Cellular Respiration and Fermentation

General Equation for Cellular Respiration

Cellular respiration is a metabolic process that converts biochemical energy from nutrients into ATP, releasing waste products. The general equation is:

• Equation:

• Reactants: Glucose and oxygen

• Products: Carbon dioxide, water, and ATP

Main Stages of Cellular Respiration and Their Locations

Cellular respiration occurs in three main stages, each in a specific location within the cell:

• Glycolysis: Cytoplasm

• Krebs Cycle (Citric Acid Cycle): Mitochondrial matrix

• Electron Transport Chain (ETC): Inner mitochondrial membrane

Fermentation: General Equations and Variations

Fermentation is an anaerobic process that allows glycolysis to continue in the absence of oxygen. Two main types:

• Lactic Acid Fermentation: (glucose to lactic acid)

• Alcoholic Fermentation: (glucose to ethanol and carbon dioxide)

Glycolysis: Start and End Products

Glycolysis is the first step in cellular respiration:

• Start: Glucose

• End: 2 pyruvate, 2 ATP, 2 NADH

• Location: Cytoplasm

Krebs Cycle: Start and End Products

The Krebs cycle further breaks down pyruvate:

• Start: Acetyl-CoA

• End: 2 CO2, 3 NADH, 1 FADH2, 1 ATP (per cycle)

• Location: Mitochondrial matrix

Electron Transport Chain: Start and End Products

The ETC uses electron carriers to produce ATP:

• Start: NADH, FADH2, O2

• End: ATP, H2O

• Location: Inner mitochondrial membrane

Roles of Components within the ETC

The ETC consists of protein complexes and electron carriers:

• Electron Carriers: NADH and FADH2 donate electrons

• ATP Synthase: Enzyme that synthesizes ATP as protons flow through it

• Oxygen: Final electron acceptor, forming water

Gas Exchange

Path of Oxygen in Human Circulatory and Respiratory Systems

Oxygen enters the body and is transported to tissues:

• Inhalation: Oxygen enters lungs

• Diffusion: Oxygen moves from alveoli to blood

• Transport: Oxygen binds to hemoglobin in red blood cells

• Delivery: Oxygen is released to tissues

Role of Hemoglobin and Hemoglobin Graphs

Hemoglobin is a protein that binds oxygen for transport:

• Function: Increases oxygen carrying capacity of blood

• Hemoglobin Graphs: Show oxygen saturation vs. partial pressure of oxygen

• Interpretation: Sigmoidal curve indicates cooperative binding

Photosynthesis

Diets of Heterotrophs and Autotrophs

Organisms obtain energy in different ways:

• Heterotrophs: Consume organic molecules for energy (e.g., animals)

• Autotrophs: Produce their own food via photosynthesis (e.g., plants)

General Equation of Photosynthesis

Photosynthesis converts light energy into chemical energy:

• Equation:

Main Reactions of Photosynthesis and Their Locations

Photosynthesis consists of two main sets of reactions:

• Light Reactions: Occur in thylakoid membranes

• Calvin Cycle (Dark Reactions): Occur in stroma

Chloroplast Structures Associated with Photosynthesis

Key structures in the chloroplast:

• Thylakoids: Site of light reactions

• Stroma: Site of Calvin cycle

• Granum: Stack of thylakoids

Connection Between Light and Dark Reactions

The products of light reactions fuel the Calvin cycle:

• NADPH and ATP: Produced in light reactions, used in Calvin cycle

• CO2 Fixation: Occurs in Calvin cycle

Comparisons Between Cellular Respiration and Photosynthesis

Both processes involve electron transport and energy conversion:

• Cellular Respiration: Breaks down glucose to produce ATP

• Photosynthesis: Synthesizes glucose using light energy

• Electron Carriers: NADH/FADH2 in respiration, NADPH in photosynthesis

Roles of Electron Carriers in Photosynthesis

Electron carriers transport energy:

• NADP+: Accepts electrons to become NADPH

• NADPH: Provides reducing power for Calvin cycle

Roles of NADPH and ATP in Photosynthesis

NADPH and ATP are essential for carbon fixation:

• NADPH: Supplies electrons for reduction reactions

• ATP: Provides energy for biosynthetic processes

Purpose of Multiple Pigments in Plants

Plants use various pigments to maximize light absorption:

• Chlorophyll a: Main pigment

• Chlorophyll b, carotenoids: Accessory pigments

• Function: Absorb different wavelengths of light

Detailed Steps of the Light Reactions

Light reactions involve several steps:

• Photon absorption: Excites electrons in chlorophyll

• Electron transport: Generates ATP and NADPH

• Water splitting: Produces O2

Alternate Mechanisms of Photosynthesis: C4 and CAM

Some plants have adaptations for photosynthesis in arid environments:

• C4 Plants: Separate carbon fixation and Calvin cycle in different cells

• CAM Plants: Fix carbon at night, store it for use during the day

• Purpose: Reduce photorespiration and water loss