Overview
This lecture covers the basic structures and differences between prokaryotic and eukaryotic cells, as well as the functions of key cell organelles.
Basic Cell Structure
- Cells are the smallest living units of organisms.
- All cells contain a cell membrane (outer boundary), cytoplasm (jelly-like fluid), and DNA (genetic material).
- Organelles are specialized parts within cells that perform unique functions.
Types of Cells
- Eukaryotic cells have a nucleus and membrane-bound organelles; found in plants and animals.
- Prokaryotic cells lack a nucleus and organelles; always unicellular, such as bacteria.
- Prokaryotic cell DNA is not contained within a nucleus.
Key Organelles and Structures
- The nucleus is the control center, contains DNA, and has a nucleolus where ribosomes are made.
- Ribosomes synthesize proteins and can float in cytoplasm or attach to the endoplasmic reticulum (ER).
- Rough ER has ribosomes; smooth ER does not.
- ER transports materials (like proteins) within the cell.
- The Golgi apparatus modifies, folds, and packages proteins and other materials.
- Vacuoles store substances; plant cells have a large central vacuole for water.
- Lysosomes digest waste and damaged cell parts using enzymes; found in animal cells.
- Mitochondria produce ATP energy via cellular respiration in both plant and animal cells.
- The cytoskeleton gives the cell shape and structure; includes microfilaments (proteins) and microtubules (hollow tubes).
Plant Cell Features
- Chloroplasts perform photosynthesis and contain green pigment chlorophyll.
- Plant cells have a cell wall for shape, support, and protection; animal cells do not.
Specialized Cell Features
- Cilia are microscopic hair-like projections; help move substances (example: respiratory tract cells).
- Flagella are tail-like structures used for cell movement; found in some bacteria and human sperm cells.
Summary Points
- Eukaryotes: nucleus & organelles; Prokaryotes: no nucleus & no organelles.
- All cells: cell membrane, cytoplasm, DNA.
- Only plant cells have chloroplasts, but both plant and animal cells have mitochondria.
Key Terms & Definitions
- Organelle — specialized cell structure with a unique function.
- Nucleus — organelle containing DNA; cell's control center.
- Cytoplasm — jelly-like fluid inside the cell.
- Ribosome — makes proteins.
- Endoplasmic Reticulum (ER) — transports materials within the cell.
- Golgi Apparatus — modifies and packages proteins.
- Vacuole — stores materials.
- Lysosome — digests waste and damaged organelles.
- Mitochondria — produces cell energy (ATP).
- Chloroplast — site of photosynthesis in plant cells.
- Cell Wall — provides structure/support in plant cells.
- Cilia — hair-like structures for movement or filtering.
- Flagellum — tail-like structure for movement.
Action Items / Next Steps
- Review diagrams of plant and animal cells, labeling key organelles.
- Write a summary comparing prokaryotic and eukaryotic cells.