Microbiology Chapter 3

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Microbiology with Diseases by Taxonomy 3rd Edition

4 Processes of Life

growth, reproduction, responsiveness, metabolism

Prokaryotes

kind of cell without a nucleus

eukaryote

kind of cell with a nucleus

organelles

specialized structures that act like tiny organs to carry on the functions of the cell

glycocalyx

gelantious, sticky substance that surrounds the outside of a cell

capsule

a glycocalyx of a bacterium composed of organic chemicals firmly attached to the cell surface

slime layer

a loose water-soluble glycocalyx, protect cells from drying out

desciccation

drying out

flagella

long structures that extend beyond the cell surface and propel a cell through the environment

3 parts of a flagella

filament, hook, basal body

peritrichous flagella

flagella that cover the surface of a cell

polar flagella

flagella only at the end of a cell

endoflagella

flagella that spiral tightly around a cell instead of protruding

taxis

movement in response to stimuli

phototaxis

movement in response to a light stimulus

chemotaxis

movement in response to a chemical stimulus

fimbriae

sticky, bristle-like projections on bacteria to allow them to adhere to substance sin the environment or to each other

biofilms

slimy masses of microbes adhering to a substrate by means of fimbriae and glycocalyces

pili

tubules composed of a protein called pilin, longer than fimbriae, shorter than flagella

4 functions of a cell wall

1. provide structure and shape to the cell
2. protect the cell from osmotic forces
3.assists in attaching to other cells
4. resists antimicrobial drugs

cocci

spherical cells that appear singly, in chains, clusters, or cuboidal packets

bacilli

rod-shaped cells that appear singly or in chains

peptidoglycan

complex polysaccaharide that makes up cell walls

glycan portions of peptidoglycan

millions of NAG and NAM molecules that are covalantly linked in chains in which NAG alternates with NAM

peptido portion of peptidoglycan

crossbridges of 4 amino acids that attach chains of NAG and NAM

2 types of bacterial cell walls

Gram-positive and Gram-negative

cytoplasmic membrane

beneath the glcocalyx and the cell wall, also called the cell membrane or plasma membrane

phospholipid bilayer

structure of the cytoplasmic membrane

hydrophilic

attracted to water

hydrophobic

repelled by water

fluid mosaic model

membrane structure with mosaic indicating the membranes proteins arranged in a mosaic and fluid indicating the protein and lipids allowed to flow freely within the membrane

functions of a cytoplasmic membrane

1. controls passage of substances into and out of the cell
2. produces molecules for energy storage
3. harvest light energy in phosynthetic bacteria

selectively permeable

allows some substances to cross the membrane and prevents others from crossing

concentration gradient

difference in concentration of a chemical on the two sides of a membrane

electrical gradient

voltage across the membrane

diffusion

net movement of a chemical from an area of higher concentration to and area of lower concentration

facilitate diffusion

proteins in the cyctoplasmic membrane act as channels or carriers to allow certain molecules to diffuse in or out of the cell

osmosis

diffusion of water across a selectively permeable membrane

isotonic

when solutions on either side of a selectively permeable membrane have the same concentration of solutes

hypertonic

when the concentrations of solutions are unequal, the higher concentration of solutes

hypotonic

when the concentrations of solutions are unequal, the lower concentration of solutes

3 mechanisms of active transport

1. uniport - one chemical at a time
2. antiport - 2 chemicals in opposite directions
3. uniport couple with a symport - - 2 substances in the same direction

group translocation

active process in some bacteria, substance being transported across the membrane is chemically changed during transport

cytoplasm

gelatinous material inside a cell

cytosol

liquid portion of the cytoplasm

nucleoid

region of a prokayote that contains the cell's DNA

inclusions

deposits found withing bacterial cytosol, include lipids, starch, or compounds containing nitrogen, phosphate, or sulfur

Where do many bacteria store carbon and energy

in molecules of glycogen or in a liquid polymer called plyhydoxbutyrate

endospore

a structure produced by some bacteria to defend it from hostile conditions

ribosomes

site of protein synthesis in cells

cytoskeleton

internal network of fibers in a cell, helps to form a cell's basic shape

analagous structures

similar structure without having a common ancestor

hami

fimbriae-like structures that radiate out from archaea, like barbed wire, function to securely attached arahaea to biological and inanimate surfaces

Functions of eukaryotic gluycocalyces

1. helping to anchor animal cells to each other
2. strengthening the cell surface
3. providing some protection against dehydration
4. cell-to-cell recognition and communication

membrane rafts

assemblages of lipids and proteins that remain together, funtctions 1. signaling the inside of a cell 2. protein sorting 3. some kinds of cell movement

endocytosis

active transport that occurs when pseudopodia surround a substance and bring it into a cell

phagocytosis

when a solid is brought into a cell by endocytosis

pinocytosis

when a liquid is brought into a cell by endocytosis

exocytosis

reverse of endocytosis, enables substances to be exported from a cell

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