Science Matters,
achieving scientific literacy
is the title of an excellent book by scientists Robert Hazen and James Trefil.
In a concise and clear way they give the reader an insight in many subjects of
the world of science.
What follows is a
list of definitions of concepts you probably have heard about, but don’t
exactly know what they mean or have forgotten about.
Enzymes
Large
molecules, which task it is to help other molecules link together. An enzyme
brings two specific molecules near each other, lets their atoms form a bond and
goes on.
Molecules of life
There
are four so-called molecules of life, indispensable to create living things.
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nucleic acids: DNA and RNA |
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proteins among which task it is to serve as enzymes |
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carbohydrates that provide fuel support |
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lipids, molecules that don't dissolve in water and that serve among other thing as cell membranes |
The Universe
The universe is
regular and predictable.
The laws of Isaac Newton
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Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it. |
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Force equals mass times acceleration. |
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To every action force there is an equal and opposite reaction force. |
Thermodynamics
First law: energy is
conserved.
Second law: energy
always goes from more useful to less useful forms.
Electricity
Electricity and
magnetism are two aspects of the same force.
Maxwell’s equations
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Like charges repel each other, unlike charges attract. |
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Moving electric charges create magnetic fields. |
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Magnetic effects can accelerate electrical charges. |
Matter
All matter is made of
atoms.
All matter is really
made of quarks and leptons (= electrons). Quarks and leptons combine to make
hadrons. Hadrons combine to make the nuclei of atoms.
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Atom: basic building block |
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Nucleus: heavy central part of every atom |
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Proton:
positively charged particle in the nucleus |
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Neutron:
electrically neutral particle in the nucleus |
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Electron:
electrically negative particle that orbits the nucleus |
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Element:
substance that can’t be broken down chemically |
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Isotope: atom for
which you know both the exact number of neutrons and of protons, for
instance the isotope carbon –14 contains 6 protons and 8 neutrons |
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Ion: atom that
has gained or lost electrons and hence has an electrical charge |
Quantum mechanics
Everything comes in
discrete units.
You can’t measure
anything without changing it.
Chemical bonding
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Ionic bond: one atom in a pair gives up an electron and the other acquires it on permanent loan |
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Covalent bond:
two atoms share their outer electrons |
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Metallic bond:
the outer electrons are shared by all atoms in the system |
Nuclear energy
Nuclear energy comes
from the conversion of mass.
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Fission: the nucleus splits |
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Fusion: two
nuclei come together |
Albert Einstein’s relativity theory
Every
observer sees the same laws of nature.
The difference between Newton and Einstein
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Newton: motion takes place along curved lines in a flat space |
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Einstein: motion
takes place along straight lines in a curved space |
Nucleic acids DNA and RNA
DNA consists of a
string of basic building blocks called nucleotides.
Nucleotides are built
from three smaller molecules
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phosphate |
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sugar: deoxyribose in DNA and ribose in RNA |
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bases: |
Each nucleotide is an
L-shaped combination of one sugar, one phosphate, and one base.
The DNA structure is
a twisted ladder of nucleotides with only four possible combinations of bases:
AT, TA, GC, and CG.
The sequence of bases
along the double helix of DNA contains the genetic code.
Genetic code:
all the information
a cell needs to reproduce itself and run its chemical factories.
The RNA structure
consists of only half the ladder: one sugar-phosphate spine with bases sticking
out. In RNA uracil U substitutes the base thymine.
RNA plays a critical
role in transferring and reading genetic messages.
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mRNA: messenger RNA moves into the main body of the cell carrying the coded information |
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tRNA: transfer
RNA links to mRNA and forms a protein |
Gene:
a specific segment of a much longer DNA molecule
Many genes can fit
along a single molecule of DNA.
Different organisms
have different numbers of genes.
Chromosomes:
one long double helix of DNA wrapped around a core of proteins
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Mitosis: division of a single cell into two identical daughters |
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Meiosis: process
of cell division that begins with a cell with a full complement of
chromosomes and ends with cells with half this complement |
Human
genome project: produce a listing of the entire human genetic code
that consists of all 23 chromosome pairs with about three billion base pairs
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Sequencing: base-by-base survey |
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