Energy and Enzymes Chapter 4 Biology exam 3 🧪
What is energy?
the capacity to do work
Two states of energy
kinetic energy- energy of motion or energy that is presenting during work
ex: an arrow shot from a bow
potential energy- stored energy that has the potential to do work but its not in active use
How is energy stored biologically?
IN FOOD
energy stored in a chemical bond
chemical bonds require energy to make a bond therefore there is energy in that bond
Breaking a bond releases energy; forming a bond requires energy (e.g., condensation).
Food is the source of energy driving endodontic reactions.
calories- unit of measurement
free energy- useable energy that can do work
the energy that a cell requires for immediate use is stored in ATP (adenosine triphosphate)
why do u have to have ATP?
because when if you dont trap energy in something you can save (ATP) you will lose it
FOOD must be converted food → ATP- transfers energy from food to cells
what kind of molecule is this?
the cells energy currency
free energy is released when 1 of the P bonds are broken
There are 2 basic types of reactions
exergonic- reactions that release energy (reactants possess more energy than products)
ex: ATP → H2O → ADP + P + free energy
endergonic- reactions that require the input of energy (the reactants posses less energy than products)
EX: ADP + P + free energy → ATP + H2O
we have to eat food to make ATP a plant has photosynthesis to make ATP
Where does this free energy come from??
FOOD
the type of food influences what kind of ATP you make
simple
carbs- 4 cal/g
proteins- 4 cal/g
fat- 9 cal/g
metabolism- the sum of all chemical reactions within a cell (within YOU)
anabolism- small molecules bond to form a larger molecules
take a bunch of anabolic you make a protein
Building up molecules: forming muscle, protein, and storing carbohydrates.
Requires energy input (endoergonic).
catabolism- larger molecules are broken down into smaller molecules
Breaking down molecules: tearing things apart, like a cat.
Releases energy (exergonic).
protein + H2O= aa+aa+aa+aa+etc..)
break apart bonds and releasing energy
exergonic?
chemical reactions are regulated by enzymes
Chemical reactions are necessary to obtain and conserve energy.
Enzymes are vital for the acceleration of chemical reactions.
Without enzymes, reactions occur too slowly to sustain life.
Enzymes lower the activation energy needed for reactions, allowing them to occur more rapidly.
without enzymes most biochemical reactions would not take place fast enough to sustain life
most chemical reactions require input energy to get started
chemical reactions happen naturally but enzymes speed up chemical reactions
activation energy- the amount of input energy required to start a reaction
Analogous to the cost of items on sale: lower activation energy means faster reactions.
Enzymes reduce the cost of catalyzing reactions, possibly using the analogy of a coupon that can be reused.
Enzymes can work thousands of times per second.
energy impacts speed of Rxn
What is an enzyme?
a biological catalyst that accelerates a chemical reaction without being used up in the reaction
Enzymes are proteins produced primarily in the rough endoplasmic reticulum (ER) by bound ribosomes.
The shape of a protein determines its function, as the enzyme's active site must match the substrate precisely.
Specificity in enzymes: only certain substrates will fit.
most enzymes are proteins
enzymes can be reused
enzyme CHARACTERISTICS:
Catalysts (enzymes) speed up reactions without being consumed.
Example of enzymes aiding in dehydration synthesis to bond two molecules together.
Energy must be supplied to form bonds, making the process endergonic (requires energy).
specific shape- shape of a protein dictates its function
specific to what “fits” to catalyze (speed up) a reaction
do not cause reactions
Rxn in both directions
enzymes speed up chemical reactions by lowering the reactions activation energy
substrate(reactant)+enzyme→complex→products + enzymes
cracker + amylase ————-simple carbs + amylase
FACTORS that affect enzymes activity
enzymes feed off reactions
if you take enzyme out- reactions are slower
temperature
as temperature increases rate of a reaction increases
Increased temperature increases reaction rates but can denature proteins if too high, losing their functional shape.
Optimal enzyme activity occurs at specific temperature ranges.temp increases molecules move faster = faster rxns
extreme temp can denature enzymes= decrease speed rxns
enzymes are specific for shape and temperature
shape dictates its function
For instance, specific enzymes hydrolyze carbohydrates into simple sugars, enhancing digestion (e.g., crackers dissolving in the mouth).
The analogy of having multiple USB cords shows that enzymes are tailored for specific reactions just like varying cables fit different devices.enzymes can only work within a certain temperature range
can only work within a certain PH range
pH
Enzymes function best in an environment suited to their structure. For instance, enzymes in the stomach require an acidic environment to work effectively.
If too acidic or basic, enzymes may become denatured and lose activity.enzymes are specific to pH
pH outside range: enzymes could be denatured (lose its normal shape and function)
Photosynthesis
Photosynthesis is the process by which plants convert light energy into chemical energy (sugar) through two main stages: Light-dependent reactions and Light-independent reactions (Calvin Cycle).
where does photosynthesis take place?
anything with chlorophyl or chloroplast
chlorophyll is the main pigment!
water out in order to get CO2 in
photo 1 sythnesis 2
light dependent reactions- photo (light)
light energy causes electrons to flow
ADP + P = ATP
photolysis occurs
a. light energy splits water
b. oxygen is given off from H2O
ATP AND NADPH are needed in the next stage of PS
H is from water
plants take sunlight and convert it into ATP
photolysis occurs
light independent reactions
“synthesis”
to make/combine
carbon fixation occurs : rubisco enzyme binds CO2 (most abundant enzyme on planet!)
food cycler with C3 cycle
ATP and NADPH (H2O) from 1st stage POWERS 2nd stage
six CO2 enters C3 cycle one 6C glucose or fructose is produced
glucose and fructose can combine to form sucrose
Location: Thylakoid membranes of chloroplasts.
Key Reactants: Light energy, water (H₂O).
Key Products: ATP, NADPH, and oxygen (O₂).
Sunlight excites electrons in chlorophyll, creating ATP and NADPH while splitting water and releasing oxygen.
a. light energy splits water
water supplies the electrons
b. oxygen is given off them H2O
you need water for a plant for electron source
Calvin Benson cycle (C3 Cycle)
what kind of plants use the C3 cycle for their food cycle?
C3 plants: most trees, beans, rice, wheat and potatoes
Function 2nd stage PS: produce sugar by- carbon fixation which the conversion of CO2 into organic compounds
ex: Glucose
problem for C3 plants
rubisco is NOT specific “unfaithful”
O2 can bind to rubisco and block CO2
OXYGEN ruins the “sweet” relationship of rubisco and CO2
cause: hot/dry conditions
C4 plants are different
use C4 cycle+ C3 cycle
more specific enzyme pep carboxylase (PEPCO) ONLY binds C02 not O2
pep co is only found in C4 plants like grasses
C4 cycle is on top of C3 cycle
C4 cycle “feeds” CO2 to rubisco enzyme → glucose is produced
C4 plants can grow in hotter/drier conditions than C3
BUT C4 plants use MORE energy
C4 plants: Most grasses such as corn sugarcane and crabgrass
plant use sugar for energy too!
6CO2 + 6H2O + light(NADPH)—> C6H12O6 +6O2 (photosynthesis)
glucose catabolism (cell respiration) ← aerobic
plants make their own food by photosynthesis but then have to eat it
C6H1206 + 6O2 —> 6CO2 + 6H2O + ATP
Do plants use photosynthesis and cell respiration?
YES
all living things need respiration
organism need food to provide free energy to make ATP
Cells require ATP for life to work
FO/ (break bonds) OD (glucose)
CO2←O2 free energy → ATP
ADP + P + free energy → ATP
endergonic RXN anabolic
glucose catabolism
glycolysis- occurs cytosol of cell
splits 6C glucose (2) 3C pyruvate (1/2 sugar)
does not use oxygen
glycolysis is an anaerobic process
metabolic pathway- a series of chemical rxns where the products of a previous rxn is used as the reactants of the next rxn
(P) from food + ADP = ATP
subtracted- level phosphorylation
what are the main products of Glycolysis?
hint: glucose was split in 2
two 3C pyruvate NO carbon lost
coenzymes save (H) from food as NADH “save pennies”
2ATP (net gain)
next step is what usually happens as long as oxygen is readily available..
coenzymes- aide chemical rxns and more
there are derived from B vitamins
and are electron carriers —> carry to mitochondria
NAD+ (nicotinamide adenine dinucleotide) made from
vitamins B3 (niacin)
NAD+ H (from food) —> NADH (carries it to mitocondria)
FAD+ (flavin adenine dinucleotide) made from
vitamin B (riboflavin)
FAD + 2H → FADH2
overview of photosynthesis
Photosynthesis Definition: Process used by plants to convert light energy into chemical energy (sugar).
Stages of Photosynthesis: Two main stages - Light-dependent reactions and Light-independent reactions (Calvin Cycle).
light dependent reactions
Location: Occurs in the thylakoid membranes of chloroplasts.
Key Reactants: Light energy, water (H₂O).
Key Products: ATP, NADPH, and oxygen (O₂).
Sunlight excites electrons in chlorophyll, which are then transferred through an electron transport chain, producing ATP and NADPH.
Water molecules are split to replace lost electrons, releasing oxygen as a by-product.
detailed process: Photo: Stands for light - Light is essential for this stage.
Synthesis: Refers to making or combining substances.
Electrons, upon sunlight exposure, gain energy and move through the electron transport system.
The energy loss as electrons flow down the chain is used to convert ADP into ATP.
Oxygen Production: Oxygen produced is derived from the splitting of water molecules.
light INDEPENDENT reactions (calvin cycle)
Location: Occurs in the stroma of chloroplasts.
Main Inputs: ATP, NADPH from the light-dependent reactions, and carbon dioxide (CO₂).
Outputs: Glucose (C₆H₁₂O₆) and other organic substances.
carbon fixation process
Carbon Dioxide Capture: CO₂ is captured and fixed into a stable form using the enzyme Rubisco.
Hydrogen Input: Hydrogen ions from water, carried by NADPH, are combined with carbon dioxide.
Energy Source: ATP provides the energy necessary for the process.
Glucose Formation: Resulting products are processed into glucose and other compounds like fructose, proteins, and fats.
the importance of water in CO2
Water (H₂O): Critical for electron supply and maintaining plant hydration, enabling the process of photosynthesis.
Role of CO₂: Acts as a building block for sugar formation. Growth and health of plants depend on CO₂ availability.
challenges faced by plants
Water Limitation: In hot and dry conditions, plants may close their stomata (openings on leaves) to conserve water, which leads to reduced CO₂ intake and can negatively affect photosynthesis.
Oxygen Inhibition: In conditions where oxygen builds up (like hot and dry environments), it can interfere with carbon fixation, causing plants to waste resources.
What kind of plants are in photosynthesis
C3: Examples: Soybeans, potatoes, rice.
Mechanism: Standard Calvin Cycle; susceptible to oxygen interference during hot, dry conditions.
Limitations: Reduced efficiency under stress, leading to potential lower food production.
C4: Examples: Sugarcane, corn.
Mechanism: Incorporate an additional step to handle CO₂ more efficiently even under stress conditions.
Uses a different enzyme (PEP carboxylase) which has a higher affinity for CO₂ than Rubisco, helping reduce oxygen competition.
Survival Mechanism: Adapted to thrive in hot, dry environments where typical photosynthesis may fail.
metabolic pathways
Glycolysis: Conversion of glucose (sugar) to pyruvate, yielding a small amount of ATP.
Importance of Enzymes: Enzymes dictate metabolic processes; each has a specific shape that optimizes its function for catalyzing reactions.
preview of aerobic cell respiration
⬇
6C glucose enters glycolysis (cytosol O2 not used)
⬇
3C pyruvate produced O2 available
⬇
aerobic
transition reaction (mitochondria)
⬇
krebs cycle
⬇
electron transport
mitochondria is the only place that you use to breathe
three stages of aerobic respiration
A. transition reaction
occurs in the mitochondria
3C pyruvate converted to 2CAcetyle (acetic acid)
C02 released
2C acetyl is lazy
could build fat
coenzyme A carries it to kreb cycle
B. krebs cycle
occurs in mitochondria
ALL IN THE MITOCHONDRIA BECAUSE AEROBIC
both 2C acetyl enter
CoA is recyled
all carbon bonds now broken (e-) H released
coenzymes NAD+ & FAD+ bind (H) “saves pennies”
NADH and FADH2 are produced
any food used for energy that break down for energy get reused in the air
4 CO2 released due to catabolism of two 2C acetyl
2 ATP produced
whats left of glucose now?
NADH and FADH2
c. electron transport chain and chemiosmosis
ETC in inner membrane of mitochondria
NADH & FADH2 release H to the ETC
only electrons (e-) enter the ETC
(e-) are passed down ETC like batons in a relay race
free energy is released in steps by redox rxns
this energy helps build H+ concentration energy
flow of H+ through ATP synthase enzyme provides energy to couple ADP + P to produce 32 ATP
Chemiosmosis includes redox rxn of the ETC and H+ gradient to provide free energy to produce ATP
O2 we breathe removes hydrogen (e-) from ETC to form H2O O2 is our final e- acceptor
review of glucose catabolism
6C glucose
⬇
glycolysis (NADH + 2 ATP) aneroobic
⬇
(2) 3C pyruvate
⬇
transition reaction (NADH + 2CO2)
⬇
(2) 2C acetyl COA
⬇
krebs cycle (4CO2 + NADH, FADH2 + 2ATP)
36 ATP made from catabolism of 1 glucose
is glucose the only molecule organism obtain energy from?
fat- approx. 400 ATP could be made
“aerobics” (cardio) burns fat first
short sprints, power lifting mostly burn glucose
cells primary use fat as energy source when sustaining activity
if food intake exceeds energy needs then sugar may be partially catabolized and stores as fat
proteins- last resort
fat enters and burns aerboic respiration starting transion reaction
aerboic respiration burns fat
what are some examples of how we use this energy?
work (growth, maintenance and reproduction_
thinking!
building molecules (endergonic rxns)
(ex: polysaccharides, proteins, etc)
muscle cell contraction
active transport
fermentation (anerboic)
occurs in the cytosol of cells after gylocolysis when oxygen is not readily avaliable
two types of fermentation
lactic acid fermentation
pyruvate converted into lactic acid
lactic acid may accumulate in muscles while working
ex: sprinting
powerligts
occurs in animals and some bacteria
the only convert food into ATP when no oxygen = glycolysis
alcoholic fermentation
occurs in plants, fungi (yeast) and bacteria
pyruvate is converted to ethanol and CO2
yeast are used to produce beer, wine and bread
fermentation does not produce ATP
it keeps glycolysis going which provides ATP when O2 is not available by recycling NAD+
Importance of Fermentation
Fermentation is essential in processes such as producing bread, wine, and cheese.
The focus of the current discussion is on how fermentation affects sales, particularly in relation to explosive activities.
Explosive Activities vs. Aerobic Exercise
Example of explosive activities:
Sprinting
Power lifting
These activities involve quick bursts of energy and are not sustained efforts, differing from cardio or aerobic exercises.
Role of Glycolysis
Glycolysis is the process that splits glucose (sugar) into two molecules of three-carbon compounds.
The process is critical for energy production, particularly during activities requiring rapid energy bursts.
Key point: No carbon is lost in the process of glycolysis while splitting sugar.
Coenzymes in Glycolysis
A critical coenzyme in glycolysis is derived from Vitamin B, which plays a key role in transporting electrons, protons, and hydrogens.
This coenzyme enables the glycolysis reaction by picking up hydrogens during the process, forming NADH.
Electron Transport and Fermentation
During glycolysis, if oxygen is present as the final electron acceptor, the electron transport chain can function effectively.
If there's no oxygen:
Electrons back up, causing a bottleneck in energy production.
The body must revert the electrons back to the original compounds, leading to the formation of lactic acid, especially noted in anaerobic respiration (absence of oxygen).
Importance of Oxygen in Energy Production
Oxygen is essential for moving to the mitochondria for the complete breakdown of glucose.
Activities demanding rapid energy often burn oxygen quickly before it can be replenished, resulting in increased lactic acid production.
Example: During fast typing or sprinting, muscles may feel fatigued from lactic acid accumulation due to insufficient oxygen supply.