1 chapter 6 chemistry in biology 6.1 atoms, elements and compounds
DESCRIPTION
2 Elements Everything is made of substances called elements About 90 elements occur naturally About 16 elements are man made Of the 90 naturally occurring elements, only 25 are essential to living thingsTRANSCRIPT
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Chapter 6 Chemistry in Biology
6.1 Atoms, Elements and Compounds
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Elements
Everything is made of substances called elements
About 90 elements occur naturallyAbout 16 elements are man madeOf the 90 naturally occurring elements,
only 25 are essential to living things
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Periodic Table of the Elements
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Reading the Periodic Table
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Periodic Table of the Elements
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Needed in Macro-amounts
Oxygen 65%Carbon 18.5%Hydrogen 9.5%Nitrogen 3.3%
Other elements are needed in trace amounts
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Trace Elements
All organisms need trace elements even though they are needed in very small amounts they are essential for life
Plants absorb the trace elements from the soil
Animals eat the plants and other animalsExamples: iron, magnesium, gold,
arsenic, copper and many others
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Atoms: The Building Blocks of Elements
Atoms is the smallest particle of an element that has the characteristics of that element
Nucleus contains protons (+) and neutrons (0)
Electrons (-) in “cloud” around nucleus
Carbon atom
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Electron Energy Levels
Certain numbers of electrons can occupy different regions around the nucleus of an atom
Energy Levels1st- closest to nucleus: 2 electrons2nd- next level out: 8 electrons3rd- further level out: 18 electrons
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Electron Energy Levels
Closest energy levels are always filled first
Carbon atoms have 6 electrons
2 electrons are in the first energy level
The remaining 4 electrons fill the second energy level
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Potassium Energy Levels
19 total electrons2 electrons in first
energy level8 electrons in second
energy level9 would be in third
energy level but this is unstable8 electrons in third1 electron in fourth
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Isotopes of an Element
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Isotopes of an Element
Atoms that have different numbers of neutron but the same number of protons
Have same protons (atomic number) but different numbers of neutrons (atomic mass)
Most isotopes are unstable and the nuclei break apart and give off radiationUseful for X raysUseful for radioactive dating
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Chemistry in Biology
van der Waals Forces
When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.
The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons.
6.1 Atoms, Elements, and CompoundsChapter 6
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Compounds and Bonding
Compounds: composed of two or more different elements that are chemically combined (bonded)
Chemical bonds hold atoms together so that they are more stable
Atoms are more stable when they have their outer electron energy levels filled
Bonds can be covalent or ionic
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Covalent Bonds
Atoms share electrons
Covalent means cooperate
A molecule is a group of atoms held together by covalent bonds
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Ionic Bonds
Ionic bonds involve gaining or losing electrons
Na has lost an electron and now has a positive charge
Cl has gained and electron and now has a negative charge
Opposite charges attract
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Ionic Bonds
Ions are atoms that have gained or lost electrons
Lose electron have a positive chargeGain electrons have a negative chargeIonic bonds are not as common as
covalent in living organisms
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Chapter 6 Chemistry in Biology
6.2 Chemical Reactions
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Chemical Reactions
When chemical reaction occur, bonds between atoms are formed or broken causing substances to combine and recombine as different molecules
All of the chemical reactions that take place in an organism is called metabolism
Chemical reaction depend on many things: temperature, concentration and pH
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Balancing Chemical Reactions
Matter cannot be created or destroyed only changed in form
So all atoms must be accounted for in a chemical reaction
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Balancing Chemical Reactions
What you start with (reactants) must equal what you end up with (products)
2H2 + O2 2H2O
2 x 2 H 2 x 2 2 O 2 x 1
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Chemistry in Biology
The activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction.
Energy of Reactions
6.2 Chemical ReactionsChapter 6
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Chemistry in Biology
This reaction is exothermic and released heat energy.
The energy of the product is lower than the energy of the reactants.
6.2 Chemical ReactionsChapter 6
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Chemistry in Biology
This reaction is endothermic and absorbed heat energy.The energy of the products is higher than the energy of the reactants.
6.2 Chemical ReactionsChapter 6
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Chemistry in Biology
A catalyst is a substance that lowers the activation energy needed to start a chemical reaction.
Enzymes are biological catalysts.
It does not increase howmuch product is made and it does not get
used up in the reaction.
Enzymes
6.2 Chemical ReactionsChapter 6
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Chemistry in Biology
The reactants that bind to the enzyme are called substrates.
The specific location where a substrate binds on an enzyme is called the active site.
6.2 Chemical ReactionsChapter 6
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Chemistry in Biology
Factors such as pH, temperature, and other substances affect enzyme activity.
6.2 Chemical ReactionsChapter 6
The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form.
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Chapter 6 Chemistry in Biology
6.3 Water and Solutions
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Mixtures and Solutions
Mixtures are combinations of substances in which the individual components retain their own properties, like sand and salt mixed together, no chemical reactions have taken place
Solutions are a type of mixture where one substance dissolves in another substanceSolvent does the dissolving: waterSolute gets dissolved: sugar
Solutions are very important in living things as we are ~75% water
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Acids and Bases
pH is a measure of how acidic or basic a substance is
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Ph Scale
Most of our foods are acidic
Most of our cleaning supplies are basic (alkaline)
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Blood pH
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Chemistry in Biology
Buffers are mixtures that can react with acids or bases to keep the pH within a particular range.
6.3 Water and SolutionsChapter 6
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Importance of Water
Most life’s process (chemical reactions) can only happen in water
Water is a transport medium: blood and sap
Water has a high specific heat; holds heat and requires more heat to change its temperature; works like an insulator
Water expands when it freezes, less dense; ice floats on top
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Structure of Water
Chemical formula: H2O
Water is polarOxygen end negativeHydrogen end positive
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Polar Covalent Bonds
The electron in the covalent bond between the hydrogen and oxygen spends more time with the oxygen
Causes the oxygen end to be slightly negative, hydrogen end to be slightly positive
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Hydrogen Bonds Form due to Polarity
Hydrogen bonds are weak bonds between molecule
Positive end of one molecule is attracted to negative end of another molecule
Causes cohesionCauses adhesion
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Water’s Hydrogen Bonds
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Chapter 6 The Chemistry of Life
6.4 The Building Blocks of Life
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Carbon
Carbon is the element present in all life substances
Carbon has a unique structure Shares four electrons Forms four covalent
bonds Can have single, double,
or triple bonds Because of bonding some
molecules of the same formula can have different shapes
CH4 Methane
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Carbon
Glucose has formula C6H12O6
Fructose has formula C6H12O6
Isomers have same formula but different
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Carbohydrates
Contain carbon, hydrogen, and oxygen
Subunit : glucoseTwo types simple and
complex
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Simple Carbohydrates: Sugars
Monosaccharides: one sugarGlucoseFructoseGalactose
Disaccharides: two sugarsSucrose: glucose and fructoseMaltose: glucose and glucoseLactose: glucose and galactose
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Simple Carbohydrates: Sugars
Fructose
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Complex Carbohydrates: Polysaccharides
Include starch, cellulose and glycogenAll are chains of glucoseDifference is how the chains are put
together and type of bonds holding the glucose together
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Starch
Carbohydrate storage for plants
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Cellulose
Carbohydrate structural support for plants and algae
Found in the cell wall to give the cell structure and support
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Glycogen
Carbohydrate storage for animals
Found in liver and can move to any location
Found in muscle and only stays in that muscle
Liver Cell
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Lipids
Contain carbon, hydrogen, and oxygen
Subunit: fatty acidThree types:
DiglyceridesTriglyceridesSterols
Many more carbon-hydrogen bonds to store large amounts of energy
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Fatty Acids
Can be saturated with hydrogen and have no double bonds (most animal fats)
Can have double bonds and be unsaturated (most plant fats)
Health risks associated with saturated fats
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Diglycerides
A Phosphodiglyceride is the main part of cell membranes
Not a large component of our body
Not a large component of the food we eat
Contain a glycerin backbone and two fatty acid chains
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Triglycerides
The most common lipid
Found in our bodies Found in the food we
eatCalled fats and oilsContain a glycerin
backbone and three fatty acid chains
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Sterols
Contain four interconnected carbon rings
Common one is cholesterol
Many other sterols are made from cholesterol
Some hormones are sterols
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Proteins
Contain, carbon, hydrogen, oxygen and nitrogen
Subunit: amino acid 20 different amino acids Linked by peptide bond
Types: structural protein and enzymes Structural- build a part Enzymes- control the rate
of chemical reactions
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Enzymes
Works on a specific substrate
Lock and key fit with the substrate
Products are releasedAfter reaction the
enzyme resumes its original shape and can react again with another substrate
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Nucleic Acids
Contain carbon, hydrogen, oxygen, nitrogen and phosphorus
Subunits: nucleotidePhosphate groupSugarNitrogen base
Types: RNA and DNA Nucleotide
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DNA and RNA
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DNA
Deoxyribonucleic acidInformation storage
for cell in cell’s nucleus
Directs cell’s activitiesGenetic code
blueprintDouble helix
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RNA
Ribonucleic acidNeeded by DNA to
make proteinsWorking copy of DNALeaves the nucleus