Eukaryotic Cell Structure and Functions

Eukaryotic Cells

• Eukaryotic cells are more efficient than prokaryotic cells due to their discrete organelles, which are specialized to carry out specific tasks.
• Eukaryotic cells are compartmentalized, allowing for separation of tasks and protection of sensitive components.

Advantages of Compartmentalization

• Separation of the nucleus and cytoplasm keeps DNA safe.
• Enzymes and substrate can be more concentrated in a small area, increasing efficiency.
• Harmful chemicals can be isolated, and pH levels can be maintained at different levels for different metabolic reactions.
• Organelles can be moved, and larger membrane surface areas can be used for processes that take place across a membrane.
• Example: Garlic cells contain alliin in vacuoles, which is converted to allicin (a toxic compound) when mixed with the enzyme alliinase, providing protection against herbivores.

Cell Specialization

• All living things are made up of cells, but individual cells in different tissues can be quite different from one another.
• The function of a cell determines its structure, and cells vary in size, shape, and organization.

SA:Volume Ratio

• Cell size is limited by energy and material requirements needed to stay alive.
• Volume determines energy consumption, while surface area determines the rate of exchange with surroundings.
• As a cell grows larger, its volume increases faster than its surface area, leading to a decrease in the SA:Volume Ratio.
• If the metabolic rate exceeds the cell's ability to obtain material, the cell will die, making it beneficial for cells to be small.

Being Multicellular

• Multicellular organisms are formed by repeated cell division and the grouping of similar cell types.
• Being multicellular allows organisms to exceed body limits caused by the SA:Vol ratio, enabling growth without increasing cell size.
• Cell specialization allows cells to become efficient in specific functions, interacting to achieve complex functions.

Differentiation

• Every cell in a multicellular organism is a clone of an original parent cell (except gametes), with identical DNA.
• Certain cells express specific genes, while others express other genes, leading to differentiation.

Stem Cells

• Stem cells are unspecialized cells with self-renewal and potency properties.
• When a stem cell differentiates and becomes specialized, it cannot change again.
• Stem cells are limited in availability.

Types of Stem Cells

• There are three types of stem cells found at different stages of development:
  • Totipotent: can form any cell type and divide into new organisms.
  • Pluripotent: can form any cell type.
  • Multipotent: can form a number of closely related cell types.