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62 Cards in this Set

  • Front
  • Back
What is the main function of mitochondria?
To convert chemical fuels into energy forms that drive cell reactions
What are other functions of the mitochondria
Steps in steroid synthesis
Where is the mitochondria located?
in all mature eukaryotic cells exc. RBC's

Found where metabolic act. is high
What is a porin?
A protein that forms a freely permeable to small ions channel
What molecule(s) is the inner membrane rich in?
Cardiolipin, pump and transport systems
What part of the metabolic pathway does the inner membrane participate in?
the ETS
Where is the ADP->ATP phosphorylating system located?
Seen as elementary particles on stalks from the inner surface of the inner membrane?
What is the function of cristae?
increase surface area
When will a cell have more cristae than another?
When that cell has a larger energy requirement than the other.
Cells ass. w/ steroid synthesis tend to have ________ shaped cristae?
The mitochondrial matrix is electron _____, whereas the innermembrane space is electron _______
dense; lucent
The intermembrane space is similar in concentration to the _______
What enzymes are located in the innermembrane space?
Creatine kinase, adenylate kinase, cytochrome C (ATP-using enzymes)
What important cellular components are present in the matrix of the mitochondria
1.Kreb's Cycle enzymes
2.B-oxidation enzymes
3.closed-circle double-stranded mitochondrial DNA
4.rRNA, tRNA, mRNA
Mitochondria are more numerous in cells using _______________?
Large amounts of energy
How does the elongation of FA's occur in the mitochondria?
by addition of acetyl-CoA
What are most mitochondrial proteins coded by?
nuclear DNA, synth. in cytosol, trans. to mito. using E-req. process
Where types of cells tend to have more mitochondria?
1.The myofibrils of skeletal and cardiac muscle
2.Basal/lateral surfaces of cells inv. in pumping ions
4.Axon Terminal
How do mitochondria grow?
By the addition of new materials produced in the cytoplasm to existing mito. components
How do proteins destined for the mitochondria get there?
A signal peptide sequence is recognized by a receptor
Where is the receptor located?
Outer mitochondrial membrane
What does the receptor do to get the precursor protein inside?
Crosses both membranes at a contact site
What happens after crossing?
Signal sequence is cleaved
How do mito. proliferate?
Organelle division (fission), not in-step with the cell cycle.
Is the mito. capable of protein synth.
a little
What does mito. DNA code for?
13 TCA Enzymes
2 rRNA's
22 tRNA's
What is the hypothesis of how mitochondria originated in cells?
When the [02] increased, primitive eukaryotic cells ingulfed aerobic bacteria via endocytosis and lived in symbiosis w/the bacteria
What three diseases are being ass. w/mitochondrial dysfunction and where is it inherited from?
Age-related diseases
2.Heart Disease
*Inherited from mother
What other organelle do peroxisomes usually ass. with?
Smooth ER
Where are large peroxisomes present?
What type of peroxisomes are found in the rest of the body?
Do peroxisomes contain DNA or RNA?
Where are peroxisomal enzymes produced?
In the cytosol
What directs peroxisomal proteins to the membrane?
Signal sequence
How do peroxisomes divide?
What do perox's do to very-long chain fatty acids?
Break down into acetyl-CoA via B-oxidation
What inclusion is commonly found in other animals peroxisomes but not humans?
urate oxidase
What are the functions of perox's?
1.Oxidze specific organic substrates
2.Segrete enzymes that use H202
3.Aids bile acid synthesis (via action of perox. enzy's)
4.B-oxidation of Very long chain FA's
What is the byproduct of oxidase action?
How is H202 destroyed?
By catalase
What causes Zelwegger Syndrome?
The failure of peroxisomal membrane transport proteins in bringing peroxisomal enzymes into the peroxisome.
What are the classifications of Zelwegger's
G1: complete loss of f(x)=death
G2: only a few peroxisomal enzymes disabled
G3: only one enzyme disabled
What is adrenoleukodystrophy?
The inability of peroxisomes to transport long-chain fatty acids into the cell, causes FA buildup: damages myelin, neurological damage
What is the intracellular digestive system?
Lysosomes and their ass. organelles
Describe the maturation of a lysosome?
1.Early endosomes take up material via endocytosis (sorting occurs)
2.Merge w/ late endosomes (sorting occurs)
3.Late endosome matures into lysosome
What is unique about the inner lysosomal membrane?
Highly glycosylated
Why does this occur?
prevents hydolases inside from digesting the lysosome's membrane
What is a residual body?
Old lysosomes containing indigestible material
What is the optimal pH of lysosomes?
What modifications occur to lysosomal enzymes in the Golgi
1.Addition of mannose-6-phophate (cis-golgi network)
2.Other carb mod's
4.Packaged into a vesicle
What purpose does the sugar groups serve on lysosomal enzymes?
Serves as a label for routing the enz's to the lysosome
What are the methods used by lysosomes to digest material?
2.Receptor-mediated endocytosis
What type of molecules enter via endocytosis?
Fluid and small proteins
What is clathrin-independent fluid phase pinocytosis?
The forming of vesicles around fluid and into the lysosome
What happens if that fluid must be digested?
Sent to Early Endosomes
How does receptor mediated endocytosis occur?
By the binding of a ligand to a receptor on the lysosomal membrane.
What does this binding cause?
"Capping"(aggregation) of the receptor-ligand processes
How are these aggregates now taken into the lysosomes?
Via vesicles formed from the molecule clathrin.
If to be digested what happens?
The vesicle fuses with an early endosome
Phagocytosis involves the uptake of ________
large, solid materials (bacteria i.e.)
What protein is used for phagocytosis?
What are the specific functions of lysosomes?
1.breakdown of worn-down or excess organelles
2.Digestion of materials
3.Thyroid Hormone secretion
4.Resorption of Bone (osteoclasts)
5.Provide nutrients during starvation