Animal vs Plant Cells

It is really obvious by sight that animals are not the same as plants. You are not going to mistake a cheetah for a tree (or at least I hope not, no-one is fast enough to escape that). The difference between plants and animals carries down to the cellular level. Animals and plants have different membrane-bound compartments with specialized functions. These are called organelles.

The basic structure of the cell types is shown below.

Both types of cells contain a plasma membrane, cytoplasm, a nucleus (plural nuclei), ribosomes, mitochondria (singular mitochondrion), and lysosomes.

Plasma Membrane – is made made up of phospholipids arranged in a bilayer. It is the boundary between the cell and the extracellular space (outside the cell) and controls what enters and what leaves the cell. It also maintains the integrity of the cell.

Cytoplasm – is made up of the liquid portion of the cell (called the cytosol) and all of the organelles. It acts as a medium in which all the chemical processes and reactions in the cell occur.

Nucleus – contains DNA (deoxyribonucleic acid), which is packaged into chromosomes, which is packaged in thread-like fibres called chromatin. The nucleus is the brains of the operation and it sends signals to all the other parts of the cell. The nuclear envelope separates it from the rest of the cell but chemicals can pass through the nuclear envelope through nuclear pores.

Nucleolus – ribosomes are assembled here and then transported to the cytoplasm. There may be more than one nucleolus in a nucleus.

Ribosomes – are responsible for making proteins. They are made from RNA (ribonucleic acid).

Mitochondria – generate all the energy required by the cell through respiration, i.e. they are the powerhouses of the cell. They are thought to have come from bacteria invading complex cells in the early stages of life on Earth. Mitochondria are able to replicate by themselves and they have their own DNA.

Lysosomes – these membrane-bound organelles have a low pH and contain enzymes that break down any viruses, bacteria, cell debris, or worn-out organelles.

Plants contain extra organelles that allow them to carry out their specific function, such as chloroplasts, a large central vacuole, a cell wall, and middle lamella.

Chloroplasts – are responsible for generating food from water, carbon dioxide, and sunlight. Similarly to mitochondria, they can replicate by themselves and have their own DNA.

Cell Wall – is a strong, rigid structure that gives plant cells their strength and shape. It also acts as a protective layer.

Middle Lamella (not shown) – binds different cell walls together.

Vacuole – is a fluid-filled sac that stores food, water and waste. It isolates harmful substances and also helps maintain the shape of the cell.

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