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54 Cards in this Set

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denaturation
destruction of a protein's three-dimensional structure
cause by heat, unfavorable pH, high salt concentration
nucleic acids
3dr most abundant component of microbial cells (after water and protein)
two types: DNA and RNA
deoxyribonucleic acid
molecule that encodes a cell's genetic information; ensures that progeny resemble parents
ribonucleic acid
interprets info for protein construction encoded in DNA
much more abundant than DNA, especially in microorganisms
ribosomes
organelles on which proteins are manufactured, composed partly of RNA
nucleotides
the building blocks of nucleic acid; each contains a phosphate group and nucleoside-composed of a 5-carbon sugar and nitrogen-containing base
pyrimidine
single-ringed molecule
cytosine, uracil, thymine
U only occurs in ribonucleotides, T occurs only in deoxyribonucleotides
purine
double-ringed molecule
adenine and guanine
type of bond that joins nucleotides
phosphodiester bonds
nucleoid
irregularly shaped region occupied by the DNA of a prokaryotic cell
peptidoglycan
part polysaccharide part protein, makes up prokaryotic cell walls; no eukaryotic cells contain it
cytoplasm
lies within envelope of cell, contains DNA and metabolic machinery.
envelope
as many as three layers
outside-->inside
outer membrane
cell wall
cytoplasmic membrane
gram-negative bacteria envelope
all three layers (outer membrane, cell wall, cytoplasmic membrane)
extra-cellular component between outer and cytoplasmic membranes - periplasm
gram-positive bacteria envelope
lack outer membrane
mycoplasmas envelope
lack outer membrane and cell wall
outer membrane of gram-negative bacteria
bilayer. inner layer composed of phospholipid, outer layer composed of mainly lipopolysaccharide (LPS)---also contains small amount of phospholipid to which some components of capsule are attached
lipopolysaccharide (LPS)
found only in outer membrane of Gram- bacteria-lipid moiety at one end, polysaccharide on the other--
lipid end=Lipid A-hydrophobic
polysaccharide tail is hydrophilic
AKA endotoxin - harmful to humans/animals
pores
small holes in outer membrane through which nutrients a gram- cell needs pass.
formed by proteins called porins
some are selective
how outer membrane is anchored to rest of envelope?
molecules of lipoprotein- bonded to cell wall at one end
other end carries a lipid that inserts into the inner surface of the outer membrane
benefits of outer membrane to gram negative bacteria
protection - gram- bacteria generally more resistant to toxic substances because they can't get through the outer membrane.
periplasm
lies inside outer membrane of gram- bacteria.
important organelle - filled with gelatinous material incl. 2 types of proteins-
enzymes-most break down certain nutrients so they can pass thru cytoplasmic membrane
binding proteins - bind to certain nutrients - facilitate their passage across outer and cytoplasmic membranes
cell wall
all bacteria except mycoplasms have strong walls made of peptioglycan
gram- :wall lies within periplasm
gram+ :outside cytoplasmic membrane
structure of cell wall
made of peptioglycan - part protein, part polysaccharide
polysaccharide (glycan) part consists of long chains of alternating units of sugars NAG and NAM- chains encircle cell
held together (cross-linked) by protein part of molecule
gram negative cell wall
peptidoglcan mesh that is only one layer thick
gram positive cell wall
many layers thick
contain 2nd component - teichoic acid- adds to structural integrety
spherical
cocci (sing)
coccus
rod-shaped
bacilli (sing)
bacillus
spiral shaped
spirilla
spirillum
short rod shaped
coccobacillus
mycoplasmas envelope
lack outer membrane and cell wall
outer membrane of gram-negative bacteria
bilayer. inner layer composed of phospholipid, outer layer composed of mainly lipopolysaccharide (LPS)---also contains small amount of phospholipid to which some components of capsule are attached
lipopolysaccharide (LPS)
found only in outer membrane of Gram- bacteria-lipid moiety at one end, polysaccharide on the other--
lipid end=Lipid A-hydrophobic
polysaccharide tail is hydrophilic
AKA endotoxin - harmful to humans/animals
pores
small holes in outer membrane through which nutrients a gram- cell needs pass.
formed by proteins called porins
some are selective
how outer membrane is anchored to rest of envelope?
molecules of lipoprotein- bonded to cell wall at one end
other end carries a lipid that inserts into the inner surface of the outer membrane
benefits of outer membrane to gram negative bacteria
protection - gram- bacteria generally more resistant to toxic substances because they can't get through the outer membrane.
periplasm
lies inside outer membrane of gram- bacteria.
important organelle - filled with gelatinous material incl. 2 types of proteins-
enzymes-most break down certain nutrients so they can pass thru cytoplasmic membrane
binding proteins - bind to certain nutrients - facilitate their passage across outer and cytoplasmic membranes
cell wall
all bacteria except mycoplasms have strong walls made of peptioglycan
gram- :wall lies within periplasm
gram+ :outside cytoplasmic membrane
structure of cell wall
made of peptioglycan - part protein, part polysaccharide
polysaccharide (glycan) part consists of long chains of alternating units of sugars NAG and NAM- chains encircle cell
held together (cross-linked) by protein part of molecule
gram negative cell wall
peptidoglcan mesh that is only one layer thick
gram positive cell wall
many layers thick
contain 2nd component - teichoic acid- adds to structural integrety
spherical
cocci (sing)
coccus
rod-shaped
bacilli (sing)
bacillus
spiral shaped
spirilla
spirillum
short rod shaped
coccobacillus
vibrio
short, comma shaped spirillum
turgor
osmotic pressure within cell
high in bacterial cell because contents are concentrated
how bacterial cells grow within rigid peptidoglycan wall
to enlarge peptioglycan shell bacteria produces enzymes that break cross-linking bonds in peptioglycan and others that reseal the breaks by adding new peptidoglycan monomers
transpeptidases
reseal breaks in peptidoglycan walls by adding new peptidoglycan monomers
autolysins
enzymes that break cross-linking bonds in peptidoglycan
penicillin-binding proteins
another name for transpeptidase enzymes; penicillin kills growing bacteria b/c inactivated transpeptidases cant close the breaks in the cell wall that autolysins make to enlarge. cell lyses (bursts) b/c wall becomes too weakened to hold turgor pressure
mycoplasmas
lack cell wall but dont lyse b/c they dont have sig. turgor pressure. maintain= [] of solutes inside cytoplasm and external environment by pumping out sodium ions
cytoplasmic membrane strengthened by sterols
L-forms
wall-less strain of bacteria
can be made artificially by treating normal bacteria with lysozome (removes walls) or penicillin (prevents synthesis)
unit membranes
cytoplasmic membranes of eukaryotes and bacteria
lipid component composed of phospholipids
form membranes spontaneously
hydrophilic head: glycerol + phosphate group
hydrophobic tail: 2 fatty acid chains