Lipids 2

Question 1

<p>Can fatty acids be converted to glucose?</p>

Answer 1

<p>No because pyruvate to acetyl conenzyme A is irreversible</p>

Question 2

<p>What does the beta-oxidation pathway do?</p>

Answer 2

<p>Degrades fatty acids two carbons at a time, producing acetyl coenzyme A, NADH and FADH₂</p>

Question 3

<p>Where does beta-oxidation occur?</p>

Answer 3

<p>Mitochondiral matrix</p>

Question 4

<p>Why can red blood cells not perform beta-oxidation?</p>

Answer 4

<p>They have no mitochondria</p>

Question 5

<p>What are the 3 stages of beta-oxidation?</p>

Answer 5

<ol> <li>Activation of fatty acid in cytosol</li> <li>Transport into the mitochondria</li> <li>Degradation to two carbon as acetyl coenzyme A</li></ol>

Question 6

<p>What do fatty acids form when they are activated?</p>

Answer 6

<p>Fatty acyl coenzyme A</p>

Question 7

What does the reaction of the activation of a fatty acid looking like?

Answer 7

Question 8

<p>Where does the activation of fatty acids occur?</p>

Answer 8

<p>The cytosol</p>

Question 9

<p>Can fatty acyl coenzyme A pass the membrane without help?</p>

Answer 9

<p>No, it needs to use the carmitine shuttle</p>

Question 10

<p>What is the process of the carnitine shutle?</p>

Answer 10

<ol> <li>Carnitine reacts with acyl coenzyme A to produce acyl carnitine which crosses the mitochondrial membrane</li> <li>Inside the mitochondria acyl carnitine reactions with coenymze A to produce acyl conenzyme A</li> <li>Carnitine crosses the membrane and returns to the cytosol to be used again</li></ol>

Question 11

<p>What enzymes are used in the carnitine shuttle?</p>

Answer 11

<p>Carnitine palmityl transferase I and II</p>

Question 12

<p>What can inhibit carnitine polmityl transerase?</p>

Answer 12

<p>Malonyl coenzyme A when their is enough broken down fatty acids</p>

Question 13

<p>What does malonyl coenzyme A ensure?</p>

Answer 13

<p>That synthesis and degradation do not happen at the same time</p>

Question 14

<p>Where does carnitine come from?</p>

Answer 14

<p>The diet</p>

<p>Made from lysine or methionine</p>

Question 15

<p>What does carnitine palmitoyl transferase dificiency lead to?</p>

Answer 15

<p>No beta-oxidation (hypoglycemia)</p>

<p>Coma</p>

<p></p>

Question 16

<p>What is the treatment of carnitine palmitoyl transferase difficiency?</p>

Answer 16

<p>Eating medium and short chain fatty acids that do not require the carnintine shuttle</p>

Question 17

<p>What are the stages of the degradation of beta-oxidation occurs in four stages?</p>

Answer 17

<ol> <li>Dehydrogenation to produce FADH₂</li> <li>Hydration</li> <li>Dehydrogenation to produce NADH</li> <li>Thiolysis (cleaved) to produce acetyl coenzyme A</li></ol>

Question 18

<p>What does each beta-oxidation cycle produce?</p>

Answer 18

<p>1 acetyl coenzyme A</p>

<p>Spieces of carbon 2 carbons shorter than the original</p>

Question 19

<p>What would 7 beta-oxidation pathways produce?</p>

Answer 19

<p>8 acetyl coenzyme A</p>

<p>7 NADH</p>

<p>7 FADH₂</p>

Question 20

<p>What is the total net energy yield of beta-oxidation?</p>

Answer 20

<p>129 ATP molecules</p>

Question 21

<p>What do very long chain fatty acids (>22 carbons) need to undergo before beta-oxidation?</p>

Answer 21

<p>Preliminary beta-oxidation in peroxisomes</p>

Question 22

<p>How are very long chain fatty acids (>22 carbons) degraded?</p>

Answer 22

<ol> <li>Preliminary beta-oxidation in peroxisomes, does not produce FADH₂so not as efficient as shorter chains</li> <li>Shortened fatty acid links to carntine and diffuses into the mitochondria for beta-oxidation</li></ol>

Question 23

<p>Why are very long chain fatty acids not as efficient as shorter ones?</p>

Answer 23

<p>Preliminary beta-oxidation in peroxisomes does not produce FADH₂</p>

Question 24

<p>What happens during starving/fasting?</p>

Answer 24

<ol> <li>Liver flooded with acetyl coenzyme A</li> <li>Acetyl coenzyme A inhibits pyruvate dehydrogenase (pyruvate to acetyl coenzyme A) and activates pyruvate carboxylase (pyruvate to oxaloacetate)</li> <li>Oxaloacetate is used to produce glucose for gluconeogenesis</li></ol>

Question 25

<p>What happens to excess acetyl coenzyme A during fasting?</p>

Answer 25

<p>Converted into ketone bodies</p>

Question 26

<p>What tissues can use ketones for fuel?</p>

Answer 26

<p>Cardiac and skeletal muscle</p>

Question 27

<p>When can brain cells use ketones for fuel?</p>

Answer 27

<p>During starvation</p>

Question 28

<p>Where are ketone bodies made?</p>

Answer 28

<p>In the liver (mitochondrial matrix) and then transported in the blood to other tissues</p>

Question 29

<p>What cannot use ketones for energy?</p>

Answer 29

<p>The liver</p>

Question 30

<p>What cannot use fatty acids for energy?</p>

Answer 30

<p>The brain</p>

Question 31

<p>Why do ketones not need albumin or lipoprotein to transport in the blood?</p>

Answer 31

<p>They are soluble</p>

Question 32

<p>What leads to high ketone concentration?</p>

Answer 32

<p>Uncontrolled diabetes or starvation</p>

Question 33

<p>What happens when the rate of ketone production becomes greater than the rate they are used?</p>

Answer 33

<p>Body becomes acid (ketosis) which causes a fruity oddur in breath due to acetone</p>

Question 34

<p>What ensure that fatty acid synthesis and degradation do not happen at the same time?</p>

Answer 34

<p>Inhibition and the two happening in different places</p>