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Biology LibreTexts

4: Parts of the Cell

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  • Introduction

    The cell theory states that all living things are composed of cells, cells are the basic units of life, and that all cells arise from existing cells. In this course, we closely study cells. There are 2 types of cells: prokaryotic and eukaryotic. Prokaryotes lack a nucleus and true organelles, and are typically significantly smaller than eukaryotic cells. Prokaryotic organisms are found within the domains Bacteria and Archaea. Eukaryotic cells do contain nuclei, as well as other organelles that work together to support homeostasis of the whole cell. Though eukaryotes are larger than prokaryotes, we must use a microscope to view all cells, which are typically too small to see with the naked eye.

    There are vast differences between cell types, but a few features are common to all cells: plasma membrane, cytoplasm, ribosomes, and cytoskeleton. All cells also use DNA for their genetic material; in eukaryotes this is within the nucleus and in prokaryotes it is found in the nucleoid region of the cytoplasm. Prokaryotes generally have a cell wall made of peptidoglycan and some have flagella or fimbriae, which are used for movement or attachment. Eukaryotes have several more organelles and are further differentiated into 2 categories: plant cells and animal cells.

    Some organelles common to eukaryotes include mitochondria, peroxisomes, vesicles, lysosomes, smooth and rough endoplasmic reticula, and Golgi bodies. Animal cells tend to lack cell walls and chloroplasts, while plant cells do contain chloroplasts and have cellulose cell walls.

    In this lab, bacterial, animal, and plant cells will be observed using the microscope. Students will draw what was visualized to record their observations.