Cell Structure Overview

Study Notes

Cell Structure

1. Overview of Cells

Basic unit of life.
Two main types: prokaryotic and eukaryotic.

2. Prokaryotic Cells

Definition: Simple, single-celled organisms without a nucleus.
Key Features:
- Cell Membrane: Phospholipid bilayer controlling entry and exit of substances.
- Nucleoid: Region containing genetic material (DNA).
- Ribosomes: Sites of protein synthesis, smaller than eukaryotic ribosomes.
- Cytoplasm: Jelly-like fluid where cellular processes occur.
- Cell Wall: Rigid structure providing shape and protection (made of peptidoglycan in bacteria).

3. Eukaryotic Cells

Definition: Complex cells with a nucleus and membrane-bound organelles.
Key Features:
- Nucleus: Contains DNA, surrounded by a nuclear envelope.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; synthesizes proteins.
  - Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
- Mitochondria: Powerhouse of the cell, site of ATP (energy) production through cellular respiration.
- Chloroplasts (in plant cells): Site of photosynthesis, contains chlorophyll.
- Lysosomes: Digestive organelles containing enzymes to break down waste.
- Peroxisomes: Break down fatty acids and detoxify harmful substances.
- Cytoskeleton: Network of fibers providing structure and facilitating movement.

4. Additional Structures

Cell Membrane: Selectively permeable, composed of a phospholipid bilayer with embedded proteins.
Vacuoles: Storage organelles; larger in plant cells for storage of water and nutrients.
Centrioles: Involved in cell division, found in animal cells.
Cell Wall (in plant cells): Provides structural support and protection; made of cellulose.

5. Differences Between Plant and Animal Cells

Plant Cells:
- Have a cell wall and chloroplasts.
- Larger central vacuole.
Animal Cells:
- Lack cell wall and chloroplasts.
- Smaller, more numerous vacuoles.

6. Cell Theory

All living organisms are composed of cells.
The cell is the basic unit of life.
All cells arise from pre-existing cells.

Overview of Cells

Cells are the fundamental building blocks of life.
Two primary categories exist: prokaryotic and eukaryotic cells.

Prokaryotic Cells

Simple organisms, typically unicellular, lacking a nucleus.
Cell Membrane: Comprises a phospholipid bilayer that regulates the movement of substances in and out.
Nucleoid: Area in the cell where genetic material (DNA) is concentrated.
Ribosomes: Function as protein synthesis sites, smaller compared to eukaryotic ribosomes.
Cytoplasm: Viscous, gel-like substance hosting various cellular functions.
Cell Wall: Rigid outer layer that maintains cell shape and provides protection; in bacteria, it's primarily made of peptidoglycan.

Eukaryotic Cells

More complex structures with a defined nucleus and membrane-bound organelles.
Nucleus: Houses the cell’s DNA, protected by a nuclear envelope.
Endoplasmic Reticulum (ER):
- Rough ER: Studded with ribosomes for protein synthesis.
- Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for cellular transport.
Mitochondria: Known as the cell’s powerhouse, responsible for ATP production via cellular respiration.
Chloroplasts (exclusive to plant cells): Responsible for photosynthesis, containing the green pigment chlorophyll.
Lysosomes: Contains digestive enzymes to breakdown waste materials.
Peroxisomes: Involved in fatty acid breakdown and the detoxification of harmful substances.
Cytoskeleton: A fibrous network that maintains cell shape and supports cellular movement.

Additional Structures

Cell Membrane: Selectively permeable barrier made of phospholipid bilayer with embedded proteins.
Vacuoles: Storage vesicles; typically larger in plant cells for maintaining water and nutrient stores.
Centrioles: Organelles critical for cell division, primarily found in animal cells.
Cell Wall (in plant cells): Provides structural support and is made of cellulose.

Differences Between Plant and Animal Cells

Plant Cells: Possess a cell wall and chloroplasts, along with a large central vacuole.
Animal Cells: Do not have a cell wall or chloroplasts, and generally contain smaller, more numerous vacuoles.

Cell Theory

All living organisms consist of cells.
The cell is recognized as the basic unit of life.
New cells arise only from pre-existing cells.

Description

Explore the fundamental components of cells with this quiz focusing on both prokaryotic and eukaryotic cell structures. Understand the key features and differences between these two types of cells, including their shapes, functions, and organelles. Perfect for biology students looking to reinforce their knowledge of cell biology.