CEL - Cell Structure [OVERVIEW]

Cell Structure

Introduction

In this cell structure module, you will learn about the structure of cells, the components that make up different types of cells, and why cells have specific sizes and features. You’ll also learn how to calculate the surface area to volume ratio for many shapes of cells. Cells are classified as either prokaryotic or eukaryotic. You’ll understand the differences between each as well as the types of cells that make up certain groups of organisms.

Check out the following video "The Inner Life of the Cell Animation" created by an animation team at Harvard for an amazing glimpse into the inner life of a cell.

List of Lessons

In this module, we will study the following topics:

    1. Cell Size: this lesson will explain how to calculate the surface area to volume ratio and use that to determine the optimum ratio for cells.
    2. Types of Cells: this lesson will differentiate between prokaryotic and eukaryotic cells as well as plant and animal cells and explain endosymbiosis.
    3. Subcellular Components: this lesson will describe many of the organelles and structures found in eukaryotic cells.
    4. Endomembrane System: this lesson will describe the organelles specific to the endomembrane system and trace the pathway from the creation of a protein to its final destination.
    5. Plasma Membrane Structure: this lesson will describe the structure and function of the plasma membrane and explain how particles move through it.

Module Objectives

By the end of this module, students will be able to:

    • Describe the structure and/or function of subcellular components and organelles.
    • Explain how subcellular components and organelles contribute to the function of the cell.
    • Describe the structural features of a cell that allow organisms to capture, store, and use energy.
    • Explain the effect of surface area-to-volume ratios on the exchange of materials between cells or organisms and the environment.
    • Explain how specialized structures and strategies are used for the efficient exchange of molecules to the environment.
    • Describe the roles of each of the components of the cell membrane in maintaining the internal environment of the cell.
    • Describe the Fluid Mosaic Model of cell membranes.
    • Describe the role of the cell wall in maintaining cell structure and function.
    • Describe the membrane-bound structures of the eukaryotic cell.
    • Explain how internal membranes and membrane-bound organelles contribute to the compartmentalization of eukaryotic cell functions.
    • Describe similarities and/or differences in compartmentalization between prokaryotic and eukaryotic cells.
    • Describe the relationship between the functions of endosymbiotic organelles and their free-living ancestral counterparts.
    • MATH SKILL: Use mathematical calculations to determine the surface area to volume ratio of different shapes.

Key Terms

Cell - the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. 

Cell membrane - a thin membrane (a double layer of lipids) enclosing the cytoplasm of a cell; proteins in the membrane control passage of ions (like sodium or potassium or calcium) in and out of the cell.

Chloroplasts - organelles found in plant cells and other eukaryotic organisms that capture light energy to conserve free energy in the form of ATP and reduce NADP+ to NADPH through a complex set of processes called photosynthesis.

Diffusion -­ the process in which there is movement of a substance from an area of high concentration of that substance to an area of lower concentration.

Endomembrane system -­ a series of structures that function in protein processing, secretion, lipid synthesis, digestive enzymes storing, and useful molecules storing. It comprises rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), Golgi apparatus, vesicles, and lysosomes.

Eukaryote -­ an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. Eukaryotes include all living organisms other than the eubacteria and archaebacteria.

Facilitated diffusion ‐ the spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients.

Mitochondria ­‐ an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner layer being folded inward to form layers (cristae).

Nucleus ­‐ a dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material.

Peroxisomes ‐ organelles present in almost all eukaryotic cells. They participate in the metabolism of fatty acids and many other metabolites.

Prokaryote ‐ a microscopic single-­‐celled organism, including bacteria and cyanobacteria, that has neither a distinct nucleus with a membrane nor other specialized organelles.

Ribosomes ‐ a minute particle consisting of RNA and associated proteins, found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins.

Selectively permeable ‐ property of biological membranes that allows only certain substances to pass through them.

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