• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

THE BRIGHTEST HUB FOR HEALTH AND WELLNESS

  • Home
  • Health
  • Medicine
  • Alternative Medicine
  • Diet and Nutrition

Gram-Positive Versus Gram-Negative Bacterial Cell Walls

January 12, 2010 by rfcamat Leave a Comment

The terms “gram-positive” and “gram-negative” are used to describe the nature of bacterial cell walls. The cell wall of a particular kind of bacteria is determined at the laboratory through an experiment called gram-staining. Determining whether a particular bacteria is gram-positive or gram-negative is important in the identification of bacterial species especially in identifying pathogenic bacteria that cause diseases to humans and animals.

There are structural differences between gram-positive and gram-negative bacterial cell walls. These differences are discussed below.

Difference in the Number of Peptidoglycan Layers that Constitutes the Cell Wall

Gram-positive bacteria have more peptidoglycan layers than gram-negative bacteria. As a result, the cell wall of gram-positive bacteria is thicker than the cell wall of gram-negative bacteria. Moreover, the gram-negative bacterial cell wall is more prone to mechanical breakage by having only few layers of peptidoglycan.

Peptidoglycan is a structural molecule that constitutes bacterial cell wall. Peptidoglycan molecules are joined together to form a peptidoglycan layer and several layers of peptidoglycan are joined together to form a thick and rigid cell wall that protects the internal structures of bacteria from damages brought about by external forces. Bacterial cell wall prevents the entry of molecules from the outer environment that can cause harm to the bacteria.

[ad#co-1]

Gram-Negative Bacterium has an Outer Membrane, Gram-Positive Bacterium Hasn’t

Gram-negative bacterial cell wall is different from gram-negative bacterial cell wall by having an outer membrane that covers the peptidoglycan layer. The peptidoglycan layers are attached to the outer membrane by lipoproteins.

The outer membrane of gram-negative bacteria is composed of lipoproteins, lipopolysaccharides (LPS), and phospholipids. The membrane helps the bacteria to survive considering the presence of external elements and forces that can harm the bacteria. The outer membrane is negatively charged, and this helps prevent the bacteria from being phagocytosed (by macrophages for example). The outer membrane also acts as a barrier for the disastrous effects of antibiotics, digestive enzymes, detergents, heavy metals, and among others.

The lipopolysaccharides (LPS) of gram-negative bacteria act as bacterial antigens. These antigens are used in the laboratory to identify a bacterial species. This is possible since each bacterium has different LPS antigen to other bacteria. Today, there are now laboratory tests that detect the antigen specific for a single bacterial species. It is now possible to identify what particular bacterium is causing an infection to an individual or even to an animal.

Difference in the Transport of Nutrients and Other Compounds towards the Bacterial Cytoplasm

Gram-positive bacteria have molecules called techoic and lipotechoic acids that transport important nutrients from the external environment towards the bacterial cytoplasm. The molecules are embedded in the peptidoglycan layer in the cell wall and regulate the entry of substances from the external environment. The molecules also act as bacterial antigens that can be detected through laboratory tests and they are utilized in the identification of bacterial species.

Gram-negative bacteria don’t have techoic and lipotechoic acids but do have molecules called porins. Porins are doughnut-shaped proteins that traverse the bacterial cell wall and create a channel for the passage of nutrients and other compounds needed by the bacteria to survive.

Labeled Diagram of Gram-Positive and Gram-Negative Bacterial Cell Walls

Comparison of Gram Positive and Gram Negative Bacteria (Image from Wikimedia Commons)
Comparison of Gram Positive and Gram Negative Bacteria

Filed Under: Biology

READ MORE

ABOUT THE AUTHOR

Raymund is a biologist by profession but with wide interest on nutrition and healthy living. He is currently a health and wellness writer in an American online publication. Blogging is one of his favorite hobbies.

Reader Interactions

Leave a Reply Cancel reply

You must be logged in to post a comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Primary Sidebar

RECENT ARTICLES

  • Why Do I Feel Tired After Eating?
  • Adverse Effects of Artificial Food Coloring on Children
  • List of Flowers You Can Eat and Their Health Benefits
  • Tips on How to Boost Your Metabolism
  • Best Workout Music for the iPod
  • What is the average bench press for a man?
  • Top 5 Healthiest Types of Cooking Oil
  • The Best Exercises for an Apple Body Shape
  • Beyonce’s Workout Secrets for a Sexy Physique
  • How Healthy Can Kimchi Be?

TOPICS

  • Allergies (5)
  • Alternative Medicine (22)
  • Biology (28)
  • Chemistry (1)
  • Diet and Nutrition (9)
  • Environmental Science (8)
  • Genetics (19)
  • Health (126)
  • Laboratory Tests (5)
  • Medicine (71)
  • Physical Fitness (1)
  • Science and Technology (1)
  • Transferred post (59)
  • Uncategorized (3)

Footer

MEDICAL DISCLAIMER

The contents of the TheBrightestHub.com Site, such as text, graphics, images, and other material contained on the TheBrightestHub.com Site (“Content”) are for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the TheBrightestHub.com Site.

Copyright © 2023 · Genesis Sample on Genesis Framework · WordPress · Log in

7ads6x98y