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66 Cards in this Set

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  • Back
Name and describe 6 dietary components
1.Carbohydrates - NOT required in diet, liver can synthesize from other sources
2.Fats - 2 essential fatty acids are required in the diet - LINOLEIC and LINOLENIC acids
3.Protein- required to sustain life, there are 10 essential amino acids in children (9 in adults)
4.Vitamins - cofactor for enzymatic reaction,some act as hormones (A, D)
5.Minerals- maintain electrolyte balance (Na and K), provide structure (Ca and P)
6.Water- universal solvent
Whats the name of the process that generates energy
Whats the name of the process that uses energy for biosynthetic reactions
Glycogen is the storage form of what?
Carbohydrates, glycogen and starch are very similar in structure, glycogen is stored in animals, starch in plants
-consists of monomeric units of glucose in chains
Where is glycogen stored?
Triacylglycerol is a storage form of what?
Where is triacylglycerol stored?
In healthy individual stored in adipose tissue
Protein is a storage of what?
Amino acids, consists of amino acids linked together by PEPTIDE bond - very strong bond
How many essential amino acids? Name them
10 (9 in adults)
Amount of energy produced by oxidizing carbohydrates
4 kcal/g
Amount of energy produced by oxidizing proteins
4 kcal/g
Amount of energy produced by fats
9 kcal/g
Amount of energy produced by alcohol
7 kcal/g
Describe general structure of amino acid
-Contain a CARBOXYL group, AMINO group and SIDE CHAIN, all attached to alpha carbon
-xcept GLYCINE (no side chain) and PROLINE (N part of the ring)
What is the usual configuration of amino acids (L or D)
L (except GLYCINE which is neither L nor D, because its not optically active and does not rotate polarized light)
What is the ionization of carboxyl and amino group of amino acids
At physiologic pH, amino acids carry a positive charge on their amino groups and a negative charge on carboxyl groups
Name 20 amino acids and their abbreviations
Alanine (Ala)
Arginine (Arg)
Asparagine (Asn)
Aspartate (Asp)
Cysteine (Cys)
Glutamate (GLu)
Glutamine (Gln)
Glycine (GLy)
Histidine (His)
Isoleucine (Ile)
Phenylalanine (Phe)
Proline (Pro)
Serine (Ser)
Tyrosine (Tyr)
Valine (Val)
Name non polar aliphatic amino acids
1. GLYCINE - simplest amino acid, doesnt have an R group, only H
6.PROLINE-N is part of the ring
Isoleucine, leucine, valine and alanine all have non polar bulky hydrophobic side chains. Electrons are shared equally between C and H, so there is no H bonding with water.
Name aromatic amino acids
Aromatic amino acids have 6 membered rings and 3 double bonds
Phenylalanine has no substituents on the ring so its hydrophobic (nonpolar)
Tryptophan has N as a substituent on the ring so it can H bond with water and therefore is polar hydrophilic
Tyrosine has OH group on the ring and is also polar hydrophilic
Name aliphatic, polar, uncharged amino acids
Those are amino acids whose side chain is an amide - ADPARAGINE and GLUTAMINE or hydroxyl group - SERINE and THREONINE
Name sulfur containing amino acids
-Cysteine has SH as a substituent and can react with another cysteine and form CYSTINE through disulfide bonds
Methionine has only S as a substituent and cant form disulfide bonds
Which amino acids are acidic
Negatively charged amino acids - ASPARTATE and GLUTAMATE
Which amino acids are basic
Positively charged amino acids - ARGININE, LYSINE, HISTIDINE
What is the main function of an amino acid in the protein
it forms PEPTIDE BOND, covalent bond between alpha carboxyl group of one amino acid and alpha amino group of next one
What does linear sequence determine in protein
LINEAR SEQUENCE determines 3D structure of the protein and its biological properties
What determines function of the protein
3D structure
Whats a primary structure of the protein
Sequence of amino acids along polypeptide chains

Whats a secondary structure of a protein
various types of local conformations in which atoms of side chains are not involved
Define tertiary structure of protein
Overall 3D conformation
Quaternary structure of a protein
Spatial arrangement of subunits in a protein that consists of more then one polypeptide chains, subunits are joined together by NONCOVALENT INTERACTIONS (same as 3D)
Name 3 types of proteis
Describe fibrous proteins
-structural or mechanical roles
-polypeptide chains interwined to form fibers
-example - hair, fur, skin
Describe globular proteins
-functional, non-structural
-chains folded on itself to give compact, rounded structure
-most are water soluble
-example - enzymes, antibodies, transport proteins
Name two types of H bonding in secondary structure of protein
Intramolecular - between different parts of same chain - ALPHA HELIX
Intermolecular - between different chains- BETA PLEATED SHEET
What stabilizes secondary structure of protein
H bonding between carbonyl oxygen of one peptide bond and amino hydrogen of another
Alpha helix
common in globular proteins, membrane spanning proteins and DNA binding proteins
-has stable rigid conformation
-carbonyl of peptide bond interacts with NH of peptide bond four amino acid residues along the chain
Beta Sheet
-H bonding occurs between neighboring strands running parallel to each other
Describe structure of keratin
-strong rope like structure of interwined ALPHA HELIXES
-major component of external protective layer
-skin, hair, nails
What is the difference between hard and soft keratins
-HARD KERATINS have high sulfur content and form many S-S bonds between chains
-SOFT KERATINS have low sulfur content and very few S-S bonds between chains
Describe structure of collagen
-consists of THREE CHAINS that wind around each other to form a TRIPLE HELIX
-Collagen contains about 1000 amino acids, 1/3 of them is GLYCINE, others are PROLINE, HYDROXYPROLINE, or HYDROXYLYSINE
What offers rigidity to collagen
What is a fundamental unit of collagen
TROPOCOLLAGEN - triple hellical rod, rigid (not elastic like alpha helix), wider then alpha helix to accomodate bulky residues of PROLINE and HYDROXYPROLINE
Describe post translational modification of collagen
-PROLINE and LYSINE are HYDROXYLATED by reaction that requires vitamin C and O2
HYDROXYPROLINE forms H bonds between chains
HYDROXYLYSINE forms covalent bonds between chains
CROSS LINKS are produced and stabilize structure
Name collagen disorders
-SCURVY - defficient collagen
-Osteogenesis imperfecta (brittle bone disease)
-Alports syndrome
-Ehlers-Damons syndrome
-Epidermolysis Bullosa Dystrophica
Describe protein folding
Proteins fold during and following synthesis along same principles as micelle formation - POLAR amino acids on surface, NON POLAR inside
What assists in vivo proten folding
Molecular chaperones (heat-shock proteins) - use ATP energy to change conformation of a protein
Describe domains in proteins
Domains are physically independent regions within overall tertiary structure of large, complex protein.Usually visually obvious, like different regions within molecule
Example - extracellular domain, catalytic doman, transmembrane domain
Describe solubility of globular proteins
Soluble in water, core of globular protein has high content of non polar amino acids, its not in contact with water and its densely packed to maximize van der waals forces.
On the surface of the protein are polar amino acids which are charged which are in contact with water
Describe prion diseases
-Protein conformational disease caused by misfolded proteins
Name forms of prion disease
-genetic (point mutation)
-Bovine spongiform encephalopathy
-Scrapie (sheep)
How are prion diseases acquired
-spontaneous mutation in gene encoding PrPc
-ingesting nervous tissue of infected animals
-injection of human growth hormone
Describe normal and misfolded proteins in prion disease
PrPc is a normal protein foind on surface of neurons
PrPsc is disease form of protein that has same sequence of amino acids but different tertiary structure (3D), it aggregates and is abnormally resistant to breakdown
Describe polymorphism
Variation of primary structure of protein, generally arise from mutations in DNA
Can be without or with consequences (sickle cell disease
-called polymorphism only when there is a significant frequency of population (20-30%)
Describe sickle cell polymorphism
-Different structure of sickle cell Hb tends to polymerize in deoxy form
-Distorts RBC into rigid sickle shape
-Sickle cells are more easily degraded which results in anemia
-Sickle cells tend to block peripheral blood vessels causing ischemia and pain
Define homolog proteins
-Proteins with highly similar sequence
-evolved from same ancestor
Define Orthologs
-From DIFFERENT species
-originated from same gene in ancestor
-normally retain function- insulin is same in humans and pork
Define Paralogs
-from SAME species
-originate from common ancestral gene
-may have differnet functions - myoglobin, different hemoglobin chains
Protein isoforms
-Perform essentially same function
-are highly homologous
-evolved from same ancestral gene
-possess DIFFERENT amino acid sequences and chemical and physical properties
Define isozyme
Proteins isoforms which are enzymes
Structure of hemoglobin
HbA (adult) consists of FOUR POLYPEPTIDE CHAINS each containing molecule of HEME
Chains are SIMILAR in 3D configuration and to single chain of myoglobin, but have DIFFERENT sequences.
Describe function of hemoglobin
OXYGEN SATURATION curve for Hba is SIGMOIDAL. Each HEME binds ONE O2. When O2 binds, HbA changes from T form (taut) to R (relaxed). Binding to one heme increases affinity for others.
What effect does binding of 2,3-BPG have on affinity
DECREASES affinity og HbA for O2, so its more readily released in tissues when its bound
Fetal Hb
-Has LOWER affinity for BPG then HbA, so HIGHER affinity for O2
Define denaturation of proteins
3D structure and biological activity of protiens is lost without breaking peptide bonds
Conditions that can denature proteins
-Extremes of pH
-High temperature
-Organic sollvents (alcohol)
-Salts of heavy metals (mercury)
Describe cystinuria
Normally amino acids are filtered by glomerular capillaries. Cystinuria is a genetic disease where protein is missing that normally responsible for rabsorption of cystine, arginine and lysine from kisneys. So, urine has elevates cystine, which precipitates and forms renal stones