Exam 1 Flashcards
(13 cards)
List the three basic forms of work and give a physiological example of each.
Transport work (moving substances across membranes); chemical work (making proteins); and mechanical work (muscle contraction).
Where do cells acquire energy from, and why do they require it?
Cells acquire energy from the external environment for growth,
repair and maintenance of their internal environment.
State the two laws of thermodynamics in your own words.
First Law: There is a fixed amount of energy in the universe. Second
Law: Without input of energy, an open system will become progres-sively less organized
___________ are enzymes which catalyze the same reaction under
different conditions or in different tissues. Enzymes can be secreted as inactive molecules called ______________.
isozymes; proenzymes or zymogens
Enzymes which transfer electrons from donor to oxygen are known
as___________, and enzymes which remove electrons and protons are known as ____________.
oxidases; dehydrogenases
In a complex metabolic pathway, the different molecules in the
reaction pathway are known as ____________. __________- allows different reactions to be controlled separately.
intermediates; Compartmentalizing
Explain how H+ movement across the inner mitochondrial mem-brane results in ATP synthesis.
H+ transported into the inner compartment stores energy in a concen-tration gradient. When the ions move back across the membrane, the released energy is trapped in the high-energy bond of ATP.
When bonds are broken during a chemical reaction, what are the
three possible fates for the potential energy found in those bonds?
Perform work, transfer to another molecule, or be released as heat.
Compare the following: (a) the energy yield from the aerobic break-down of one glucose to CO2 and H2O, and (b) the energy yield from one glucose going through anaerobic glycolysis ending with lactate. What are the advantages of each pathway?
Aerobic breakdown=30932 ATP; anaerobic breakdown=2 ATP.
Anaerobic is faster and does not require oxygen, but energy yield is
lower.
Briefly describe the processes of transcription and translation.
Which organelles are involved in each process?
Transcription: synthesis of RNA from the sense strand of DNA.
Takes place in the nucleus. Translation: conversion of informa-tion coded in mRNA into a string of amino acids. Takes place on ribosomes.
When pairs of high energy electrons pass along the electron transport system, how is the released energy used in the mitochondria?
The energy is used to concentrate H+ ions from the matrix into the
intermembrane space of the mitochondria.
Explain the chemiosmotic theory to account for the synthesis of
numerous ATP molecules.
Potential energy stored by concentrating H+ ions in the intermem-brane space is used to make ATP molecules. As H+ ions diffuse into the mitochondrial matrix through the ATP synthase, their kinetic energy is used to phosphorylate ADP molecules to form ATP.
