Final Exam Flashcards
What are the three classifications of carbohydrates?
- Monosaccharides
- Disaccharides
- Polysaccharides
Name the three monosaccharides
Glucose, Fructose, Galactose
Name the three disaccharides and their monosaccharide components
Maltose: Glucose+Glucose
Lactose: Glucose+Galactose
Sucrose: Glucose+Fructose
Name the three polysaccharides
Starch
Glycogen
Cellulose
Aldehyde functional group
Hydrogen, Carbonyl, Carbon
Keton functional group
Carbon, Carbonyl, Carbon
Monosaccharide with an ____ group is an aldose while a monosaccharide containing a ____ is a ketose
Aldehyde; Ketone
What is another name for aldotriose?
Glyceraldehyde
What is another name for ketotriose
Dihydroxyacetone
What are enantiomers
Non-super imposable mirror images
What are diastereoisomers
Not mirror images
How are D and L forms determined?
By the -OH group on the chiral C atom furthest from the carbonyl end (aka the most oxidized end) that determines D or L configuration. If the -OH is on the right then it is D- and if the OH is on the left it is L
Nearly all carbohydrates are members of the D family
What are epimers?
Sugars that are diastereoisomers and only differ in configuration at a single asymmetric center
What are the two possible configurations of monosaccharides?
D and L
What is the general formula of a carbohydrate?
(CH2O)n
An aldehyde plus an alcohol forms what?
A hemiacetal
A ketone plus an alcohol forms what?
A hemiaketal
Alpha is ___ and Beta is ____
down; up
What is an anomer?
An isomer that differs in arrangement of bonds around the hemiacetal carbon
Why does cyclisation of D-glucose give 2 isomers, alpha-D-glucose and beta-D-glucose
When carbonyl group of C1 of D-glucose reacts with C-5 hydroxyl group, a new chiral carbon is created (C1). In the alpha-isomer of the cyclic sugar, the C1 hydroxyl group is below the ring; in the beta-isomer, the C1 hydroxyl group is above the ring
Maltose linkage
Derived from the condensation of glucose and glucose which forms alpha 1,4 glycosidic linkages
Full linkage alpha-d-glucose(1,4)-alpha-d-glucose
Lactose linkage
Derived from the condensation of galactose and glucose to form a B 1,4 glycosidic linkage
Full linkage:
Beta-d-galactose-(1,4)-alpha-D-glucose
Sucrose linkage; anything special about sucrose?
Derived from the condensation of glucose and fructose but the anomeric C of both sugars is used in the formation of the glycosidic bond
*Is a non-reducing sugar b/c anomeric carbons of both glucose and fructose are used – therefore sucrose does not have a free –OH and is not a reducing sugar
Alpha (1,2) glycosidic bond
Alpha-D-glucose-(1,2)-beta-D-fructose
Amylose; composed of & linkages
a linear, unbranched chain of alpha-D-glucose units (up to 4000 units) - alpha-1,4 glycosidic bonds
-has both a reducing and nonreducing end
Amylopectin; composed of and linkages
Has a glucose backbone – branches leading to one reducing and many non-reducing ends
Branches are attached to the main chain from the C1 of one alpha-D-glucose to the C6 hydroxyl group of alpha-D-glucose in the main chain - alpha-1,6 glycosidic bonds
Glycogen linkages
A highly branched molecule structurally similar to amylopectin but has more numerous alpha-1,6 glycosidic linkages (thus higher molecular weight)
-also consists of a single reducing end and numerous non-reducing ends
What is the linkage in cellulose?
Beta 1,4
- cellulose consists of a linear chain of several hundred to thousands of B-D-glucose units
- cellulose is the most abundant polysaccharide
Outcomes of Glycolysis
4 ATP Produced (net gain of 2)
2 Pyruvate
Outcomes of TCA
2 ATP
2 Acetyl CoA
Outcomes of ETC
34 ATP
Which step of glycolysis is the Hexose Stage?
The first half of glycolysis is the hexose stage
Step 1-4 ; Phosphorylation of glucose by hexokinase or glucokinase
Glucose 6 phosphate isomerase catalyzes the isomeraization
of of G6P
Phosphofructokinase phosphorylates F6-P
Clevage of F-1,6 P by fructose bisphosphate aldolase to produce DHAP and G3P
What does the first phase of glycolysis produce? Second?
G3P and two pyruvates
What is the net reaction of glycolysis
Glucose + 2 ADP + 2 NAD+ + 2 Pi —-> 2 Pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O
What are the three possible fates for pyruvate?
In yeast (anaerobic fermentation):
Glucose ->pyruvate->ethanol
In muscle (anaerobic respiration): Glucose -> pyruvate -> lactate
In muscle (aerobic respiration) Glucose -> pyruvate -> acetyl CoA
Two step process to convert pyruvate to ethanol
- pyruvate is decarboxylated to acetaldehyde by pyruvate decarboxylase
- Acetaldehyde is reduced to ethanol by NADH and alcohol dehydrogenase
Equation to convert pyruvate to ethanol
Glucose + 2 ADP +2 Pi + 2 H+ —->
2 Ethanol + 2 CO2 +2 ATP + 2 H2O
What enzyme do mammals lack that yeast do not that allows them to convert pyruvate to ethanol
What happens to pyruvate instead?
- Pyruvate decarboxylase
- Pyruvate converted to lactate where it is then transported to the liver for gluconeogensis
What is the equation for converting pyruvate to lactate
Glucose + 2 ADP +2 Pi ——-> 2 Lactate + 2 ATP + 2 H2O
What are the three irreversible steps of glycolysis?
1,3, and last
Hexokinase
PFK1
Pyruvate kinase
Inhibitors and activators of PFK1
- High ATP = allosteric inhibitor
- High AMP and ADP - allosteric activators
Which steps of glycolysis use ATP
Step 1
Glucose -> G6P
Step 3
Fructose-6-phosphate to fructose 1,6 bisphosphate
Which steps of glycolysis produce ATP
1,3-bisphophoglycerate ->3 phosphoglycerate
Phosphoenolpyruvate to pyruvate
Pyruvate (the end product of glycolysis) must be converted to ____ before it enters the CAC
Acetyl CoA
Each molecule of pyruvate is transported across the _____ mitochondrial membrane into the _______
Inner; matrix
_______ transports pyruvate and H+ from the inter membrane space to the interior space of the mitochondrion
Pyruvate translocase
What enzyme converts pyruvate to acetyl coA; what is the equation?
How many ATP produced?
Pyruvate dehydrogenase
Pyruvate + CoA-SH + NAD+ ——> Acetyl CoA + CO2 + H+ + NADH
2 NADH (3 ATP per NADH) = 6 ATP
Which steps are oxidation steps in the TCA cycle?
4; 3,4,6,8
End products of TCA cycle
3 NADH, 1 FADH, and 1 GTP
What are the irreversible reactions of the TCA cycle
Step 1: Oxidation of acetyl CoA where 2 acetyl CoA condense with 4 OAA to form citrate
Step 3: first oxidation step and formation of alpha ketoglutarate
Step 4: Second oxidation and formation of succinyl CoA
Equation of the citric acid cycle
Acetyl CoA + 3NAD+ + FAD + GDP + Pi + 2H2O —–> CoA-SH + 3NADH + 3H+ + FADH2 + GTP + 2CO2
How many ATP are produced from the CAC
24 total
3 NADH ->9 ATP (3 ATP for each NADH)
1 FADH2 ->2 ATP (2 ATP for each FADH2)
1 GTP -> 1 ATP
Total: 12 ATP per acetyl CoA -> (x2 Acetyl CoA)
=24
Gains of the catabolism of glucose through glycolysis and the citric acid cycle
Oxidation of 2 molecules of acetyl CoA by the citric acid cycle and oxidative phosphorylation produces 24 molecules of ATP
Glycolysis generates: 2 NADH (6 ATP) and 2 ATP = 8ATP
Pyruvate dehydrogenase complex generates 6 ATP
Total of 38 moles of ATP per mole of glucose oxidised to CO2 and water
ETC
The Electron Transport chain is a series of electron carrier in the inner membrane of the mitochondria. Electrons are passed form NADH to oxygen (the final acceptor), moving protons from the matrix to the inter membrane space. FADH also donates electrons to the chain, releasing hydrogen ions into the inter membrane space. Eventually, the high H+ concentration in the inter membrane space causes some of the ions to flow down the concentration gradient and back into the matrix through ATP synthase, producing ATP
What are the two mobile electron carriers in the ETC?
Coenzyme Q (between complexes I and III) and Cytochrome C (between complexes III and IV)
Chemiosmosis
The movement of ions across a semipermeable membrane
Gluconeogenesis
The conversion of pyruvate to glucose from non carbohydrate precursors
*noncarb precursors are first converted to pyruvate
What are the three noncarb precursors
Lactate, amino acids, and glycerol
Net equation for gluconeogenesis
2Pyruvate + 2NADH + 4ATP + 2GTP + 6H2O + 2H+ —>Glucose + 2NAD+ + 4ADP + 2GDP + 6Pi
Which steps of glycolysis are in the triose stage?
The second half
The Pentose Phosphate pathway; produces?
-Divided into oxidative and non oxidative stages
- After conversion to glucose 6-phosphate, glucose can enter the PPP (aka hexose monophosphate shunt)
- PPP runs parallel to glycolysis
Produces NADPH and forms ribose-5-phosphate
In what tissues is the PPP active?
Ones that synthesize fatty acids or steroids
PPP Oxidative stage
Glucose 6-phosphate + 2NADP+ + H2O ———> Ribulose 5-phosphate + 2 NADPH + CO2 + 2H+
PPP Non oxidative stage
Ribulose 5-phosphate —-> 2 Fructose 6-phosphate + Glyceraldehyde 3-Phosphate
Glycogenolysis
Degradation of glycogen
Which end are glucose residues removed from during phosphorolysis
the non reducing end
(only acts on alpha-1,4-linkages
Glycogen ____ stops ____ residues from a branch point with ____ bond and resulting _____ is further degraded by a _______ enzyme
Phosphorylase; 4; alpha 1-6; limit dextrin; glycogen-debranching
______ activity of the glycogen deb ranching enzyme catalyzes the relocation of _____ glucose residues to allow the deb ranching enzymes to _________
Glucanotransferase; 3; remove the remaining alpha 1,6 linked glucose molecule to produce a free glucose molecule and an elongated unbranched chain
What is the end product of glycogenolysis
Glucose-1-phosphate
What happens to glucose-1-p after glycogenolysis?
converted to G6P by phosphoglucomutase
What are the steps to incorporate one G6P into glycogen?
***Glucose converted to G6P by hexokinase
G6P –> G1P (Phosphoglucomutase)
G1P —> UDP-Glucose (UDP-Glucose pyrophosphorylase)
-UDP-Glucose -> Glycogen (glycogen synthase
Role of insulin in blood glucose and glycogen
- fed strate
- B cells
- Increases the rate of glucose transport into muscle and adipose tissue via GLUT 4 glucose transporter
- stimulates glycogen sythesis
Role of glucagon in blood glucose and glycogen
- Alpha cells
- low blood glucose (fasted state)
- Stimulates glycogen degradation
- Only liver cells are rich in glucagon receptors
Adrenaline and role in blood glucose and glycogen
- A catecholamine
- flight or flight
- stimulates breakdown of glycogen to G1P (which is converted to G6P)
- Increased G6P levels increase the rate of glycolysis in muscle and glucose release to the bloodstream from the liver
Glycogen phosphorylase is ______ in the _____ state and glycogen synthase is more active in the _______ state
more active; phosphorylated; dephosphorylated
4 Parts of an amino acid
side chain (R) Amino group (NH2) H Carboxyl group (COOH)
Two stages of amino acid degradation and where?
-In the liver
Stage 1: The alpha amino nitrogen must be removed (via transamination and
oxidative deamination reactions) – amino group eventually ends up as urea
Stage 2: remaining carbon skeletons are then shuttled into central metabolic pathways (eg. Citric acid cycle)
Result of transamination
A new keto acid and glutamate
Which enzyme catalyzes the interconversion of aspartate and alpha ketoglutarate to OAA and glutamate
Aspartate transaminase
What enzyme is often used as a clinical diagnostic test for liver function
Aspartate transaminase (AST)
Which enzyme catalyses the interconversion of alanine and alpha- ketoglutarate to pyruvate and glutamate
Alanine transaminase (ALT)
Which enzyme is useful for screening for liver associated problems
ALT
What compound do transamination and oxidative deamination generate in large amounts
Ammonium ion - NH4+
What are the 3 enzymes of the urea cycle that are located in the cytosol
argininosuccinate synthase, arginase and argininosuccinate lyase
What are the two enzymes of the urea cycle that are located in the mitochondria
ornithine transcarbamoylase and carbamoyl phosphate synthase
Overall reaction of the urea cycle
CO2 + NH4+ + 3ATP + aspartate + 2H2O —> urea+2ADP+2Pi +AMP+PPi +fumarate+5H
In every turn of the urea cycle ___ nitrogens are eliminated 1 from ____ and 1 from ____
2; oxidative deamination of glutamate; alpha amino group of aspartate
What is the committed step in the urea cycle
Biocarbonate ion and NH4 reacting to form carbamoyl phosphate
Fate of ketogenic amino acids
Metabolized to acetoacetate or acetate
fate of glycogenic amino acids
Pyruvate or TCA intermediates
What is the definition of a hormone
A substance that is synthesized and secreted by specialized cells and carried via the blood circulation to target cells
Name 4 sites of hormone secretion
Pineal gland, Hypothalamus, Pancreas, Thyroid Gland
What are the three categories of hormones
Autocrine
Paracrine
Endocrine
What is an autocrine hormone
A hormone that acts upon the secretory cell
What is a paracrine hormone
A hormone that acts on adjacent cells
What is an endocrine hormone
A hormone that acts on target cells at a distance (usually travels via the bloodstream to distance target cells)
What are the five classifications of hormones
Peptides Proteins Steroids Amino Acid Derivatives Eicosanoids
Peptide hormones are synthesized as protein precursors known as
Preprohormones
Once a preprohormone is produced what happens
It is targeted to the Golgi where a signal sequence is removed to form a pro hormone where it is then processed into the active hormone and packaged into secretory vesicles
What is an example of a peptide hormone
Insulin
Describe insulin biosynthesis
- Preproinsulin is synthesized as a random coil on membrane associated ribosomes
- After membrane transport the signal peptide sequence is cleaved off, resulting in proinsulin which folds into a stable conformation
- Disulfide bond formation occurs
- Connecting sequence (C-peptide) is cleaved out by endopeptidases to leave the mature insulin molecule
Proinsulin processing: Where does trypsin cleave?
- C-peptide and A chain
- C-Peptide and B-chain
- Carboxypeptidase B-like enzyme removal of basic amino acid residues
Effects of insulin on carbohydrate metabolism
- increase glucose uptake in muscle and adipose tissue
- Increase glycolysis in muscle and adipose
- increase glycogen synthesis in muscle, adipose, and liver
- inhibits glycogenolysis and gluconeogenesis
- increase glucose oxidation in Pentose, Phosphate Pathway
Direct negative feedback
where rate of hormone production/secretion is related to the blood concentration of metabolite ex. insulin and blood glucose control
-Insulin acts on target cells (e.g. muscle) ultimately to decrease blood glucose concentration, a change in blood glucose alters insulin secretion from pancreatic beta-cells
What effects does insulin have on lipid metabolism?
- Inhibits rate of lipolysis (lipid breakdown) in adipose tissue
- Stimulates fatty acid (FA) and triacylglycerol (TG) synthesis in adipose tissue & liver
- Increases VLDL synthesis in liver
- Increases lipoprotein lipase + uptake of blood TG’s in adipose tissue.
- May decrease rate of FA oxidation in liver
What effect does insulin have on protein metabolism
In general insulin encourages protein synthesis rather than amino acid oxidation.
- Increases transport of some amino acids (aa’s) into muscle, adipose, liver & other cells.
- Increases protein synthesis in muscle, adipose & liver cells.
- Decreases rate of protein breakdown in muscle
Where are steroid hormones derived from?
The gonads, the adrenal cortex, and the placenta in pregnancy
What are the five major categories of steroid hormones?
- Progestins
- glucocorticoids,
- mineralocorticoids -androgens
- estrogens
What is the precursor of all other steroid hormones?
Cholesterol; it is converted to pregnenolone via a two step process
After pregnenolone is produced what happens
It is converted to progesterone by oxidation of the hydroxyl group to a ketone and isomeraization of a double bond
In the synthesis of steroid hormones what is the branch point between glucocorticoids and androgens
17-hydroxyprogesterone
Where is cortisol synthesized?
In the adrenal cortex in response to signals from the adrenocorticotropic hormone (ACTH)
What is the primary role of cortisol? Other roles?
to increase survival during periods of stress when glucocorticoid
secretion can increase by almost 10-fold
- Mobilize energy through glucose homeostatic mechanisms (raise blood glucose)
- Suppress the immune system
- Modulation of skeletal processes
- “Fight or flight hormone”
What are the two groups of hormones derived from the amino acid tyrosine
- Thyroid hormones
- Catechlamines
What are two thyroid hormones made by modifying tyrosine residues in the protein thyroglobulin
- Thyroxine
- Triiodothyronine
Effects of thyroid hormones on metabolism
- Produce a general increase in the metabolism of carbohydrates, fats, proteins
- Increase oxygen consumption and heat production directly in heart, kidney, liver, and muscle
Effects of thyroid hormones on growth and development
- Important for normal response to the thyroid hormone calcitonin
- Skeletal bone development
- Growth and maturation of the CNS
Catecholamines are also known as ____ and ____
Neurohormones and neurotransmitters
Where are catecholamines mainly produced
In the adrenal medulla
What are the most common catecholamines
Epinephrine
Norepinephrine
Dopamine
Dihydroxy-phenylalanine
What are some of the actions of catecholamines
- Important in the fight or flight response
- Exert a powerful stimulant effect on the heart: increase heart rate, and increase force of contraction
- Convert energy stores to freely available fuel: (glycogen to glucose and stored fat to free fatty acids)
4 Families of eicosanoids
Prostaglandins
Thromboxanes
Leukotrienes
prostacyclin
What are eicosanoids derived from?
Arachidonic acid
What are prostaglandins
-“Hormone-like”
unsaturated carboxylic acids
consisting of a 20-carbon skeleton that contains a 5 ring carbon
-Exert effects on cells that produce them and other cells of the body
Actions of prostaglandins
- Stimulation of smooth muscle
- Regulation of steroid biosynthesis
- Inhibition of gastric secretion & hormone-sensitive lipases
- Inhibition and stimulation of platelet aggregation
- Regulation of nerve transmission
- Sensitization to pain
- Mediation of inflammatory response
Membrane receptors
-Embedded in the cell membrane.
-Often are G-protein coupled receptors with 7- transmembrane domains
-Usually are receptors which respond to
neurotransmitters, peptides and proteins.
Intracellular receptors
- Present in the cytoplasm or nucleus
- Respond to hydrophobic signal molecules such as steroids and thyroid hormones
What are the two hormonal mechanisms
-Enzyme activation or inhibition via second messengers – epinephrine, glucagon and insulin work in this way
-Stimulation of the synthesis of particular proteins, by direct action through activation of
specific genes in the cell nucleus
Peptide and protein hormones tend to use which hormone mode of action?
-Use of second messengers ex. cyclic AMP
Involvement of a peptide hormone in the control of cellular function starting and continuing with:
-the synthesis of the hormone in its endocrine cell
-release into bloodstream in response to specific
stimulus
-binding to a specific target cell receptor
-intracellular second messenger release
-biological effect on target tissue
-feedback control mechanism acting to down-regulate
hormone producing cell
Which hormone mode of action do steroid hormones use?
-Direct action on the activation of specific genes
~the hormone crosses the plasma membrane and binds to specific receptor proteins in the cytoplasm
- The receptor hormone complex dimerizes and migrates to the nucleus where it interacts with specific DNA sequences called hormone responsive elements
- Hormones in this class include: steroids, thyroid hormones, and hormonal forms of vitamin D
How does the liver help to remove hormones from the bloodstream?
Metabolizes by conjugating with water soluble metabolites (glucuronide)
-secreted to bile, excreted in feces or can enter bloodstream and be excreted by the kidneys
How do the kidneys help to remove hormones from the blood stream?
By inactivating them and excreting the constituent amino acids directly into the urine
How are steroid hormones eliminated
Mammalian cells lack the ability to completely degrade steroid compounds. As a result most become conjugated through their hydroxyl groups to glucuronate or sulfate and are eliminated in the urine
What are the three key elements of nucleic acids
heterocyclic nitrogenous base, sugar and phosphate(s)
In RNA the sugar is ribose whereas in DNA the sugar is 2-deoxyribose
Nucleic acid bases can be divided into what two categories
Purines and Pyrimidines
Purines
Adenine and Guanine
Pyrimidines
Cytosine
Thymine
Uracil (RNA)
Nucleotide components
Base + sugar + phosphate
Nucleoside components
Base + sugar
Nucleotides are ____ acids
Strong
Bases in nucleotides can exist as ______ which are structural isomers differing only in _________
Tautomers; location of H atoms and double bonds
What are the two important features of polynucleotides
- Sense or directionality
2. Individuality
What is the secondary structure of nucleic acids?
Two strand helix stabilized by hydrogen bonding between bases on opposite strands if bases were paired up in a particular way
DNA base pairs?
A and T
C and G
Salvage pathways
Synthesizing nucleotides that have become available in the diet or from the enzymatic breakdown of nucleic acids
Purine nucleotide degradation leads to production of _____
Uric acid
Purines ->uric acid steps
Nucleotidases convert nucleotides to nucleosides; purine nucleoside phosphorylase (PNP) catalyzes removal of ribose-1-phosphate moiety; free bases oxidized by xanthine dehydrogenase to uric acid
In some mammals uric acid is degraded further into…?
Allantoin which can then be further oxidized into allantoic acid…some animals can even catabolize it further into urea
What happens when humans have an excessive accumulation of uric acid?
Gout; which arises from overproduction of purine nucleotides, impaired uric acid excretion from kidneys, or both
De novo synthesis of pyrimidine ring involves 2 precursors
Aspartate and carbamoyl phosphate
What are lipids
Naturally occurring molecules that are grouped together based on being soluble in non polar solvents
-may be hydrophobic or amphipillic
What are the two essential lipids?
- alpha-linolenic acid (n-3)
- linoleic acid (n-6)
What are the four main groups of lipids
Fatty acids, Glycerides, Non-glycerides, Complex lipids
What are the two fatty acids
- saturated
- unsaturated
What are the 3 fatty glycerides
Monoglycerides
Diglycerides
Triglycerides
What are the 3 nonglycerides
- Sphingolipids
- Steroids
- Waxes
What is an example of a complex lipid
Lipoprotein
What are three functions of lipids?
- Energy
- Cell membrane and structure
- Hormones
What is the end product of beta oxidation?
Acetyl CoA
Saturated fats have a ______ melting point than unsaturated fatty acids of the same C length
High
Most double bonds are in the ____ formation
Cis
Delta system
-Numbers from the carboxyl end to the first unsaturated carbon
N minus system
Numbers from the terminal methyl carbon to the first
unsaturated carbon, “substracts” those carbons, and places these numbers in parentheses
α-Linolenic acid – 18:3 (n-3) #3 from methyl carbon CH3-CH2-CH=CH-CH2-CH=CH-CH2-CH=CH(CH2)7COOH
Omega system
Numbers from the terminal methyl carbon to the first unsaturated carbon
α-Linolenic acid -- 18:3 ω3 #3 from methyl carbon CH3-CH2-CH=CH-CH2-CH=CH-CH2-CH=CH(CH2)7COOH
Common name, IUPAC for C18:0
Stearate; Stearic Acid
Octadeconate
Common name and IUPAC name for C18:1 n-9
Oleate ; 9-Octadecenoic acid
Cis Δ9 octadeconoate
Common name and IUPAC for C18:3
Linoleate
Octadeconoate
4 Chemical reactions of fatty acids
Esterification, Acid Hydrolysis, Saponification; Reaction at double bond (hydrogenation)
Product of Esterification
Carb acid + Alcohol —> Ester + Water
Acid hydrolysis
*Reverse esterification (producing fatty acids from esters)
Rxn also called hydration
Ester + water –> Carb acid + alcohol
Saponification
The base-catalyzed hydrolysis of an ester
The product – ionised salt (soap)
Soap - Long uncharged hydrocarbon tail & a negative charged terminus they form micelles that dissolve oil and dirt particles
Even numbered eicosanoids are ____ inflammatory while _____ numbered eicosanoids are anti inflammatory
Pro inflammatory; even
Thromboxane
Stimulates constriction of blood vessels and platelet aggregation
Prostacyclin
Inhibits platelet aggregation and causes dilation of blood vessels
What are the two classes of glycerides?
- Neutral glycerides
- Phosphoglycerides
Phosphoglycerides
- Phosphate (polar) head
- Nonpolar tail
Sphingolipids
Spingosine backbone (contains a long chain, and a nitrogen containing alcohol)
- Amphipathic
- Structural components of cellular membranes
Sphingomyelins
- Located throughout the body
- Important for structural components of nerve cell membranes
3 Glycosphingolipids
- Cerebrosides
- Sulfatides
- Gangliosides
Cerebrosides
- contain the sphingosine backbone attached to a fatty acid and a carbohydrate (most often glucose or galactose).
- Those that contain several carbohydrates are called gangliosides
Ex: Glucocerebroside
Galactocerebroside
found almost exclusively in the membranes of brain cells
Sulfatides
derived from galactocerebroside that contain a sulfate group
What is cholesterol synthesized from?
Acetic acid
What does HDL do?
Carry cholesterol out of the blood for excretion
What does LDL do?
Carry cholesterol to body cells for use
Atherosclerosis
Occluding of blood vessels leading to HBP, coronary heart disease and others
What are the 4 classes of complex lipids
Chylomicrons
VLDL
LDL
HDL
Chylomicrons
carry triglycerides from intestine to other tissues
Very low density lipoprotein (VLDL
bind triglycerides synthesised in liver & transport to adipocytes for storage
Low density lipoprotein (LDL
bind cholesterol & transport it to peripheral tissues – regulate cholesterol levels
High density lipoprotein (HDL)
bound to plasma cholesterol & transport cholesterol from peripheral tissues to the liver
What are the four steps of beta oxidation?
Oxidation
Hydration
Oxidation
Split
What are the three ketone bodies?
Acetone
Acetoacetic acid
beta-hydroxybutyric acid
Which ketone cannot be used?
Acetone; it is excreted in the urine or exhaled
Under normal conditions the brain uses ____ as its source of energy. Under fasting conditions the brain uses ____ as its source of fuel
Glucose; ketone bodies
Under resting conditions the skeletal muscle uses ______ as a fuel source. When working it will ________
Fatty acids; break down own stores of glycogen to produce glucose-6-phosphate
If the production of pyruvate exceeds the oxygen capacity of the muscle cell, then pyruvate is converted into ____
Lactate
During fasting/starvation the liver will convert ______ to acetoacetate and other ketone bodies
FAtty acids
GLUT 1
Red Blood Cells
GLUT 2
Liver
GLUT 3
Brain
GLUT 4
Adipose and Muscle
Insulin is an ____ hormone where glucagon is a ____ hormone
Anabolic; catabolic
Insulins roles
- Favors glycogen storage
- Boosts protein synthesis
- Promotes glycolysis
- Increases conversion of carbohydrates to fatty acid
- Promotes glucose uptake in muscle and adipose
Insulin signals transcription of which enzymes
Glucokinase
PFK 1
Pyruvate kinase
Acetyl CoA Carboxykinase
Glucagon roles
Promotes glycogen breakdown
Promotes gluconeogenesis
Stimulates fat breakdown
Glucagon signalling causes a increase in cAMP levels
This results in the net ________ of
several key metabolic enzymes
Phosphorylation
Roles of Cortisol
- Promotes gluconeogenesis.
- Mobilizes amino acids from extrahepatic tissues.
- Inhibits glucose uptake in muscle and adipose tissue.
- Stimulates fat breakdown - lipolysis.
Which enzymes are induced by the signaling of cortisol
PEPCK
Fructose 1,6 biphosphate
Glucose 6 Phosphate
Hormone Sensitive Lipase
What is one of the fastest enzymes known
Carbonic anhydrase
What is enzyme specificity due to?
Precise interactions of substrate with enzyme due to the 3D structure of the enzyme
6 Classes of Enzyme
TILLOH: Transferases Isomerases Ligases Lyases Oxioreductases Hydrolases
6 Classes of enzyme with examples
TILLOH AT AR GS F LD P
“At Arizona Georgia State Florida LondonDerry Pigs”
Alanine Transaminase Alanine Racemase Glutamine Synthetase Fumarase Lactate Dehydrogenase Phosphatase
An enzyme without its cofactor is a ?
Apoenzyme
A completely catalytically active enzyme is called a…?
Holoenzyme
Co enzymes
Small organic molecules derived from vitamins
Co factors
Metals
Tightly bound coenzymes are called _____ groups
Prosthetic
Reaction takes place spontaneously only if delta G is _____ and ____
Negative; Exergonic
Reaction cannot take place spontaneously if delta G is _____ and ____
Positive; Endergonic
When is Vmax reached? What does it tell us?
When the enzyme is saturated with substrate; turnover rate of an enzyme
Km is equal to
Substrate concentration at which the reaction velocity is half its maximal value
A low km value indicates _____
Tightly bonded substrate
3 main types of reversible inhibition
Competitive inhibition
Uncompetitive inhibition
Noncompletitive inhibition
Competitive inhibitor
- resembles the substate and binds only to the free enzyme active site
- has no effect on Vmax but increases Km
Uncompetitive inhibition
- Binds only to the enzyme-substrate complex and not the free enzyme
- Decreases vmax and decreases km
Noncompetitive
- can bind to both the free enzyme and the enzyme substrate complex
- decreases vmax and does not change Km
Irreversible enzyme inhibition
Form stable covalent bonds with the enzyme
