Cell Structure and Function

• Cell is the main component of any living organism
• Cells are the building blocks of organisms.
• Unicellular organisms live and replicate independently due to cell components.
• Onion cells, plant cells, contain a cell wall on the outer side and a cell membrane within it
• Human cheek cells have an outer cell membrane or plasma membrane.
• Inside Human cheek cells there is a membrane-bound nucleus
• The nucleus contains DNA
• The cytoplasm is important for cellular activities in both plant and animal cells, with chemical reactions keeping the cell in a living state

Cellular Organelles

• Cell membrane is in animal cells
• Cell wall is in plant and fungi cells
• Nucleus
• Ribosomes
• Endoplasmic Reticulum (ER)
• Golgi apparatus
• Mitochondria
• Lysosomes
• Vacuoles
• Plastids (in plants)
• Cytosol and Cytoskeleton

Cell (Plasma) Membrane

• Lipids and proteins are the main components
• Carbohydrates may also be present
• Phospholipids (lipid + phosphate) are the major type of lipids found in the cell membrane
• Glycoprotein (carbohydrate + protein) may also be present
• Lipids are found in two layers, known as the lipid bilayer

Membrane Bilayer Arrangement

• The polar (hydrophilic) head faces the outer sides in the bilayer arrangement
• The hydrophobic tails face the inner part in the bilayer arrangement
• The nonpolar (hydrophobic) tail is protected from the aqueous environment as its location is between the polar heads
• Cholesterol is also contained in the membrane, in addition to phospholipids
• Proteins are classified as integral or peripheral
• Integral proteins are integrated within the bilayer either partially or totall
• Peripheral proteins lie on the surface of the membrane

Plasma Membrane Location

• Phospholipids are the building blocks
• They have polar groups, phosphate groups, and glycerol
• There are hydrophilic heads and hydrophobic fatty acid tails
• Integral proteins are embedded within this layer, and carbohydrates are attached to the surface

Cell Membrane Components

• Cholesterol
• Carbohydrates
• Glycoprotein
• Integral protein
• Peripheral protein

Plasma Membrane Importance

• Isolates cells from the outer environment
• Protects the cell
• Transports nutrients into the cell
• Transports toxic substances out of the cell
• Facilitates cell-cell communication

Nucleus

• The nucleus is a very essential part of the cell
• It is in the center of the cell and contains the genetic material (DNA)
• The nucleus distinguishes eukaryotic cells
• DNA processes occur inside the nucleus
• The outer covering layer is the nuclear envelope or nuclear membrane, separating the nuclear content from other parts of the cell
• Nucleolus is a spherical structure in the cell's nucleus with a primary function is to produce and assemble the cell's ribosomes

Ribosomes

• These are non-membrane bound particles
• Found free floating in the cytoplasm or attached to Rough Endoplasmic Reticulum (RER)
• These are small spherical organelles and are found in a very high amount within the cell
• They are called protein factories, as they are the very important organelles in protein synthesis

Endoplasmic Reticulum (ER)

• The Endoplasmic Reticulum (ER) with ribosomes on the outer surface is called Rough Endoplasmic Reticulum (RER)
• Where there is an absence of ribosomes they are smooth and known as Smooth Endoplasmic Reticulum (SER)
• Rough Endoplasmic Reticulum (RER) is frequently observed in the cells which are actively involved in protein synthesis
• Smooth Endoplasmic Reticulum (SER) is the major site for synthesis of lipid

Mitochondria

• The single one is called mitochondrion
• Mitochondria are oval bodies with double membrane, containing folded inner membranes
• Known as the power house of the cell as it is responsible for energy production
• The inner part is called matrix and contains single circular DNA molecules, a few RNA molecules, and ribosomes

Cytosol

• A gel-like substance floating in the cell

Cytoplasm

• Consists of organelles and cytosol

Cytosol and Cytoplasm

• The place of many processes are related to protein and carbohydrates

Cytoskeleton

• The protein filament structures are present in the cytoplasm