Fatty acids can easily be used to generate energy for the cell. Which of the following fatty acids will yield more energy? Explain your answer
(a) CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH=CH-COOH
(b) CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH
(c) CH3-CH=CH-CH2-CH2-CH2-CH2-CH=CH-COOH
(d) CH3-CH2-CH2-CH2-CH2-CH2-CH2-COOH
(b) This fatty acid has 10 carbons [as opposed to 8 in (d)] and has a completely saturated hydrocarbon tail [options (a) and (c) are monounsaturated and diunsaturated, respectively). The total number of carbons determines how many acetyl CoA molecules can be derived from it; in this case it is 5.The fact that all hydrocarbon bonds are saturated means that an FADH2 molecule will be generated in the first step of the fatty acid cycle, converting a carbon–carbon single bond into a carbon–carbon double bond. If that bond is already reduced, the cycle begins at the second step. As a result, FADH2 is not generated in that cycle, lowering the total number of cofactors that can be used by the electron-transport chain to generate a proton gradient.
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True or false: Monosaccharides can be found in linear form, but in living organisms are much more commonly found in cyclic form
A. true B. false
Which of the following statements is true?
a. Although hormones are carried to all parts of the body, they produce effects only in cells with proper receptors. b. Hormones are limited to steroid compounds. c. Hormones are secreted by specialized exocrine glands. d. Most hormones are controlled by positive feedback mechanisms involving the pituitary gland. e. Target cell response to the secretion of a hormone is as rapid as an effector response in the nervous system.
Normal cells stop their division when it gets too crowded, which is celled ______ inhibition.
a. density-independent b. density-dependent c. contact inhibition d. none of the above
When a plasma membrane allows some substances through but not others, it is ________ .
a. nonpolar b. polar c. able to use active transport d. selectively permeable e. diffusible