Biology Lecture Notes: Cell Types and Modifications

Learning Objectives

Distinguish prokaryotic and eukaryotic cells based on their features.
Classify different cell types in plant and animal tissues and specify their functions.
Describe cell modifications that lead to adaptation for specialized functions.

Cell theory was formulated by several scientists.
- Answer: Fact
Classical cell theory proposed in the mid-19th century has six postulates.
- Answer: Fake
The word organelle translates to 'little organs' and they have specific functions.
- Answer: Fact
All organelles found in animal cells are also found in plant cells.
- Answer: Fake
The invention of the microscope led to numerous discoveries about the cell.
- Answer: Fact

Definition: Simple unicellular organisms with no nucleus or membrane-bound organelles.
Examples: Bacteria
DNA Location: Nucleoid region in the cytoplasm
Size: Smaller than eukaryotes
Reproduction: Binary fission
Cell Wall: Chemically complex
DNA Structure: Circular and haploid

Definition: Organisms with a nucleus enclosed by a membrane and other membrane-bound organelles.
Examples: Protista, Fungi, Plantae, Animalia
DNA Location: Inside a membrane-bound nucleus
Size: Larger than prokaryotes
Reproduction: Mitosis and meiosis
Cell Wall: Present only in plant cells, simple structure
DNA Structure: Linear and diploid

Size: Prokaryotes (smaller), Eukaryotes (larger)
Cell Type: Prokaryotes (unicellular), Eukaryotes (unicellular or multicellular)
Nucleus: Prokaryotes (absent), Eukaryotes (present)
Membrane-bound Organelles: Prokaryotes (absent), Eukaryotes (present)
Cell Wall: Prokaryotes (complex), Eukaryotes (simple and only in plants)
Reproduction: Prokaryotes (binary fission), Eukaryotes (mitosis/meiosis)
DNA Structure: Prokaryotes (circular, haploid), Eukaryotes (linear, diploid)

Definition: The process by which generic cells change into specific cells to perform distinct functions.
Occurs in: Mostly in multicellular organisms, particularly during embryonic development.
**Examples in Animals: **
- Red Blood Cells: Carry oxygen, no nucleus, biconcave shape, contains hemoglobin.
- White Blood Cells: Immune defense, irregular shape, produce antibodies.
- Sperm Cells: Fertilization, long tail, many mitochondria, acrosome with enzymes.
- Egg Cells: Large and nutrient-rich, undergo chemical changes post-fertilization.
- Neurons: Transmit nerve impulses, long axons, insulated by myelin, branching dendrites.
- Muscle Cells: Facilitate movement, elongated, elastic, many mitochondria.

Guard Cells: Regulate transpiration, open/close stomata.
Root Hair Cells: Absorb water and minerals, long and thin, large surface area.
Photosynthetic Cells: Found in leaves, contain chloroplasts for photosynthesis.
Xylem Vessels: Transport water and minerals, strong due to lignin, no protoplasm for efficient transport.

Cilia: Hair-like structures for movement, found in respiratory tract and fallopian tubes.
Flagella: Tail-like structures for movement, found in sperm and bacteria.
Villi/Microvilli: Increase surface area for absorption, found in the intestines.
Pseudopods: Temporary cytoplasm extensions for movement and ingestion, found in certain protists.

Specialized cells grouped together to perform a specified function are called?
- Answer: C (Tissues)
Having membrane-bound organelles is characteristic of which type of cell?
- Answer: A (Eukaryotes)
True statement about cell specialization?
- Answer: B (All cells in organisms originated from a single cell that specializes)
Specialized cell controlling opening and closing of stomata in plants?
- Answer: B (Guard Cell)
Component giving cells strength and preventing bursting during water transport?
- Answer: C (Lignin)

Unique characteristics and specialized functions of cells make them great and essential for the survival and efficiency of organisms.