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SPONCH CaFe
What is the SPONCH CaFe?
In the video for Session 1, our host Dr. Doug Zook offered
a simple mnemonic to remember the key elements that compose living
things: the SPONCH CaFe. The letters are symbols for chemical
elements: carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus
(P),
sulfur (S), calcium (Ca) and iron (Fe). Although the symbols
are not in order of relative abundance (that would be OCHNCaPSFe — hardly
simple to say!), together these elements compose 99.8% of all
living things.
The elements represented by the SPONCH
CaFe
What role do the various elements play?
You may recall
from Session 1 that the molecules that compose living things
are called organic molecules. Organic molecules are
built from repeated subunits that are built from the elements
in the SPONCH CaFe. Let’s take a look at some representative
subunits to see where these elements are found.
| Organic molecule |
Subunit |
Elements |
Example |
| Carbohydrate |
Sugar |
C,H,O |
Glucose |
| Protein |
Amino acid |
C, H, O, N
(S in some) |
Two linked amino acids:
Cysteine and Alanine |
| Lipid |
Fatty acid |
C, H, O
(P and N in some) |
Glycerol linked to three fatty acid chains |
| Nucleic acid |
Nucleotide |
C, H, O, P, N |
Two linked nucleotides:
Thymine and Adenine
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Carbohydrates store energy. The starch in a potato is
a good example. They also act as structural components, such
as the cellulose that makes a celery stalk stringy or the chitin that
composes
the outer skeleton of a beetle.
Proteins are what the cell uses
to translate the information in DNA into cell products. Proteins
act as enzymes, which are important
in making chemical reactions happen in cells. There are also
structural proteins. Hair and cartilage are good examples.
Lipids perform a variety of functions. Fats store energy. Cell membranes
are made of a type of structural lipid. Sex hormones,
such as testosterone and estrogen, are made of lipids. The pigment
chlorophyll,
which is important in photosynthesis, is a lipid.
Nucleic acids include DNA, which carries genetic information, and RNA, which
translates that information into proteins.
What
about the other elements?
The other elements in the SPONCH CaFe
are calcium (Ca) and iron (Fe). Calcium is an important structural
component. Bones and
teeth contain calcium. It’s also critical in keeping body chemistry
in balance. Iron is important in the synthesis of hemoglobin,
which is responsible for carrying oxygen in blood.
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SPONCH CaFe
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