Overview
This lecture covers the basic structure and classification of cells, including organelles, differences between prokaryotic and eukaryotic cells, and unique cell features.
Cell Basics
- Cells are the smallest living units and have a cell membrane, cytoplasm, and DNA.
- The cell membrane separates the cell's interior from the environment.
- Cytoplasm is a jelly-like fluid inside the cell.
- DNA is the cell's genetic material.
Types of Cells
- Eukaryotic cells have a nucleus and membrane-bound organelles, found in plants and animals.
- Prokaryotic cells lack a nucleus and organelles; their DNA is not contained in a nucleus (e.g. bacteria).
- Prokaryotic cells are always unicellular.
Organelles and Their Functions
- Organelles are specialized cellular parts with specific functions.
- The nucleus acts as the control center and contains DNA.
- Chromatin is the loose form of DNA; it condenses to form chromosomes during cell division.
- The nucleolus in the nucleus makes ribosomes.
- Ribosomes synthesize proteins and can be free or attached to endoplasmic reticulum (ER).
- Rough ER has ribosomes and smooth ER does not; ER transports materials in the cell.
- Golgi apparatus modifies and packages proteins and other materials.
- Vacuoles store substances; central vacuole in plant cells stores water.
- Lysosomes break down worn-out cell parts and debris using enzymes.
- Mitochondria produce ATP through cellular respiration, powering cell activities.
- The cytoskeleton provides cell shape and includes microfilaments and microtubules.
Specialized Structures
- Chloroplasts in plant cells perform photosynthesis and contain green pigment chlorophyll.
- Plant cells have a cell wall for support and protection; animals cells do not.
- Cilia are hair-like projections in some animal cells for movement or trapping particles.
- Flagella are tail-like structures for movement; found in some bacteria and sperm cells.
Key Terms & Definitions
- Eukaryotic cell — cell with nucleus and membrane-bound organelles.
- Prokaryotic cell — cell without nucleus or membrane-bound organelles.
- Organelle — specialized part of a cell with a unique job.
- Nucleus — controls the cell and stores DNA.
- Ribosome — makes proteins.
- Endoplasmic reticulum (ER) — transports materials; rough (with ribosomes) and smooth (without).
- Golgi apparatus — modifies and packages proteins/materials.
- Vacuole — storage sac.
- Lysosome — breaks down cell waste.
- Mitochondrion — produces cellular energy (ATP).
- Cytoskeleton — helps maintain cell shape.
- Chloroplast — converts sunlight to energy in plant cells.
- Cell wall — rigid outer layer in plant cells.
- Cilia — hair-like structures for movement.
- Flagellum — tail-like structure for movement.
Action Items / Next Steps
- Review differences between prokaryotic and eukaryotic cells.
- Memorize organelle functions.
- Study key terms and definitions.