Bio 2730 Chapter 3 - Microscopy and Cell Structure

Capsule

small, tight, defined outer gel-like layer; gelatinous and distinct

slime layer

larger, messier layer; diffuse and irregular

Morphology

the study of the form of things

Bacilli

rod-like

Cocci

spherical

Spirillum

thick, rigid spiral

Vibrio

a curved or comma shape

Spirochete

thin, flexible spirals

Diplococcus

two spherical chain; cells divide on one plane

Staphylococcus

cells divides in several planes at random

Sarcina

cell divides in two or more planes perpendicular to one another; packets of 8 cells

Phospholipid bilayer/cytoplasmic membrane

consists of two layers of phospholipids, with a hydrophobic (water-hating) interior and a hydrophilic (water-loving) exterior

Phospholipid

make up cell membranes; a lipid containing a phosphate group in is molecule

Osmosis

diffusion of water across a semipermeable membrane

Plasmoptysis

effect of a hypotonic solution

Plamolysis

effect of a hypertonic solution

Hypotonic solution

when the concentration is lower than the concentration of another solution

Hypertonic solution

when the concentration of the solute outside the cell is greater than the solution inside the cell

Proton Motive Force (PMF)

a form of energy; used to make ATP, drive flagellum, or to drive transport proteins to move substances against their concentration gradient

Facilitated diffusion

allows a substance to move across the membrane, but only down its concentration gradient

Active transport

uses energy (ATP or PMF) to move a substance across the membrane against a concentration gradient

Group translocation

chemically alters the substance as it is transported across the membrane

Penicillin

prevents the cross-linking of NEW peptidoglycan, stopping or hampering cell division; affects gram-positive cells more then gram-negative

Lysozyme

an innate defensive antimicrobial enzyme found in tears, saliva, and many other bodily fluids that cuts certain linkages in peptidoglycan, significantly weakening the cells

Flagellum

primary means of movement; energetically intensive

Pili

allow attachment/adherence of cells to surfaces and sex pili are involved in DNA transfer

Chemotaxis

phenomenon whereby organisms direct their movements according to certain chemicals in their environment

Chromosome

DNA molecule that contains all genetic information required by the cell

Nucleoid

condensed chromosome

Ribosome

protein factories of the cells, complex assembled of several proteins and RNA

Plasmid

small loops of DNA that carry unusual genes (often antibiotic resistances or enzymes to eat types of food) that can be exchanged between bacteria with sex pili

Endospore

small, dormant, highly specialized copy of the cell maintained intracellularly, usually only produced when conditions turn unfavorable

Phagocytosis

cells engulf particulate material such as bacteria

receptor-mediated endocytosis

cells take in material that has bound to receptors

pinocytosis

cells take in liquids

Where is peptidoglycan found in relationship to the membrane(s) in Gram-positive bacterial cells? Gram-negative?

Gram-positive

- External to the plasma membrane

Gram-negative

- outside the plasma membrane but inside a second, outer membrane

What does peptidoglycan physiologically do for bacterial cells?

Provides structure and shape to bacterial cells

What are the 4 'P's?

Purple

Positive

Peptidoglycan

Penicillin

What antibiotics that we mentioned in class affect peptidoglycan and how does that help in clearing infections?

Penicillin - prevents the cross-linking of NEW peptidoglycan, stopping or hampering cell division; affects gram-positive cells more than gram-negative

Lysozyme - an innate defensive antimicrobial enzyme found in tears, saliva, and many other bodily fluids that cuts certain linkages in peptidoglycan, significantly weakening the cells

Understand the structure of the cytoplasmic membrane, it's constituents and their diversity.

The structure of the cytoplasmic membrane consists of a phospholipid bilayer embedded with proteins. Phospholipid molecules are arranged in opposing layers, their heads interact with aqueous solutions. Cytoplasmic membrane surrounds the cytoplasm, separating it from the external environment and transmitting information about the external environment to the inside of the cell

List the three primary functions of the cytoplasmic membrane.

- Selective permeability

- Transport proteins

What is the structural difference between Gram-positive & Gram-negative bacteria?

Gram-positive

- Thick layer of peptidoglycan; consists of many layers (7-9) locked together

- External to the plasma membrane

- Vulnerable to peptidoglycan formation blockers

Gram-negative

- Thin layer of peptidoglycan (1-3)

- Cell wall is outside the plasma membrane but inside a second, outer membrane making it vulnerable to penicillin

Where is lipopolysaccharide (LPS)/endotoxin found in Gram-negative bacteria? What does endotoxin produce as a symptom of infection in humans?

- Found in the outer membrane

- LPS, causes fever and potent immune reactions

Know the example bacterium that does not have a cell wall (and name the disease it causes).

Mycoplasma pneumoniae (walking pneumonia)

If a pathogenic bacterium produces a thick slime layer, is likely more or less pathogenic?

Less

Name the three functions of pili.

- To allow the cell to adhere to specific surfaces

- To help the move on solid surfaces

- To allow two bacteria to join to exchange genetic material (sex pilus)

Name the three functions of flagella.

Primary means of movement pushing the cell through liquid and penetrate thick mucus gel

What is the primary means of movement in most bacteria?

Flagellum

Can bacteria have multiple chromosomes? How many identical copies of the chromosome does E. coli have in the cell at any given time?

- Can have multiple circular or linear chromosomes, though a single, large, circular chromosome is most common

- E. coli maintains 2-8 copies of its chromosome in each cell

Name the three possible locations of endospores.

- terminal spores

- subterminal spores

- central spores

What is the best description of the way bacteria move?

Tumble - roll/run - tumble

What organelle is responsible for modifying macromolecules made in the ER and 'shipping' them to the appropriate locations of the cell?

Golgi Apparatus

Uniporter

Transports one direction across the membrane

antiporter

A carrier protein that transports two molecules across the plasma membrane in opposite directions.

symporter

functions as a co-transporter

What is the primary difference in appearance of the overall cell cytoplasm between prokaryotes and eukaryotes?

Prokaryotes

- None

Eukaryotes

- Many organelles, nucleus, ER, cytoskeleton

What is the most common number and conformation of bacterial chromosome(s)?

60% of bacteria are one circular