Cell Structure and Function

Cell Structure and Function

Cell Membrane

• Semi-permeable membrane that surrounds the cell
• Composed of phospholipid bilayer with embedded proteins
• Regulates what enters and leaves the cell

Cell Wall

• Rigid layer outside the cell membrane in plants, fungi, and some bacteria
• Provides support, protection, and maintains cell shape

Cytoplasm

• Jelly-like substance inside the cell membrane
• Site of many cellular activities, including metabolism and protein synthesis

Nucleus

• Control center of the cell where DNA is stored
• Surrounded by a double membrane called the nuclear envelope

Mitochondria

• Powerhouses of the cell, responsible for generating energy through cellular respiration
• Have their own DNA and can reproduce independently

Endoplasmic Reticulum (ER)

• Network of membranous tubules and cisternae
• Involved in protein synthesis, folding, and transport

Ribosomes

• Small organelles found throughout the cytoplasm
• Site of protein synthesis

Lysosomes

• Membrane-bound sacs containing digestive enzymes
• Responsible for cellular digestion and recycling of cellular waste

Cytoskeleton

• Network of filaments that provides structural support and shape to the cell
• Involved in cell division, movement, and signaling

Cell Junctions

• Specialized structures that connect cells and allow for communication and exchange of molecules
• Types: tight junctions, desmosomes, and gap junctions

Cell Structure and Function

Cell Membrane

• Acts as a semi-permeable barrier, controlling what enters and leaves the cell
• Composed of a phospholipid bilayer with embedded proteins, allowing for selective permeability
• Regulates the movement of substances across the cell membrane

Cell Wall

• Provides structural support, protection, and maintains cell shape in plants, fungi, and some bacteria
• Rigid layer consisting of cellulose, chitin, or peptidoglycan, depending on the organism

Cytoplasm

• Jelly-like substance inside the cell membrane, where many metabolic processes occur
• Site of glycolysis, citric acid cycle, and fatty acid synthesis
• Supports cellular activities, such as protein synthesis and cell division

Nucleus

• Control center of the cell, containing most of the cell's genetic material (DNA)
• Surrounded by a double membrane called the nuclear envelope, which regulates the movement of molecules

Mitochondria

• Responsible for generating energy for the cell through cellular respiration (aerobic and anaerobic)
• Have their own DNA, known as mtDNA, and can reproduce independently
• Found in both eukaryotic and prokaryotic cells

Endoplasmic Reticulum (ER)

• Involved in protein synthesis, folding, and transport to the Golgi apparatus
• Rough ER has ribosomes attached, while smooth ER lacks ribosomes
• Plays a role in lipid synthesis and detoxification

Ribosomes

• Site of protein synthesis, where mRNA is translated into amino acid chains
• Found throughout the cytoplasm, either freely floating or attached to the ER
• Consists of two subunits: a large subunit and a small subunit

Lysosomes

• Contain digestive enzymes, responsible for breaking down and recycling cellular waste
• Membrane-bound sacs that fuse with vesicles and autophagosomes to digest cellular debris
• Involved in cellular defense against foreign substances and pathogens

Cytoskeleton

• Provides structural support, shape, and mechanical resistance to the cell
• Composed of three main components: microtubules, microfilaments, and intermediate filaments
• Involved in cell division, movement, and signaling

Cell Junctions

• Specialized structures that connect cells, allowing for communication and exchange of molecules
• Types include tight junctions, desmosomes, and gap junctions
• Play a crucial role in maintaining tissue structure and function