BECOM Final (High Yield) Flashcards
Saturated hydrocarbons
No double bonds
Unsaturated
One or more double (or triple) bonds
Oxidation
Addition of O, N, S or removal of electrons (us. attached to hydrogen as H●)
Reduction
Addition of hydrogen (electrons) or removal of O, N, S
Complete oxidation yields
CO2 and H2O
Amino acid + Amin acid form
amide (peptide) bond
Zwitterion
molecule having separated positively and negatively charged group
ex. @ pH 7.4 carb acid ionized and amino group pronated
Dextrose =
glucose
sucrose =
glucose + fructose
pyranose =
6 carbon ring
furanose =
5 carbon ring
M (molarity) =
mol / L
m (molality) =
mol / Kg
Activation energy
amount of energy need to reach a transition state making a reaction occur
Four Major Biochemical Macromolecules
Proteins (amino acid polymer)
TAGs (lipid polymer)
DNA, RNA (nucleic acid polymer)
Polysaccharide (carbohydrate polymer)
anabolism and catabolism occur by
condensation and hydrolysis
ATP’s phosphate bonds are
Phosphoanhydride bonds
Substrate level phosphorylation
direct transfer of a phosphoryl group from one compound to ADP (or GDP)
ex. glycolysis
Oxidative phosphorylation (OXPHOS)
a process in which oxidation of carbon substrate provides reduced coenzymes. These reduced coenzymes are used to establish a proton gradient. The natural dissipation of this gradient is coupled to the production of ATP from ADP.
ex. ETC
Major cofactors involved in central metabolic pathway
NADH
NADPH
FADH2
FMNH2
Metabolic need for oxygen
Oxygen takes up H+ making a gradient for the ETC.
Final e- acceptor
Kwashiorkor
Adequate total calories with deficiency in protein content
Marasmus
Inadequate calories with respect to protein and carbohydrate
pyruvate -> lactate (enzyme and cofactor used)
pyruvate dehydrogenase (NADH -> NAD+)
Where does glycolysis, pyruvate oxidation of acetyl CoA, Kreb cycle, and ECT occur
cytosol
matrix of mitochondria
matrix of mitochondria
intermembrane space
Thermogenin (UCP-1)
acts as an uncoupler in brown adipose to provide heat
DNP
unnatural uncoupler that binds H+ in high concentration and release H+ at low concentrations
Rotenone
Cyanide and carbone monoxide
oligomycin
complex I
complex III
ATP synthase
Thiamine
B1
part of pyruvate dehydrogenase complex
Niacin
B3
component of NAD (contains part that gets reduced)
Pantothenic Acid
B5
component of CoA
Cobalamin
B12
one carbon carrier
stored in the liver
Absorption of B12
- R-binders (gastric mucosa) bind B12 and are carried to small intestine where protease (pancreases) break down R-binders releasing B12 so intrinsic factors (parietal cells) can bind to B12 and the complex can be absorbed in the ileum
- intrinsic factor unbinds B12 in blood where transcobalamin binds B12 and carries it to liver (storage) or other tissues (use)
primary protein bond
covalent
secondary protein bond
hydrogen
Tertiary and Quaternary bonds
hydrogen bonds, LDF, Salt bridges, disulfide bonds
Phosphorylation post translation modification (amino acids and why)
add phosphate to serine, threonine, and tyrosine
-OH group on the side chain undergoes condensation reaction with phosphate
Glycosylation post translation modification
attach N (asparagine) or O (serine threonine and tyrosine) to amino acid side chain
Ubiquination post translation modification
add ubiquitin to lysine residue of a target protein for degradation
Cofactor
An inorganic or organic molecule require by a protein for activity (e.g. Zn++)
Coenzyme
An ORGANIC cofactor (e.g NAD, FAD)
Prosthetic group
a tightly bound co-factor (e.g. Heme) that is COVALENTLY bonded
Forces that stabilize proteins (covalent and non covalent)
Covalent: disulfide
Non covalent: H bonds, Ionic (salt bridges), Hydrophobic
How do reducing agents denature proteins
they break sulfide bonds
Denaturing of proteins
Heat pH Organic solvents Detergents Ionic Strength Reducing agents (break disulfides) Mechanical stress (shaking)
Lysosomal Protein Turnover
EXTRACELLULAR proteins taken into cell and shuttled to lysosome where they are broken down by proteases called CATHEPSIN (cysteine derivative)
The Ubiquitin-Proteosome Pathway
INTRACELLULAR proteins are tagged by 4 ubiquitin at a lysine residue and carried to proteasome were they are degraded and recycled
-(ATP dependent process)
Metabolic acidosis
Low pH
Low HCO3-
-Increased production of metabolic acids (eg. lactate from anaerobic respiration) (low o2) or failure to excrete acids (kidney problems)
Metabolic alkalosis
High pH
High HCO3-
Respiratory acidosis
Low pH
High CO2
-hypoventilation (shallowing breathing)
Respiratory alkalosis
High pH
Low CO2
-hyperventilating
Ferrous
2+
Ferric
3+
Cooperativity bindig
as more oxygen binds to Hb the affinity for oxygen increases (sigmoidal curve)
Bohr effect
Higher CO2 (lower pH; tissue side) -> O2 affinity drops -RIGHT SHIFT
Where does CO2 and 2,3 BPG binds on Hb
- terminal amine (not heme)
- middle negative region (squeezes O2 out)
Haldane effect
high affinity for CO2 decreases when high O2 concentrations
why does HbF have a higher affinity for HbA
2,3 BPG cant bind to HbF
Hydroxyurea
medication used to induce more HbF in sickle cell pateints
sickle cell anemia cause
Glutamate (negative) -> valine (no charge)
Cyanosis
is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface having low oxygen saturation.
Left shift and right shift in sigmoid curve caused by
carbon monoxide poisoning and Bohr effect
hydrolase
A + H2O -> B + C
Oxidoreductase
catalyzes oxidation or reduction reactions
Lyase
cleaves C-C, C-S, or C-N bonds
Transferase
Ax + B -> A + Bx
Isomerase
two compounds with same formula but different arrangements
Ligase
A + B -> AB
allosteric reg. binds
non covalently at a site away from active site (allosteric site)
Acetylcholinesterase catalytic triad
serine histidine and glutamate
Uncompetitive inhibitor
Inhibitor binds ES but ONLY WHEN active site is occupied by substrate.
Suicide inhibitor
bind to active site (covalently), modifying active site
α-amylase
cleaves α-1,4 linkages between glucose residues
-Product: Dextrins (linear and branched oligosaccharides)
Pancreatic α-amylase
cleaves α-1,4 linkages
- Product: dissacharides (maltose, isomaltose), trisaccharides (maltotriose), oligosaccharides (limit dextrins)
Sucrase-isomaltase
splits sucrose, maltase, maltotriose, dextrins
Lactase
hydrolyzes ß-1,4 bond of glucose and galactose
Sucrase
hydrolyzes α-1,2 bond of glucose and fructose
Maltose =
glucose + glucose
Lactose =
galactose + glucose
Lactose intolerance
Lactase Deficiency
Glycogen polymer form and why
polymer of (α1,4)-linked glucosyl units with (α1,6)-linked branches every 8-12 residues.
- Minimizes osmotic effects of intracellular glucose
- The highly branched structure permits rapid glucose release from glycogen stores
GLUT1
RBC
GLUT2
Liver & pancreatic B cells (insulin release)
GLUT3
Brain
GLUT4
Skeletal muscle & adipose
-insulin responsive
GLUT5
Fructose transporter in intestine luminal epithelium and sperm
Mutarotation
Beta glucose (break) Alpha glucose
PRPP is used in
- De novo synthesis of both purine & pyrimidine nucleotides
- The salvage of both purine & pyrimidine bases
- The synthesis of NAD from tryptophan
Inhibitors and activators of purine synthesis?
Inhibitors: AMP ADP GMP ATP GDP GTP
Activator: PRPP
Lesch-Nyhan Disease
Deficiency in HGPRTase
Purine synthesis
ribose sugar -> phosphate -> base
Hereditary Orotic Aciduria
(high level of orotic acid)
-Orotate phosphoribosyl transferase def.
Thioredoixin
UDP -> dUDP then dUMP -> dUTP through folate cycle
Thioredoixin
UDP -> dUDP then dUMP -> dUTP through folate cycle
phospholipase 1
cleave at sn1
phospholipase 2
cleaves at sn2
phospholipase C
cleaves phosphate closer to sn3
phospholipase D
Cleves phosphate closer to charged head group
HMG-CoA pathway
makes cholesterol
7-a-hydroxylase
makes bile salts out of cholesterol
VLDL
takes TAGs from liver to tissue (endogenous)
Chylomicron
take TAGs from intestine to liver (exogenous)
LCAT
in HDL takes cholesterol -> cholesteryl ester
-keeps cholesterol gradient
ApoCII
activates LPL (tags -> glycerol + FA)
glycerolkinase
take glycerol from VLDL and chylomicron to make TAG
acetyl CoA carboxylase
FAs synthesis rate limiting enzyme
-needs B7 (biotin)
Thromboxane
- TXA2
- promates aggregation of platelets and vasocontriction
- COX1
- inhibits prostacycylin
Prostacyclin
- PGI2
- inhibits platelet aggregation and stimulates vasodilation
- COX2
Leukotrienes
- mediate allergic response inflammation
- 5LOX
NSAIDS inhibit
COX1/2
Tocopherols (vitamin E)
stabilize lipid membrane by reacting with ROS
Sphingolipids
myelin sheath lipid membrane
Phosphatidyl Inositol
inositol connected to C3 of DAG (IP3 messenger -> PLC (Ca2+ release))
Cardiolipin
stabilizes ETC complexes
Depolarization
decrease Vm
Hyperpolarization
increase Vm
I = G (V - E)
Current = Conductance (Driving Force)
Driving force = membrane potential - equilibrium potential
permeability = conductance
- Na higher driving force than K
Intracrine
signals are produced by the target cell that stay within the target cell. Example: secondary messengers
Autocrine
signals are produced by the target cell, are secreted, and affect the target cell itself or a near by cell of the same type via a receptor. An example of this are immune cells.
Paracrine
signals target cells in the vicinity of the emitting cell. E.g. neurotransmitters.
Endocrine
signals target distant cells. Endocrine cells produce hormones that travel through bloodstream to reach all parts of the body. E.g. hormones.
Juxtacrine
signals target adjacent (touching) cells. These signals are transmitted along cell membranes via protein or lipid components integral to the membrane and are capable of affecting either the emitting cell or cells immediately adjacent. E.g. gap (tight junctions, notch signaling, etc).
GEF
GDP -> GTP
GAP
GTP -> GDP
Phosphodiesterase
breaks down cAMP
RTK mutations
- RTK: becomes dimerized and phosphorylated with out ligand bound
- Overexpression: large amount of kinases in the membrane
- Activating mutation: produce a product that mimics phosphorylation or conformational change of kinase
kB inhibits
NFkB (inflammatory response)
Philadelphia chromosome
BCR-ABL (ATP) complex -> phosphorylated and disassociates causing cell proliferation
graded potential vs action potential
- summation (cell body)
- all or nothing (axon hillocks)
Conduction Velocity of the Action Potential
Diameter of axon
Myelination
Resistance
2 Types of Synapses
-Chemical synapses use neurotransmitters (most!)
One way transmission
-Electrical synapses pass electrical signals via gap junctions.
Often both directions
Eye
Postsynaptic Effects
-Alter chemically gated ion channel (open or close)
EPSP (excitatory)
IPSP (inhibitory)
-Activate 2nd messenger systems
1. Open specific ion channels on the postsynaptic membrane
2. Activation of cAMP or cGMP
3. Activation of one or more intracellular enzymes
4. Activation of gene transcription
classic neurotransmitter inhibitors
GABA
glycine
MAO
breaks down serotonin (5 HT)
Choline acetyltransferase
makes acetylcholine out of choline + acetyl CoA
Inactivation of Neurotransmitters
glial cells
enzymes break down neurotransmitters
diffuse out of synaptic cleft to blood stream
Spatial Summation
net sum of inputs spatially (surface area) on the presynaptic neuron determine the level of excitability.
Temporal Summation
net sum of inputs per unit of time on the presynaptic neuron determine the level of excitability.
effect of acidosis on neuro
depresses neuronal activity (Na+ (in) exchanged for H+ (out))
-high H+ outside no exchange for Na+ and
effect of alkalosis on neuro
increases neuronal excitability
C peptide (insulin)
proinsulin contains C peptide and when C peptide is cleaved out to make mature insulin
Fasting state AMP vs ADP
more AMP than ADP in fasting state because of adenylate cyclase enzyme reaction
Adenylate cyclase
ADP + ADP = AMP + ATP
Acetyl CoA carboxylase activator and inhibitor
activator: citrate
inhibitor: palmitoyl CoA (A CoA carb is phosphorylated)
Where do e- leak from
I and III not IV
myeloperoxidase
makes bleach (literally, HOCl) from H2O2 + Cl-
NO normally involved in vasorelaxation via
soluble guanylate cyclase
Constitutive isoforms
vasorelaxation
Inducible isoform
iNOS (NOS2), in macrophages and microglia (brain macrophages)
Nrf2/Keap1
Nrf2 disassociated in stress times (inc ROS) and promotes antioxidant
Cori Cycle
lactic acid taken in by the liver and made back into glucose
beriberi (Wernicke-korsakoff syndrome)
B1 def (a-ketoglutarat dehydrogenase)
pelagra
B3 (NADH)
Sulfonylurea
blocks K+ leak channels in pancreatic B cells causing depolarization and release of insulin
Malate-Aspartate Shuttle
OAA -> malate in cytosol (NADH -> NAD)
Malate -> OAA in mitochondria (NAD -> NADH)
Glycerol 3P Shuttle
Cytosol: DHAP -> Glycerol 3-P (NADH -> NAD+)
Mitochondrial membrane: Glycerol 3-P -> DHAP (FAD -> FADH2)
Pyruvate Dehydrogenase Complex
Pyruvate -> Acetyl CoA
- Irreversible reaction
- occurs in mitochondrial matrix
- releases CO2
Pyruvate Dehydrogenase Complex uses 5 cofactors
TPP (B1), lipoate, FAD (B2), NAD+ (B3), and CoA (B5)
When energy level of the cell is high or oxygen is lacking, PDC activity is
turned off
pyruvate carboxylase
pyruvate -> OAA
- occurs in mitochondria
- requires CO2 (biotin)
Acetyl CoA effect on PDH and Pyruvate carboxylase
(- PDH)
+ pyruvate carboxylase
von Gierke disease
Glucose 6-phosphatase deficiency
-glycogen stuck in the liver
Glycogenesis enzyme
synthesis of glucagon
-glycogenin
glycogenolysis
Glycogen degradation
Sympathetic Innervation Only (non-dually innervated)
- Arteriolar smooth muscle – blood pressure
- Kidney – body fluid balance and blood pressure
- Sweat glands
- Adipose (lipolysis)
- Clotting
alpha 1
Smooth muscle contraction (NE>EPI)
alpha 2
Also presynaptic inhibition of NE release (NE>EPI)
beta 1
Cardiac, renin release from kidney, lipolysis (NE=EPI)
beta 2
Smooth muscle relaxation (EPI» NE)
Sympathetic Branch: Stimulation
Pupil dilation (mydriasis) Dry mouth Sweat production Increased heart rate & force of contraction Bronchiole dilation Fuel mobilization (glucose, lipolysis) Blood vessel constriction Coagulation Ejaculation/orgasm
Sympathetic Branch: Inhibition
Increased digestion Pancreas secretion Urination Slow heart rate Reduce blood pressure
Adrenal Medulla Primary neurotransmitter
Epinephrine (80%)
NE 20%
Parasympathetic Branch: Actions
Digestion Salivation Insulin release Urination Erections (arousal)
what does the vagus nerve not innervate
eye
Organophosphate poisoning causes
S.L.U.D.G.E.(M)
-Salivation, lacrimation, urination, defecation, gastrointestinal, emesis, muscle spasm/miosis (pinpoint pupil)
Parasympathetic Branch: Inhibition
Inhibit digestion
Reduces secretory functions (dry mouth)
Increases heart rate
stress sweat gland vs thermoregulation sweat gland
stress: alpha 1
thermo: muscarinic
alpha 1 g protein cascade
inc IP3/DAG -> inc Ca2+ ->vasoconstriciton
beta 1
inc cAMP -> inc HR
-key to increase HR
Inc. NE (bp)
Inc. bp (more alpha than beta but beta has higher affinity for NE)
Dec. NE (bp)
Dec. bp (more alpha than beta but beta has higher affinity for NE)
b stimulation to lung and heart
bronchodilation
inc HR
Helicase
separates the helix by breaking the hydrogen bonds between complementary bases
SSBP
prevent reannealing of the duplex
Topoisomerase
prevents supercoiling
Primase
lays down the RNA primer
DNA Pol I
replaces the RNA bases of the primer with DNA bases
Ligase
facilitates the formation of phosphodiester bonds and joins Okazaki fragments.
shelterin
protein complexes that specifically bind to telomeric DNA repeats and protects them from being recognized by DNA repair proteins
exonuclease activity
-3’-to-5’
-Replication errors produce a DNA mismatch and inability of the mismatched bases to form the appropriate H bonds
This leads to displacement of the 3-OH into the 3-to-5 exonuclease “site” of the enzyme
MYH glycosylase
- Base excision repair
- Damaged base is recognized and cleaved leaving a sugar with no base attached in the DNA
Poly-ADP-ribose polymerase (PARP)
binds to the strand break and recruits other repair proteins.
Nucleotide Excision Repair is used to fix
UV radiation thymine dimers
Nonhomologous End Joining occurs in what type of cell
non dividing
Homologous Recombination Repair occurs in what type of cell
actively dividing
HATs vs HDAC
transfer ACoA to lysine removing lysine
pos. charge (DNA unwind)
Methylation
- This favors the incorporation of DNA into heterochromatin (tightly packed, no transcription)
- associates with the 6’ carbon of cytosine and adds a methyl group to the 5’ carbon
- can be passed down
Heat shock protein
cortisol has higher affinity for glucocorticoid receptor than HSP
-TAD binds coactivators, DBD binds the hormone response element of the DNA, ultimately leading to transcriptional activation of response genes
eIF3 and reg
prevents premature association of 40S and 60S subunits
-inactive when phosphorylated (times of stress)
eIF2-GTP
binds to initiator tRNA
eIF4 and reg
bound to mRNA join 40S subunit
-activated by insulin
Peptidyl transferase
catalyzes peptide bond formation between amino acids attached to tRNAs at the P and A sites, elongating the polypeptide and transferring it to the tRNA at the A site
eEF2
translocates the ribosome, moving it three nucleotides toward the 3’ end of the mRNA
stop codons
UAA, UAG, UGA
Release factors (RF)
bind a stop codon in the A site
Tetracyclines, including doxycycline
prevent the binding of aminoacyl-tRNA by blocking the A (aminoacyl) site of the 30S ribosome
Aminoglycoside antibiotics (Streptomycin Kanamycin and tobramycin)
have an affinity for the 30S ribosome subunit
Erythromycin, roxithromycin, and clarithromycin
all prevent elongation at the transpeptidation step of synthesis by blocking the 50S polypeptide export tunnel
Lincomycin and clindamycin
are specific inhibitors of peptidyl transferase
Diphtheria toxin
inactivate eukaryotic elongation factor eEF2, thereby inhibiting eukaryotic protein synthesis
Proto-oncogenes mutations
Mutation in coding region
Regulatory region
Translocation novel protein
Gene amplification
BAD
- proapoptotic
- phos by Akt (inactive)
P53 and stimulates
gardian of the genome
-stimulates p21 is a universal cyclin/cdk inhibitor (CKI), it prevents the phosphorylation of Rb, keeping Rb bound to E2F
Rb
sequesters the transcription factor E2F
- Ras/Raf leads to induction of transcription of cyclin D
- Cyclin D binds to CDK4/6
- Cyclin D/CDK4/6 phosphorylates Rb
- Rb changes conformation and releases E2F
MDM2
tags P53 for degradation when DNA is successfully repaired
BAX
stimulated by P53 and causes apoptosis
β-catenin and APC
APC bind β-catenin causing APC degradation
-when not bound to APC β-catenin catenin translocates to the nucleus and activates transcription of myc and cyclin D
Autosomal Recessive Inheritance
- The disease is not usually seen in each generation, but if an affected child is produced by unaffected parents, the risk to subsequent children is ¼
- The sex ratio of affected offspring is expected to be equal
- If both parents have the disorder, all children will have it
Autosomal Dominant Inheritance
- Each individual who has the disease has at least one affected parent
- Fathers can give to DAUGHTERS and SONS
- Males and females are affected in equal numbers
Huntington’s disease is
Autosomal Dominant Inheritance
-late onset
Xeroderma pigmentosum is
Autosomal Recessive Inheritance
Hemophilia A is
X-linked Recessive Inheritance
X-linked Dominant Inheritance
Males cant pass X linked trait to son
but all daughters will be effected
Congenital hypertrichosis is
X-linked Dominant Inheritance
Mosaics
is a type of genetic mosaicism where more than one set of genetic information is found specifically within the gamete cells
-effects child but not parent
Apical epidermal ridge
Initiates proximally, grows distally
Proximal elements (humerus, femur) form before distal elements (radius/ulna, tibia/fibula)
-secretes FGF8, FGF4
-problem limb will grow in wrong place
paraxial mesoderm
All axial and appendicular skeletal muscles, and all of the skeleton except the cranium
surface ectoderm
Limb skin, hair, skin glands, and nails
Wnt mutations can cause
osteogenesis imperfecta
Zone of Polarizing Activity (ZPA)
-Determines A-P axis of limb bud
-Sonic hedgehog (Shh or SHH) is strongly expressed at the ZPA
-
Upper limb rotates
dorsally (laterally)
-week 8
Lower limb rotates
ventrally (medially)
Week 5 Week 6 Week 7 Week 8
Week 5: limb bud and plate
Week 6 notches between webbed fingers
Week 7: short fingers slightly webbed
Week 8: fingers and toes separated
blood supply to growing arm
axial artery
Meromelia
Can be caused by HOX mutations
Synaptotagmin
binds Ca2+
Synaptobrevin
bound to vesicle
RYR1 receptor
found in skeletal muscle SR
-DHPR bound to RYR
RYR2 receptor
found in cardiac muscle SR
Twitch vs Treppe
-single stimulation of a muscle fiber
-staircase increase in muscle contraction as more and muscle fibers are stimulated
increase in force produced with each contraction
Tetanus vs tetany
tetanus is fatigue caused by bacteria while tetany is fatigue caused by excursion
Longer muscle length
greater velocity and less force
Shorter muscle length
less velocity and greater force
Slow vs Fast twitch
Slowest Type 1 < Type 2a < Type X < Fastest Type 2b
Greatest tension (force) occurs between
100-120%
myosin light chain phosphatase
removal of phosphate from myosin light chain and
resulting decreases in actin-myosin
cross bridging
myosin light chain kinase
phosphorylates myosin during SM contraction
Cardiac Muscle force electrical carried via
Desmosomes allow force to be transferred Gap Junctions (connexions) provide electrical connection
preload
inc length of muscle = inc preload
afterload
inc after load = dec contractility
contractility
NE and EPI: inc contractility
Ach: dec contractility
Vernix caseosa
Periderm cells and sebum make up
-protect baby from abiotic fluid
fingerprints
Epidermal ridges produce grooves
Ichthyosis
Skin is characterized by dryness and fishskin-like scaling (lizard)
what all are associated with the hair follicle
- sebaceous gland
- appocrine sweat glands (axilla and pubic)
Eccrine sweat glands
alone sweat gland
lanugo hairs
Help hold vernix caseosa on the skin, which protects the skin
Alopecia
bald spot
lamellar granules
- Their water-resistant glycolipid slows water loss
- in stratum granulosum
Skin physical barrier
resistance to mechanical stress and absorption/evaporation of substances (water)
-Keratin and glycolipids block most water and water- soluble substances
skin Chemical Barriers
-Skin secretions Low pH retards bacterial multiplication Sebum and defensins kill bacteria -Melanin Defense against UV radiation damage
Skin Biological Barriers
-Dendritic cells of epidermis Present foreign antigens to white blood cells -DNA Its electrons absorb UV radiation Radiation converted to heat
↑ Body Core temp
Thermoreceptors in hypothalamus (primary driver) and skin (secondary) respond -> ↑ cholinergic stimulation -> vasodilation of blood vessels in dermis
↓ Body temp
Thermoreceptors in hypothalamus (primary driver) and skin (secondary) respond -> ↑ adrenergic stimulation -> vasoconstriction of blood vessels in dermis
type I keratin
acidic keratins (contain acidic acids)
type II keratin
basic keratins (contain basic amino acids)
Transglutaminase
lysine + glutamine forms amide bond
- gives structural stability to keratins int. filaments
- doesn’t just happen in keratin
tyrosine hydroxylase
enzymes used to convert tyrosine to melanin
-Cu2+ dependent
phenylalanine hydroxylase
phenylalanine -> tyrosine (BH4 dependent)
Melanin production
P53 -> POMC -> B endorphins and a MSH (MC1R) -> inc cAMP -> MITF -> pigments
