Cell Theory and Cell Types

###细胞理论

• Cells are the basic structural and functional units of living organisms
• All living organisms are composed of cells, either single-celled (unicellular) or multi-celled (multicellular)
• Cells arise from pre-existing cells

Prokaryotic and Eukaryotic Cells

• Prokaryotic cells (bacteria) lack a true nucleus and have their genetic material in the cytoplasm
• Eukaryotic cells (plants, animals, fungi, and protists) have a true nucleus that contains genetic material
• Both types of cells have genetic material, cytoplasm, and ribosomes
• Prokaryotic cells lack membrane-bound organelles, whereas eukaryotic cells have them

Cell Membrane and Cytoplasm

• Cell membrane (plasma membrane) is semi-permeable, regulating the flow of materials into and out of the cell
• Cytoplasm is a jelly-like substance that contains organelles and supports cellular activities
• Cytoplasm is present in both prokaryotic and eukaryotic cells
• Organelles in the cytoplasm include ribosomes, which produce proteins

Ribosomes

• Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells
• They synthesize proteins based on genetic information from DNA
• Ribosomes may be free in the cytoplasm or attached to the endoplasmic reticulum

Eukaryotic Cell Organelles

• Nucleus contains genetic material (DNA) and controls cellular activities
• Nucleus has a nuclear envelope and nucleolus, where ribosomes are synthesized
• Endoplasmic reticulum (ER) is a network of membranous tubules and sacs
• ER has two types: rough ER (with ribosomes) and smooth ER (without ribosomes)
• Rough ER is involved in protein synthesis and transport
• Smooth ER is involved in detoxification and lipid synthesis

Golgi Apparatus

• Golgi apparatus is a complex of flattened sacs and tubules
• It receives vesicles from the ER and modifies, sorts, and packages proteins and lipids for transport
• Golgi apparatus determines the destination of proteins and lipids

Mitochondria

• Mitochondria are organelles found in both plant and animal cells
• They generate energy for the cell through cellular respiration
• Mitochondria use glucose and oxygen to produce ATP

Other Organelles

• Lysosomes are membrane-bound sacs that contain digestive enzymes
• Peroxisomes are involved in the breakdown of fatty acids and amino acids
• Plant cells have a central vacuole that stores materials and helps maintain cell shape
• Animal cells have multiple small vacuoles for storage and other functions
• Plant cells have a cell wall that provides additional protection and shape maintenance

Cell Theory

• Living organisms are composed of cells, which are the basic structural and functional units
• Cells arise from pre-existing cells, and all living organisms are either single-celled (unicellular) or multi-celled (multicellular)

Cell Types

• Prokaryotic cells lack a true nucleus and have genetic material in the cytoplasm
• Eukaryotic cells have a true nucleus containing genetic material
• Both cell types have genetic material, cytoplasm, and ribosomes

Cell Structure

• Cell membrane is semi-permeable, regulating the flow of materials into and out of the cell
• Cytoplasm is a jelly-like substance containing organelles and supporting cellular activities
• Prokaryotic cells lack membrane-bound organelles, whereas eukaryotic cells have them

Ribosomes

• Ribosomes are non-membrane-bound organelles in both prokaryotic and eukaryotic cells
• They synthesize proteins based on genetic information from DNA
• Ribosomes may be free in the cytoplasm or attached to the endoplasmic reticulum

Eukaryotic Cell Organelles

• Nucleus contains genetic material (DNA) and controls cellular activities
• Nucleolus is the site of ribosome synthesis
• Endoplasmic reticulum (ER) is a network of membranous tubules and sacs
• ER has two types: rough ER (with ribosomes) for protein synthesis and transport, and smooth ER (without ribosomes) for detoxification and lipid synthesis

Golgi Apparatus

• Golgi apparatus receives vesicles from the ER and modifies, sorts, and packages proteins and lipids for transport
• It determines the destination of proteins and lipids

Mitochondria

• Mitochondria generate energy for the cell through cellular respiration
• They use glucose and oxygen to produce ATP

Other Organelles

• Lysosomes contain digestive enzymes for cellular digestion
• Peroxisomes break down fatty acids and amino acids
• Plant cells have a central vacuole for storage and maintaining cell shape
• Animal cells have multiple small vacuoles for storage and other functions
• Plant cells have a cell wall providing additional protection and shape maintenance