Cellular Functions Study Notes

Study Notes

Electron Transport Chain

Situated in the inner mitochondrial membrane; crucial for aerobic respiration.
Transfers electrons from NADH and FADH2 through a series of proteins.
Establishes a proton gradient that drives ATP synthesis.

Oxygen Requirement

Aerobic respiration requires oxygen for ATP production.
Anaerobic respiration occurs in the absence of oxygen, utilizing fermentation processes.

Photosynthesis

Converts light energy into chemical energy (glucose) using carbon dioxide and water.
Primarily takes place in chloroplasts of plant cells.

Photosynthesis Phases

Light-dependent Reactions:
- Occur in thylakoid membranes.
- Transform solar energy into ATP and NADPH; split water and release oxygen.
Calvin Cycle (Light-independent Reactions):
- Takes place in the stroma of chloroplasts.
- Utilizes ATP and NADPH to convert CO2 into glucose.
- Overall equation: 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2.

Cell Membrane Structure

Composed of a phospholipid bilayer, proteins, cholesterol, and carbohydrates.
Phospholipids have hydrophilic heads and hydrophobic tails, creating a semi-permeable membrane.
Integral and peripheral proteins aid in transport, signaling, and structural integrity.
The Fluid Mosaic Model illustrates the dynamic nature of the cell membrane.

Cell Signaling Pathways

Involves a series of molecular interactions leading to cellular responses.

Types of Signals

Autocrine: Cells signal themselves.
Paracrine: Signals travel to adjacent cells.
Endocrine: Hormones circulate in the bloodstream.

Receptors

Membrane-bound: Bind to external signals, triggering internal pathways.
Intracellular: Bind to signals that can penetrate the cell membrane.

Pathway Components

Ligands: Molecules that convey signals.
Signal Transduction: Converts a signal into a functional response.
Second Messengers: Molecules like cAMP that amplify the signal within cells.

Cell Cycle and Division

Consists of several phases controlling cell growth and division.

Phases of the Cell Cycle

Interphase:
- G1 Phase: Growth and protein synthesis.
- S Phase: DNA replication occurs.
- G2 Phase: Prepares the cell for mitosis with growth and organelle duplication.
Mitosis: Division resulting in two genetically identical daughter cells.
- Phases include Prophase, Metaphase, Anaphase, and Telophase.
Cytokinesis: Physical separation of the cytoplasm into daughter cells.

Regulation of the Cell Cycle

Cyclins and cyclin-dependent kinases (CDKs) regulate progression through the cycle.
Critical checkpoints (G1, G2, and M) ensure accurate cell cycle progression and genetic integrity.

Cellular Respiration

Converts glucose and oxygen into ATP, carbon dioxide, and water.

Phases of Cellular Respiration

Glycolysis: Takes place in the cytoplasm; breaks glucose into pyruvate while generating ATP and NADH.
Krebs Cycle (Citric Acid Cycle): Occurs in mitochondria; processes pyruvate into CO2, generating ATP, NADH, and FADH2.

Description

Explore the intricacies of cellular functions with a focus on cell membrane structure and cell signaling pathways. Learn about the composition of cell membranes, the roles of various proteins, and the different types of cellular signals that facilitate communication. This guide is essential for understanding fundamental biological processes.