Botany C2 PDF

Read Chapter two in your textbook before proceeding z Chapter Two: Chemistry of Life © Bauman Books, Inc.  z Basics of Life Chapter two in the book starts with a discussion of the basics of life, but I think the material fits...

Read Chapter two in your textbook before proceeding z Chapter Two: Chemistry of Life © Bauman Books, Inc.  z Basics of Life Chapter two in the book starts with a discussion of the basics of life, but I think the material fits better in Chapter three, so that is where I moved the discussion © Bauman Books, Inc.  z Definitions Elements--the fundamental units of matter Atom--the smallest piece of an element Molecule--chemical combinations of two or more atoms Compound--two or more different elements in a molecule Macromolecules--extremely large molecules that make up the basic building blocks of cells: Carbohydrates Proteins Lipids Nucleic acids © Bauman Books, Inc.  z Chemistry Basics Elements--the fundamental units of matter Fundamental elements of life C HOPKINS CaFe Mg NaCl Si Carbon Hydrogen Calcium Magnesium Sodium Silicon Oxygen Iron Chlorine Phosphorus Potassium Natrium= Latin for sodium Iodine Nitrogen Sulfur Ferrous= Latin for iron Kalium = Latin for phosphorus Organic chemistry--chemistry of the element carbon in association with hydrogen Organic chemical--molecules with both hydrogen and carbon; note: in chemistry, organic does not mean “natural” or “good for you” © Bauman Books, Inc.  z Chemistry Basics Macromolecules of life Carbohydrates Proteins Lipids Nucleic acids © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Protons--positive electrical charge; number of protons determines which element it is © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Electron shells Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; orbit around the nucleus in a pathway called a shell © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Electron shell shells Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; orbit around the nucleus in a pathway called a shell © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Electron shell shells Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; orbit around the nucleus in a pathway called a shell © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Electron shell shells Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; orbit around the nucleus in a pathway called a shell © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Electron shell shells Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; orbit around the nucleus in a pathway called a shell © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Atoms are composed of: Electron shell shells Protons--positive electrical charge; number of protons determines which element it is Neutrons--no electrical Nucleus charge (neutral) Electrons--negative electrical charge; always same number of electrons as protons; orbit around the nucleus in a pathway called a shell © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Each shell can hold a Electron shell specific number of electrons The first shell holds a maximum of two electrons © Bauman Books, Inc.  z Chemistry Basics Simplified structure of an atom Each shell can hold a Electron shell specific number of electrons The first shell holds a maximum of two electrons The second shell can hold up to eight electrons © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Atoms form chemical bonds with one another using their electrons © Bauman Books, Inc.  z Chemistry Basics Chemical bonds The outermost shell of an Valence shell atom is known as the valence shell © Bauman Books, Inc.  z Chemistry Basics Chemical bonds The outermost shell of an Valence shell atom is known as the valence shell In this carbon atom), there are six protons, so there are six electrons. The first shell has two electrons, and the second shell has four. © Bauman Books, Inc.  z Chemistry Basics Chemical bonds The outermost, valence Valence shell shell of a carbon atom is its second shell, which can hold eight electrons, so carbon’s valence shell is “missing” four electrons. © Bauman Books, Inc.  z Chemistry Basics Chemical bonds The outermost, valence Valence shell shell of a carbon atom is its second shell, which can hold eight electrons, so carbon’s valence shell is “missing” four electrons. © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Now let’s see how an atom Valence shell fills its valence shell © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Many atoms fill their valence shells by sharing electrons with other atoms. Since atoms are sharing valence electrons, we call the bonds they form covalent bonds © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Here the carbon atom shares an electron with each of four hydrogen atoms Now the carbon’s valence Hydrogen atom shell is full (eight electrons) (one proton, one electron) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Here the carbon atom shares an electron with each of four hydrogen atoms Now the carbon’s valence Hydrogen atom shell is full (eight electrons) (one proton, one electron) We represent this with the chemical formula CH4 © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Here the carbon atom shares an electron with each of four hydrogen atoms Now the carbon’s valence Hydrogen atom shell is full (eight electrons) (one proton, one electron) We represent this with the chemical formula CH4 Covalent bonds are the strongest chemical bonds © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Another type of chemical bond is an ionic bond To illustrate, we will use sodium (Na) and chlorine (Cl) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds One electron in valence shell (third shell) Another type of chemical bond is an ionic bond. To illustrate, we will use sodium and chlorine Sodium has eleven electrons: 2 in 1st shell, 8 in 2nd shell, and 1 in the 3rd shell, which can hold eight Atoms are more stable with a full valence shell, which is easily accomplished when Na sodium loses one electron © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Loses one electron so now the outer shell is full; valence +1 Sodium’s valence is plus one (+1); it has one extra electron in its valence shell When it loses its valence electron, it loses a negative charge, so now sodium has a +1 charge and is called a positive ion, also known as a cation Na+ © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Loses one electron so now the outer shell is full; valence +1 An ion is an atom with an electrical charge A positive ion is a cation Na+ (Na cation) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Seven electrons in valence shell valence - 1 Chlorine has 17 protons and 17 electrons: 2 in 1st shell one, 8 in 2nd shell, and 7 in 3rd shell, which is the valence shell Since the 3rd shell can hold 8 electrons, it is one short Chorine’s valence is therefore -1 Cl © Bauman Books, Inc.  z Chemistry Basics Chemical bonds In this example, sodium loses its ”extra” valence electron to chlorine Na+ Cl- (Na cation) (Cl anion) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds In this example, sodium loses its ”extra” valence electron to chlorine Both now have full outer shells of eight electrons Chlorine is now a negatively charge ion, an anion Na+ Cl- (Na cation) (Cl anion) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds In this example, sodium loses its ”extra” valence electron to chlorine Both now have full outer shells of eight electrons Chlorine is now a negatively charge ion, an anion Na+ Cl- (Na cation) (Cl anion) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds In this example, sodium loses its ”extra” valence electron to chlorine Both now have full outer shells of eight electrons Chlorine is now a negatively charge ion, an anion Positive and negative charges attract one another, which holds the Cl- two ions together in an Na+ (Cl anion) ionic bond (Na cation) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Ionic bonds are not as strong as covalent bonds, because the atoms are not sharing electrons; instead, one atom has “taken” an electron from the other Na+ Cl- (Na cation) (Cl anion) © Bauman Books, Inc.  z Chemistry Basics Chemical bonds The third type of chemical bond is a partial bond called a hydrogen bond Hydrogen bonds form when a hydrogen atom covalently bonds to another atom, but hydrogen’s electron spends most of its time orbiting the O H H other atom H2O This results in a partial positive charge on the hydrogen and a partial negative charge on the other atom © Bauman Books, Inc.  z Chemistry Basics Chemical bonds The third type of chemical bond is a partial bond called a hydrogen bond δ- A partial positive charge is indicated by the symbol δ+ δ+ δ+ and a partial negative O H H charge by the symbol δ- H2O © Bauman Books, Inc.  z Chemistry Basics Chemical bonds δ+ Hydrogen bond The third type of chemical bond is a partial bond δ+ called a hydrogen bond δ- δ- A partial positive charge is indicated by the symbol δ+ δ+ δ+ and a partial negative O H H charge by the symbol δ- A hydrogen bond exists when the δ+ on a hydrogen atom is attracted to a δ- on another atom © Bauman Books, Inc.  z Chemistry Basics Chemical bonds δ+ Hydrogen bond Many hydrogen bonds can occur δ+ A single hydrogen bond δ- δ- is very weak because it results from the attraction of fleeting δ+ partial electrical δ+ δ+ charges, O H H δ- But, thousands or millions of hydrogen bonds together can hold molecules to particular shapes, such as the δ+ familiar double helix of DNA © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Many hydrogen bonds can occur A single hydrogen bond is very weak because it results from the attraction of fleeting partial electrical charges, But, thousands or millions of hydrogen bonds working together can hold molecules to particular shapes, such as the familiar double helix of DNA © Bauman Books, Inc.  z Chemistry Basics Chemical bonds δ+ Hydrogen bond Hydrogen bonding between molecules of δ+ one type is called cohesion δ- δ- δ+ δ+ δ+ O H H δ- δ+ © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Hydrogen bonding between molecules of one type is called cohesion δ- Hydrogen bonding between different δ+ molecules is called δ+ adhesion O δ- H H © Bauman Books, Inc.  z Chemistry Basics Chemical bonds Cohesion and adhesion play significant roles in plant physiology δ- δ+ δ+ O δ- H H © Bauman Books, Inc.  z Chemistry Basics Macromolecules of life Carbohydrates Proteins Lipids Nucleic acids © Bauman Books, Inc.  z Chemistry Basics Carbohydrates C, H, O Monomers (building blocks)--sugars, monosaccharides Polymers (two or more monomers)--disaccharides, starch, cellulose, lignin © Bauman Books, Inc.  z Chemistry Basics Proteins C, H, O, N, S Monomers (building blocks)--amino acids Polymers (two or more monomers)--polypeptides, proteins © Bauman Books, Inc.  z Chemistry Basics Lipids C, H, O, P Fats Monomers (building blocks)--fatty acids, glycerol Saturated fats--every carbon is fully “loaded” with hydrogen Unsaturated fats-- some carbon atoms form double covalent bonds between them, so there is less hydrogen and “kinks” in the molecules Phospholipids Monomers (building blocks)--fatty acids, glycerol Waxes Monomer--fatty acid Steroids Monomers--four “rings” of carbon atoms © Bauman Books, Inc.  z Chemistry Basics Nucleic acids C, H, N, P ATP--short term, “rechargeable” energy molecule of cells DNA--deoxyribonucleic acid, genetic material of cells RNA--ribonucleic acid, carries genetic information from DNA during protein synthesis © Bauman Books, Inc.  z Chemistry Basics Macromolecules of life Carbohydrates Proteins Lipids Nucleic acids © Bauman Books, Inc.