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Chemistry > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

where are proteins synthesized

A

-in the liver

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2
Q

what are the functions of proteins

A

1.catalyzing reactions - enzymes
2.transport metals - Fe Cu
3.hormone receptor- thyroid/steroid receptors
4.structure and support- Collagen
5.part of immune response - AB
6.coaugulation - fibrinogen
7.maintaining oncotic pressure - albumin

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3
Q

what is the protein composed of?

A

C- CARBON
H-hydrogen
O-Oxygen
N-Nitrogen
S-Sulphur

proteins are made up of amino acids

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4
Q

what are differences in proteins determined by

A

-number of amino acids
-sequence of amino acids
-the way the protein is folded
-chemical properties

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5
Q

how many AA are there

A

-there are 9 essential dietary intake
-6 semi essential - premies cannot make them so they may be given them
-6 non essential and made by the body

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6
Q

what is the structure of amino acids

A

1 amino acids has 1 amino group (NH2) and 1 carboxyl (cooh)

-has one r group (side chain - creates the functionality) and hydrogen atom

-the NH2 and COOH are attached to the alpha carbon atom (the middle carbon)

  • have a ball and stick model
    -are tetrahedral structures
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7
Q

What is the chiral carbon

A

-amino acid structure 4 groups are attached
-the alpha carbon is asymmetric in all amino acids except glycine
-the alpha carbon is known as the chiral carbon since 4 groups can attach themselves to it
-meaning it is optically active
-can exist as enantiomers or optical isomers

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8
Q

what is an enantiomer

A

-D and L forms of amino acids
-they are mirror groups but not superimposable
-D form is dextrorotatory clockwise
-L form levorotatory- rotating counterclockwise
-lights is rotated through the fluid

all naturally occurring

amino acids in nature are in the L form

LOOK AT SLIDE

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8
Q

What are the amphoteric properties of AA

A
  • aa ionize in solution which can yield a zwitterion

-can act as acid or base
-Acids donate H+ COOH is donor (cation)
-base accepts H+ - NH2 is an acceptor (anion)

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9
Q

what is the isoelectric point

A

-pH when aa has net zero charge
-equal pos and neg charges
-molecule is dipolar - ampholyte (can be pos OR neg)
-each aa has different IEP

adding acid -net pos
adding OH - net basic

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10
Q

what is a buffer

A

-needs weak acid/base with corresponding salt
-aa and proteins are buffers

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11
Q

what classifies an amino acid

A

R group
and groups of non polar and polar

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12
Q

what is a non polar AA

A

-hydrophobic
-9 amino acids

Aliphatic - r group is a straight chain

aromatic- has benzene/aromatic rings

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13
Q

What is a polar amino acid

A

Neutral - the cooh=amino groups
-contain hydroxy, sulfur or amide R–C=O
-not charged
-polar side chains making them hydrophilic

Acidic-more cooh than amino
-2 amino acids
-highly polar, negatively charged at physi pH

Basic - more amino than cooh
-3 amino acids
-contains an amine NH3
-side chain is positively charged
-heterocyclic - ring structure with O or N

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14
Q

what are peptides and how are they formed

A

-amino acids are joined together through amide linkages called peptide bonds

-amide is NH-C=O (the bond between the N and C)

formed through covalent bonds via reactions like condensation

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15
Q

how are polypeptides named*** learn how

A

-the amino group NH2 that joins for the peptide bond keeps their full name
- if a cooh is supplied it ends with yl

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16
Q

what is the primary structure of protein

A

-linear linked by peptide bonds - genetic code
-number and sequence determine shape and function
-info contained in DNA
-aa substitutions can cause mutations

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17
Q

what is the 2ndry structure of proteins

A
  • aa in chains start folding
    -3D shape through bends and coils
    -becomes a alpha helix shape that is stabilized by intrachain hydrogen bonds between aa and cooh
    -parallel or anti parallel strands
    -no R group involvement
    intrachain H bonds are weak
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18
Q

what is the tertiary structure of proteins

A

-2ndary structures that condense to form the tert structure
-3D globular shape from the folding and bending of the helical coil
-structures stabilized by R group interactions***
-salt linkages
-van der waals forces
-dipole - dipole interactions
-disulfide linkages
-the hydrophobic groups get clustered in middle leaving the philic chains outside
-enzymes
-final form for some

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19
Q

What are quaternary structures of proteins

A

-more than one folded unit, singles all joined together
-joined by non covalent bonds (ionic, hydrogen, dipole-dipole)
-like hemoglobin 4 polypep chains and 4 heme groups carries O

20
Q

what is denaturation

A

-change that alters protein shape while leaving peptide bonds intact
-irreversible
-decreases solubility
-increases susceptibility

21
Q

what are forms of physical denaturation

A

shaking
* H bonding disrupted by
agitation

heating
60-70°C

UV rad
* high frequency
vibration breaks H bonding
* sterilization

microwave

22
Q

what are forms of chemical denaturation

A

-organic solvents like alcohol or acetone which disrupt intra H bonds by forming intermolecular H bonds with protein

pH extremes -
acidic/basic conditions - disrupt H and diS bonds
- strong acids can degrade protein
- proteins precipitate when IEP is reached

salts of heavy metal
- salt linkages are disrupted and proteins end up precipitating out of solution

-reducing agents - break s-s bonds

23
Q

what is the hydrolysis of proteins

A

-when covalent bonds are cleaved by addition of water molecules
- the primary structure is destroyed
-results in constituent aa
-denaturation makes proteins more susceptible to hydrolysis

-strong acids or bases and high temps can cause complete hydrolysis resulting in amino acids

enzymes like proteases, trypsin, chymotrypsin neutral pH and body temperature partake in incomplete hydrolysis which gives peptides and aa

24
Q

What are simple proteins

A

-only have aa
-major plasma prots are ALB and GLOB

ALB- soluble in water, transports non water soluble constituents and can be analyzed seperately. most amounts

GLOB- not soluble in water but solube in dilute salt solutions, 4 types

25
Q

what are conjugated proteins

A
  • have a non protein prosthetic group

lipoprotein = aa + CHOL, TRIG

glycoprotein = aa + CARB

nucleoprotein = aa + DNA/RNA

Phosphoprotein = AA + po4

Chromoprotein = AA+ pigmented group

metalloprotein = aa + metal group

26
Q

What does protein solubility depend on

A
  • particle size
    you can have true solutions (smallest), colloidal (middle), suspension -biggest
27
Q

what are true solutions

A

smallest size
-homogenous mixture
-no settling
-cant be filtered
-diffuses across membranes
-forms crystalloids

URINE

28
Q

what are suspensions

A

-biggest size can see with your eyes
-solute is insoluble in a solvent
-settles out
-can separate from solvent by filtration

BLOOD

29
Q

What are colloids

A

-middle sized
-solute is insoluble but still doesnt settle out
-globular particles (colloid) that are disperse evenly
-colloid is dispersed phase and solvent is dispersion medium

-called a colloid dispersion

MILK

30
Q

what are the two properties of colloids

A

Brownian movement

Tyndall effect

31
Q

What is the Brownian movement

A

slow , random erratic movement of colloidal particles as they are hit by solvent particles (dispersion medium)
-not seen in true solutions
-non motile bacteria

32
Q

what is the tyndall effect

A

-the visibility of light passing through a colloidal dispersion
-used to quantitate proteins
-not for true solutions

33
Q

What are lyophobic/lyophilic colloids

A

Lyophobic
-solvent hating
-hydrophobic
- C and H only on side chains

Lyophilic
- solvent loving
-hydrophilic
-O and N on side chains can form H bonds

34
Q

how do colloids work in dialysis

A

-diffusion (movement of particles from high to low across a semi perm membrane)
-plasma proteins would be the colloids retained in blood
-small MW waste is removed (k, cr, urea)

35
Q

do proteins carry an electrical charge

A

-they do except when at their IEP
-charge through side chain ionization
-replusive forces keep them in solution
-attract a water shell

-proteins are least soluble when molecules aggregate leading to precipitation

-all proteins are negatively charged in plasma 4.7-7.2 while blood is 7.35-7.45

36
Q

why is salt concentration of a solution important

A
  • can make water shell larger or smaller
37
Q

What is salting in

A

low salt concentration increases protein solubility
-salt ions attracted to protein
-water molecules attracted to salt charge increasing water shell

38
Q

what is salting out**

A

high salt concentration decreases protein solubility
-very high ionic strength
-salt ions attract water to themselves
-decreases water shell

39
Q

what precipitate proteins

A
  • to clean up the specimen of any proteins that could interfere with the chemical reaction - foaming, turbidity, light scatter

-reversible: proteins are not denatured and fuction is restored once the agent is removed

40
Q

zwitterion

A

molecule with both a negative and positive charge,
the net charge is zero at specific pH

41
Q

ampholyte

A

compounds that when dissolved in water (which is itself an amphoteric compound) can act either as acid or as a base

42
Q

hepatic damage, burns, trauma, infections

A

albumin ↓, globulin ↑ (total protein N, ↓)

43
Q

malabsorption

A

albumin ↓, globulin ↔

44
Q

multiple myeloma

A

albumin ↔, globulin ↑

45
Q

Wilson’s disease

A

ceruloplasmin ↓

45
Q

iron deficiency anemia

A

transferrin ↑

45
Q

myocardial infarction

A

CK-MB ↑, myoglobin ↑, troponin I ↑

Chemistry (12 decks)

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