Cell Structures and Metabolism Flashcards
3 major divisions of the living world
bacteria
archaea
eukaryotes
plasma membrane function
selective barrier and enables cells to maintain integrity to function as a coordinated chemical system
nucleus function
store house of genetic information
endoplasmic reticulum function
lipid and protein biosynthesis and intracellular Ca2+ store
rough ER function
Membrane bound ribosomes which allows for co-translational translocation of protein peptides chains into the ER concomitant with protein synthesis
smooth ER function
Regions of ER that lack ribosomes. Regions of smooth ER from which transport vesicles bud off and carry newly synthesized proteins and lipids to the Golgi are known as transitional ER. In cells that specialize in lipid metabolism the synthesis occurs in the smooth ER. In muscle cells the expanded smooth ER is specialized for Ca2+ storage and is called the sarcoplasmic reticulum.
golgi function
major site of carbohydrate synthesis, sorting and dispatching of products made in the ER
mitochondria function
energy metabolism (oxidative phosphorylation and krebs cycle). also has a distinct mitochondrial DNA genome separate from nuclear DNA
lysosomes function
site of intracellular digestion of macromolecules, very heterogenous in terms of morphology, hydrolytic enzymes in lysosomes are all acid hydrolases
prokaryotic vs. eukaryotic cells
cell membrane?
prokaryote: yes
eukaryote: yes
prokaryotic vs. eukaryotic cells
nucleus?
prokaryote: no
eukaryote: yes
prokaryotic vs. eukaryotic cells
chromosomes?
prokaryote: 1 (not a true chromosome)
eukaryote: many
prokaryotic vs. eukaryotic cells
ER?
prokaryote: no
eukaryote: yes
prokaryotic vs. eukaryotic cells
vesicles?
prokaryote: yes
eukaryote: yes
prokaryotic vs. eukaryotic cells
golgi?
prokaryote: no
eukaryote: yes
prokaryotic vs. eukaryotic cells
mitochondria?
prokaryote: no
eukaryote: yes
prokaryotic vs. eukaryotic cells
cytoskeleton?
prokaryote: yes/no
eukaryote: yes
prokaryotic vs. eukaryotic cells
ribosomes?
prokaryote: yes (smaller)
eukaryote: yes (larger)
prokaryotic vs. eukaryotic cells
size?
prokaryote: 1-10 microns
eukaryote: 10-100 microns
fimbriae (or pili) function
attachment to surfaces
flagella function
motility
LPS function
activate inflammatory responses
capsule function
may play a role in dental caries
gram positive
thick peptidoglycan
single inner membrane
teichoic acid
gram negative
thin peptidoglycan
inner and outer membrane
LPS associated with outer leafet of outer membrane
why is gram positive purple-blue?
the thick peptidoglycan prevents crystal violet from being washed out with ethanol
why is gram negative pink?
the thin peptidoglycan allows crystal violet to wash out
peptidoglycan is comprised of chains of alternating
N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) sugars crosslinked by oligopeptides
transpeptidase
responsible for the crosslinking of peptidoglycan
transpeptidase is inhibited by
the antibiotic amphicilin
mechanism of amphicilin
kills gram positive bacteria (because they have a thick peptidoglycan layer) by preventing the formation of peptidoglycan
mitochondria is the site of
oxidative phosphorylation and ATP production within the cell
mitochondria contains a small
circular genome
the bulk of proteins found in mitochondria come from the
nuclear genome, not mitochondrial genome
glycolysis occurs in the cytoplasm to generate
pyruvate
how is pyruvate transported into the mitochondrial matrix?
it crosses the outer mitochondrial membrane through the voltage gated anion channel
not clear how it crosses the inner membrane
once pyruvate enters the matrix it is then converted to
acetyl-coA by the pyruvate dehydrogenase complex
acetyl-coA transfers its acetyl group to oxaloacetate to form
citrate
NADH binds to
complex 1 to generate 3H+
FADH binds to
complex 2 to generate 2H+
concentration gradient causes the ATP synthase to
spin and form ATP
each proton that is pumped through the channel can generate
1 molecule of ATP
fatty acid beta-oxidation generates much more
NADH
net product in the cytosol from glycolysis from 1 glucose
2 pyruvate
2 NADH
2 ATP
net product in the mitochondria from the pyruvate dehydrogenase complex and citric acid cycle
2 pyruvate= 2 acetyl coA + 2 NADH
2 acetyl coA= 6 NADH + 2 FADH2 + 2 GTP
net product in the mitochondrion
2 acetyl coA= 8 NADH + 2 FADH2 + 2GTP
net products from oxidation of one molecule of palmitoyl CoA in the mitochondrion (fatty acid oxidation and citric acid cycle)
1 palmitoyl coA= 8 acetyl coA + 7 NADH + 7 FADH2
8 acetyl coA= 24 NADH + 8 FADH2 + 8 GTP
net products from oxidation of one molecule of palmitoyl CoA in the mitochondrion
1 palmitoyl coA= 31 NADH + 15 FADH2 + 8 GTP
glycolysis has a net yield of
2 ATPs and 2 NADH molecules
citric acid cycle produces
2 ATP
8 NADH
2 FADH2
NADH yields
3 ATP
FADH2 yields
2 ATP
a molecule of glucose can therefore produce a net yield of
30-32 ATP
gatty acid beta-oxidation of palmitate (16C sugar) yields
31 NADH
15 FADH2
8 GTP
palmitate yield is therefore
131 ATP
2 ATP used in the initial activation
therefore, 129 ATP
however, a more precise yield of NADH and FADH2 is
2.5 NADH
1.5 FADH2
because realistically we will not have 100% effectiveness
biofilm
a cooperating community of microorganisms within a matrix that is attached to a surface
biofilms develop in any
fluid filled environment containing microorganisms that are subjected to stress or fluid flow
dental biofilms exist on
the tooth surfaces and mucosal surfaces of the oral cavity
explain the production of biofilms & microbial stage cycle
a pellicle forms within seconds and attachment of pioneering bacteria conditioning (largely gram positive cocci (streptococci)).
within minutes, cross-linkning via fusoformbacterium species occurs as a log phase of expansion as the bacteria multiply and divide.
after hours, stationary phase occurs with predominately gram negative bacteria.
after days, nutrient supply diminishes and bacteria die.
the pellicle forms from proteins in the
saliva orGCF
the pellicle serves as a
conditioning film for attachment of the initial colonizing bacteria
why do some people get cavities and others dont?
diversity difference in the distribution on bacteria and biofilm composition
the bacteria within the colonies communicate with one another via
chemical signals
these microcolonies also adjust their pH and can have varying nutrient supplies which can induce
novel gene expression within the bacteria in the biofilm
fluid channels allow for movement of
nutrients, waste products, metabolites, enzymes, and o2
fluid channels are
porus channels
carcinogenic bacteria produce extracellular polysaccharides from
sucrose
sucrose is split into
glucose and fructose
glucose can be built into homopolymers of glucose called
glucans
such as mutan (water insoluble) and dextran (water soluble)
fructose can be built into homopolymers called
fructan
consisting of beta 1,2 and beta 2,6 linkages
these extracellular polysaccharides serve as a
nutritional source for bacteria, which supports further adhesion and subsequent accumulation of plaque
sucrose is highly
soluble
sucrose diffuses rapidly into the
plaque biofilm where it serves as a substrate for production of the extracellular polysaccharides and acids
the main causal agents for caries are (3)
streptococcus mutans
lactobacillus casei
lactobacillus fermentum
saccharolytic bacteria derive energy from
glycolysis
in anaerobic metabolism,
pyruvate generates lactic acid, which lowers the pH, acidity dissolves enamel, and eventually forms carries
biofilms on the tooth surface will form a
dental plaque
once dental plaque becomes calcified, it is termed
calculus (tartar)
calculus can only be removed through
dental cleaning, rock hard
in patients with healthy dentition and no periodontal disease, most bacteria in the dental biofilms are
gram-positive
the bacteria mainly ferment sugars to the final end product of
lactic acid (saccharolytic microbiota/fermentation)
the production of lactic acid results in low pH, which can result in
demineralization of the tooth enamel and dentin, resulting in a carie
asaccharoyltic bacteria derive energy from
amino acids
free amino acids can be
deaminated or reduced
alanine deamination to
pyruvate and NH3 to form lactate which forms ammonium lactate
reduction of glycine forms
acetate and NH3
reduction of cysteine forms
propinate
HS
NH3
reduction of alanine forms
propinate
H2O
NH3
constituents of dental plaque (3)
ammonium acetate
ammonium propinate
ammonium butyrate
dental plaque occurs on the
tooth and gingival margin because there is a higher pH, so the tooth is not demineralized
dental calculus further promotes
assacharolytic fermentation
as cysteine and methionine are fermented, one of the end products is
hydrogen sulfide
hydrogen sulfide causes
oral malodor
often associated with periodontal disease
you dont see caries in the gingival margin because
the high concentration of ammonia ions (high pH)
saliva is composed of
99%
contains Na, K, Ca, Mg, bicarbonate, phosphates, immunoglobulin proteins, enzymes, mucins, and nitrogenous products sushc as urea and NH3
3 types of saliva
serous
mucos
mixed serous and mucos
serous saliva is the main product of the
parotid glands
mucos saliva is the main product of the
minor glands
mixed serous and mucos is the main product of the
sublingual and submandibular glands
saliva functions (5)
lubrication and protection buffering action and clearance maintenance of tooth integrity antibacterial activity taste and digestion
how much saliva do we produce
750-1000 mL per day
where does all the saliva go?
we swallow it
GCF
gingival crevicular fluid
how much GCF do we produce
1-2 mL per day
where is GCF secreted
into the gingival sulcus
gingival sulcus
between the surface of the tooth and the free margin of the epithelium lining of the gingiva
functions of GCF (4)
cleansing the sulcus
improve adhesion of the epithelium to the tooth
antimicrobial properties
antibody defense of the gingiva
beneath healthy gingival sulcus, the gingival crevicular fluid provides an environment that is rich in proteins and fermentation of amino acids to produce
ammonia (asaccharoyltic bacteria/fermentation)
high ammonia concentration causes a high pH region that prevents dental caries from developing but can lead to the
precipitation of calcium and phosphate on a dental biofilm (plaque) and eventually the formation of a dental calculus
