Biochemistry Block 2

Question 1

Types of Cell Signalling

Answer 1

1. Endocrine
2. Paracrine
3. Neuronal
4. Contact Dependent

Question 2

Endocrine Signalling

Answer 2

Hormones are released into blood stream and act diffusely on targeted cells throughout the body

Question 3

Paracrine Signalling

Answer 3

“Neighbour”- local mediators (example: Eicosanoids & Nitric Oxide)

Question 4

Neuronal Signalling

Answer 4

Neurotransmitters carry signals between neurons to other neurons (examples: Acth, dopamine, serotonin)

Question 5

Contact Dependent Signalling

Answer 5

Direct contact between cells/or cell matrix. No secretion of molecules (Examples: plasmodesmata, gap junctions)

Question 6

Types of Growth factors (4)

Answer 6

1. Epidermal
2. Nerve
3. Platelet Derived
4. Eicosanoids (prostaglandins, leukotrienes, thromboxanes)

Question 7

3 Types of Cell surface receptors

Answer 7

1. Ion-channel linked
2. Enzyme-linked
3. G-protein

Question 8

2 Types of Intracellular receptors

Answer 8

1. Gene regulating
2. Enzymatic

Question 9

Enzyme-linked

Cell surface receptor

Answer 9

Single pass
Activates tyrosine kinase

Question 10

G-protein coupled receptors

Cell surface receptor

Answer 10

Act with aid of GTP
7 pass protein

Question 11

Gs

Answer 11

Activates adenylyl cyclase

Question 12

Gi

Answer 12

Inhibits adenylyl cyclase

Question 13

Gq

Answer 13

Activates phospholipase C

Question 14

Gt (transducin)

Answer 14

Activates cGMP-phosphodiesterase in vertebrates rod photoreceptors

Question 15

Steps of G-proteins

Answer 15

1. Hormone binds to receptor (GDP to GTP)
2. G-protein breaks into subunits
3. Alpha subunit activates adenylate cyclase which catalyzes cAMP from ATP
4. GTP is hydrolyzed to GDP
5. Now inactivated the G protein separates from the enzyme and can be reused again

Question 16

Intracellular receptors

Answer 16

1. Reside in the cytoplasm and translocate to the nucleus
2. Reside in nucleus bound to DNA
3. Reside in nucleus bound to proteins

Question 17

Gene regulation receptors

Answer 17

“Transcription factors”
1. Binding of the hormone induces conformational changes in the receptor
2. It then binds to regulatory DNA to affect transcription

Question 18

Second messengers

Answer 18

Small molecules produced in the cytoplasm in response to activation of a cell surface receptor

Question 19

Signal amplification

Answer 19

Signal process is amplified at each step, ensuring a swifter transmission

Question 20

Scaffolding proteins

Answer 20

1. Bind to activated receptors
2. Hold several molecules of a kinase in place-increasing transduction

Question 21

Characteristics of Metabolism

Answer 21

1. Irreversible
2. Each step is catalyzed by a specific enzyme
3. Has a first committed step
4. Regulated
5. Occur in specific cellular locations (eukaryotes)

Question 22

Catabolism

Answer 22

1. Degradation
2. Convergent
3. Oxidative
   Products include: (NADH, NADPH, ATP, FADH2)

Question 23

Anabolism

Answer 23

1. Synthesis
2. Reductive
3. Divergent
4. Uses ATP
   Products: NAD+, FAD, ADP, NADP+

Question 24

What is the link between Catabolism and Anabolism?

Answer 24

ATP

Question 25

Regulation of Metabolic Pathways

Answer 25

1. Gene regulation 2. Cellular regulation 3. Biochemical regulation (allosteric/covalent modification)

Question 26

Feed Cycle

Answer 26

2-4 hrs after a meal 1. Increase plasma glucose, TAGS, and amino acids 2. B-cells in pancreas release insulin-glucose moves into cells 3. Starts anabolism

Question 27

What is the nutrient distribution center?

Answer 27

Liver

Question 28

Fast Cycle

Answer 28

1. Decrease in plasma glucose, amino acids, and TAGs 2. Glucagon/Epi secretion 3. Catabolic phase

Question 29

What does the Liver do for energy in the fast cycle?

Answer 29

1. Increase glycogen degradation 2. Gluconeogenesis 3. B-oxidation 4. Ketogenesis

Question 30

What does the Adipose Tissue do for energy in the fast cycle?

Answer 30

Increase in TAG degradation providing fatty acids to the liver

Question 31

What does the Muscles do for energy in the fast cycle?

Answer 31

1. Use both fatty acids and ketone bodies 2. Degrades protein and provides amino acids to liver for gluconeogenesis

Question 32

What does the Brain use for energy in the fast cycle?

Answer 32

1. Glucose 2. Ketone Bodies

Question 33

Fate of Pyruvate Anaerobic

Answer 33

Lactate (Lactate dehydrogenase)-->Cori Cycle

Question 34

Fate of Pyruvate Aerobic

Answer 34

Acetyl CoA (PDH)-->TCA Cycle

Question 35

3 Irreversible Reactions in Glycolysis

Answer 35

1. Hexokinase 3. PFK-1 10. Pyruvate kinase

Question 36

2 Substrate Level Phosphorylation in Glycolysis

Answer 36

1. Phosphoglycerate kinase 2. Pyruvate kinase

Question 37

Where does Glycolysis take place?

Answer 37

Cytosol

Question 38

Energy of Aerobic Glycolysis

Answer 38

1. Investment 2 ATP 2. Gain 2 NADH (3 ATP per) 3. 4 ATP TOTAL = 8ATP

Question 39

Energy of Anaerobic Glycolysis

Answer 39

1. Investment 2 ATP 2. Gain 4 ATP TOTAL = 2 ATP

Question 40

Inhibitors of Glycolysis

Answer 40

1. Arsenate 2. Fluoride

Question 41

Where does complete oxidation of glucose take place?

Answer 41

1. Brain 2. Skeletal Muscles

Question 42

What is the main source of energy in RBCs?

Answer 42

Anaerobic glycolysis

Question 43

What is PFK-2

Answer 43

Fructose 2,6 bisphosphate

Question 44

In the presence of insulin what does PFK-2 do?

Answer 44

Activates PFK-1 (glycolysis)

Question 45

In the presence of glucagon what does PFK-2 do?

Answer 45

Activates gluconeogenesis

Question 46

What is the link between glycolysis and TCA?

Answer 46

Pyruvate Dehydrogenase (PDH)

Question 47

What does 2,3-bisphophoglycerate help with?

Answer 47

Helps unload oxygen at tissues

Question 48

4 molecules that pyruvate can form

Answer 48

1. Acetyl CoA 2. Oxaloacetate (CO2) 3. Alanine (Transamination) 4. Lactate

Question 49

General Functions of Lipids (6)

Answer 49

1. Structural 2. Membranes 3. Energy source (lipids yield more energy) 4. Energy storage (TGAs) 5. Insulation 6. Specialized Fx (hormones, cofactors)

Question 50

What role do membranes play? (4)

Answer 50

1. Enable separation 2. Selective permeability 3. Allow organisms to generate energy 4. Separate incompatible metabolic processes

Question 51

Where does the synthesis of cholesterol take place? (4)

Answer 51

1. LIVER 2. Adrenal Cortex 3. Testes 4. Ovaries

Question 52

What cannot cross a phospholipid bilayer without help?

Answer 52

LARGE, CHARGED, POLAR

Question 53

What residues make up Maltose?

Answer 53

2 glucose residues Alpha 1-4 Reducing sugar

Question 54

What resides make up Sucrose?

Answer 54

Glucose and fructose Alpha 1,2 Non-reducing sugar

Question 55

What residues make up Lactose?

Answer 55

Glucose and Galactose Beta 1,4 Reducing sugar

Question 56

What makes up Starch?

Answer 56

Amylose (10-30%) Amylopectin (70-90%)

Question 57

What is Amylose?

Answer 57

Glucose Homopolysaccharide Alpha 1,4 Straight chained

Question 58

What is Amylopectin?

Answer 58

Glucose Homopolysaccharide Alpha 1,4 and alpha 1,6 (branches) Branches every 25-30 residues

Question 59

What is Glycogen?

Answer 59

Glucose Homopolysaccharide Alpha 1,4 and Alpha 1,6 (branches) Branches every 8-10 residues

Question 60

What is Cellulose?

Answer 60

Linear polysaccharide of glucose Beta 1,4 Resistant to acid hydrolysis and digestive enzymes

Question 61

What is Chitin?

Answer 61

Homopolysaccharide of N-acetylglucosamine Beta 1,4

Question 62

What is Hyaluronic Acid?

Answer 62

Composed of alternating D-glucuronic acid and N-acetyleglucosamine Beta 1,4 and beta 1,3 Lubricant in synovial fluid

Question 63

What are Chondroitins?

Answer 63

Alternating disaccharide of Glucoronate and N-acetylgalactosamine Beta 1,4 and beta 1,3