Cellular Metabolism III

Question 1

Cellular respiration vs cellular metabolism

Answer 1

Cellular respiration is only catabolic (releasing energy). Cellular metabolism is anabolic (requires energy) and catabolic

Question 2

Sources of energy when no glucose

Answer 2

1. Other carbohydrates
2. Fats
3. Proteins
   Their catabolic pathway connects to glycolysis and Kreb’s cycle, making ATP

Question 3

Monosaccharide

Answer 3

Single sugar, glucose, fructose. Single carbon ring

Question 4

Disaccharide

Answer 4

2 monosaccharides joined together, sucrose, lactose

Question 5

Polysaccharide

Answer 5

More than 2 monosaccharides joined together, glycogen

Question 6

Glycogen

Answer 6

Stores glucose as monomeric unit and has branches. In large amounts in muscle cells and liver

Question 7

Glycogenesis

Answer 7

Make glycogen from glucose-6-phosphate. 1 ATP is needed per 1 glucose to place glucose into glycogen

Question 8

Glycogenolysis

Answer 8

Break down glycogen to glucose-6-phosphate

Question 9

Gluconeogensis

Answer 9

Making glucose-6-phosphate from non-carbohydrate sources, occurs in liver and kidneys. It is how proteins and lipids contribute

Question 10

Glycolysis

Answer 10

Breaking down glucose-6-phosphate to make pyruvate

Question 11

Other carbohydrates

Answer 11

Can be converted to glucose-6-phosphate to be incorporated into the various metabolic pathways

Question 12

Enzymes removing phosphate group from glucose-6-phosphate

Answer 12

Glucose will be released into blood stream

Question 13

Insulin

Answer 13

Released from beta cells in pancreas after large meal. Endocrine molecule that travels in blood when glucose is high. Causes cells to make glycogen to store glucose and make ATP through glycolysis

Question 14

Glucagon

Answer 14

Released by pancreas when glucose is low. Similar to epinephrine. Causes cells to do glycogenolysis and inhibit glycogenesis

Question 15

Carbohydrate digestion

Answer 15

Begins in mouth by salivary amylase, which breaks polysaccharides to smaller polysaccharide chains or disaccharides. The mouth products travel to stomach, then to duodenum, where pancreatic amylase breaks it down to disaccharides. The small intestine releases disaccharidases that break disaccharides to monosaccharides. Monosaccharides are taken up by enterocytes of small intestine

Question 16

Lipids

Answer 16

Long, hydrocarbon chains. C-H bonds are reduced. More energy than carbohydrates.

Question 17

Triglycerides

Answer 17

A lipid, the main fat ingested that enters glucose catabolism. Made of glycerol backbone that is esterified to 3 hydrocarbon chains.

Question 18

Cholesterol

Answer 18

A lipid, enters glucose catabolism

Question 19

Lipolysis

Answer 19

Lipase enzymes break down triglycerides to glycerol and fatty acids

Question 20

Glycerol after lipolysis

Answer 20

Phosphorylated to become glyceraldehyde-3-phosphate (G3P) (DAP) (PGAL), which is one of the intermediates of glycolysis. It can now enter glycolytic pathway to make ATP or make glucose through gluconeogenesis.

Question 21

Beta-oxidation

Answer 21

Uses fatty acids from lipolysis. Occurs in mitochondrial matrix. Fatty acid is first activated with ATP. Breaks off 2 carbons at a time at the beta-position (the second carbon from the carboxylic acid end) of the fatty acid chain. The 2 carbons broken off make acetyl-CoA, which can join oxaloacetate to make citrate in Kreb’s cycle. Beta-oxidation also makes 1 NADH and 1 FADH2, which grab the electrons and hydrogen during this oxidation process.

Question 22

Total ATP from beta-oxidation with Kreb’s cycle and ETC

Answer 22

~120 ATP per fatty acid chain

Question 23

Lipid digestion

Answer 23

Not broken in mouth or stomach. At duodenum, bile is released from gallbladder, which emulsifies the fats. Pancreas releases pancreatic lipase that break down the lipids into fatty acid chains and monoglycerides, which are absorbed by enterocytes of small intestine.

Question 24

Lipoproteins

Answer 24

Lipids surrounded by soluble proteins called apoproteins Lipoprotein types are classified by density, which is determined by their fat/protein ratio. ‘Large and less dense’ lipoprotein is when the ratio is large

Question 25

Chylomicron

Answer 25

Initial transporter that leads the enterocytes to the small intestine. Enters lacteals, which are small lymphatic vessels that take fats into the lymphatic system, and then to the rest of the body.

Question 26

LDLs

Answer 26

Low density lipoproteins. Low density of proteins, unhealthy, lots of fats and cholesterol that can clog up the vessles

Question 27

HDLs

Answer 27

High density lipoproteins, high density of proteins, healthy, transports fat away from the tissues and delivers fat to the liver. In the liver, cholesterol for example can be used to make bile.

Question 28

Proteins

Answer 28

Made of amino acids. If excess amino acids exist, the cell uses them for energy. Can be converted to metabolic intermediate such as acetyl-CoA, pyruvate or oxaloacetate

Question 29

Amino acid structure

Answer 29

Central carbon with carboxylic acid, amino group, H, R group

Question 30

Oxidative deamination

Answer 30

Remove nitrogen group (amino group) from the amino acid in order to make metabolic intermediates from proteins. Most amino acids are deaminated in the liver. Product after deamination is ammonia (NH3)

Question 31

Ammonia

Answer 31

High concentrations are toxic. Converted to urea, which is excreted as urine

Question 32

Lipid digestion

Answer 32

Starts in stomach where pepsin is released to breakdown proteins into smaller polypeptides. In small intestine, peptidase enzymes specific to certain amino acid chain (such as trypsin, chymotrypsin, carboxypeptidase) breaks down polypeptide to smaller pieces, until they become amino acids. Amino acids are absorbed by small intestine