Exam #1 Flashcards
Body functions act as a _____________ unit.
Integrated/interdependent
Most cells are exposed to the ___________ environment.
Internal
Cells live in an _______ environment.
Aqueous
How are body compartments separated?
By epithelial membranes (membranes tend to be semipermeable).
Total body water can be divided into….
Intracellular fluid and extracellular fluid.
What is plasma?
Fluid surrounding blood cells.
What does interstitial mean?
(Fluid) Between
What are the two characteristics of exchange between external and internal environments?
1) It is indirect.
2) Only occurs in certain systems: lungs, G.I. tract, and kidneys.
What are examples of mechanisms that homeostasis maintains/controls?
Temperature, blood pressure, and molecular concentration.
What does disruption of homeostasis lead to?
Disease and/or death.
Homeostasis requires…
Organ system integration.
In negative feedback, if a regulated variable increases, the system responds to make it……
Decrease.
What are the three general body structures that underlie negative feedback?
1) Receptor
2) Integrating center
3) Effector organs
What signal does the integrating center (in negative feedback) receive?
Afferent signal.
What signal does the effector organs (in negative feedback) receive?
Efferent signal.
How does fever enhance immune responses?
Increases mobility of leukocytes, phagocytosis, and T cell proliferation.
How does a fever increase the body temperature set point?
The white blood cells notice the pathogen and secrete pyrogens, like interleukin. Interleukin causes the hypothalamus in the brain to reset the set point upwards.
What is an example of a positive feedback loop being terminated?
Na+ channels cause a rapid influx of sodium, but eventually closes. This causes K+ to leave.
What are some examples of surfaces covered by epithelial cells?
Skin, lungs, glands, stomach, intestines, and blood vessels.
What type/s of muscle cells execute voluntary movement?
Skeletal.
What type/s of muscle cells execute involuntary movement?
Cardiac and smooth.
What are the afferent and efferent mechanisms of neurons?
Afferent: receiving information from receptors or other neurons.
Efferent: transmitting information to muscles, glands, or other neurons.
What is the composition of lipids?
Heterogenous chemical structure with sterol rings, long hydrocarbon tails.
Glycerol head with fatty acid tails.
What are the functions of lipids?
Membrane structure, energy storage, and intracellular/intercellular signaling.
What are the types of lipids?
Triglycerides, ketones, phospholipids, eicosanoids, and steroid.
What does amphipathic mean?
Hydrophilic and hydrophobic in nature.
The cell membrane is a phospholipid bilayer. What does the hydrophobic nature of the membrane serve?
It makes it a barrier for water soluble substances: ions, glucose, amino acids, etc.
How is the degree of saturation determined?
By the number of double bonds. The more double bonds, the more saturated that substance is.
What does the degree of saturation affect?
The fluidity of the lipid.
Unsaturated = kinked and don’t pack well together.
Saturated = straight and can pack together well.
What is a function of adipose cells?
To store/metabolize fatty acids to help maintain blood glucose/energy levels near homeostasis.
Steroids are derived from…
Cholesterol.
Cholesterol makes up ____ of membrane lipids.
50%
Polysaccharides are derived from…
Photosynthesis.
Are polysaccharides polar or nonpolar?
Polar, so they dissolve in water.
What are the functions or polysaccharides?
Building blocks of other macromolecules, energy source, and modify structure/function of other macromolecules.
Monosaccharides are the building blocks of….
Polysaccharides AND nucleotides.
Monosaccharides join via _________ to form polymers.
Glycosidic bonds
What types of polysaccharides modify the functions of other macromolecules?
Glycolipids function in the adhesion of membranes.
Glycoproteins function in trafficking and folding of proteins.
Nucleic acids are a template for ________.
Proteins
What are functions of DNA?
Stores the genetic code in the nucleus, template for transcription and replication.
Proteins are composed of ___ amino acids.
20
What dictates amino acid interactions and ultimate protein folding?
R-group chemistry
Amino acids are linked via ______ bonds.
Peptide, which is a strong covalent
What is the function of chymotrypsin?
Cuts other proteins in digestion, attacks peptide bonds of digested material.
What is the function of enzymes?
Increase the likelihood os chemical reactions but do not allow new reactions.
Once an enzyme stabilize transition state intermediate…
It allows a faster reaction.
What does ATP synthetase do?
Positions ADP and PO4 sufficiently close to allow them to chemically bond to form ATP.
What do anabolic reactions require?
Energy input (stored as potential energy).
What do anabolic reactions produce?
Synthesis of large molecules from smaller ones.
What do catabolic reactions produce?
A release of energy. Its purpose is to break down large molecules into smaller products.
The law of mass action determines…
the direction of a reaction
What does an increased concentration of reactants cause in a reaction?
Push forward TOWARDS products.
What does an increased concentration of products cause in a reaction?
Push reaction in reverse.
What are two things that SOME enzymes require to form an appropriately folded active site?
Cofactors or coenzymes.
What are some factors that affect enzyme rates?
Temperature, pH, enzyme/substrate concentration, affinity for the substrate, and allosteric interactions.
What happens to the rate of an enzyme if the substrate concentration is increased?
It increases as well.
What happens to the rate of an enzyme if the affinity for that substate is increased?
It increases as well.
How do allosteric interactions affect enzyme rates?
A chemical modulator binds to the enzyme at a DIFFERENT location than the active site, which changes the enzyme conformation. This change particular occurs in the active site shape.
Either activates or inhibits the enzyme.
How do covalent modifications affect enzyme rates?
This typically happens after an allosteric interaction occurs. An enzyme (like kinase) may activate an enzyme once it has transitioned, while another enzyme (phosphotase) reverses the activation. The enzyme returns to its original shape.
What are some components of a cell membrane?
Amphipathic lipids and proteins (enzymes, receptors, transporters, and cytoskeletal anchors).
What is an example of a protein that helps cells to form tissues/organs?
Cadherins.
What body structures use tight junctions?
G.I. tract, kidneys, blood brain barrier.
What protein/s are used to form intercellular ridges?
Claudin and occludin.
If solutes aren’t able to pass through cells because of tight junctions, how are they able to pass?
They must cross epithelial cell plasma membrane.
What protein/s form channels/pores to allow quick communication for tissue to function as a unit?
Connexins.
What body structures use gap junctions?
Heart, smooth muscle, and neurons.
What is the nucleolus’s function?
Ribosome synthesis.
What two processes take place in the nucleus?
DNA replication and transcription.
What structure allows macromolecules (mRNA, proteins, etc.) to pass in/out of the nucleus?
Nuclear pores
What protein molecule packs DNA?
Histone proteins.
What is DNA called in the interphase stage?
Chromatin.
What is DNA called in mitosis?
Chromosomes.
What is meant by the term “differential expression”?
Some DNA directly codes for proteins, while much of the rest of the DNA helps regulate gene expression.
What occurs in transcription
1) RNA polymerase binds to the promoter.
2) DNA uncoils and separates.
3) free RNA nucleotide aligns with DNA and is added to the new RNA strand.
4) RNA polymerase moves down the DNA and RNA elongates until RNA polymerase is met with a stop codon.
After processing in transcription, where does the mRNA go?
Cytoplasm.
How does translation begin?
Ribosomes attach to the mRNA strand.
What is ribosomes’ function in translation?
To read the triplet nucleotide code, bring one amino acid in for ever 3 nucleotides (which are attached to one another via peptide bonds).
What is the three step process of translation?
Initiation, elongation, and termination.
The destination of polypeptides are translated in….
cytosol
What is the signal sequence of secretory pathway polypeptides?
Endoplasmic reticulum Transport vesicle Golgi complex Secretory vesicle Plasma membrane
What is the function of the rough Endoplasmic reticulum?
Ribosome synthesis of secretory pathway proteins (being sent to the plasma membrane).
What is the function of smooth Endoplasmic reticulum?
Lipid synthesis and calcium storage.
What are the functions of the Golgi Complex?
Processing/sorting for membrane-bound and secretory proteins.
Synthesis of complex polysaccharides.
Glycosylation of membrane-bound and secretory proteins (helps determine their cellular destination and function).
What is the sequence of endomembrane system trafficking?
Endoplasmic reticulum
Golgi complex
Secretory vesicle
Plasma membrane
What three components are the cytoskeleton made up of?
Microfilaments, intermediate filaments, and microtubules.
What monomers make up microfilaments?
Actin.
What monomers make up intermediate filaments?
Various proteins.
Ex: keratin in skin.
What monomers make up microtubules?
Tubulin.
What are microtubule functions?
Intracellular movement of organelles ad vesicles, mitotic spindle formation, and specialized cell motility.
What are two ATP dependent motor proteins?
Kinesin and dynein.
What are the functions of actin?
Maintenance of cell shape, whole cell movement, scaffold for muscle contraction.
What are the functions of intermediate filaments?
Mechanical strength of cell, stress buffer (elastic).
What does the axon diameter of a neuron dictate?
Velocity of electrical conduction.
What are the functions of lysosomes in a cell?
Sequesters enzymes (hydrolases, proteases, lipases, etc), nonselective digestion of macromolecules.
What are the characteristics of ATP?
Provides energy for most cellular processes.
Transfers energy from metabolic breakdown of macromolecules into useful energy.
Transient energy storage is 90 seconds.
What is the purpose of the outer membrane of the mitochondria?
Porins let molecules (pyruvate, ATP) in and out.
What is the purpose of the matrix of the mitochondria?
Place for pyruvate oxidation and Kreb’s cycle.
What is the purpose of the inner membrane of the mitochondria?
Electron transport, oxidative phosphorylation, and ATP synthesis.
What is the product of glucose metabolism?
CO2, H2O, and 38 ATP.
What are the steps of glucose metabolism?
1) Glycolysis
2) Linking step - pyruvate oxidation
3) Kreb’s cycle
4) Oxidative phosphorylation
5) ATP synthesis (from electron transport and proton pumping)
Glycolysis converts glucose into…
2 pyruvates, NADH, and ATP.
Once the pyruvate from glycolysis enters the mitochondria, it is…
Converted into Acetyl CoA.
How is a pyruvate converted into Acetyl CoA?
By pyruvate dehydrogenase.
What are the products of the linking step?
Acetyl CoA, NADH, and CO2.
Where does the Kreb’s cycle occur?
Mitochondrial matrix.
What are the products of the Kreb’s cycle?
ATP, NADH, FADH2, CO2.
Where does oxidative phosphorylation occur?
Mitochondrial inner membrane.
What are the products of oxidative phosphorylation?
H+ (goes into intermembrane space) and 34 ATP.
What are two types of passive transport?
Simple diffusion and facilitated diffusion.
What three factors govern the permeability of individual molecules across membranes?
Size (small), polarity (nonpolar), and charge (neg).
True or false: hydrophobic molecules easily cross membranes.
True
The direction of simple diffusion is dictated by…
Chemical gradient/driving force.
What is the chemical gradient/driving force?
Molecules move from high to low concentration.
The magnitide of chemical driving force is proportional to…
The size of the concentration gradient.
True/false: hydrophilic molecules easily cross membranes.
False
What three factors does facilitated diffusion require?
Specific, subject to inhibition, and displays saturation kinetics.
The Glucose Transporter moves glucose _________ times faster than simple diffusion.
50,000
How does GLUT1 work?
Glucose binds on the extracellular face, conformational change occurs, glucose is expelled into the cytoplasm. It then returns to its normal shape.
The direction of passive ion movement across a membrane is dictated by…
electrical driving force.
The net charge of a typical resting cell is _____.
-70mV
Ion channels facilitate the movement of ions down their…
electrochemical gradient.
The net charge of (K+, Na+, and Ca++) in a typical resting cell…
K+ = OUT Na+ = IN Ca++ = IN
Ion channels are selective for…
K+, Na+, Ca++
Ion channels are gated by…
Ligand, voltage, and mechanically.
True/false: ion channels do not saturate.
True
Ion pumps are apart of…
Active transport, because it utilizes ATP.
What is the function of Na+/K+ ATPase?
Helps establish electrochemical gradient present across all animal cells. It is electrogenic, which pumps out 3 Na+ and 2 K+ in.
What is the function of Calcium ATPase?
Pumps Ca++ (against the electrochemical gradient) into the endoplasmic reticulum or out of the cell.
Inside of the cell is _____ mOsm.
300
Water will not _____ solutes until isotonic.
dilute
What is the state of cells of a person with cystic fibrosis?
Dehydrated mucus infected with bacteria.
True or false: endocytosis allows the import of large extracellular molecules into the cell.
True
True or false: exocytosis allows the import of large extracellular molecules into the cel..
False - exocytosis is the release of intracellular molecules.
What is a molecule/s imported into the cell via phagocytosis?
Macrophage or bacteria.
What type of endocytosis helps control the cell surface area?
Bulk phase pinocytosis.
What type of endocytosis brings in concentrated cargo, like cholesterol, via coat proteins?
Receptor mediated endocytosis.
True/false: receptor mediated endocytosis uses ATP.
False - it uses GTP via dynamin.
Exocytosis is either ___________ or ______________.
Constitutive
Regulated
Membrane fusion is mediates via _________ proteins.
SNARE
What calcium sensor regulates the late steps of exocytosis in vesicle fusion?
Synaptotagmin.
True/false: Many steroid receptors are intercellular.
False - they are intracellular.
What receptor translocates to the nucleus to affect the transcription of specific genes?
Ligand bound receptor.
What is an example of a ligand gated ion channel?
Nicotinic Acetylcholine Receptor.
Which ion predominates the nicotinic acetylcholine receptor?
Na+
Sodium
Tyrosine kinase receptor activation leads to..
Ca ++ release from the ER storage.
Concentration of Ca ++ is 10,000 ________ in the cytosol than in the extracellular matrix.
lower
G-Protein coupled receptors are a major class of signal transuction receptors. An example of this would be…
Muscarinic Acetylcholine Receptor.
In Muscarinic AChR, the binding of ligand changes receptor conformation so that it can interact with…
G-protein
What is a major target for many g-protein linked receptors?
Adenylate Cyclase.
Protein kinases add ____ to a substrate.
PO4
True/false: phosphorylation is NOT reversible.
False.
