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Introduction to cells
Learning objectives
After completing this study unit, you will be able to:
- Describe the parts of a typical cell
- Define intracellular and extracellular environments
- Classify organelles of the cell and list one major function of each
Introduction
The cell is the structural and functional unit of living organisms. A typical cell consists of a cell membrane (plasma membrane), cell nucleus and cytoplasm. The cell membrane forms a selectively permeable barrier between the intracellular and extracellular environments. The cytoplasm includes the intracellular fluid (cytosol) and organelles, except for the nucleus.
Cell organelles can be classified into non-membranous and membranous. The non-membranous organelles are the cytoskeleton, ribosomes and proteasomes. The membranous organelles are the nucleus, mitochondria, peroxisomes, rough and smooth endoplasmic reticulum, Golgi apparatus, and lysosomes.
Each of these organelles contributes to the smooth functioning of the cell.
Explore concepts
Parts of a typical cell
A typical cell has a cell membrane, nucleus and cytoplasm (cytosol with organelles).
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:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/cytoplasm-3/hQgf1IJFxQRJCCl8zBUg_cytoplasm.jpg "Cytoplasm (Cytoplasma); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/nucleus-1/kqGEjwcBkSldfBOFt3XlVQ_Nucleus.png "Cell nucleus (Nucleus); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/cytosol/eREjkPNk09uvd0ACeP2Mww_cytosol.png "Cytosol; Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/cytoskeleton/TAY4xoOjGwNoFXaFGa1opQ_Cytoskeleton.png "Cytoskeleton; Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/ribosome/GTrjTskN6QPCeEUfGwf2Lg_Ribosomes_magnified.png "Ribosome (Ribosoma); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/mitochondrion-of-the-eukaryotic-cell/gxnSx2Aay7zsImuNyY2Frw_Mitochondrion_magnified.png "Mitochondrion; Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/peroxisome/j8k0La4HOLsCDYSxDfmGvw_Peroxisome_magnified.png "Peroxisome (Peroxysoma); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/rough-endoplasmic-reticulum/OqTFr7w0SOGamrMFuad1gg_Rough_endoplasmic_reticulum.png "Rough endoplasmic reticulum (Reticulum endoplasmicum granulosum); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/smooth-endoplasmic-reticulum/K11E1hvwZPSgF0C0EQ2vGQ_Smooth_endoplasma_reticulm.png "Smooth endoplasmic reticulum (Reticulum endoplasmicum non granulosum); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/golgi-apparatus/SOj9WkuH98CG1chXZJtxw_Golgi_apparatus.png "Golgi apparatus (Apparatus golgiensis); Image: Paul Kim"){kind=logo}
:watermark(/images/watermark_only.png,0,0,0):watermark(/logos/logo_url.png,-10,-10,0):format(jpeg)/images/learnable/lysosome/TbbLnBxWJseXFKn8lz1tLw_Lysosome_magnified.png "Lysosome (Lysosoma); Image: Paul Kim"){kind=logo}
Plasma membrane
Plasmalemma
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Synonyms:
Cell membrane, Membrana cellularis
Classification of organelles
Based on the presence or absence of a membrane, organelles can be classified into non-membranous and membranous organelles.
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Take a quiz
Check how well you know the parts of a cell with this quiz!
Summary
Parts |
Cell membrane: Selectively permeable barrier that separates the intracellular and extracellular environments |
|---|---|
Intracellular vs extracellular environments |
Intracellular environment: Inside the cell |
Non-membranous organelles |
Cytoskeleton: Structural support, movement, cellular extensions (microvilli, cilia, flagella) |
Membranous organelles |
Nucleus: Contains DNA, command center of the cell |
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