Life-forms are all made up of matter, and they exist in many different forms.
There are elements in matter.
Substances that can't be broken down into simpler substances by chemical means are called elements.
Oxygen, carbon, hydrogen, and nitrogen make up the majority of the mass of living things.
Smaller quantities of other elements are also present.
Four percent of a living thing's weight is made up of these elements.
Some elements are called trace elements because they are only required in very small quantities.
Iron, I, and copper are trace elements.
Oxygen and hydrogen are found in the macromolecules.
Nitrogen is found in the body.
nucleic acids and some lipids have a trace amount of Phosphorus in them.
The smallest element that retains its characteristic properties is the atom.
The building blocks of the physical world are the atoms.
There are small particles called protons, neutrons, and electrons in atoms.
Let's look at an atom.
There are particles in the nucleus of an atom.
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The negatively charged particles spin around the nucleus.
Particles are larger than electrons.
For our purposes, electrons are massless.
Most atoms have the same number of electrons and protons.
The number of protons and neutrons in the nucleus is different for some atoms.
The atoms are called isotopes.
Over time, some isotopes decay predictably.
Ancient artifacts can be dated by looking at the rate of decay of carbon-14.
This process is called dating.
A chemical compound is formed when two or more elements are combined in a ratio.
Sometimes a compound has different properties than the elements.
Oxygen and hydrogen are gases in nature.
They pass into a liquid state when they combine to make water.
A chemical reaction happens when hydrogen and oxygen atoms form water.
The atoms of a compound are held together by chemical bonds.
An ionic bond is formed when electrons are transferred from one atom to another.
One atom loses electrons and becomes negatively charged, and the other atom gains electrons and becomes positively charged.
The atoms have charged forms.
The attraction between the two oppositely charged ionises results in an ionic bond.
The charged ion Na + and Cl are formed when Na reacts with Cl.
electrons are shared between atoms The bond between the atoms is called nonpolar covalent.
The bond between the electrons is called polar covalent.
A single covalent bond is formed when one pair of electrons is shared between two atoms.
A double covalent bond is formed when two pairs of electrons are shared.
A triple covalent bond is formed when three pairs of electrons are shared.
Water is an important substance in nature.
Water plays an important role in chemical reactions.
Let's take a look at the properties of water.
There are two hydrogen atoms and an oxygen atom in water.
The bonds between hydrogen and oxygen are not shared equally by the electrons in water.
The hydrogen atoms have a partial positive charge and the oxygen atoms have a partial negative charge.
Molecules with both positive and negative charges are said to be polar.
Water is a polar molecule.
The negatively charged ends of other polar compounds are attracted to the positively charged elements of the water molecule.
The positively charged ends of polar compounds attract negatively charged ends.
The formation of water beads or raindrops can be seen as a result of these forces.
Intermolecular attractions are called hydrogen bonds.
Hydrogen bonds are chemical bonds that form when a hydrogen atom is attracted to another hydrogen atom.
Water is held together by hydrogen bonds.
When hydrogen bonds are present in large numbers, they are strong.
Water can be used as a solvent because it reacts well with other polar substances.
The hydrogen bonds that hold water together contribute to a number of special properties.
Water has a tendency to stick together.
The water exhibits cohesive forces.
Life is very important to these forces.
Water is pulled on neighboring water during transpiration.
All the way down the plant vessels, these draw up the molecule immediately behind them.
The water moves up the stem because of the chain of water molecule.
Water molecule like to stick to other substances.
They're difficult to separate because of the water.
The ability of water to rise up the roots, trunks, and branches of trees is accounted for by the cohesion and adhesion forces.
capillary action is the phenomenon that occurs in thin vessels.
The surface tension of water is related to the cohesiveness of the water molecule.
The surface of water has a tension that is similar to a taut trampoline.
Light things like leaves and water striders can sit atop the surface without sinking.
Water has a high heat capacity.
In plain English, heat capacity is the ability of a substance to resist temperature changes.
When you heat an iron kettle, it gets hot very quickly.
It has a low specific heat.
It doesn't take a lot of heat to increase the temperature of the kettle.
Water has a high heat capacity.
It takes a lot of heat to get the temperature to go up.
The boiling point of water is very high.
If someone goes out on a warm day, it is important that liquid water doesn't boil away.
One of the things that helps keep the temperature stable in our oceans is water's ability to resist temperature changes.
It's also why organisms that are mostly made up of water are able to keep their body temperature constant.
One of the most important properties of water is hydrogen bonding.
Solid water expands on freezing when four water molecules are bound in a lattice of ice.
The denser the molecule is, the more it moves closer together.
The molecule density in liquid water is slightly denser than in solid water.
If you leave a soda can in your car in the winter, it will pop, because water expands on freezing and becomes less dense than liquid water.
Animals can live underneath the ice on the top of lakes or streams because of the property of water.
If ice was denser than water, it would sink to the bottom.
All aquatic life wouldn't survive.
Water can be dissolved in other polar substances.
The water has certain properties.
There is a high heat capacity in water.
Water expands when it is cold.
Water is important because most reactions occur in watery solutions.
If the solution in which they occur is acidic, basic, or neutral, reactions are also influenced.
A solution with a lot of hydrogen ion is acidic.
If you put acid in water, it will release a lot of hydrogen ion.
You usually think of lemons when you think of acids.
If you squeeze lemon juice into a glass of water, the solution will become acidic.
That's because lemons release a lot of H + into the solution.
Bases do not release hydrogen ion when added to water.
They release a lot of hydroxide ion.
A basic solution is said to be alkaline.
Bases are usually slippery.
The majority of common soap is composed of bases.
Don't forget to look at the equations and formulas sheet.
A pH scale can be used to measure the acidity or alkalinity of a solution.
The scale is numbered from 1 to 14.
The neutral pH is 7.
The concentration of hydrogen ion in a solution can be used to determine whether the solution is acidic, basic, or neutral.
A solution with a lot of hydrogen ion will be acidic and have a low pH.
A decrease in the pH is caused by an increase in H + ion levels.
The pH scale is not a linear scale.
A tenfold change in hydrogen ion concentration is represented by a change of one pH number.
A pH of 3 is ten times more acidic than a pH of 4.
In the reverse direction, a pH of 4 represents a tenfold decrease in acidity compared to a pH of 3.
As the concentration of H + ion increases, the pH becomes smaller.
If we use the equation, we can see that the concentration of H + ion in stomach acid is 10 -2 M. You can double-check the numbers with your calculator.
The scale below shows that stronger acids have lower pHs.
A solution with a low concentration of hydrogen ion will have a high pH.
The AP Biology Equations and Formulas sheet has the equation for pH listed.
You won't be expected to perform calculations using this equation.
You should know how the equation works and when it's useful.
Let's talk about a special group of compounds now that we've talked about chemical compounds in general.
Most of the chemical compounds in living organisms have a skeleton of carbon atoms surrounded by hydrogen atoms.
These are known as organic compounds.
Inorganic compounds are those that do not contain carbon atoms.
Salt is an insturment.
Carbon is a versatile atom, meaning that it can bind with other carbons, as well as other elements such as nitrogen, oxygen, and hydrogen.
The activities necessary for life are carried out by the resulting molecules.
Carbon atoms and hydrogen atoms are found in organic compounds.
Carbon atoms and hydrogen atoms are not found in organic compounds.
Macromolecules are chains of building blocks.
The individual building blocks are called monomers.
Carbohydrates are organic compounds that contain carbon, hydrogen, and oxygen.
The elements are usually in a ratio of 2:1.
The formula C n H 2n O n can be used to represent the proportion of elements within the molecule.
Monosaccharides, disaccharides, and polysaccharides are the most common types of carbohydrates.
A monosaccharide is a single saccharide.
Cells use monosaccharides as an energy source.
Two sugars are the most common.
Monosaccharides include Galactose, ribose, and deoxyribose.
The chemical formula C 6 H 12 O 6 is used to calculate six-carbon sugars.
It is the most popular sugar around.
The favorite food of plants isglucose, which is an important part of the food we eat.
In order to provide energy, living organisms break down glucose.
This ancient biochemical process is called cell respiration and can be performed by almost all living organisms.
Fructose is a common sugar in fruits.
Look for the carbon molecule with a lot of OHs and Hs attached to it.
There are two different forms here.
A water molecule is lost during the process of synthesis dehydration.
When two monosaccharides are joined, the bond is called a glycosidic linkage and the resulting sugar is called a disaccharide.
The disaccharide is formed from two sugars.
Lactose is found in dairy products.
That's called hydrolysis and it means "water" and "breaking".
The bond between the two monomers is broken by the water.
In biology, hydrolysis is a common reaction.
Dehydration synthesis is a common reaction for joining things.
Polysaccharides are made up of many units of monosaccharides.
Polysaccharides can be branched or unbranched.
You will need to know the most common polysaccharides for the test.
There are sugar storage molecules.
Animals and plants have sugar in them.
The cell walls in plants are made up of b-glucose, which is made up of Cellulose.
It is supposed to lend structural support.
Humans can't digest b-linked glucose, which is found in wood.
When we eat plants, we can get some nutrition from their stored starch, but not from their cell walls.
As fiber roughage, this passes through us.
Fiber is important in the diet, but you should probably leave the firewood alone.
The structure, function, and regulation of your tissues and organs are dependent on the function of your cells.
There are a lot of different types.
The building blocks of the human body are made up of mino acids.
They have carbon, hydrogen, oxygen, and nitrogen atoms.
There are 20 different types of amino acids.
You don't have to memorize all of the 20 acids.
You have to remember that every molecule has four important parts around a central carbon: an R-group, a carboxyl group, and an NH 2.
This is a typical amino acid.
The side chain is called the R-group because it is the only group of acids that differ.
As in the case of the hydrogen atom and charged carbon skeleton, the R-group associated with an amino acid could be simple or complex.
Look for the carboxyl molecule if you want to see an amino acid.
The side chains for each acid are different.
You don't have to memorize the structures of the side chains for individual amino acids, but you should know that they can vary in composition, polarity, charge, and shape depending on the side chain that they have.
The side chain's polarity affects whether an animo acid is hydrophilic or hydrophobic.
On the next page, you can see all the 20 amino acids.
They are in some categories: nonpolar, polar un charged, and polar charged.
A one-letter name is given to each of the three-letter abbreviations we've listed.
For example, histidine can be referred to as His or just H.
On the next page, you can see that two of the amino acids donate a protons, making them negatively charged.
They are usually positively charged when they accept protons.
The atom sulfur is only found in two of the two amino acids.
This reference page is a good place to start learning about the common acids.
You don't have to memorize them all.
Two acids form a dipeptide.
The dehydration synthesis process is the same as before.
A bond is formed when a water molecule is removed.
The bond between two acids has a special name.
A polypeptide is an organic compound if a group of amino acids is joined together.
A three-dimensional structure is formed when a polypeptide chain twists and folds.
The carboxyl end of the chain always has the new amino acid added to it.
The polypeptide needs to go through a number of changes before it can be called aProtein.
There are four levels of structure.
The primary structure is the linear sequence of the amino acids.
The coil or zigzagging pattern is formed when the polypeptide begins to twist.
These are examples of secondary structures.
The different R-groups of the amino acids are interacting with each other.
Each R-group has its own shape, size, charge, and so on.
Depending on the order in which the amino acids are in, theProtein can twist and fold in different ways.
This is the reason why there are so many different shapes.
The secondary structure is formed by the interaction between the primary and secondary structure.
After the secondary structure changes the polypeptide can now interact with each other.
The tertiary structure is what this is called.
The exterior of most proteins are found in an acidic environment.
The interior of the proteins is usually home to hydrophobic amino acids and regions.
Two cysteine amino acids can form a bond with each other to form a disulfide bond.
The molecule is usually locked into a stable shape by the tertiary structure.
Several different polypeptide chains interact with each other to form a quaternary structure.
There are different polypeptide chains that come together.
Only those that have folded correctly can perform their function.
There are mistakes in the chain that can lead to nonfunctional proteins.
One more thing, in some cases, the folding of proteins involves other proteins called chaperonins.
They make the process more efficient.
Steroids are one of the most common examples of triglycerides.
Lipids are important because they function as structural components of cell membranes, sources of insulation, signaling molecule, and a means of energy storage.
The cells that make up the fat in our bodies are called adipocytes, and they are filled with triglycerides.
Each triglyceride is made of a glycerol molecule with three fatty acid chains attached to it.
A long chain of carbons covered in hydrogen is a fatty acid chain.
A carboxyl group is found at one end of the chain.
The carboxyl groups of the two acids are important.
Carboxyl groups have acid in their name.
Let's look at it.
Each of the carboxyl groups of the three fatty acids must react with one of the three hydroxyl groups of the glycerol molecule to make a triglyceride.
The water molecule is removed.
The removal of water is required for the creation of a fat.
An ester linkage is formed between the glycerol molecule and the fatty acids.
It can be saturated with hydrogens along its long carbon chain or it can have a few gaps where double bonds exist instead of a hydrogen.
There is a double bond in the chain.
There are many double bonds within the fatty acid.
There is a special class of lipids called phospholipids.
Take a look at the cholesterol.
Some of the unique properties of phospholipids make them very important.
The tails of the two acids are water-hating.
Just like oil and water don't mix.
The reason for this is that the nonpolar substances don't mix well with the polar ones.
The "head" of the lipid is water-loving, meaning that it mixes well with water.
The negative charge draws it to the positive end of the water molecule.
The molecule is an amphipathic because it has both a hydrophilic and a hydrophobic region.
The side that likes to hang out with water is the one that hates to.
The two acid chains orient themselves away from the water.
Keep these properties in mind.
We'll see how this relates to the structure and function of cell membranes later.
Cholesterol is a type of cholesterol.
Cholesterol is a four-ringed molecule.
It helps to hold things together when it's very high.
The nucleic acids are the fourth class of organic compounds.
Carbon, hydrogen, oxygen, and nitrogen are contained in nucleic acids.
Nucleic acids are made up of simple units.
You will need to know about the two types of nucleic acids for the exam.
You will be expected to know about the two types of nucleic acids shown here.
The "blueprints" of all life are contained in DNA.
It's important that RNA is used for synthesis.
When we talk about heredity, we'll talk about genes in more detail.
The table summarizes the important macromolecules.
There are two or more elements in a compound.
The bonds that hold the Molecules together are ionic and covalent.
Hydrogen bonding is important for the following properties of water: Cohesionadhesion surface tension high heat capacityexpansion on freezingpolar structureability to dissolved other polar (hydrophilic) substances but inability to dissolved non polar (hydrophobic) substances is important for biological reactions.
Solutions can be acidic, basic or neutral.
Carbon atoms are contained in organic molecules.
There are many monomers bound together in biology.
The dehydration reactions that lead to the creation of these polymers.
The breakdown of these polymers occurs.
There are important organic macromolecules in biology.
There are 20 different amino acids, each with a different R-group, that link together to form polypeptides.
The final structure of the chain is made from special shapes.
The structure can be divided into four parts: primary, secondary, tertiary and quaternary.
Cholesterol is a type of cholesterol.
Nucleic acids are chains of either genes or nucleotides.
The genetic recipes are in the body.
Chapter 15 contains answers and explanations.
Water has unique structural and chemical properties that are critical to life.
The human cells have a pH of 7.4.
The basic units of the molecule are called mino acids.
All life forms on the planet.
Stanley Miller and Harold Urey conducted an experiment at the University of Chicago to see if the conditions of the early Earth would have favored the formation of larger, more complex organic molecules.
In the experiment, basic organic chemicals were sealed in a flask and exposed to electric sparks and water vapor in order to recreate the atmosphere of the primitive Earth.
After one day of exposure, the mixture in the flask had turned pink in color, and later analysis showed that at least 10% of the carbon had been transformed into simple and complex organic compounds.
No nucleic acids were found in the mixture.
cysteine and methionine could not be formed in this experiment.
A scientist believes that the Miller-Urey experiment failed to yield the nucleic acids because of the absence of critical chemical substrates that would have existed on the primordial Earth due to volcanism.
Catabolism is the breaking down of complex macromolecules into their basic components.
Catabolism is used for many biological processes.
Maltotriose is a trisaccharide composed of three sugars.