Biology - Chapter 2 : Cell The Unit of Life

Define Cell

Cell is the functional and structural unit of Living organisms.

Define Cell Membrane and Cell Wall

The cell membrane is a selectively permeable barrier surrounding the cell that regulates the movement of substances in and out, while the cell wall is a rigid outer structure found in plant cells, providing support and protection.

Cytoplasm

Cytoplasm is the semi-liquid substance within a cell that holds organelles and is the site for many cellular processes.

Endoplasmic Reticulum

It is an irregular network of double membranes distributed over the entire cytoplasm in a cell.

Ribosomes

They are small numerous small granules either scattered freely in the cytoplasm or attached to the the membranes of the endoplasmic reticulum. They are factories for the synthesis of proteins.

Mitochondria

Mitochondria is known as powerhouse of cell because it produces adenosine triphosphate (ATP) through cellular respiration, providing energy for the cell's activities.

Golgi apparatus

A cellular organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles. In plants they are known as dictyosomes.

Lysosomes

Organelles that contain digestive enzymes to break down waste materials and foreign substances around them.

Centrosomes and Centrioles

Centrosomes are cellular structures that organize microtubules and play a critical role in cell division, while centrioles are cylindrical structures within the centrosome that help in the formation of spindle fibers during mitosis.

Plastids and its Types and Definitions

Plastids are double-membrane organelles found in plant cells and are involved in the synthesis and storage of food. The main types include chloroplasts for photosynthesis, chromoplasts for pigment synthesis, and leucoplasts for storage.

Nucleus

The control center of the cell that holds the genetic material (DNA) and coordinates activities such as growth, metabolism, and reproduction.

Prokaryotic Cells

Simple, unicellular organisms without a nucleus, such as bacteria, characterized by their lack of membrane-bound organelles.

Eukaryotic Cells

Complex cells with a nucleus and membrane-bound organelles, found in plants, animals, and fungi.

Chromosomes

Structures within the nucleus that contain DNA and carry genetic information, essential for cell division and inheritance.

Protoplasm

The living substance of a cell, consisting of the cytoplasm and nucleus, where various cellular processes occur and cellular components are suspended.