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

What happens to excess acetyl coenzyme A during fasting?

Answer 25

Converted into ketone bodies

Question 26

What tissues can use ketones for fuel?

Answer 26

Cardiac and skeletal muscle

Question 27

When can brain cells use ketones for fuel?

Answer 27

During starvation

Question 28

Where are ketone bodies made?

Answer 28

In the liver (mitochondrial matrix) and then transported in the blood to other tissues

Question 29

What cannot use ketones for energy?

Answer 29

The liver

Question 30

What cannot use fatty acids for energy?

Answer 30

The brain

Question 31

Why do ketones not need albumin or lipoprotein to transport in the blood?

Answer 31

They are soluble

Question 32

What leads to high ketone concentration?

Answer 32

Uncontrolled diabetes or starvation

Question 33

What happens when the rate of ketone production becomes greater than the rate they are used?

Answer 33

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

Question 34

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

Answer 34

Inhibition and the two happening in different places