Cell Theory: Cell Structure and Function Notes - PDF
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This document details cell theory, the core principle that all organisms are composed of cells. It elaborates on multicellular and unicellular organisms, and differentiates between prokaryotic and eukaryotic cells. Key cellular structures and their functions, such as cell walls, membranes, chloroplasts, and mitochondria, are also explained.
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**Cell theory** - All organisms are made of cells - Cells are the basic units of life - Cells come from pre-existing cells that have multiplied. **Multicellular organisms** Living things that consist of more than one cell. They are eukaryotes, and examples can include mushrooms, animals,...
**Cell theory** - All organisms are made of cells - Cells are the basic units of life - Cells come from pre-existing cells that have multiplied. **Multicellular organisms** Living things that consist of more than one cell. They are eukaryotes, and examples can include mushrooms, animals, and plants. they have specialised functions. **Unicellular organisms** Living things that consist of one cell are know as unicellular organisms. They can't been seen with the naked eye. **Prokaryotic cells** - Prokaryotic cells are unicellular - They are 1-10 micrometres in size - They do not contain membrane-bound organelles. No nucleus, mitochondria, chloroplasts, nucleus, Endoplasmic reticulum, Golgi body, lysosomes, etc. - The chromosome is a single circle (there is only one) and it is located in the cytoplasm. - Examples can be bacteria cells **Eukaryotic cells** - 10-100 micrometres in size - Contain membrane-bound organelles - Have a nucleus - Chromosomes are many linear chromosomes and are kept in the nucleus. - Examples can include plant and animal cells. - **Cell wall** -- Provides structural support and protection to plant, fungal, and bacterial cells. - **Cell membrane** -- Controls the movement of substances in and out of the cell. - **Chloroplasts** -- Carry out photosynthesis to produce energy in plant cells. - **Vacuole** -- Stores water, nutrients, and waste, helping maintain cell pressure. - **Cytoplasm** -- A jelly-like substance that holds organelles and supports cellular processes. - **Mitochondria** -- Generate energy (ATP) through cellular respiration. - **Golgi body** -- Modifies, sorts, and packages proteins and lipids for transport. - **Nucleus** -- Contains genetic material (DNA) and controls cell activities. - **Endoplasmic reticulum (ER) smooth and rough** -- Smooth ER synthesizes lipids, while rough ER has ribosomes for protein production. - **Ribosomes** -- Synthesize proteins by translating genetic instructions. - **Lysosomes** -- Break down waste and cellular debris using digestive enzymes. - **Vesicles** -- Transport materials within and outside the cell. - **Capsule** -- A protective outer layer found in some bacterial cells. - **Pili** -- Hair-like structures that help bacteria attach to surfaces and transfer DNA. - **Flagellum** -- A whip-like structure that enables cell movement.
