Cellular Respiration
● Engage Adenosine Triphosphate (ATP)
● 6 sugars
○ Major source of energy for cell
○ Carbohydrates
○ Cells break down glucose a 6-C sugar to make ATP (energy)
● C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + usable energy (ATP)
● Three stages
○ 1) Glycolysis
■ Starts out with a 6 carbon chain → two, three carbon chains (requires
two ATP) (makes 4 ATP)
● Enzyme cuts the chain in half
■ Happens in the cytoplasm
■ No oxygen is required
■ Net gain of 2 ATP at the expense of 2 ATP
■ Free electron and hydrogen combine with organic ion carriers called
NAD → NADH + H
○ 2) Krebs Cycle (Citric Acid Cycle)
■ Happens in the mitochondrial matrix
■ Energy yield → 2 ATP and more electrons
■ Acetyl-CoA (2-C) combines with 4-C to form 6-C Citric Acid
■ Citric Acid changed to 5-C then to a 4-C
■ Gives off a CO2 molecule
■ Cycle Always reforming a 4-C molecule
■ Breakdown of Pyruvic Acid
● Happens in mitochondria
● Pyruvate (3-C) → Acetic acid (2-C)
● 3rd C forms CO2
■ Second Part of cycle
○ 3) Electron Transport Chain (ETC)
■ Happens in the inner membrane of mitochondria
■ Energy yield → Total of 32 ATP
■ O2 combines with TWO hydrogen to form water
■ Exhale - CO2, H20 comes from cellular respiration
● Aerobic Respiration
○ With oxygen
○ Happens in the mitochondria
○ “Normal” cellular respiration equation
○ Makes large amounts of ATP energy
● Anaerobic Respiration
○ Weight lifting
○ Machines that offer resistance
○ Dumbbells
○ Fermentation
■ Lactic acid fermentation
● Builds in muscles when oxygen levels are depleted (feel the
burn!)
● Glucose → Lactic Acid + 2 ATP
■ Alcoholic Fermentation
● Yeast/fungus & Bacteria
● Converts sugars (grapes, barley, wheat, etc.) into energy with
the by-product alcohol
● Glucose → Ethanol + CO2 + 2 ATP
Aerobic Respiration Anaerobic Respiration
Ability to be sustained: Forever Short term only
Production of ATP: 36 ATP per 1 glucose 2 ATP per 1 glucose
Process: Oxygen is used to make ATP Inorganic molecules other
than oxygen are used to
make ATP
Where chemical reactions Cytoplasm and Cytoplasm
takes place: mitochondria
Requirement of sunlight: No No
Carbon dioxide: Yes Released during alcoholic
fermentation
Not released during lactic
acid fermentation
Main function: Production of energy (ATP) Production of energy (ATP)
from food/glucose from food/glucose (when O2
is not available)
Photosynthesis
● Heterotroph - eat sugar, ex. Humans
● Autotrophs - make their own sugars/energy from the sun, ex. Plants, anything that
is green
○ Stored as carbohydrate in their bodies
● Process of synthesizing from the sun
● 6CO2 + 6H2O → C6H12O6 + 6O2
Light
● Carbon dioxide + water → sugars and oxygen
● Chloroplast
● Electron carriers
○ High energy electrons require specific carriers
○ A carrier molecule is a compound that can accept a pair of high energy
electrons and transfer them to another molecule
○ One molecule is known as NADP+ which will accept and hold 2 electrons and
H+ ion to convert to NADPH
○ NADPH is a form of energy produced from photosynthesis
● Light Dependent Reactions
○ Require light to happen
○ Use energy from light to produce ATP and NADPH
○ Produce oxygen gas
○ Takes place in the thylakoid membranes of chloroplasts
○ Steps
■ Pigments in photosystem II absorb light
■ Light energy is absorbed by electrons
■ The electrons (high energy) are passed to the electron transport chain
■ New electrons from water molecules keep the reaction going (H2O)
■ As electrons are removed from the water molecules oxygen is left
behind and released into the air (H+ → NADP, O2 → Air)
● Cut bond - makes energy
■ High energy electrons move through the electron transport chain
from photosystem II to photosystem I
■ The energy is used to transport H+ from the stroma into the inner
thylakoid space
■ Pigments in photosystem I use energy from light to re-energize
electrons and this is picked up by NADP+ to produce NADPH
■ The movement of the H+ ions creates a high concentration of charge
across the membrane - this provides the energy to make ATP = ETC in
cellular resp.
■ ATP synthase allows the H+ ions to pass through the membrane
■ As H+ ions pass through the ATP synthase, an ADP and phosphate
bind in order to form ATP
○ Light Dependent reactions use water, ADP, NADP+, and produce oxygen and
ATP and NADPH
● Light Independent Reactions (Calvin Cycle)
○ Plants use energy that ATP and NADPH contain to build high energy
compounds for storage
○ These high energy compounds are sugars
○ This reaction does not require light and can also be called light Independent
Reactions.
○ This happens in the stroma of the chloroplasts
○ Steps
■ Carbon dioxide molecules enter the cycle from the atmosphere
■ Six carbon dioxide molecules enter the cycle and combine with six 5
carbon molecules to form 12, 3-carbon molecules
■ The 12, 3-carbon molecules are converted into high energy forms. The
energy used for this comes from ATP and NADPH
■ Two of the 12, 3-carbon molecules are removed from the cycle and
are used by the plant to produce sugars, lipids, and other compounds
■ The remain 10, 3-carbon molecules are converted back to the six 5-
carbon molecules and are used to start the cycle again
● Van Helmont was the first to know that plants make carbohydrates from just carbon
dioxide, water, and light energy through an experiment
Chemosynthesis
● The process of converting inorganic compounds/chemicals into food/glucose
● Purpose
○ Creates glucose from inorganic compounds/chemicals
● Where?
○ Deep in the ocean by hydro-thermal vent communities
○ No light
● Organisms
○ Tube worms?
○ Bacteria that live inside the tube worms
● Both chemosynthesis and photosynthesis involve an energy source. However,
photosynthesis gives off oxygen while chemosynthesis produces sulfur.
● Hydrogen sulfide, carbon dioxide, and water go in the process → sugar, sulfur
compound
● Compare/Contrast
○ Photosynthesis uses sunlight energy, while chemosynthesis does not
○ Both use carbon dioxide and water
○ Both use inorganic compounds
○ Both produce glucose
○ Photosynthesis produces oxygen while chemosynthesis produces sulfur
Mitosis
● Cell division - making 2 new identical cells
● Used only by eukaryotes
● Chromosomes - compacted DNA
● The purpose of DNA replication is to have identical DNA in new cells
● 2n → 2n same number of chromosomes
○ n - 1 set of chromosomes
○ 2n = diploid - 2 sets
● Humans have 46 chromosomes (2 sets of 23)
○ 22 Autosomal
○ 1 sex chromosomes (XY) (XX) (XO)
● Necessary for maintenance and repair
● DEad and old cells are replaced with new ones
● Cell Cycle
○ Interphase
■ Normal resting phase of cells
■ G1 → period of cell growth
■ Chromosomes duplicate
■ G2 → cell prepares for division
■ What is a checkpoint?
● A stop in interphase that ensures proper cell division.
● No mistakes in DNA replication.
● “Bad” cells are stopped and not replicated
○ Mitosis
■ Prophase
● The cell prepares for cell division
● DNA in the nucleus begins to condense.
■ Metaphase
■ Anaphase
■ Telophase
■ Cytokinesis
