unit 2 carbs lipids proteins enzymes

8/3/2019 Unit 2 Carbs Lipids Proteins Enzymes

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CARBOHYDRATES


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Fatty Acids Long chain hydrocarbons with a terminal

carboxylic acid group

The properties are determined by chain length and

# double bond (saturated or unsaturated)

General formulaCH3(CH2)nCOOH(n is normally an even number)


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Saturated vs Unsaturated Unsatd FA have lower mp than satd(at same length)

Polyunsatd has the lowest mp

Unsaturation causes kinking (less T to separate solid to liquid)


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Shorterchains

have

lower

mp thanlonger

ones


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Other Topics Covered (in text)

Saponification and hydrogenation(stoichiometry)

Determining saponification products


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PROTEINS


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Alpha Amino Acids

The 20 amino acids found in proteins arecalled alpha amino acids (the amino group

is linked to the carbon atom next to theCOOH carbon)

The most important aspect of the sidechains or R groups is their polarity, and

amino acids are classified into 4 groupsbased on polarity

Nonpolar, polar but neutral, acidic and basic


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Should be atotal of 9

* AddPhenylalanineand Tryptophanfrom aromaticslide


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Should be atotal of 6

* Add Tyrosinefrom aromaticslide

Alsocalledpolar

neutral


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BASIC


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ACIDIC


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PENTAPEPTIDE

S G Y A L


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Sickle Cell Anemia

Hemoglobin is a protein with a quarternary structure

(made from 2 similar types of proteins that stick

together)

heme is made of 4 groups (cofactor) globin is the apoprotein

Both subunits must be present for Hb to work (pick

up and release O2)

Carried by red blood cell (gives rbc their color)- picks

up O2 in the lungs and delivers it to the peripheral

tissues to maintain the viability of the cells

Chemical

Connection

14D


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Hemoglobin Made of 4 protein chains (tetramer- 2a and 2b) and

a heme group with Fe (can bind 4 O molecules)

The b subunit is not expressed before birth

g substitutes forb up until birth (2a and 2g)

During fetal development the hemoglobin form is

HbF (transports O2 around the body of developing

baby during last 7 months of pregnancy). HbF binds O2 with greater affinity than HbA (adult

hemoglobin with b)


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HbA starts being made by the baby a few weeks beforebirth

Less and less HbF made after birth and more HbA (HbFnot turn into HbA)

Takes about 2 years for baby to completely switch over

Normal HbF does not mean can make normal HbA

Sickle Cell Disease is caused by abnormal HbA (calledHbS)

Very rare gene alteration (mutation) caused by a varietyof accidents in nature

Genes are inherited so an abnormal Hb (resulting from agenetic mutation) will also produce a modified Hb in theoffspring


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Inherited disease (autosomal recessiveoccurs insomeone who has inherited HbS from both parents

Carriers (trait) just have HbS from one parent (can pass it

on) Caused by point mutation in the beta gene (glu to val) that

produces a structurally abnormal Hb (normal rbc are disc-shaped (crescent)

When oxygen levels are low or [HbS] is high, the HbSclusters together and gives rbc a sickled shape (deformedand rigid)

Sickled rbc get trapped within small blood vessels andblock them (deprive them of oxygen)

Characterized by episodes of pain, chronic hemolyticanemia, severe infections (eventual organ damage-repeated crisis leads to damaged kidneys, lungs, bones,eyes, CNS- downstream organs)

Starts in early childhood


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symptoms Sickled bc are fragile and inflexible

Painful episodes due to blocked blood vessels and

damaged organs

Certain situations lead to it 9dehydration,infection, fever, bleeding, cold exposure, drug and

alcohol use, pregnancy, stress

Can be severe and require hospitalization for paincontrol and IV fluids

Signs- paleness, yellow eyes/skin, growth

retardation


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treatment

Hydroxyurea is a drug used that turns HbF formationback on (dilutes [HbS] in blood) Problems arise asHbF shuts off (most HbF is normal)

Prevents painful crisis due to sickling

First approved drug for causitive treatment of SCD Study in 1995 showed it decreased # attacks and

increased survival time of patients

Treatment only recommended for >18 years who

have had > 3 crisis in previous years Blood test taken every 2 weeks to ensure blood count

not too low (side effect)


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ENZYMES Large molecules that increase the rate of achemical reaction without themselves being

changed Vast majority are globular proteins

Dont change the position of equilibrium

but increase the reaction rate by loweringthe activation energy

Extremely effective and specific


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NAMING/ CLASSIFYING

ENZYMES Names derived from reaction they catalyze

and/or compound they act on

Classified in 6 major groupsOxidoreductases (redox reactions)

Transferases (transfer reactions)

Hudrolases (hydrolysis reactions)

Lyases (formation/removal of double bonds)

Isomerases (isomerization reactions)

Ligases (synthesis reactions)


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ENZYME TERMINOLOGY cofactors- nonprotein part of enzyme

can be metal ions (Mg2+, Zn2+)

organic cofactors are called coenzymes

apoenzyme- protein part of enzyme

substrate- compound that binds to enzymes active site and ischanged

activation- initiation process for an enzyme

inhibition- process of making an active enzyme inactive

competitive- bind to enzyme active site and prevent substrate frombinding

noncompetitive- bind to other portion of enzyme and alter tertiary

structure

activity- measurement of how much rates are increased


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FACTORS AFFECTING

ACTIVITY The effect of concentration, temperature and pHon enzyme activity (how much rate is increased)

1)If the [S] is kept constant, as long as [E] is less than

[S], the rate will increase continuously and linearly(double [E], rate doubles)

2)If the [E] is kept constant, and you increase the [S]you will get a saturation curve. Once all of the enzyme

active sites are occupied, increasing the [S] will notincrease the rate.


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FACTORS AFFECTING ACTIVITY

3) Temperature changes the structure of an enzyme. Thishinders the substrate from fitting in the active site.Once the optimal temperature is reached, the rate ofreaction will begin to decrease

4) pH effects resemble temperature. All enzymes operatebest at certain ph values (near 7). Drastically changingthe pH can irreversibly alter the shape of a protein orenzyme.


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INHIBITION

COMPETITIVE INHIBITORS

Bind to the enzymes active site and inhibits thesubstrate from binding

NON-COMPETITIVE INHIBITORSBinds elsewhere and changes the structure of the

enzymes active site (thus inhibiting the substrate frombinding)

MODELS FOR ENZYME MECHANISM


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MODELS FOR ENZYME MECHANISM

There are 2 common models for how E-S

complexes are formed:1) LOCK AND KEY MODEL- Simplest

- lock is the active site and the key is the substrate

- E is rigid body with an opening (active site)- Only one kind of substrate can fit and open it

- Restrictive (E not static but dynamic; flexible active site)

2) INDUCED FIT MODEL

- Substrate enters and causes the shape and size of theenzymes active site to change- Latex glove and hand (gloves changes when hand is inserted)

unit 2 carbs lipids proteins enzymes

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