Intro to metabolism

Question 1

the principal donor of free energy in biological systems

Answer 1

ATP

Question 2

used primarily to generate ATP

Answer 2

NADH

Question 3

used primarily in reductive biosynthesis

Answer 3

NADPH

Question 4

what causes PKU

Answer 4

there’s a defect in phenylalanine hydroxylase so phenylalanine can’t be degraded and tyrosine cant be made
-tetrahydrobiopterin is a cofactor

Question 5

what is downregulated in PKU

Answer 5

-tissue proteins
-melanin
-catecholamine
-fumarate acetoacetate

Question 6

what is upregulated in when phenylalanine is not degraded?

Answer 6

phenylpyruvate, phenyllactate, phenylacetate
-toxic compounds in neurological tissue that cause intellectual disabilities

Question 7

how is tetrahydrobiopterin synthesized

Answer 7

in the body from GTP

Question 8

what is the treatment for PKU?

Answer 8

-restrict phenylalanine in diet (not completely)
-supplement with tyrosine

Question 9

if you discontinue your tyrosine rich diet, what you happen to you?

Answer 9

your IQ can decline

Question 10

atypical non-classical malignant phenylketonuria

Answer 10

-defect in either the synthesis of tetrahydrobiopterin or dihydropterin reductase, which regenerates the cofactor
-severe CNS disorders that don’t respond to diet change

Question 11

how can neurological symptoms that arise from atypical PKU be resolved?

Answer 11

L-dopa and 5-hydroxytryptophan

Question 12

THB is a cofactor that is required for synthesis for________________________________

Answer 12

dopamine, epinephrine, norepinephrine, and serotonin

Question 13

the absorptive state

Answer 13

-store energy as fat
-perform anabolic reactions (repair what might’ve broken down during fast)
-fed state after meal

Question 14

the fasting state

Answer 14

-maintain blood glucose
-limit proteolysis

Question 15

glycolysis

Answer 15

metabolize glucose to pyruvate + energy

Question 16

gluconeogenesis

Answer 16

synthesize glucose from precursors

Question 17

fatty acid oxidation

Answer 17

Metabolize fatty acids to acetyl CoA + energy

Question 18

citric acid cycle

Answer 18

metabolize acetyl CoA to carbon dioxide + energy

Question 19

glycogenesis

Answer 19

convert glucose to glycogen for storage

Question 20

glycogenolysis

Answer 20

convert glycogen to glucose when needed

Question 21

pentose phosphate pathway

Answer 21

convert glucose to ribose-5-phosphate for nucleotide synthesis + energy + NADPH

Question 22

ketone body synthesis

Answer 22

produce an alternative energy source during starvation

Question 23

oxidative phosphorylation

Answer 23

convert energy to ATP

Question 24

urea cycle

Answer 24

convert excess ammonia to urea for excretion

Question 25

what is stage 1 of catabolism

Answer 25

Complex macromolecules of starch, protein, and triacylglycerols are broken down into smaller units, such as monosaccharides, amino acids, glycerol, and fatty acids. During this stage, little or no free energy is trapped.

Question 26

what is stage 2 of catabolism

Answer 26

The simple molecules of different kinds are catabolized to a few molecules that can be oxidized to carbon dioxide and water along a common pathway. In this stage, some free energy is trapped as ATP.

Question 27

what is stage 3 of catabolism

Answer 27

It consists of the citric acid cycle, the electron transport system and oxidative phosphorylation. Together, these processes oxidize acetyl CoA to CO2 and water, and produce most of the ATP in the cell.

Question 28

where are pathways compartmentalized

Answer 28

-cytosol (glycolysis, pentose phosphate pathway, fatty acid synthesis) -mitochondrial matrix (citric acid cycle, oxidative phosphorylation, oxidation of fatty acids, ketone body formation) -cytosol plus mitochondrial matrix (gluconeogenesis, urea cycle)

Question 29

signals the fed state, the availability of glucose in the blood

Answer 29

insulin

Question 30

signal the fasting state in which the level of glucose in the blood is low

Answer 30

glucagon and epinephrines

Question 31

signals stressful states when mobilization of fuel is required

Answer 31

epinephrine

Question 32

what are some non-hormonal regulation of metabolic pathways

Answer 32

-availability of substrates -allosteric control -gene expression

Question 33

interplay of hormonal and non-hormonal regulation of metabolic pathways

Answer 33

-covalent modification: hormone-triggered reaction cascades result in the covalent modification of a key enzyme of a pathway -ex. glucose---->glycogen glycogen---->glucose

Question 34

glucose ----> glycogen (fed state)

Answer 34

glycogenesis

Question 35

glucose -----> pyruvate (fed state)

Answer 35

glycolysis

Question 36

glycogen ----> glucose (fasting state)

Answer 36

glycogenolysis

Question 37

pyruvate ----> glucose (fasting state)

Answer 37

gluconeogenesis

Question 38

flow of key metabolic intermediates

Answer 38

glucose 6-phosphate pyruvate acetyl CoA

Question 39

what are the different pathways that glucose 6-phosphate is involved in?

Answer 39

-glucose in gluconeogenic tissues -glucose 1-phosphate used in glycogen synthesis -pyruvate via glycolysis -ribose 5-phosphate for nucleotide synthesis, via pentose phosphate pathway

Question 40

what pathways is pyruvate involved in?

Answer 40

-oxaloacetate and metabolized via the citric acid cycle -acetyl coA by pyruvate dehydrogenase -alanine via transamination -lactate in muscle tissue

Question 41

what pathways is acetyl coA involved in?

Answer 41

-oxidized to CO2 via the citric acid cycle -fatty acid synthesis -3-hydroxy-3-methylglutary CoA, a precursor of cholesterol, ketone bodies

Question 42

liver in metabolism

Answer 42

-maintenance of blood glucose levels -during fed state, it takes up excess glucose and stores it as glycogen or converts it to fatty acids -during the fasting state, it exports glucose derived from glycogen and gluconeogenesis -fatty acid synthesis -ketone body synthesis during fasting state -synthesis of plasma lipoproteins

Question 43

skeletal muscle in metabolism

Answer 43

-maintains large stores of glycogen which provide a source of glucose for energy during exertion -in resting muscle the preferred fuel is fatty acids -muscle protein may be mobilized as a fuel source

Question 44

heart muscle in metabolism

Answer 44

contains essentially no fuel reserves and must be continuously supplied with fuel from the blood, primarily fatty acids

Question 45

adipose in metabolism

Answer 45

-primary function is storage of metabolic fuel in the form of triacylglycerols -during the fed state, it synthesizes triacylglycerols from glucose and fatty acids -during the fasting state triacylglycerols are converted to glycerol and fatty acids

Question 46

brain in metabolism

Answer 46

-normally uses glucose as an exclusive fuel, except during starvation when it can adapt to use ketone bodies -contains essentially no fuel reserves and must be continuously supplied with fuel from the blood