Brief Review

Catecholamines

Know the biochemical and physiological effects of Epinephrine.

The biosynthesis of Epinephrine and Norepinephrine, you DO NOT need to draw this pathway but you do need to recognize its features, including the reactants, products and enzymes their co-factors.

Sites of Synthesis and Regulation and Release, you should know where the catecholamines are made/stored and in response to what, i.e. stress or a real/perceived threat.

Degradation by COMT and MAO results in many compounds.....

Catecholamines act through two major clases of receptors designated a- or b- adrenergic, each consists of 2 subclasses, i.e. a₁, a₂, b₁ and b₂.

You should know the second messengers for the G_s, G_i and G_p receptors.

Don't worry about the "Cyclic AMP" picture.

Understand the next step in the G-protein receptor story, i.e. following activation of Adenylate Cyclase c-AMP is produced which then activates Protein Kinase A.

Fat Metabolism: Overview and Synthesis

Export of Acetyl CoA for Fatty Acid Biosynthesis- know the picture showing the transport of Acetyl CoA from the mitochondria to the cytosol.

Acetyl CoA Carboxylase- important reaction.

Fatty Acid Synthase- know ALL of the reactions and the chemistry (structures) involved in the synthesis of palmitic acid (palmitate).

Acyl-CoA Synthetase- important reaction (activation of fatty acids).

Regulation of Lipogenesis- understand this.

Esterification- don't worry about this material.....

Fat Metabolism: Degradation

Physiological Pathway of Lipid Oxidation- understand this.

Lipolysis- know the roles of Hormone-Sensitive Lipase and Lipoprotein Lipase, don't worry about the Overview of Hepatic Fatty Acid Degradation picture.

Carnitines Role in Mitochondrial Fatty Acid Transport- important information to know.

b-Oxidation of Free Fatty Acids: Odd and Even Chains- understand the pathway, know the end-products and over-all energy production from each (even and odd).

Understand Normal Prevention of Ketoacidosis and what tissues can use ketones as fuels. Don't worry about the Ketone Body Formation in Liver or Ketone Body Oxidation pictures.

Fat Metabolism: Regulation and Integration

Important- Hormone-Sensitive Lipase, Acetyl CoA Carboxylase, Coordinated Control and the Conditions favoring Lipogenesis vs. Lipolysis. Do not worry about the "Interrelationship" diagrams or the Energy Comparisons. Do, however, look at the summary table following the Energy Comparison data and understand "fuel efficiency".

Arachidonic Acid Metabolism

Understand the General material about Prostaglandins, i.e. physiological effects.

Liberation of Arachidonic Acid and its Metabolism- the "Big Picture" is important, also inhibitors of Phospholipase A₂ and Cyclooxygenase.

The Three Series of Eicosanoids and Their Biosynthetic Origins- Understand this picture, i.e. how the Series 3 prostaglandins are synthesized from the Essential Fatty Acids but certainly don't memorize all of the different Series 3 compounds!

Conversion of Arachidonic Acid to Series 2 PG's and TX's- just realize that all of the Series 2 compounds come from a central intermediate, PGH₂.

Structure and Mechanism of Aspirin Inhibition and the Conversion of Arachidonic Acid to Series 4 Leukotrienes- don't worry about this.

Understand Platelet Aggregation including the physiology and biochemistry of PGI₂ (G_s), TXA₂ (G_i), PGI₃ and TXA₃.

Understand the role of leukotrienes and Peptido-leukotrienes in allergic reactions.

Vioxx and Cyclooxygenase- the picture is not important but you should understand the mechanisms and physiological responses of COX-1 vs. COX-2.

Amino Acid Metabolism

Metabolic Fates of Amino Acids: You do not need to know this picture but you do need to know what Ketogenic and Glucogenic mean and which amino acids go into which pathways (see Below).

Ketogenic vs. Glucogenic:

Glucogenic- amino acids which can be converted into glucose (CHO producing), Pyruvate or a TCA cycle intermediate that can be converted to OAA is produced in the final step of its metabolism.

Ketogenic- amino acids which can be converted into fat (fat producing), Acetyl CoA or Acetoacetyl CoA is produced in the final step of their metabolism. (Acetyl CoA condenses with OAA so the net gain of OAA is zero since one molecule is consumed for each molecule produced (acetyl CoA))

Metabolism of Phe and Tyr (Liver): You do not need to draw this pathway but you do need to recognize its features and know the reactants, products and enzymes their co-factors and any consequences of their deficiencies.

Metabolism of Met and Cys: You do not need to draw this pathway but you do need to recognize its features and know the reactants, products and enzymes their co-factors and any consequences of their deficiencies.

Cystathione--synthase: Homocysteine ----> Cystathione

Co-factor: pyridoxine

Deficiency: homocystinuria, increased levels of homocysteine which has a reactive sulfur group that can bind to a number of proteins.

Protein Turnover / Ammonia Metabolism

Know which Amino Acids are "Essential".

Understand Protein Turnover, Nitrogen Economy, the Regulation of Protein Turnover and Nitrogen Economy and the physiological Roles of Protein Degradation / Metabolism.

Ammonia Metabolism and Nitrogen Waste- the Transaminase reaction and the Glutamate Dehydrogenase reaction are important. Don't worry about the Nitrogen Excretion table.

The Urea Cycle- know the Structures of all Substrates/ Products and the names of the Enzymes.

Clinical Correlate: Inherited Hyperammonemia- don't worry about this material.

Heme Metabolism

Heme Synthesis and Heme Metabolism- know the names (no structures!) of the substrates, products and enzymes, also points / types of regulation (inhibition and activation).

Clinical Correlate: the Van den Bergh Test and Types / Causes of "Jaundice" are important.

Overview of Biochemical Endocrinology

Understand the Properties of Hormones.

Hormones Controlling Glucose Homeostasis- if you don't already, you should know this.....

Classification of Hormones by Receptor Properties and General features of Hormone Classes- ALL of this material is important.

Understand how G_s, G_i and G_p proteins work (see also "Membranes I and II", "Insulin and Glucagon", "Catecholamines" for G-protein review).

Clinical Correlate: Bacterial Toxins- understand how cholera and pertussis toxins cause the over-production of c-AMP.

Vitamin A and Vision

Know the Role, Active Forms (no structures), Sources and Consequences of Deficiencies.

The Chemistry, Metabolism and Functions of Vitamin A- know the names of the substrates, products and enzymes. Know the functions (physiological / biochemical roles) of the different active forms. Note which reactions in the pathway are reversible and which are not.

The Actions of the Noncovalent Vitamin A Binding Proteins- skip this.

The Participation of Retinal in the Visual Cycle- understand this diagram in a very "general" way, i.e. what happens when a photon of light enters the picture, understand what the "door" being OPEN or CLOSED means to vision etc.

Vitamin A Toxicity and Symptoms- know this.

How Vitamin A Receptors Fit Into the Superfamily of Retinoid, Thyroid and Steroid Hormone Nuclear Receptors- just understand that they are Group I receptors, i.e. the hormones diffuse into the cell and form some kind of receptor-hormone complex which then produces it's effects in the nucleus of the cell (Nuclear Receptors-mechanism of action not well understood).

© Dr. Noel Sturm 2013