Module 2 - Cellular Physiology Flashcards
What are the principles of cell theory?
- Cells are the smallest structural and functional unit capable of life
- Functionality depends on anatomy of specific cells
- Cells are living building blocks of all organisms
- An organism’s anatomy and physiology depend on the individual and collective characteristics of its cell’s anatomy and physiology
- All new cells and new life arise only from pre-existing cells
- Cells of all organisms fundamentally similar in anatomy and physiology
How many specialized cell types exist in the human body?
About 200
What are 3 major parts of all cells, regardless of specialization?
o Plasma membrane
o Nucleus
o Cytoplasm
What is the structure and function of the plasma membrane?
- Lipid occurs in 2 layers, called a bilayer with a sandwich-like structure
- Composed primarily of proteins and lipids, especially phospholipids
- Substantial amounts of cholesterol (also a lipid) that helps stabilize the membrane
- Acts as a selective barrier between cellular contents and extracellular fluid
- Controls traffic in and out of the cell
What is the structure and function of the nucleus?
- Contained in every human cell except red blood cells
- Composed primarily of histone protein and DNA enclosed in a double-layered membrane
- Acts as a control center of the cell, providing storage of genetic information
- Nuclear DNA provides codes for synthesis of structural and enzymatic proteins and serves as blueprint for cell replication
What is the structure and function of the endoplasmic reticulum?
• Extensive, continuous membranous network of fluid-filled tubules and flattened sacs
• Forms new cell membrane and other cell components and manufactures products for secretion
May be smooth or rough
What is rough endoplasmic reticulum?
- Endoplasmic reticulum studded with ribosomes
* The ribosomes are where the amino acids are chemically linked to form proteins
What is smooth endoplasmic reticulum?
- No ribosomes present
- Site of lipid and membrane synthesis
- Site of calcium storage
What is the structure and function of the Golgi complex?
- Series of flattened sacs usually curled at the edges
- Proteins and lipids are modified, packaged, and distributed from here
- The sacs pinch off bits of themselves to form vesicles that contain the products as they move to their final destination
What is the structure and function of the lysosomes?
- Derived from sacs of the Golgi body
- Contains hydrolytic enzymes break down particles of food taken into the cell and make the products available to the cell
- Destroy foreign substances and cellular debris
What is the structure and function of the centriole?
• Usually paired, small barrel-shaped organelles that consist of nine short triplet microtubules
• Site of growth of new microtubules including
o Cytoplasmic transport microtubules
o Microtubules that form the mitotic spindle
What is the structure and function of the peroxisomes?
- Membranous sacs containing oxidative enzymes
* Perform detoxification activities
What is the structure and function of the mitochondria?
• Often called powerhouses of the cell
• Rod or oval shaped bodies enclosed by 2 membranes
o Inner membrane folded into cristae that project into an interior matrix
• Carbohydrates, lipids, and proteins broken down here to form ATP (adenosine triphosphate)
• Contains enzymes for citric acid cycle and electron transport chain
• The site where oxygen you breathe used in “cellular respiration”
What is the structure and function of the vaults?
- Shaped like hollow octagonal barrels
* Serve as cellular trucks for transport from nucleus to cytoplasm
What is the structure and function of the intermediary metabolism enzymes?
- Dispersed within the cytosol
* Facilitate intracellular reactions involving the degradation, synthesis, and transformation of small organic molecules
What is the structure and function of the ribosomes?
- Granules of RNA and proteins
- Some attached to rough endoplasmic reticulum, some free in the cytoplasm
- Serve as workbenches for protein synthesis
What is the structure and function of the transport, secretory, and endocytotic vesicles?
- Transiently formed, membrane-enclosed products synthesized within or engulfed by the cell
- Transport and/or store products being moved within, out of, or into the cell, respectively
What is the structure and function of the inclusions within the cytosol?
- Glycogen granules, fat droplets
* Store excess nutrients
What is the structure and function of the microtubules?
• Long, slender, hollow tubes composed of secretory vesicles
• Maintain asymmetric cell shapes and tubulin molecules
• Coordinate complex cell movements, specifically
o Facilitating transport of secretory vesicles within cells
o Serving as main structural and functional component of cilia and flagella
o Forming mitotic spindle during cell division
What is the structure and function of the microfilaments?
• Intertwined helical chains of actin molecules
• Composed of myosin molecules (also present in muscle cells)
• Play a vital role in various cellular contractile systems including
o Muscle contraction
o Ameboid movement
• Serve as mechanical stiffener for microvilli
What is the structure and function of the intermediate filaments?
- Irregular, threadlike proteins
* Help resist mechanical stress
What is intermediary metabolism and where does it occur?
- Chemical reactions inside the cell that involve degradation, synthesis, and transformation of small organic molecules
- Captures energy and provides raw materials for cell functions
- All occur in cytosol
What are anabolic reactions and what does it require?
- Synthesis of molecules that build up organs
* Requires building blocks and energy to be present
What are catabolic reactions?
• Breakdown complex molecules into simpler ones
What ATP pathway is used for immediate ATP production that is required at times such as the onset of intense exercise?
Substrate level phosphorylation
Where does substrate level phosphorylation occur?
Cytosol of skeletal muscle and brain cells
What is creatine phosphate (CP) and how is it used?
• Also called phosphocreatine
• Stored in the cytosol and is stored energy for skeletal muscle
• Creatine kinase is enzyme involved in this creation
• Energy released when the bond between phosphate and creatine is broken
o This energy and the phosphate can be donated to ADP to form ATP
• Reaction is reversable, energy and phosphate from ATP can combine with creatine to form CP again
o Created once there is enough ATP available
• ATP levels remain relatively stable, CP levels vary greatly
What is McArdle disease, what are the signs and symptoms, and what is the treatment?
Lack of phosphorylase enzyme needed for first step of glycolysis resulting in lack of glycogen needed for muscle contractions. Symptoms include muscle fatigue, pain, and cramps. Treatment aimed at correcting enzyme deficiency and may involve gene-therapy
What is glycolysis and what does it produce?
• 10 separate sequential reactions that break down simple sugars into pyruvic acid molecules
• Not very efficient ATP production and cannot meet body needs alone
• Energy released produces
o 2 molecules of ATP
o 2 molecules of NADH
o 2 pyruvic acid molecules
Describe the process of pyruvate decarboxylation
• Pyruvic acid moves into mitochondrial matrix via monocarboxylate transporter protein
• Enzyme pyruvate dehydrogenase metabolizes pyruvic acid
o This results in decarboxylation
Removal of carbon and forms CO2 and is eliminated
Transfers H to NAD+ to form NADH
o Pyruvate is converted to acetyl coenzyme A (acetyl CoA)
What are other names for the tricarboxylic acid cycle?
TCA cycle or Krebs cycle
How many TCA cycles are made per 1 molecule of glucose?
2
How many molecules of ATP is made from each TCA cycle?
1
What is the most important function of the TCA cycle?
• Prepares hydrogen carrier molecules for next step that produces most energy
Where does the TCA cycle take place?
Mitochondrial matrix
What is GDP and how does it relate to the TCA cycle?
guanosine diphosphate which picks up a phosphate group released from the TCA cycle forming DTP which can be used to form ATP from ADP
What is the original acid that Acetyl CoA combines with to begin the TCA cycle?
oxaloacetic acid
What happens to the carbon atoms released in the TCA cycle?
Expelled from the body as CO2 via the respiratory system
What are the 2 hydrogen carrying molecules released at the end of the TCA cycle?
NADH and FADH2
Where does the electron transport chain occur?
In the inner lining of the mitochondrial membrane lining the cristae
Which stage of ATP production uses a chemiosmotic mechanism?
Electron transport chain
What are the 4 steps taken to aerobically break down sugar into ATP?
Glycolysis
Pyruvate decarboxylation
Tricarboxylic acid cycle
Electron transport chain
What inputs the energy into the electron transport chain?
NADH and FADH2
How does the electron transport chain?
• Steps include electron carrier molecules I to IV, the quinone pool (Q), and cytochrome c (C)
• Some energy used to pump H+ ions into the intermembrane space
o ATP synthase enzyme activated by flow of H+ back into matrix
o Energy of flowing H+ used to take ADP and Pi and create ATP
What is oxidative phosphorylation?
• Entire sequence of mitochondrial biochemical reactions using oxygen to extract energy from nutrients in food and transforms it into ATP, producing carbon dioxide and water in the process
How many ATP molecules is made from each NADH and FADH2 molecule?
- Each NADH leads to 3 ATP molecules
* Each FADH2 leads to 2 ATP molecules
How many molecules of ATP can be created from 1 molecule of glucose?
• Theoretically, 38 molecules of ATP per molecule of glucose
o The system is not 100% efficient however, so realistically its about 30-32 ATP
What is the main dietary source of energy for the body and what can be used as back ups?
- Glucose is the main dietary source of energy
- Fats (fatty acids) can be used when necessary
- Proteins (amino acids) are usually used for protein synthesis but can be used as a last resort for fuel
How does anaerobic ATP synthesis work?
• The only process that can occur during anaerobic conditions is glycolysis forming:
o 2 molecules of ATP
o 2 molecules of NADH
o 2 pyruvic acid molecules
• The pyruvate is converted to lactic acid consuming NADH produced during glycolysis
What main activities require the input for ATP?
Synthesis of new chemical compounds (anabolic reactions)
Membrane transport
Mechanical work such as contraction of muscle
What form of ATP production does red blood cells use and why?
Glycolysis. They have low energy requirements as they do not contract and as they have no nucleus they do not have protein synthesis
What does trilaminar mean in reference to the plasma membrane?
- Appearance of 3 layers when viewed by an electron microscope
- Two dark layers separated by a light middle layer
What is the phospholipid layer and what is it called in the plasma membrane?
• Lipid occurs in 2 layers, called a bilayer with a sandwich-like structure
What is the phospholipid bilayer composed of?
- Composed primarily of proteins and lipids, especially phospholipids
- Substantial amounts of cholesterol (also a lipid) that helps stabilize the membrane
What is the function of the plasma membrane?
- Acts as a selective barrier between cellular contents and extracellular fluid
- Controls traffic in and out of the cell
What are the two ends of a phospholipid?
Head - Phosphate group
Tail - 2 fatty acid tails
What is the polar end and what is it’s importance to the phospholipid layer?
- Negative charge of the phosphate group
- React with water and are referred to as hydrophilic (water loving)
- Are exposed to the water on the outside and inside of the cell
What is the non-polar end and what is it’s importance to the phospholipid layer?
- Two neutral fatty acid tails per phospholipid
- Avoid water and are referred to as hydrophobic (water fearing)
- Face each other on the inside portion of the membrane
- Serve as a barrier for water soluble substances across the membrane
What is a fluid mosaic model and why is the plasma membrane named that?
• Fluid in nature
o Phospholipids are not held in place and are free to move and rearrange themselves
• Name comes from changing pattern of proteins within the bilayer
What are glycolipids and what is their importance to the plasma membrane?
- Molecules of the external lipid layer that have a carbohydrate molecule attached
- Allow cells to recognize each other
Are proteins fixed in place in the plasma membrane?
• No, they are free to move within the membrane
o Some anchored by cytoskeleton
What are integral proteins and what purpose do they serve the plasma membrane?
• Span the entire width of the membrane, protruding on both sides
What are peripheral proteins and what are their importance to the cell membrane?
- Attach to the membrane surface
- Usually temporary
- Are anchored by integral proteins or by attachment to the lipid bilayer
What are glycoproteins and how are they important to the plasma membrane?
- Carbohydrate molecule attached to a protein on the outside of the cell
- Allow cells to recognize one another
What are channel proteins?
- Water filled channels for membrane transport
- Serve as carriers of small water-soluble substances
- Specific shape of inside of channel can make it selective to the ions that can pass through
- May close as a result of a change in the channel shape
What are carrier molecules?
- Specific to a particular molecule or closely related molecules
- Different cell types have different carriers depending on cell needs
What are docking-marker acceptors?
- Located on the inner surface of the membrane
* Have a lock and key mechanism with secretory vesicles allowing exocytosis
What are membrane-bound enzymes?
- May be located on inner or outer surface
- Control specific chemical reactions
- Different cell types have different enzymes depending on cell needs
What are the receptors in the plasma membranes?
- Located on the outer surface
- Respond to specific molecules such as hormones in the cellular environment that alter the activity of the cell
- Different cell types have different receptors depending on cell functions
What are glycoproteins?
- Carbohydrate molecule attached to a protein on the outside of the cell
- Allow cells to recognize one another
What are cell adhesion molecules (CAMs)?
• Proteins that connect to other cells and connective tissue fibers
What are cadherins?
- Located on the surface of adjacent cells
* Form zipper-like adhesions between adjacent cells
What are integrins?
• Span entire membrane
• Connect to the cytoskeleton as well as the extracellular environment to lock them in place
• Some may act as signalling molecules
o Signal for growth or for immune system cells
What is the extracellular matrix and how does it play a roll in cell adhesions?
- Meshwork of fibrous proteins embedded in watery interstitial fluid
- Acts as a biological glue for cells
What are collagen fibers and what do they provide?
- Cable-like fibers or sheets
* Provide tensile strength
What are elastin fibers and what do they provide?
- Rubber-like fiber
* Allows for stretching and recoil (elasticity)