  • None
  • Monotrichous (polar flagellation): single flagellum at one end of the cell
  • Amphitrichous: single flagellum at each end
  • Lophotrichous: a tuft of many flagella at one end
  • Peritrichous: flagella located on many sides of the bacterial cell (peri = “around”)
  • Present in: all spirilla, half of the bacilli, and few coccus
29
Q

Appendages for Attachment

A

Hair-like structures that extend from the cell wall in all directions, but are not used for locomotion; fimbriae and pilus

30
Q

Fimbriae

A

Short, but numerous tubes composed of protein that have a tendency to stick to surfaces; adhere to epithelial cells, allowing the cells to invade the tissues (E. coli in the intestines)

31
Q

Pilus

A

Long, less numerous, hollow, tubular structures found in gram negative bacteria and some gram positive bacteria; links the cytoplasm of one bacteria with the cytoplasm of another bacteria of the same species; used to exchange plasmids (conjugation)

32
Q

Bacterial Chromosome

A

A single, double-stranded, circular piece of DNA containing genes that code for cell maintenance and growth; contains only 3000-4000 genes (25000-32000 in humans); found in the nuclear region of a bacterial cell; attached to the cell membrane

33
Q

Plasmids

A

Very small, circular pieces of DNA that are not essential for bacterial growth and cell maintenance; free-floating and not attached to the cell membrane but can incorporate themselves into a bacterial chromosome on occasion

34
Q

Plasmid Functions

A

Can provide information that can be helpful to survival, but not essential:
- Resistance to drugs
- Production of toxins
- Production of enzymes
Often transferred to other bacterial cells by conjugation to convey additional resistance

35
Q

70S Ribosome

A

Used in protein synthesis; only true organelle found within prokaryotic cells (15000 in protoplasm); ribosomal RNA (rRNA) - 60%, proteins - (40%)

36
Q

Ribosomal Subunits

A

Two subunits (S are Svedberg units which weigh molecular units, the higher the value the heavier the unit):

  • Bacterial cells: 30S and 50S subunits
  • Eukaryotic cells: 40S and 60S subunits
37
Q

Cytoplasmic Inclusions

A

Small, membrane bound structures that will contain various substances:

  • energy-rich organic substances (glycogen), which are produced in times of plenty and used when the environment is low in energy sources
  • gases used in buoyancy and floatation (aquatic systems only)
38
Q

Granules

A

Areas within a cell that contain inorganic crystals, but are not membrane bound; store important resources that are essential elements (sulfur, phosphate) in building macromolecules

39
Q

Endospores

A

A small, protected, dormant bacteria that will germinate under favorable growth conditions into a new bacterial cell, genetically identical to the cell that produced it:

  • only produced by some gram positive rods (Bacillus and Clostridium)
  • produced when condition become unfavorable for further bacterial growth and survival is in question (loss of nutrient source, drying of environment)
  • produced for survival, not reproduction
  • energetically costly
40
Q

3 Layers of an Endospore

A
  • Spore Coat: outer layer that provides a nearly impervious barrier to many chemicals
  • Cortex: Middle layer that contains many calcium salts and dipicolinic acid; keeps core very dry to prevent water from reaching it
  • Core: Innermost layer that contains the bacterial chromosome (DNA)
41
Q

Resistance of Endospores

A

Very resistant to environmental extremes:

  • High temperatures
  • Desiccation
  • Chemicals and radiation
  • Nearly ensures immortality
  • Once favorable conditions are sensed, can quickly (1.5 hours) germinate into a bacterial cell
42
Q

Bacterial Shapes

A

Vary greatly depending on the cell wall composition and nutritional state or slight differences in genes:

  • coccus: sperical
  • bacillus: rod
  • spirillus: spiral
43
Q

Bacterial Arrangements

A

Ways bacteria are found due to cell division and how they stick together after they divide; always to the bacteria by its largest possible:

  • di: two
  • strep: long chains
  • staph: irregular clusters
44
Q

Coccus Arrangements

A
  • Single cell
  • Diplococcus
  • Tetrad: clusters of four
  • Streptococcus
  • Staphylococcus
  • Sarcina: clusters of 8, 16, 32 or more cells in a perfect cube shape
45
Q

Bacillus Arrangements

A
  • Single cell
  • Diplobacillus: joined end-on-end
  • Streptobacillus: long end-on-end chains
  • Palisades: side-by-side arrangement
46
Q

Spirillus Arrangements

A

Rarely found in any arrangement but a single cell (can be found in short chains)

BIO 111 (15 decks)

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