Final W4

Question 1

There is a strong correlation between high levels of cholesterol in ___ and ___ disease. Cholesterol is a crucial component of ___ ___ and an important precursor to ___ hormones and __ ___. All ___ can synthesize cholesterol

Answer 1

blood, cardiovascular, cellular membranes, steroids, bile acids, cells

Question 2

Stage one of cholesterol formation involves 2 molecules of ____ condensing to form _____. This product then condenses with a third molecule of acetyl-CoA to yield _____. This product is reduced to ____.

Answer 2

acetyl-CoA, acetoacetyl-CoA, HMG-CoA, mevalonate

Question 3

In stage two of cholesterol formation, ___ ______ groups are transferred to mevalonate. The intermediate ________ _____ releases ____ and phosphate, producing an activated ____

Answer 3

3 phosphate, 3-phospho 5-pyrophosphomevalonate CO2, isoprene

Question 4

In stage 3 of cholesterol formation, 2 activated isoprenes condense, forming __ ___ with __ carbons. This product ___ with another activated isoprene forming ___ ___ with ___ carbons. Two molecules of this product condense, forming ___ with ___ carbons

Answer 4

geranyl pyrophosphate, 10, condenses, farnesyl pyrophosphate, 15, squalene, 30

Question 5

In the last stage of cholesterol formation __ ___ catalyzes the addition of one ___ atom from O2 to the end of squalene, forming an ____. ____ results in the formation of ___ which contains the __ rings characteristic of the steroid nucleus. Several additional reactions add and reposition ___ groups to form cholesterol.

Answer 5

squalene monooxygenase, oxygen, epoxide, cyclization, lanosterol, 4, methyl

Question 6

Cholesterol can be formed into __ ___ which emulsify dietary fats, __ ___ which are hydrophobic molecules for lipoprotein transport, or ____ ___ such as testosterone and estradiol

Answer 6

bile salts, cholesterol esters, steroid hormones

Question 7

hormone that promotes the activation of HMG-CoA reductase

Answer 7

insulin

Question 8

Hormones that promote the inactivation of HMG-CoA reductase

Answer 8

glucagon, AMPK

Question 9

___ ___ __ is the leading cause of death in developed countries. ___ are the most widely used drugs for lowering ___ cholesterol levels. They are ___ ___ of HMG-CoA reductase, resembling the substrate ____. The most widely used statin is _____.

Answer 9

coronary heart disease, statins, serum, competitive inhibitors, mevalonate, atorvastatin

Question 10

Ketone bodies are produced in the ___ as an alternative fate for acetyl-CoA. ___ is produced in smaller quantities and exhaled. ___ and ______ are transported by blood to extrahepatic tissues. The ____ relies heavily on ketone bodies for fuel because fatty acids cannot cross the BBB

Answer 10

liver, acetone, acetoacetate, D-beta-hydroxybutyrate, brain

Question 11

The synthesis of ketone bodies occurs in the __ __ of _____. First two molecules of acetyl-CoA condense to form _____. This condenses with another molecule of acetyl-CoA forming ___. This produced is cleaved to free ____ and ____. The latter is ___ reduced to ____ or ____ to acetone

Answer 11

mitochondrial matrix, acetoacetyl-CoA, HMG-CoA, acetyl-CoA, acetoacetate, reversibly, D-beta-hydroxybutyrate, decarboxylated

Question 12

The breakdown of ketone bodies occurs in the mitochondria in __ ___. First, D-beta-hydroxybutyrate is oxidized to ____. This is then metabolized to ____. This produced is cleaved to 2 molecules of ___ which enters the citric acid cycle

Answer 12

extrahepatic, acetoacetate, acetoacetyl-CoA, acetyl-CoA

Question 13

___ consumes oxaloacetate and slows citric acid cycle. The slowing of the citric acid cycle promotes __ ___ production. The release of ___ during the formation of acetoacetate enables the continued oxidation of __ ___.

Answer 13

gluconeogenesis, ketone body, CoA, fatty acids

Question 14

During starvation, gluconeogenesis is __ to provide ___ to tissues such as the brain. This depletes citric acid cycle ___, resulting in ____ producing ketone bodies.

Answer 14

active, glucose, intermediates, acetyl-CoA

Question 15

In people with diabetes, insufficient ___ prevents glucose uptake from the blood. Low glucose in cells stimulates ___ and ____, which depletes the citric acid cycle intermediates and produces ___ ___. Thus these individuals have a much higher concentration of ___ in the blood and urine.

Answer 15

insulin, beta-oxidation, gluconeogenesis, ketone bodies, acetoacetate

Question 16

a condition in which the concentration of ketone bodies in the blood, tissues, and urine is abnormally high

Answer 16

ketosis

Question 17

dietary proteins are degraded to free __ ___ within the gastrointestinal tract. In the stomach, proteins stimulate the secretion of ____, which stimulates the secretion of ____ and _____. The latter is activated by autocatalysis at low _____. Active ___ cleaves polypeptides into peptides

Answer 17

amino acids, gastrin, HCl, pepsinogen, pH, pepsin

Question 18

Acidic stomach contents enter the small intestine and trigger the secretion of __, which stimulates the secretion of ___ to neutralize HCl. ____ is also secreted to stimulate release of several pancreatic ____ such as ____, ____ __ and ___. Active proteases cleave peptides into a mixture of free amino acids.

Answer 18

secretin, bicarbonate, cholescytokinin, proteases, trypsinogen, chymotrypsinogen, procarboxypeptidases A, B,

Question 19

an inactive precursor of an enzyme

Answer 19

zymogen

Question 20

In the small intestine, the free amino acids such as ___ and ____ are then transported into ___ cells, and transported to the __ via the __

Answer 20

di, tri-peptides, epithelial, liver, blood

Question 21

the dynamic regulation of a balanced functional proteome

Answer 21

proteostasis

Question 22

the degradation and resynthesis of proteins

Answer 22

protein turnover

Question 23

Ubiquitin is a ___ residue protein present in all ____ cells. This tags proteins for ____. The c-terminal ___ forms a ___ bond with ___ residues on target proteins

Answer 23

76, eukaryotic, destruction, glycine, covalent, lysine

Question 24

First the free ____ group of the c-terminal glycine residue in ubiquitin is bound to an ___ ___ enzyme through a ___ linkage. Then ubiquitin is transferred to an ______ _____ enzyme. An ______ ____ catalyzes transfer of ubiquitin from from E2 to the target protein

Answer 24

carboxyl, E1 activating, thioester, E2 conjugating, E3 ligase

Question 25

____ is 4 ubiquitin monomers linked by ___ bonds. Each bond is formed by the linkage of the ___ at the c-terminal to the _____ of a ___ residue. This is the primary signal for protein ____.

Answer 25

tetraubiquitin, isopeptide, carboxyl, lysine, degradation

Question 26

To a large extent, the half life of a cytoplasmic protein is determined by its ___ terminal residue. A yeast protein with a Met at its n-terminus has a half life of _____h. A yeast protein with an Arg at it’s n-terminus has a half life of ______. The N-terminal residue can be modified by ____ modifications

Answer 26

amino, <20, 3 minutes, posttranslational

Question 27

Ubiquitinated proteins are degraded by a large complex known as the ___ _____. It is made up of two ___ subunits and two ____ subunits. The general structure contains a ____ core with two regulatory particles at each end of the barrel.

Answer 27

26S proteasome, 19S, 20S, barrel-like

Question 28

The 19S regulatory particle has ___ subunits and forms a ___ at the end of the core particle. It recognizes ubiquitinated proteins and ___ and ___ them, then translocates the protein into the ___.

Answer 28

18, cap, deubiquinates, unfolds, core

Question 29

The 30S core particle consists of ___ rings arranged to form a barrel-like structure. The outer rings are formed with _____ ____ subunits, and the inner rings are formed from __ ___ subunits. ___ ___ subunits have protease activity

Answer 29

4, 7 alpha, 7 beta, 3 beta

Question 30

HPV expresses the ___ protein, which ___ and also binds ____, which is a tumor suppressor, and ____ a E3 ligase. The enhanced ubiquitination of p53 drives __ ___

Answer 30

E6, dimerizes, p53, E6AP, cancer progression

Question 31

Ubiquitinated proteins are processed to peptides within the ___ and ubiquitin is recycled. The peptide fragments are further digested to free __ _____ which can be used for ___. Amino groups can be excreted via the ___ ___, while carbon skeletons can be used for ___, ketone bodies, or __ __ synthesis

Answer 31

proteasome, amino acids, biosynthesis, urea cycle, gluconeogenesis, fatty acid