Looks like no one added any tags here yet for you.
polymerization
creation of a polymer by the bonding of multiple subunits.
2 molecules with reactive functional groups: OH and H.
Each monomer in protein is an amino acid
proteins
make up 50% of body’s dry mass
multiple functions: enzymes and support
made of amino acids
amino acids structure
all have an amino group and carboxyl group
R group is attached to alpha carbon
diff. amino acids have diff. R groups- which give amnio acids diff. properties
20 diff. amino acid monomers
amino acids
nonpolar or polar?
polar: have oxygen or sulfer at terminal end
acidic or basic
acidic: donates a proton from R group (gets a negative charge)
basic: accepts proton (gets a positive charge)
how to determine a R group
check if acidic or basic (charge or not)
if neither, check for polarity (oxygen and sulfer)
nonpolar amino acids
glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, proline
polar amino acids
serine, threonine, cysteine, tyrosine, asparagine, glutamine
peptide bonds
links amino acids together to form proteins
proteins linked together by ribosome using mRNA
before linked by peptide bond, dehydration reaction removes water
lose water between every peptide bond
protein structure
the order (polarity) of amino acids does not matter
4 levels of structure: primary, secondary, tertiary, and quaternary
primary structure
amino acids and peptide bonds
flexible and linear chain
(amino acid) determined by gene sequence
secondary structure
shapes are formed by hydrogen bonding between atoms of a polypeptide backbone (not R groups)
many H bonds can make these stable structures
helices: alpha helix and beta pleated sheets
tertiary structure
overall 3-dimensional shape of a single polypeptide (mostly dictated by chem of R-groups)
non-polar R-groups get buried into middle of protein (excluded by water) and interacted with each other by Van Der Waals forces
polar R-groups- H bond with water and other hydrophilic R-groups at the surface
interactions between side chains- ionic bonds, covalent bonds, hydrogen bonds, Van der Waal
quaternary
interactions between multiple polypeptides, protein subunits
ex. collagen made of 3 diff. polypeptides that are intertwined together
ex. hemoglobin made from diff. polypeptide subunits that come together
protein models
ribbon model
space-filling model
wireframe model
ribbon model
just the backbone
shows secondary structures
spare-filling model
shows the electron orbit shells of each atom in the protein
hard to see where chemical interactions are occur
wireframe model
shows all of the covalent bond of backbone and r-groups
good to see how chemical interactions occur
protein interactions
specific r-groups on one protein will interact with specific r-groups on another protein
in ex. antibody will bind tightly to the flu virus protein so the immune system can destroy the virus
other protein/protein interactions are weaker and much more transitioning
enzymatic proteins
selective acceleration of chemical reactions
ex. digestive enzymes catalyze the hydrolysis of bonds on food molecules
defensive proteins
protection against disease
ex. antibodies inactivate and help destroy viruses and bacteria
storage proteins
storage of amino acids
ex. casern (protein in milk) is major source of amino acids for babies
ovalbumin is protein of egg white (used as amino acid source developing embryo)
plants has storages proteins in seeds
transport proteins
transport of substances
ex. hemoglobin, iron containing protein of vertebrae blood, transports oxygen from lungs to other parts of body
ex. cell membrane - channel and carrier proteins
hormonal proteins
coordination of an organisms activities
ex. insulin, hormone secreted by pancreas, caused other tissues to take up glucose, regulates blood sugar concentration
receptor proteins
response of cell to chemical stimuli, important for receiving info, cell communication, action potentials
contractile and motor proteins
movement
ex. motor proteins responsible for undulations of cilia and flagella
actin and myosin responsible for muscle contractions
structural proteins
support, found all throughout body (collagen)
ex. keratin is protein of hair, horns feathers, and other skin appendages
insects and spiders use silk fibers to make their cocoons and webs repetitively
collagen and elastin proteins provide fibrous network in animal connective tissue
protein coding
big consequences for changes in primary protein sequence
can cause sickle cell anemia
metabolism
organized as metabolic pathways that included multiple steps
enzymes catalyze each step
build or break down chemical to make other chemicals
liberate/store energy used to do cellular or organismal function
metabolites are the molecules in pathways
metabolic pathways
pathways involve multiple reactions
catabolic
breaks things down and releases energy
anabolic
build things up and requires energy
forms of energy
kinetic, thermal, potential, and chemical
kinetic energy
relative motion
thermal energy
kinetic energy associated with random movement
potential energy
not kinetic, static objects still have energy
(energy with no motion)
chemical energy
potential energy that is available for release
energy in covalent/peptide bonds
1st law of thermodynamics
energy cannot be created or destroyed
energy can be transformed (converted)
2nd law of thermodynamics
entropy(disorder)- increases in isolated system
transformation to energy is never 100% efficient (lose a lot of energy as heat)
quantity vs quality
free energy
G is Gibbs constant
the amount of energy in “the system”
in a chemical reaction, the system, changes (so does free energy)
reactants have initial state/energy
products have final state/energy
G = final - initial
exergonic reactions
reactants have more free energy than the products
energy is released
reaction is spontaneous, not instantanous
endergonic reactions
reactants have less free energy than the products
energy input is required
not spontaneous
ATP energy coupling
cellular work: chemical, transport, mechanical
all require energy, typically ATP
exergonic reactions can be coupled with those that are endergonic
ex. glutamine synthesis and ATP hydrolysis- adds initial and final energies to get new G.
energy barriers
spontaneous reactions are not instantaneous
transition states: intermediate state with stressed bonds
some energy must be put in
activation energy (Ea)- enzymes lower it
enzymes speed it up
add an enzyme, the reaction is catalyzed
enzymes bind to the reactant molecules very tightly and put stress in specific bonds of reactants
lowers Ea required for reaction to occur because bonds are easier to break
‘normal’ biological temperatures
no change in free energy of reaction
enzymes are specific
for specific reactants and specific products
lock and key model
very specific
relied on polarity and acidity/basicity
active site
can only fit specific molecules
induced fit models
focuses on shape enzymes and substrates are 3D compounds
shape is essential, but so are other properties
denature
change the nature of protein
changes the shape of proteins, results in it losing its function
results from bad environment for protein
environmental factors
temperature- increase breaks hydrogen bonds and desulphate bonds which change structure
pH- increase or decrease breaks ionic bonds which changes structure
competitive inhibition
slows rate of reaction
inhibitor molecules resembles substrate
binds to active site and occupies it
actual substrate cannot bind to active site
substrate inhibition is a form of competitive inhibition
blocks active site
noncompetitive inhibitor
slows down rate of reaction
does not have similar properties of substrate
inhibitor molecule does not bind to active site
changes enzyme shape
active site can’t bind to substrate
feedback inhibition is example
allosteric enzyme regulation
enzyme complex oscillating between state
reaction rate depends on proportion that is active
compounds can bind to enzymes- activators and inhibitors
activators
bind allosteric site
stabilizes active form
faster reaction rate
inhibitors
bind allosteric site
stabilize inactive form
slower reaction rate
feedback inhibition
many enzyme pathways are self-regulated
synthesis pathway with multiple enzymic reactions
final product- inhibits an enzyme
prevents further production
product used- inhibition removed and pathway proceeds
living cells
require energy from outside sources (except autotrophs)
energy flows into ecosystem in the form of sunlight and ultimately leaves as heat
photosynthesis generates organic molecules and oxygen which are used in cellular respiration
cells use chemical energy stored in organic molecules to generate ATP, which powers cellular work
yield energy by oxidizing organic fuels- electron transfer
catabolic molecules
breakdown of complex molecules (glucose) and releases energy
molecules store energy in their bonds and generates ATP for cellular work
energy is released when electrons move
reduction and oxidation reactions (redox)- catabolism and anabolism
oxidation reactions
oxidation- electron donor
becomes oxidized
reducing agent
reduction reactions
electron acceptor
becomes reduced
oxidizing agent
redox reactions
transfer of electrons during chemical reactions releases energy stored in organic molecules
this energy is use to synthesize ATP
electron shuttles
nicotinamide adenine dinucleotide (NAD+)
important oxidizing agent (electron acceptor)
shuttles electrons from ‘glucose’ to the ETC (electron transport chain)
oxidized form- NAD+
reduced form- NADH
electron transport
electrons ultimately move toward oxygen
if uncontrolled, may turn into explosive release of heat and light energy
if controlled, uses PE and gives cell time to use energy efficiently
methods of ATP production
substrate level phosphorylation
oxidative phosphorylation
substrate level phosphorylation
direct
ADP is a substrate of an enzyme
used about 10% of the time (not efficient)
oxidative phosphorylation
indirect thorough chemiosmosis
uses redox reactions of the electron transport chain
used about 90% of the time
what is metabolized?
organic substances/molecules
lipids, carbohydrates, nucleic acids, and proteins
carbohydrates
in ratio: 1 carbon, 2 hydrogens, 1 oxygen
functions: fuel (makes ATP), energy storage (stores starch or glycogen, structural component
all sugars have: a carbonyl group, other carbons with a hydroxyl group
what do different sugars differ in?
number of carbons
where carbonyl group is (isomers)
symmetry of -OH groups around the carbons (stereoisomers)
aldehyde
carbon double bonded to an oxygen (carbonyl) at the end of a sugar
ketone
carbon double bonded to an oxygen (carbonyl) in the middle of a sugar
monosaccharides
5-carbon sugars and 6-carbon sugars
5-carbon: ribose and ribulose
isomers- same chemical formula, different structure or arrangment
6-carbon: glucose, galactose, and fructose
stereoisomers- function groups can be on either side of carbon
can be linear or a ring
glycosidic linkages
join 2 simple sugars together
dehydration reaction forms either alpha or beta linkages (requires energy)
dehydration reactions
chemical reactions in which water molecules are removed from a compound or a mixture
These reactions typically involve the loss of a water molecule (H2O) from a larger molecule
alpha linkages (glycosidic)
all hydroxyl groups are on the same side
below carbon 1 (plane)
storage carbs
beta linkage (glycosidic)
hydroxyl groups are alternating sides
above plane
structural carbs
storage carbs
all alpha form
allows them to tightly pack together (because hydroxyl us below plane)
starch storage- alpha glucose
structural carbohydrates
OH is on opposite sides they’re paired to (beta)
has hydrogen bonding
forms matrix and strong support
glucose in beta form
not linear
disaccharides
2 monosaccharides put together
ex. sucrose = glucose + fructose (linkage is 1-2 glycosidic linkages)
ex. lactose = galactose + glucose (linkage is beta 1-4 linkage- not linear)
ex. maltose = made of 2 glucose (linkage alpha 1-4 linkages), storage carb- linear, alpha
polysaccharides
100-1000s of repeating subunits
ex. amylose- very linear, alpha chain, storage, 1 branch
ex. amylopectin- linear, alpha chain, storage, slightly branched
ex. glycogen- linear, alpha chain, very branched, found in animals
ex. cellulose- not linear, beta chains, structural, found in plants
glycosidic linkage make structural polymers
glycosidic linkages of cellulose differ from those of starch because the ring of glucose in the 2 polymers are slightly different
cellulose contains beta glucose
starch contains alpha glucose
structural carbs
chitin- animal, glucose with extra functional group that contains nitrogen
monomer- N-acetyl-glucosamine (NAG)
used to make arthropod exoskeletons and fungi cell walls
lots of H-bonding between parallel strands gives a strong material thats further hardened by proteins
evolution of pathways
glycolysis was likely one of the first pathways - due to not using oxygen (3.5 billion years old)
early atmosphere was anaerobic (no oxygen)
fermentation- simple, cycles protein
‘anaerobic respiration- complex, more efficient
aerobic respiration- was a relatively easy change from anaerobic respiration, oxygenation of atmosphere (2.7 billion years ago),
glycolysis
cells used glucose as energy source (not just glucose, other molecules can be broken down in different pathways that connect)
earliest pathway
involves 10 enzymic reactions including: phosphorylation (substrate level ATP synthesis), redox reactions, isomerization
glycolysis- overall reaction
1 glucose (6C) —→ 2 pyruvate
energy investment- 2 ATP
energy payoff- 4 ATP and 2 NAD+ reduced to NADH
substrate level phosphorylation (ATP synthesis in glycolysis)
reactant: substrate + ADP + P
product: ATP
fermentation
organisms surviving without atmospheric oxygen
organisms without the electon transport chain
organisms must regenerate NAD+
available organic molecules can act as oxidizing agents (several diff. pathways), typically toxic end products (waste)
glycolysis can still function
Ethanol fermentation
glycolysis produces 2 ATP, 2 NADH, 2 pyruvate
pyruvate decarboxylation- liberation of CO2- produced acetaldehyde
acetaldehyde accepts electrons from NADH, regenerates NAD+ and forms ethanol
yeast, some bacteria
step 1. remove carbon
step 2. NADH donates electrons to acetydehyde
lactic acid fermentation
glycolysis produces: 2 ATP, 2 NADH, 2 pyruvate
pyruvate-accepts electrons from NADH (recycles NAD+ and forms lactate)
lactic acid bacteria
in humans- ‘anaerobic exercise’
what processes evolved after fermentation?
pyruvate oxidation into Acetyl-CoA- energy from pyruvate
Citric Acid Cycle- energy from pyruvate
the electron transport chain- harnesses energy from NADH e-
pyruvate oxidation
acetyl CoA (2C) production
pyruvate is transported to mitochondrial matrix
3 step reaction:
liberation of CO2 (removal)
reduction of NAD+
addition of coenzyme A (CoA)
makes 2 NADH
citric acid cycle
occurs within mitochondrial matrix
cycle series of 8 enzymatic reactions
acetyl-CoA (2C) + oxaloacetate —→ citrate
products (per acetyl-CoA)- 1 CoA, 2 CO2, 3 NADH, 1 ATP, 1 FADH2
used substrate level phosphorylation
electron transport chain
series of electron carries that NADH and FADH2 donate electrons o
occurs in plasma membrane of prokaryotes and mitochondria in eukaryotes (between intermembrane space and mitochondrial matrix)
first ETC was in bacteria
involved in both aerobic and anaerobic respiration
what reactions occur in the electron transport chain?
sequential redox reactions
multiple small changes in free energy (G < 0)
energy released is coupled with moving protons against their gradient (energy used for PMF)
bacteria: from intracellular to extracellular
eukaryotes: to intermembrane space from mitochondrial matrix
*gradient is from proton motive force (H+)
possible final anaerobic electron acceptors
ferric iron (Fe3+)- pumps most protons
nitrate (NO2-)- pumps mid amount of protons
sulphate (SO 2-)- pumps least amount of protons
*fewer protons pumped, lower proton motive force, and less ATP by ATP synthesis = small difference in free energy
ATP synthase
a proton channel on the inner membrane (enzyme)
4 H+ moving through —> produced 1 ATP
occurs after ETC
chemiosmosis
movement of H+ down its concentration gradient
energy-coupling mechanism that uses energy stored in the form of an H+ gradient across a membrane
energy from gradient comes from exergonic redox reactions
in photosynthesis: products of light reactions go to the calvin cycle (ATP and NADPH)
anaerobic respiration
with no O2, some bacteria can use alternative final electron acceptors
this pathway involves: glycolysis, pyruvate oxidation and citric acid cycle, the electron transport chain
ATP is produced by: substrate level phosphorylation and proton motive force and ATP synthase
*efficiency of ATP production depends on final electron acceptor
photosynthesis
provides energy for life
converts light energy into chemical energy
evolved about 3 billion years ago (started among bacteria)
creates all O2 in the air
an anabolic pathway
dependance on photosynthesis in organisms
direct: autotrophs- uses photosynthesis to convert light energy
indirect: heterotrophs- can’t take sunlight and make it into energy