Chapter 1 Exam # 1 Flashcards
The plasma membrane is a sheet-like structure composed solely of lipids. (T/F and Why?)
F, also composed of proteins and carbohydrates
The lipid bilayer determines the function of the plasma membrane while the proteins are primarily responsible for the structure of the membrane (T/F and Why?)
F, The lipid bilayer determines the STRUCTURE of the plasma membrane while the proteins are primarily responsible for the FUNCTION of the membrane
The various components within a cell (e.g., mitochondria) are not “free-floating” in the cytosol, but rather are held in place by the cytoskeleton.
T
Peripheral proteins are involved in cell-cell recognition, whereas integral proteins function primarily as receptors/ transporters.
T
The reason different cells express different proteins is because they contain different sequences of DNA in the nucleus.
F, All cells contain the same DNA; however, not all genes are expressed in all cells.
Polysomes function to transcribe mRNA into proteins.
F, Translate, not transcribe.
When discussing enzyme kinetics, Km refers to the substrate concentration at which the enzyme is saturated and functioning at maximal velocity.
F, Km is substrate concentration at half of maximal velocity.
If two enzymes (e.g., pyruvate dehydrogenase and pyruvate carboxylase) compete for the same substrate (pyruvate), the one with the higher Km has less affinity and will be more active when pyruvate concentrations are high.
T
Most cellular reactions are irreversible since the same enzyme that catalyzes the conversion cannot catalyze the reverse reaction.
F, Most cellular reactions are reversible and catalyzed by the same enzyme. The rate-limiting enzymes tend to be irreversible to contribute to regulation of the pathway
Allosteric regulation of enzymes is carried out by modulators, other proteins that bind to the enzyme to inhibit its activity.
Modulators are substrates, intermediates, and products in the relevant pathway, not proteins
