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Biological macromolecules review

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Key terms

Biological macromoleculeA large, organic molecule such as carbohydrates, lipids, proteins, and nucleic acids.
MonomerA molecule that is a building block for larger molecules (polymers). For example, an amino acid acts as the building blocks for proteins.
PolymerA large molecule made of repeating subunits (monomers). For example, a carbohydrate is a polymer that is made of repeating monosaccharides.

Types of biological macromolecules

Biological macromoleculeBuilding blocksFunctionsExamples
CarbohydratesMonosaccharides (simple sugars)Provide cells with quick/short-term energy, source of dietary fiberGlucose, sucrose, starch, cellulose, chitin
LipidsFatty acids and glycerolProvide cells with long-term energy, make up biological membranesFats, phospholipids, waxes, oils, grease, steroids
ProteinsAmino acidsProvide cell structure, send chemical signals, speed up chemical reactions, etcKeratin (found in hair and nails), hormones, enzymes, antibodies
Nucleic acidsNucleotidesStore and pass on genetic informationDNA, RNA

Common mistakes and misconceptions

  • Describing macromolecules as “large” is relative. We refer to them as “macro” because they are large compared to other, smaller molecules. However, this does not mean that they are large enough to view with the naked eye. Even a large protein, like hemoglobin, is still a million times smaller than a grain of rice!
  • Not all fats and carbohydrates are “bad.” Information about different kinds of diets can be confusing and may lead someone to believe that all fats or all carbohydrates are unhealthy. This simply isn’t the case. Fats and carbohydrates are actually essential for cellular function!

Want to join the conversation?

  • stelly blue style avatar for user Zara Z
    how can lipids act as a chemical messenger?
    (5 votes)
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  • duskpin sapling style avatar for user Elodie
    Are phospholipids polymers?
    (3 votes)
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  • blobby green style avatar for user gracem3430
    why are vitamins not digested in the body
    (5 votes)
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    • piceratops tree style avatar for user lilliebet05
      Vitamins are not digested, whereas, they are absorbed.

      Vitamins are organic compounds that are required for normal animal metabolism but are either not created in the body or are created in insufficient amounts and must be received through your diet. Almost all of vitamin absorption goes to the small intestine.

      Vitamin absorption in the intestine is important for avoiding deficiency disorders, and it can be limited by a variety of factors, including intestinal disease, genetic abnormalities in transport molecules, excessive alcohol use, and drug interactions.
      (2 votes)
  • blobby green style avatar for user isa 😊
    which would be the differences between DNA and RNA were not very clear to me, they seem technically the same and I cannot differentiate them very well
    (4 votes)
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  • mr pants orange style avatar for user Alejandre, Andrew
    is amino acids used in protein shake
    (2 votes)
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  • old spice man green style avatar for user Sonya
    Why aren't minerals a macromolecule?
    (2 votes)
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  • blobby green style avatar for user Marina McNamara
    After reading the key terms, I am a little bit confused.. to my understanding, monomers are the makeup of polymers... is that correct? If so, are the terms "polymer" and "biological macromolecules" synonymous?
    (2 votes)
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    • winston baby style avatar for user Jessica Cruijff
      As I understand it, polymers are a subdivision of biological macromolecules. 'Polymer' is the branch of macromolecules that is made up of ONLY ONE monomer that repeats itself.

      For example, a carbohydrate is a macromolecule that is classified as a polymer because it is made up of repeating monosaccharides, but a fat (lipid) is a macromolecule that cannot be further classified because if you look under the 'monomers' column, it is built up by more than one monomer.

      Hope this helped!
      (3 votes)
  • blobby purple style avatar for user kneesofdoom
    When the body doesn't have any lipids or carbs for energy, does the body use protein as a last resort or when is protein used? After a workout when you don't eat? I'm just curious.
    (2 votes)
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    • male robot donald style avatar for user Tybalt
      Protein is indeed used like a last resort! After carbs are completely depleted, the body will switch to fatty acids as the main energy source, powering essential body systems like the nervous and circulatory systems. If the body is left like this for several days, cells will begin to break down protein in conjunction with the fat. This is dangerous in the long run, especially if the fat storages are completely used up, as the loss of proteins cause organ damage. When this protein breakdown occurs and when it will become fatal, however, depends on the person.

      As starvation typically happens over the period of several days, the body does not have to use many--if any--proteins to power itself should you skip a meal on purpose every day. Here, you might be breaking fat instead. However, every person is different, and one diet plan or fasting regimen can have vastly different effects on a person.

      Did this help, and was I clear?
      (3 votes)
  • duskpin ultimate style avatar for user Cassius Alabanza
    Which biological molecule is made up of nucleotides?
    (2 votes)
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    • leaf green style avatar for user asenger2
      Nucleic acids are made up of nucleotides. Nucleic acids are used to store and pass on heritable traits through genetic information, basically a blueprint on how to make a human, through DNA and RNA. Hope this helps!
      (3 votes)
  • eggleston blue style avatar for user Rose Sam
    can someone give me the basic idea of how nucleic acids end up being instructions for how we look our height and ... ?
    (3 votes)
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    • spunky sam blue style avatar for user ‏‏‎ ‎Oliver

      So basically nucleic acids are different structures that form long strands of DNA or RNA, which is our genetic code basically. These nucleic acids form what are called nucleotides, which then form the DNA and RNA.

      Nucleic acids are found in every living thing, from bacteria to viruses (though there is still a debate as to whether viruses are living or not).

      I hope this answered your question.
      (1 vote)