bio mcat

proteins

macromolec ar polymers
enzymes that make them are called polymerases
reactions are called polymerization reactions
often run via dehydration synthesis
condensation
opposite is hydrolysis - split polymer
monomer - animo acid (20)

protein backbone

amine group, carbone and carboxyl group

condensation reaction (dehydration synthesis)

a chemical reaction in which two or more molecules combine to produce water or another simple molecule

hydrolysis reaction

A chemical reaction that breaks apart a larger molecule by adding a molecule of water

primary structure

The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain.

secondary structure of protein

alpha helix and beta pleated sheet
interactions between backbone atoms (hydrogen bonds)

tertiary structure

The third level of protein structure; the overall, three-dimensional shape of a polypeptide due to interactions of the R groups of the amino acids making up the chain.
interaction between R groups
- noncovalent (nonpolar/non-polar, polar/polar, acid/base)
- covalent - disulfide bridges

quaternary structure

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.
- side chain interactions between diff polypeptides

Protein functions

enzyme catalysis, defense, transport, support, motion, regulation, storage

carbohydrates

- monomer - monosaccharides (CnH2nOn)
- glucose, fructose, galactose - C6H12O6, 6 carbon sugars
- ribose, deoxyribose - 5 carbon sugars

disaccharides

sucrose, lactose, maltose
- 2 monosaccharides

sucrose

glucose + fructose

lactose

glucose + galactose

maltose

glucose + glucose

Polysaccharides

large macromolecules formed from monosaccharides
- glycogen, starch, cellulose
- function - cellular energy, cell surface markers, adhesion

glycogen

storage form of glucose in animals

starch

storage form of glucose in plants

cellulose

plant structure

Lipids

- monomer - hydrocarbon
- saturated and unstaurated

unsaturated fats

liquid at room temperature, double bonds

saturated fats

A fat that is solid at room temperature and found in animal fats, lards, and dairy products.

Triglycerides

an energy-rich compound made up of a single molecule of glycerol and three molecules of fatty acid.
- functions - eaten and stored this way, stored energy
- store energy

glycerol

A three-carbon alcohol to which fatty acids are covalently bonded to make fats and oils.

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.
- functions - cell membrane

Terpenes

built from multiple isoprene units

monoterpene- 2 isos
squalene- 6 isos (tripene), component of ear wax
terpenoids- functionalized terpenes, cholesterol and steroid hormones, vitamin A
- need at least 2 isoprenes to make a terpene

Squalene

triterpene (6 isoprene units)
function - precursor for cholesterol, steroids and ear wax
- can be modified by addition of other elements to create terpenoids (vitamin A)

Cholesterol and derivatives

3 6-carbon rings + 1 5-carbon ring
functions
- cell membranes
- bile salts
- steroid precursor
- vitamin D precursor

Thermodynamics equation

ΔG \= ΔH - TΔS

ΔG

Gibbs free energy

ΔH

enthalpy - potential energy (heat)

ΔS

entropy - disorganized

T

temperature

TΔS

kinetic energy

+ΔG

non-spontaneous

-ΔG

spontaneous

ΔG \= 0

equilibrium

exergonic reaction

A spontaneous chemical reaction in which there is a net release of free energy.
- release heat

endergonic reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings.
- takes in heat

activation energy

the minimum amount of energy required to start a chemical reaction
- energy needed to produce the transition state
- as Ea increases rate decreases

A + B -\> ABCD -\> C + D
which is transition state

ABCD

A + B -\> ABCD -\> C + D
which is reactant

A + B

A + B -\> ABCD -\> C + D
which is products

C + D

reaction coordinate graph

x-axis is reaction progression
y-axis is free energy

peaks are transition states
valleys are intermediates

the highest peak is the rate limiting step
difference between reactant energy and highest peak is Ea

catalysts lower peaks, does not affect equilibrium
ΔG \= products - reactants

catalyst

makes Ea smaller so increases reaction rate
- does so by stablizing transition state
physiological catalysts
- must increase the rate of the reaction, must not be used up in the reaction, specific fro a particular reaction

allosteric site

A specific receptor site on some part of an enzyme molecule remote from the active site.

active site

The part of an enzyme or antibody where the chemical reaction occurs.
where substrate bines

"OFF"/"Tense" enzymes

active site in diff conformation so substrate cant bind
-need to either phosphorylate or dephosphorylate or allosteric regulation

"On"/"relaxed" enzyme

enzyme that can catalyze the reaction since the binding site suits the conformation fo the substrate
- done via phosphorylation or allosteric regulation

negative feedback

A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

positive feedback

A type of regulation that responds to a change in conditions by initiating responses that will amplify the change. Takes organism away from a steady state.
- must have exterior regulator

V vs [S] plot

is similar to a logistic growth graph
in the beginning, there is high affinity(1)
then as more substrates are added it causes less affinity(2) to the point where no matter how much substrate is added there is no affinity(3)
S- substrate
E- enzyme
V- rate of product formation

Km

1/2 Vmax
\[S] required to reach 1/2 V max
- an affinity the enzyme has for the substrate
- strong affinity - low Km
- low affinity - high Km

\[S] << [E]

V vs S is linear (beginning of graph)
rate of product formation is linear

\[S] ~ [E]

rate of product formation is curving

\[S] \>> [E]

rate of product formation levels off

Vmax

maximum initial velocity or rate of an enzyme-catalysed reaction.
- depends only on enzyme
- enzyme youre using
- enzyme concentration

competitive inhibition

substance that resembles the normal substrate competes with the substrate for the active site
- binds at active site
- V max stays the same
-Km increases

non-competitive inhibitor

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate.
binds at allosteric site
- Vmax decreases
- Km stays the same

Uncompetitive inhibition

-Binds at allosteric site of ES complex
-Decreases Vmax
-Decreases Km

mixed inhibition

binds at allosteric site E or ES
Vmax decreases
Km varies

Lineweaver-Burk Plot

1/v \= (Km/Vmax)(1/[S]) + 1/Vmax

Veins

Blood vessels that carry blood back to the heart
-pressure low
- blood moves by anything that squishes the vessels (normal body movement)
- valves
- no muscular walls
-not elastic

Artery

A blood vessel that carries blood away from the heart
- pressure high
blood moved by forward momentum (pressure gradient)
- muscular walls
-elastic

capillaries

site of nutrient/waste exchange
- fluid flows in or out to lypmh through osmosis

lymph nodes

concentrated area of WBC
- fluid flows in and out through osmosis
- exposed to B cells, T cells, etc

lymphatic system

structurally like veins

superior and inferior vena cava

veins that carry deoxygenated blood to the right atrium from the systemic circuit

tricuspid valve

valve between the right atrium and the right ventricle

pulmonary semilunar valve

heart valve opening from the right ventricle to the pulmonary artery

pulmonary artery

artery carrying oxygen-poor blood from the heart to the lungs
to lungs

pulmonary veins

Deliver oxygen rich blood from the lungs to the left atrium
to heart (left atrium)

bicuspid (mitral) valve

valve between the left atrium and the left ventricle.

aortic semilunar valve (aortic valve)

permits blood to flow in only one direction from the left ventricle to the aorta

right atrium

Receives deoxygenated blood from the body

left atrium

receives oxygenated blood from the lungs

right ventricle

pumps deoxygenated blood to the lungs

left ventricle

pumps oxygenated blood to the body

systole

Contraction of the heart

diastole

Relaxation of the heart

1st sound (lub)

-Close atrial ventricular valves
-Begin systole

2nd sound "dup"

-Close semilunar valves
-Begin diastole

blood pressure

systolic/diastolic \= pressure in arteries when heart is contracted/ pressure in arteries when heart is relaxed

blood pressure is directly proportional to

cardiac output and peripheral resistance

cardiac output

heart rate x stroke volume
vol pumped/min

stroke volume

vol pumped/beat
- change when
change in vol, activity level, posture

heart rate

number of beats per minute

stroke volume change when

change in vol, activity level, posture

peripheral resistance

the opposition to flow that blood encounters in vessels away from the heart
how hard it is to move blood throuhgout the vessels

vessels constricted

decrease diameter, decrease flow, increase resistance, increase blood pressure

vessels dilated

increase diameter, increase flow, decrease resistance, decrease blood pressure

cardiac muscle action potential

1. Rapid depolarization due to Na+ inflow when voltage-gated fast Na+ channels open
2. Plateau (maintained depolarization) due to Ca2+ inflow when voltage-gated slow Ca2+ channels open and K+ outflow when some K+ channels open
3. Repolarization due to closure of Ca2+ channels and K+ outflow when additional voltage-gated K+ channels open
- long refractory period of the cardiac muscle cell action potential prevents the frequency of action potentials from increasing high enough to cause summation of twitches and cardiac tetancy

Cardiac Autorhythmic Cell Action Potential

-40 resting membrane potential - slowly drift up (slow depolarization due to Na leak channels)
pace maker potential \= -60mV
threshold \= -30mV
initial depolarization - Na+ influx
rapid depolarization - Ca2+ spike
repolarization - K+ efflux
- start the action potential for the whole heart
- in cardiac conduction system

cardiac conduction system

a system of specialized muscle tissues that conducts electrical impulses that stimulate the heart to beat
- SA node -\> AV node -\> bundle branches -\> purkinje fibers
- SA leakiest to sodium - pacemaker
- atrial and ventricular contraction systems are not electrically connected
- AV nodes delays impulse allowing atria to contract before ventricules
- contract from bottom of heart to top of heart where aorta is in ventricules

blood composition

54% plasma, 45% formed elements, 1% Leukocytes

plasma

water, electrolytes, glucose, hormones, wastes, plasma proteins, lipoproteins

leukocytes

white blood cells and platelets

Blood gas transport

Mechanisms used to transport O2 and CO2 through the bloodstream

non-specific immunity

barriers - skin, mucus, hair, earwax
chemicals - mucus, lysozyme, stomach acid, enzymes, complement system
cells - macrophages, neutrophils, eosinophils, dendritic, basophils

antigen

a foreign protein that triggers an immune response

antibody

a highly specific marker for an antigen