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stasis and cell biology
stasis and cell biology
What is the body fluid compartment that makes up approximately two-thirds of total body water?
Intracellular Fluid (ICF).
ICF ~67% of totaly body water, ECF ~ 33% (split between interstitial fluid and plasma)
What type of reaction requires energy input because the products have more free energy than reactants
Endergonic reaction
Exergonic reactions release free energy
What is the final electron acceptor at the end of the electron transport chain?
Oxygen (O2)
How many Na+ ions and K+ ions are pumped, and in which directions, by the Na+/K+ ATPase pump per ATP hydolyzed
3 Na+ out of the cell, 2 K+ into the cell
This helps maintain the negative potential inside the cell (-70mV)
What type of chemical bond involves equal sharing of electrons, making the molecule nonpolar and hydrophobic?
Non-polar covalent bond
What type of feedback loop amplifies deviations from a set point until a specific end goal is achieved
Positive Feedback
Contrast with negative feedback, which counteracts changes to maintain dynamic constancy.
How do catalysts (enzymes) speed up the rate of chemical reactions without being consumed?
By lowering the activation energy required to start the reaction.
(Enzymes do not change the initial reactants or final products, nor the equilibrium constant)
What pathway converts one glucose molecule into two pyruvate molecules without using oxygen
Glycolysis.
Yields a net of 2 ATP, 2 NADH, and 2 Pyruvate per glucose.
What is the term for the passive movement of water across a semipermeable membrane toward higher solute concentration?
Osmosis
What secondary active transport process couples the movement of Na+ down its concentration gradient with another molecule moving in the same direction?
Cotransport
During protein synthesis, what process involves converting an mRNA sequence into a polypeptide chain at the ribosome?
Translation
Transcription happens in the nucleus (DNA -> pre-mRNA), whereas translation happens at the ribosome in the cytoplasm (mRNA -> Protein).
What coenzymes serve as hydrogen and electron carriers during cellular respiration
NAD+ and FAD
NAD⁺ and FAD act as coenzymes that pick up hydrogen and high-energy electrons during cellular respiration, becoming NADH and FADH₂. These then carry the electrons to the ETC, where their energy helps drive ATP production.
What metabolic pathway in the liver converts muscle-derived lactate back into glucose?
The Cori Cycle
Lactate produced in skeletal muscle during anaerobic respiration is transported to the liver, converted to glucose via gluconeogenesis, and sent back.
What transport mechanism uses ATP to move ions against their concentration gradient?
Primary active transport
What regulatory mechanism occurs when the final product of a metabolic pathway inhibits an early rate-limiting enzyme?
End-Product Inhibition
Prevents wasteful overproduction of cellular metabolites.
A person begins exercising in a hot environment. Their core temperature rises above the normal set point, triggering sweating and increased blood flow to the skin. Which sequence BEST represents this feedback loop, and what fits into each part?
Stimulus → Receptor → Integrating center → Effector → Response
What is the specific region of an enzyme where the substrate binds?
Active site
In which specific cellular compartment does glycolysis take place?
Cytoplasm (cytosol)
If a cell with an intracellular osmolarity of 300 mOsm is placed in a 400 mOsm solution, what will happen to the cell volume?
The cell will shrink
Because water will leave the cell toward the hypertonic solution.
A hormone cannot cross the plasma membrane, so it binds to a receptor on the cell surface. The receptor activates a G protein, which then activates an enzyme that produces cAMP. Why is cAMP useful if the G protein has already been activated?
cAMP acts as a Second Messenger
This amplifies and relays the signal inside the cell, activating downstream proteins
A cell needs to bring a large particle from outside the cell into its cytoplasm. Because the particle is too large to pass through a membrane protein, the plasma membrane surrounds and engulfs it, forming a vesicle. What process is occurring, and does it require energy?
Endocytosis, specifically phagocytosis if the particle is large. It requires ATP/energy because the cell is actively changing its membrane to bring the material inside.
A reaction initially speeds up as substrate concentration increases but eventually reaches a point where adding more substrate no longer substantially increases reaction rate. What explains this observation?
The enzymes have become saturated
A student says, "One glucose molecule goes through the Krebs cycle twice because glucose makes two cycles." Is this statement completely correct? Explain.
The Krebs cycle turns twice per glucose, but glucose itself does not directly enter the cycle.
One glucose → 2 pyruvate → 2 acetyl-CoA → 2 turns of the Krebs cycle.
A molecule is small but highly polar and needs to cross the plasma membrane. It cannot pass directly through the phospholipid bilayer. What type of transport would allow it to cross without directly using ATP, and what determines the direction of movement?
Facilitated diffusion
The molecule moves down its electrochemical/concentration gradient through a membrane protein.
Which protein structure level is involved with the formation of the helix or sheet shape in a protein chain, due to hydrogen bonds forming between peptide bond regions
Secondary Structure