chapter 2 botany 1a

8/13/2019 Chapter 2 Botany 1A

1/76

The ChemicalComposition of Cells

Chapter 2


2/76

LEARNING OBJECTIVE 1

Describe the basic structure of an atom,and explain ionic, covalent, and hydrogen

bonds


3/76

Atoms

Atom smallest possible particle of anelement that still possesses and elements

property

Subatomic particles: Proton- positive electric charge, small mass Neutron- uncharged, about same mass as proton Electron- negative charge, extremely small mass


4/76

Neutron

Electron

Proton

+

+++

++

+

Fig. 2-1, p. 24


5/76

Isotopes of Hydrogen

Isotopes similar elements that contain different numbers of neutrons


6/76

Electrons

Move around the nucleus at differentenergy levels

Allow elements to combine chemically toform chemical compounds

Ions are atoms which tend to gain or loseelectrons


7/76

Electron Configurations


8/76

(b) Carbon (C)(6p, 6n)

Electron

Nucleus

First (lowest)

energy level

Second energylevel

(a) Hydrogen (H)(1p)

Fig. 2-3ab, p. 25


9/76

(d) Nitrogen (N)

(7p, 7n)

(c) Oxygen (O)

(8p, 8n)

Fig. 2-3cd, p. 25


10/76

(e) Sodium (Na)

(11p, 12n)

(f) Chlorine (Cl)

(17p, 18n)

Fig. 2-3ef, p. 25


11/76

Atoms are capable of forming

bonds Chemical bond attractive force that holds 2 or more

atoms together

Chemical bonds form compounds


12/76

KEY TERMS

IONIC BOND An electrostatic attraction between oppositely

charged ions

COVALENT BOND A chemical bond involving one or more

shared pairs of electrons


13/76

Ionic Bonding


14/76

11 protons 17 protons

and

11 electronsSodium (Na)

17 electronsChlorine (Cl)

10 electrons

Sodium ion (Na+)

18 electrons

Chloride ion (Cl)

+

Fig. 2-4a, p. 26


15/76

Arrangement of atoms in acrystal of salt

Sodium chloride (NaCl)

Cl Na+

Cl

Cl

Na+Na+

Na+

Fig. 2-4b, p. 26


16/76

Covalent Bonding in Hydrogen


17/76

Hydrogen (H) Hydrogen (H) Molecular hydrogen (H2)

Fig. 2-5, p. 27


18/76

Covalent Bonding in Methane


19/76

Types of Covalent Bonds

Nonpolar covalent bonds electrons are equally

shared

Polar covalent bonds electrons are unequally

shared


20/76

KEY TERMS

HYDROGEN BOND An attraction between a slightly positive hydrogen

atom in one molecule and a slightly negative atom

(usually oxygen) in another molecule


21/76


Discuss the properties of water, andexplain the importance of water to life


22/76

Why is water important?

Essential to life Controls our climate Shapes continents


23/76

Water is a polar substance

Polar substance substances with partial charges


24/76

Water

Has a strong dissolving ability Molecules form hydrogen bonds with one another

(cohesion)

Molecules form hydrogen bonds to substances withionic or polar regions (adhesion)


25/76


Distinguish between acidsand bases, anddescribe the pH scale


26/76

Acids and Bases

Definition Acidsdissociate in water to form hydrogen

ions (protons, H+)

Basesdissociate in water to yield negatively

charged hydroxide ions (OH-)


27/76

pH Scale

A measure of the relative concentrationsof H+and OH-in a solution

A solutions acidity or alkalinity isexpressed in terms of the pH scale


28/76

ACID RAIN!!

Accumulation of sulfur oxides andnitrogen oxides in the atmosphere

Suflur oxide &nitrogen oxide combinewith water to form SULFURIC andNITRIC ACID


29/76


Describe the chemical compositions andfunctions of carbohydrates, lipids, proteins,and nucleic acids


30/76

Carbohydrates Include sugars, starches, cellulose

Important fuel molecules, components of molecules(nucleic acids) and cell walls


31/76

Carbohydrates

Types of carbohydrates1. Monosaccharides - simple sugars

2. Disaccharides-two monosaccharide units

3. Polysaccharides- many monosaccharide

units


32/76

Common Monosaccharides


33/76

Sucrose Synthesis


34/76

Starch: A Storage Polysaccharide


35/76

Cellulose: A Structural

Polysaccharide


36/76

Lipids

Organic compounds that have a greasy consistency, donot readily dissolve in water


37/76


38/76

Lipids

Types of Lipids:1. Neutral fats2. Oils3. Phospholipids

4.

Pigments and Waxes


39/76

Lipids

Neutral fats / oils1. Neutral fats solid at room temperature2. Oil- liquid at room temperature

Contain a molecule of glyceroljoined to one, two orthree fatty acids

Glycerol 3 carbon compound that contains ahydroxyl group

Usually used as a source of energy


40/76

Formation of a Neutral Fat or Oil


41/76

Lipids

Fatty acids Long, unbranched

hydrocarbon chainwith a carboxyl group

at one end Types:

Saturated contain nocarbon to carbon

double bonds

Unsaturated contain1 or more carbon to

carbon double bonds


42/76

Saturated Unsaturated


43/76

Lipids

Phospholipids Important component of the cell membrane Consists of a glycerol molecule and 2 fatty acids


44/76

Lipids

Waxes Cutin waxy substance found in the outer wall of

epidermal cells

Suberin substance found in the walls of cork cells

Prevent water loss


45/76

Protein

A macromolecule composed of amino acidsjoined bypeptide bonds

Order of amino acids determines structure and functionof a protein molecule


46/76

Proteins

Enzymes A protein which controls the rate at which a chemical

reaction occurs

Highly specific E.g. Sucrase

Substrate the material in which theenzyme works on


47/76

Amino Acids

Basic unit of proteins Contain a carbon atom bonded to an amino acid

(-NH2), a carboxyl group (-COOH2) and a side

chain, designated R


48/76

Peptide Bonds

Bonds that links one amino acid to another as aresult of a condensation reaction

Several amino acids connected to each othercan form a polypeptide chain


49/76

Organization of Protein Molecules

Organization of Protein


50/76

Organization of Protein

Molecules

Primary linear sequence of amino acids Secondary spiral helix

Tertiary over-all shape of a polypeptide chaindetermined by interactions of side chains of aa

Quaternary 2 or more polypeptide chainsassociate to form one final protein molecule


51/76

(d) Quaternary(a) Primary (b) Secondary (c) Tertiary

Fig. 2-15, p. 37


52/76

Nucleic Acids

Macromolecules that are made out of carbon,hydrogen, nitrogen and phosphorous

Control the cell

s life processes

Deoxyribonucleic acid (DNA) Transmits information from one generation to the next

Ribonucleic acid (RNA) Involved in protein synthesis


53/76

Nucleotides

Repeating units that form nucleic acids Order of nucleotides in a nucleic acid chain determines

the specific information encoded

Parts of a nucleotide1. Nitrogenous base2. 5-carbon sugar

3. Phosphoric acid


54/76

Nucleic Acids


55/76

Nucleic Acids


56/76

Phosphate

Adenine(a nitrogenous

base)

Deoxyribose(a five-carbon sugar)

(a) Nucleic acids are composed of nucleotides. Like allnucleotides, this DNA nucleotide has three parts: a nitrogenous

base, a five-carbon sugar, and a phosphate group.

H H

Fig. 2-18a, p. 39

Two sugar-phosphatebackbones


57/76

backbones

Pairedbases

Region of

hydrogen bonding

(c) The DNA molecule is a double helix

consisting of two nucleotide chainsjoined by their paired bases.

(d) A small part of a DNA molecule isunwound to show how the bases pair

(the region of hydrogen bonding).Fig. 2-18cd, p. 39


58/76

ATP Adenosine triphosphate Modified nucleotide Composition:

Base adenine Sugar ribose 3 phosphate molecules


59/76


60/76

Enzymes

Speed up a chemical reaction by loweringits activation energy(energy needed to

initiate the reaction)

Most enzymes are highly specific andcatalyze only a single chemical reaction

Without enzymes, chemical reactions incells would occur too slowly to support life


61/76

Enzymes and Activation Energy


62/76

Enzyme-Substrate Complex


63/76

Active sites

Enzyme Substrates Enzymesubstratecomplex

Enzyme Products

Fig. 2-17, p. 38Stepped Art


64/76


State the firstand second laws ofthermodynamics, and describe how eachapplies to plants and other organisms


65/76

KEY TERMS

FIRST LAW OF THERMODYNAMICS Energy cannot be created or destroyed,

although it can be transformed from one form

to another

SECOND LAW OF THERMODYNAMICS When energy is converted from one form to

another, some of it is degraded into a lower-

quality, less useful form


66/76

Energy

The ability to do work

Plants and other organisms cannot createthe energy they require to live, but must

capture energy from the environment and

use it to do biological work


67/76

E


68/76

Entropy

Measure of the disorder of less usable energy Continuously increases in the universe as

usable energy is converted to lower-quality, lessusable form (heat)

As each energy transformation occurs inorganisms, some energy changes to heat

Given off into the surroundings Can never be used again for biological work


69/76

A i i H A B d


70/76

Animation: How Atoms Bond

CLICKTO PLAY


71/76

Animation: Miller s Reaction


72/76

Animation: Millers Reaction

Chamber Experiment

CLICKTO PLAY

Animation: Structure of Starch


73/76

Animation: Structure of Starch

and Cellulose

CLICKTO PLAY

Animation: Triglyceride


74/76

Animation: Triglyceride

Formation

CLICKTO PLAY


75/76


76/76

chapter 2 botany 1a

Documents