Studied by 14 people
What are elements?
substances that cannot be broken down into simpler substances
What are the 4 most common elements?
carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)
What are the CHON elements used for?
building biological molecules and forming storage compounds and cells in all organisms
What are trace elements?
elements required by an organism only in very small quantities
What are examples of trace elements?
iron (Fe), iodine (I), and copper (Cu)
What are atoms?
the units of life and the building blocks of the physical world
What are protons?
positively charged (+) particles
What are neutrons?
uncharged particles
What are electrons?
negatively charged (-) particles
What are isotopes?
atoms that have the same number of protons but differ in the number of neutrons in the nucleus
What are compounds?
2 or more elements held together by chemical bonds
What are the different types of chemical bonds?
ionic, covalent, and hydrogen
What is an ionic bond?
a bond formed between 2 atoms when one or more electrons are transferred from atom to another
What are ions?
the charged forms of the atoms in ionic bonds
What are covalent bonds?
bonds between atoms that share electrons
What are nonpolar covalent bonds?
covalent bonds that share electrons equally
What are polar covalent bonds?
covalent bonds that share electrons unequally
What are hydrogen bonds?
weak chemical bonds that form when a hydrogen is covalently bonded to an oxygen atom
What special properties does hydrogen bonding give water?
cohesion
adhesion
surface tension
high specific heat
unique characteristics as ice
What is cohesion?
the linking together of like molecules
How does cohesion help water transport in plants?
by helping hold together the column of water within the cells
What is adhesion?
the clinging of one substance to another
How does adhesion help water transport in plants?
by helping resist the downward pull of gravity
What is surface tension?
a measure of how difficult it is to stretch or break the surface of a liquid
How is the surface tension of water significant?
water has unusually high surface tension, making it behave as though it were coated with an invisible film
What is specific heat?
the amount of heat that must be absorbed or lost for 1g of a substance to change its temperature by 1°C
How is water’s high specific heat significant in nature?
a large body of water can absorb and store a huge amount of heat from the sun in the daytime and during the summer while warming up only a few degrees, and at night and during the winter, the gradually cooling water can warm the air
ocean temperatures are stabilized, creating a favorable environment for marine life
since organisms are made primarily of water, they are better able to resist changes in their own temperature
What are the properties of ice?
it is less dense than liquid water and thus can float
water expands when it solidifies, forming a lattice structure
How are the properties of ice significant in nature?
if ice sank, all bodies of water would freeze, making life as we know it impossible on Earth
when a deep body of water cools, the floating ice insulates the liquid water below, preventing it from freezing and allowing life to exist under the frozen surface
When is a solution acidic?
if it contains a lot of hydrogen ions (H+)
What happens if you dissolve an acid in water?
it will release a lot of hydrogen ions
When is a solution basic?
if it contains a lot of hydroxide ions (OH-)
What happens if you dissolve a base in water?
it will release a lot of hydroxide ions
What are organic molecules?
molecules that contain carbon
What are inorganic molecules?
molecules that do not contain carbon
Why is carbon important for life?
it is a versatile atom, meaning that it has the ability to bind not only with other carbons but also with a number of other elements, including nitrogen, oxygen and hydrogen
What are monomers?
the individual building blocks of a polymer
What are polymers?
chains of building blocks in macromolecules
What is dehydration synthesis?
the formation of polymers by removing water to form a bond
What is hydrolysis?
the breaking apart of polymers by adding water to break a bond
What are macromolecules?
the 4 classes of organic compounds to life on earth
What are the 4 macromolecules?
carbohydrates, proteins, lipids and nucleic acids
What are elements make up carbohydrates?
carbon, hydrogen and oxygen in a 1:2:1 ratio
What are the most common monosaccharides?
glucose and fructose
What are monosaccharides the energy source for?
cells
How are glucose and fructose depicted?
as either “straight” or “rings” with Hs and OHs attached to them
What are disaccharides formed by?
glycosidic linkage
What is maltose formed from?
2 glucose molecules
What are polysaccharides?
many repeated units of monosaccharides in branched or unbranched chains
What are examples of polysaccharides?
starch, cellulose, glycogen, chitin
What is the function of starch?
to store sugar in plants
What is the function of glycogen?
to store sugar in animals
What is the function of chitin and cellulose?
to provide structural support
What are proteins important for?
structure, function, and regulation of tissues and organs
What is the structure of proteins?
an amino group (-NH2), a carboxyl group (-COOH), a hydrogen, and an R-group surrounding a central carbon
What are the monomers of proteins?
amino acids
What elements are in proteins?
carbon, hydrogen, oxygen and nitrogen
How many different amino acids are there?
20
How do we distinguish between amino acids?
based on their R-group
How do you spot amino acids?
by looking for the amino group (NH2), then looking for the carboxyl molecule
What does side chain polarity affect?
whether an amino acid is more hydrophobic or more hydrophilic
What are the polymers of proteins?
polypeptides
What is a dipeptide?
2 amino acids joined together when the carboxyl group of one combines with the amino group of another
What is a peptide bond?
the bond between 2 amino acids
What is the primary structure of a protein?
the linear sequence of the amino acids
What are the secondary structures of a protein?
the coils (alpha helix) and zigzags (beta-pleated sheets) that form when a polypeptide begins twisting
What is the tertiary structure of a protein?
the interaction of amino acids that were far apart from each other prior to polypeptide reshaping
What is the quaternary structure?
the interaction of different polypeptide chains
What elements do lipids consist of?
carbon, hydrogen and oxygen
What are examples of lipids?
triglycerides, phospholipids, steroids
Why are lipids important?
due to their nonpolar structures
What are the functions of lipids?
structural components of cell membranes, sources of insulation, signaling molecules, and a means of energy storage
What are triglycerides?
a glycerol molecule with 3 fatty acid chains attached to it
What are saturated fatty acids?
fatty acids saturated with hydrogen along its long carbon chain
What are unsaturated fatty acids?
fatty acids that have a double bond in their chain
What is lipid saturation?
the extent that saturation in a lipid can affect its structure and function; the more double bonds that exist within a lipid, the more unsaturated it is
What is the structure of phospholipids?
2 fatty acid tails and 1 negatively charged phosphate head
Why are the phospholipid heads hydrophobic?
because their lack of polarity prevents them from mixing well with water
Why are the phospholipid tails hydrophilic?
because their polarity allows them to mix well with water
What is cholesterol?
a four-ringed molecule that is found in membranes
What is cholesterol important for?
making certain types of hormones and vitamin D
What elements are in nucleic acids?
carbon, hydrogen, oxygen, nitrogen, and phosphorus
What are the monomers of nucleic acids?
nucleotides
What does DNA contain?
the hereditary “blueprints” of life
What is RNA essential for?
protein synthesis
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