Unit2

• Structure of Bacterial Cells: - Bacterial cells have a cell wall, cell membrane, cytoplasm, ribosomes, circular DNA (nucleoid region), and plasmids.
• Structure of Plant and Animal Cells: - Plant cells have a cell wall, absent in animal cells. - Both have a cell membrane, nucleus, cytoplasm, ribosomes, and mitochondria. - Chloroplasts are unique to plant cells, while animal cells may have smaller vacuoles.
• Cell Membrane: - Structure: A thin layer around the cell. - Function: Maintains cell structure and controls substances entering and leaving the cell.
• Cytoplasm: - Structure: Jelly-like substance inside the cell. - Function: Contains dissolved salts, nutrients, and organelles; site for most chemical reactions in the cell.
• Nucleus: - Structure: Usually round, enclosed by a nuclear membrane; contains chromosomes (DNA and proteins). - Function: Controls cell activities and inheritance of characteristics.
• Mitochondria: - Structure: Powerhouse of the cell. - Function: Generates energy through cellular respiration.
• Ribosomes: - Structure: Tiny structures, free in cytoplasm or attached to Endoplasmic Reticulum (ER). - Function: Site of protein synthesis.
• Vesicles: - Structure: Membrane-bound sacs. - Function: Transport substances within the cell.
• Cell Wall (in Plant Cells): - Structure: Made of cellulose. - Function: Maintains cell structure and provides protection.
• Vacuole (in Plant Cells): - Structure: Large fluid-filled space. - Function: Stores cell sap (water, sugars, salts) and contributes to cell structure.
• Chloroplasts (in Plant Cells): - Structure: Site for photosynthesis; contains chlorophyll. - Function: Captures light energy for food production through photosynthesis.
• Plasmid and Circular DNA (in Bacterial Cells): - Structure: Small, circular DNA fragments. - Function: Carry additional genetic information; involved in processes like antibiotic resistance.
• New cells are produce by division of existing cells which is called mitosis
• specialized cells are - ciliated cells, root hair cells. palisade mesophyll cells, neurons, red blood cells, sperm and egg cells
• ciliated cells- movement of mucus in trachea and bronchi
• root hair cells- absorption of water and mineral ions from the soil
• palisade mesophyll cell- photosynthesis
• neurons- conduction of electrical impulses
• red blood cells- transport of oxygen
• sperm and egg cells- reproduction
• cells are the basic unit or building block of life
• tissues- many similar cells working together and performing the same function
• organs- many similar tissues working together to perform a particular function
• organ system- a collection of different organs working together and performing a particular function
• organism- a collection of systems work together to perform an independent organism
• size of specimen is calculated by:- magnification= image size divided by actual size