Biochemical Processes in Eukaryotic Cells

Definition and Importance

• Eukaryotic Cells: Advanced cells possessing organelles, enabling them to perform a wide range of functions. These are fundamental to the existence of complex life forms.
• Photosynthesis: A process in which green plants, algae, and certain bacteria transform light energy into glucose, using carbon dioxide and water. This process is essential for generating energy and oxygen, crucial for life on Earth.
• Cellular Respiration: A mechanism that transforms nutrients into chemical energy (ATP) essential for cellular functions.
• Homeostasis: The regulated and stable state of an organism's internal environment, maintained through various biochemical processes.

Coordination in Eukaryotic Cells

• In eukaryotic cells, interactions among organelles and responses to environmental stimuli ensure effective cellular performance. Internal coordination is regulated by the cytoskeleton and cytoplasm, which facilitate communication and mobility among organelles.

Organelle	Function
Chloroplasts	Photosynthesis
Mitochondria	Respiration
ER	Protein and lipid synthesis
Nucleus	Contains genetic material and coordinates activities

Cellular Signalling Pathways

• Cellular Signalling: Involves pathways that include receptors and secondary messengers. This is fundamental for processes such as photosynthesis and respiration through feedback mechanisms.

Signalling Molecule	Primary Impact	Response Example
Receptors	Trigger cellular responses	Hormone binding to cells
Secondary Messengers	Enhance signals and coordinate actions	Muscle contraction, nerve impulse transmission

Photosynthesis Process

Light-dependent Reactions

• Location: Occur within the thylakoid membranes of chloroplasts.
• Functions include:
  • Photon absorption.
  • Production of ATP and NADPH, essential for the Calvin Cycle.

Calvin Cycle (Light-independent Reactions)

• Carbon fixation involves capturing CO₂ to synthesise organic compounds.
• Rubisco is the enzyme playing a pivotal role in carbon fixation.

Factors Affecting Photosynthesis

• Elements such as light intensity, CO₂ concentration, and temperature greatly influence the rate of photosynthesis.

Cellular Respiration Process

Overview of Steps

• Glycolysis: Takes place in the cytoplasm, breaking down glucose into pyruvate, yielding 2 ATP and 2 NADH.
• Krebs Cycle: Occurs in the mitochondria, generating energy carriers NADH and FADH₂.
• Electron Transport Chain (ETC): Utilises these carriers to produce ATP via a proton gradient.

Respiration Types: Aerobic vs Anaerobic

Respiration Type	Oxygen Requirement	End Products	ATP Yield
Anaerobic	No	Lactic Acid/Alcohol	2 ATP
Aerobic	Yes	CO₂, Water	Up to 38 ATP

Waste Removal and Energy Utilisation

• Waste Removal: Eukaryotic cells eliminate unnecessary or toxic substances through exocytosis to sustain cellular health and homeostasis.

Exocytosis

• Involves vesicle transport, membrane fusion, and releasing contents, crucial for removing cellular waste and transporting materials.

Role of Lysosomes and Protein Processing

• Lysosomes: Break down waste materials using enzymes and recycle cellular components.
• Endoplasmic Reticulum and Golgi Apparatus: Participate in processing and delivering proteins for exocytosis.

Glossary

• NADH: An electron carrier that stores energy for the electron transport chain.
• FADH₂: Another electron carrier transferring electrons to the ETC.

Through these processes, eukaryotic cells manage energy transformation, uphold internal stability, and execute efficient waste removal, underscoring their essential roles in living organisms.