Cell Tour and Organelles Function

Introduction

• Overview of cell structure and function of various organelles.
• Emphasis on building a picture of a cell for better understanding.

Plasma Membrane

• Definition: Barrier separating the cell from its external environment.
• Function: Controls internal cell environment, present in all organisms.

Nucleus

• Structure: Surrounded by a membrane with pores.
• Function: Stores DNA (genetic information) in chromosomes or chromatin.
• Contains the nucleolus, which makes ribosomes.

Ribosomes

• Types: Free-floating and bound.
• Function: Sites of protein synthesis.
  • Free Ribosomes: Make proteins for use within the cell.
  • Bound Ribosomes: Attached to the nucleus or endoplasmic reticulum (ER); build proteins for secretion.

Endoplasmic Reticulum (ER)

• Types: Rough ER with ribosomes attached and Smooth ER lacking ribosomes.
• Rough ER: Produces proteins for export.
• Smooth ER: Produces lipids (sterols, hormones) and detoxifies substances (e.g., in the liver).

Golgi Apparatus

• Structure: Stack of membrane-bound sacs.
• Function: Modifies, stores, and ships products from the ER using vesicles.
• Part of the endomembrane system.

Endomembrane System

• Pathway for manufacturing and shipping cellular products.
  • Products made in ER, processed in Golgi apparatus, and transported via vesicles.
  • Final destination could be intra- or extracellular.

Lysosomes

• Function: Digest macromolecules with enzymes in an acidic environment (similar to a cellular stomach).
• Exclusive: Found only in animal cells.

Peroxisomes

• Function: Break down harmful substances, producing peroxide in the process.

Mitochondria

• Structure: Double membrane with highly folded inner membrane.
• Function: Site of cellular respiration; converts macromolecule energy into ATP.
• Present in both plant and animal cells.

Cytoskeleton

• Structure: Network of fibers.
• Function: Provides structure and aids in movement, acting like train tracks for organelles.

Cytoplasm

• Definition: Fluid in which organelles are embedded.

Plant Cell-Specific Organelles

• Chloroplasts: Site of photosynthesis; converts light energy into chemical energy.
• Central Vacuole: Stores water, aids in structure, and breaks down waste.
• Cell Wall: Provides rigidity and structure, made of cellulose.

Summary

• Animal and plant cells share many organelles with similar functions.
• Unique structures exist in plant cells (e.g., chloroplasts, central vacuole, cell wall) and animal cells (lysosomes).
• Understanding organelles’ roles in processes like the endomembrane system is crucial.