PART4 - CELL AND CELLULAR ORGANELLES:

Cell Theory and Its 3 Tenets

All living things are composed of cells.
The cell is the basic unit of life.
All cells arise from pre-existing cells Cells Are Microscopic**:
Cells are small to maximize surface area-to-volume ratio, improving efficiency in material exchange

Cells are generally microscopic - explain why

Cells are microscopic to maximize surface area for efficient material exchange

Nucleus

Structure: Membrane-bound, contains DNA.

Function: Controls cell activities and genetic information storage

Ribosomes

Structure: Composed of RNA and proteins, found free or on rough ER.

Function: Protein synthesis

Rough Endoplasmic Reticulum (ER)

Structure: Membrane network with ribosomes attached.

Function: Synthesizes proteins for export or membrane

Smooth Endoplasmic Reticulum (ER)

Structure: Membrane network without ribosomes.

Function: Synthesizes lipids and detoxifies

Golgi Apparatus

Structure: Stacked membrane sacs.

Function: Modifies, sorts, and ships proteins and lipids

Lysosomes

Structure: Membrane-bound vesicles with enzymes.

Function: Digests cellular waste and macromolecules.

Peroxisomes

Structure: Membrane-bound with oxidative enzymes.

Function: Detoxifies and breaks down fatty acids.

Vacuoles

Structure: Membrane-bound storage sacs.

Function: Store nutrients and waste

Mitochondrion

Structure: Double membrane with inner folds (cristae).

Function: ATP production through cellular respiration

Chloroplast in plant cells, not in animals

Structure: Double membrane with internal thylakoid stacks.

Function: Conducts photosynthesis.

Cytoskeleton

Structure: Network of microtubules, microfilaments, and intermediate filaments.

Function: Supports cell shape and enables movement.

Structures in Centrioles, Cilia, Flagella, and Microvilli

Centrioles: Made of microtubules, involved in cell division.

Cilia and Flagella: Microtubule-based structures for movement.

Microvilli: Finger-like extensions to increase surface area for absorption

Components of the Endomembrane System and Their Functions

Nuclear Envelope: Encases the nucleus; connects with rough ER.

Rough ER: Protein synthesis with ribosomes.

Smooth ER: Lipid synthesis and detoxification.


Golgi Apparatus: Modifies, sorts, and packages proteins/lipids.


Lysosomes: Digest cellular waste and macromolecules.


Vesicles: Transport materials between system components.


Plasma Membrane: Exports proteins and lipids outside the cel

How the Endomembrane System Works Together

Synthesized proteins/lipids are modified in Golgi, transported by vesicles for cell use or secretion

Plant Cell Organelles Not in Animal Cells

Cell Wall: Structural support.

Chloroplasts: Photosynthesis.

Central Vacuole: Stores nutrients, maintains pressure