Download Chapter 1: Biology: Exploring Life 1.1 Life`s levels of organization

Chapter 1: Biology: Exploring Life
1.1 Life’s levels of organization define the scope of biology
• Life’s structural hierarchy
– Defines the scope of biology, the scientific
study
of life
• An ecosystem consists of all the organisms living in a par ticular area
– As well as the nonliving environmental components
• All the living organisms in an ecosystem
– Make up a community
• A population
– Consists of a localized group of individuals of a species
• An individual living entity
– Is an organism
• The hierarchy continues downward with
– Organ systems
– Organs
– Tissues
– Cells
– Organelles
– Molecules
1.2 Living organisms and their environments form interconnecting webs
• Ecosystems are characterized by the cycling of chemical nutrients from
the atmosphere and soil
– To producers to consumers to decomposers and back to the
environment
• Energy flows one-way through an ecosystem
– From the sun to producers to consumers and exits as heat
1.3 Cells are the structural and functional units of life
• A cell
– Is the basic unit of life
• New proper ties emerge
– From the complex organization of a system, such as a cell
• Eukaryotic cells
– Contain membrane-enclosed organelles, including a DNAcontaining nucleus
• Prokaryotic cells
– Lack such organelles
1.4 The unity of life: All forms of life have common features
• DNA is the genetic information
– For constructing the molecules that make up cells and organisms
• Each species’ genetic instructions
– Are coded in the sequences of the four building blocks making up
DNA’s two helically coiled chains
• All organisms share a common set of features
– Ordered structures
– Regulation of internal conditions
–
Growth and development
• Energy use
• Response to environmental stimuli
• The ability to reproduce and evolve
1.5 The diversity of life can be arranged into three domains
• Organisms are grouped (classified)
– Into the prokaryotic domains Bacteria and Archaea and the
eukaryotic domain Eukarya
• Domain Eukarya includes
– Protists (protozoans and algae, falling into multiple kingdoms)
– The kingdoms Fungi, Plantae, and Animalia
1.6 Evolution explains the unity and diversity of life
• Charles Dar win
– Synthesized the theory of evolution by natural selection
• Natural selection is an editing mechanism
– That occurs when populations or organisms, having inherited
variations, are exposed to environmental factors that favor the
reproductive success of some individuals over others
• All organisms have adaptations
– That have evolved by means of natural selection
1.7 Scientists use two main approaches to learn about nature
• Science
– Is a way of knowing
– Seeks natural causes for natural phenomena
• In discovery science
– Scientists describe some aspect of the world and use inductive
reasoning to draw general conclusions
• In hypothesis-based science
– Scientists attempt to explain
obser vations by testing hypotheses
1.8 With hypothesis-based science, we pose and test hypotheses
• Hypothesis-based science involves
– Obser vations, questions, hypotheses as tentative answers to
questions
– Deductions leading to predictions, and then tests of predictions to
see if a hypothesis is falsifiable
• Deductive reasoning is used in testing hypotheses as follows
– If a hypothesis is correct, and we test it, then we can expect a par
ticular outcome
• In experiments designed to test hypotheses
– The use of control groups and experimental groups helps to control
variables
1.8 Biology is connected to our lives in many ways
Chapter 2: The Chemical Basis of Life
2.6 Electron arrangement determines the chemical properties of an atom
• Electrons in an atom
– Are arranged in shells, which may contain different numbers of
electrons
• Atoms whose shells are not full
– Tend to interact with other atoms and gain, lose, or share electrons
• These interactions
– Form chemical bonds
2.7 Ionic bonds are attractions between ions of opposite charge
• When atoms gain or lose electrons
– Charged atoms called ions are created
• An electrical attraction between ions with opposite charges
– Results in an ionic bond
• Sodium and chloride ions
– Bond to form sodium chloride, common table salt
2.8 Covalent bonds join atoms into molecules through electron sharing
• In covalent bonds
– Two atoms share one or more pairs of outer shell electrons,
forming molecules
2.9 Unequal electron sharing creates polar molecules
• A molecule is nonpolar
– When its covalently bonded atoms share electrons equally
• In a polar covalent bond
– Electrons are shared unequally between atoms, creating a polar
molecule
2.10 Hydrogen bonds are weak bonds important in the chemistry of life
• The charged regions on water molecules
– Are attracted to the oppositely charged regions on nearby
molecules
• This attraction forms weak bonds
– Called hydrogen bonds
2.11 Hydrogen bonds make liquid water cohesive
• Due to hydrogen bonding
– Water molecules can move from a plant’s roots to its leaves
• Insects can walk on water due to surface tension
– Created by cohesive water molecules
2.12 Water’s hydrogen bonds moderate temperature
• Water’s ability to store heat
– Moderates body temperature and climate
• It takes a lot of energy to disrupt hydrogen bonds
– So water is able to absorb a great deal of heat energy without a
large increase in temperature
• As water cools
– A slight drop in temperature releases a large amount of heat
• A water molecule takes energy with it when it evaporates
–
•
Leading to evaporative cooling
A water molecule takes energy with it when it evaporates
– Leading to evaporative cooling
2.13 Ice is less dense than liquid water
• Hydrogen bonds hold molecules in ice
– Farther apart than in liquid water
• Ice is therefore less dense than liquid water
– Which causes it to float
• Floating ice
– Protects lakes and oceans from freezing solid
2.14 Water is the solvent of life
• Polar or charged solutes
– Dissolve when water molecules surround them, forming aqueous
solutions
2.15 The chemistry of life is sensitive to acidic and basic conditions
• A compound that releases H+ ions in solution is an acid
– And one that accepts H+ ions in solution is a base
• The pH of most cells
– Is kept close to 7 (neutral) by buffers
• Buffers are substances that resist pH change
2.16: Acid precipitation threatens the environment
• Some ecosystems are threatened by acid precipitation
• Acid precipitation is formed when air pollutants from burning fossil fuels
– Combine with water vapor in the air to form sulfuric and nitric
acids
• These acids
– Can kill trees and damage buildings
2.17 Chemical reactions change the composition of matter
• In a chemical reaction
– Reactants interact, atoms rearrange, and products result
• Living cells carry out thousands of chemical reactions
– That rearrange matter in significant ways
Chapter 3: The Molecules of Cells
3.1 Life’s molecular diversity is based on the properties of carbon
• A carbon atom can form four covalent bonds
– Allowing it to build large and diverse organic compounds
• Hydrocarbons
– Are composed of only hydrogen and carbon
• Some carbon compounds are isomers
– Molecules with the same molecular formula but different structures
3.2 Functional groups help determine the properties of organic compounds
• Examples of functional groups
• Functional groups are particular groupings of atoms
• That give organic molecules particular properties
3.3 Cells make a huge number of large molecules from a small set of small molecules
• The four main classes of biological molecules
– Are carbohydrates, lipids, proteins, and nucleic acids
• Many of the molecules are gigantic
– And are called macromolecules
• Cells make most of their large molecules
– By joining smaller organic molecules into chains called polymers
• Cells link monomers to form polymers
– By a dehydration reaction
• Polymers are broken down to monomers
– By the reverse process, hydrolysis
3.4 Monosaccharides are the simplest carbohydrates
• The carbohydrate monomers
– Are monosaccharides
• A monosaccharide has a formula that is a multiple of CH2O
– And contains hydroxyl groups and a carbonyl group
• The monosaccharides glucose and fructose are isomers
– That contain the same atoms but in different arrangements
• Monosaccharides can also occur as ring structures
3.5 Cells link two single sugars to form disaccharides
• Monosaccharides can join to form disaccharides
– Such as sucrose (table sugar) and maltose (brewing sugar)
3.7 Polysaccharides are long chains of sugar units
• Polysaccharides are polymers of monosaccharides
– Linked together by dehydration reactions
• Starch and glycogen are polysaccharides
– That store sugar for later use
• Cellulose is a polysaccharide found in plant cell walls
3.8 Fats are lipids that are mostly energy-storage molecules
• Lipids are diverse compounds
– That consist mainly of carbon and hydrogen atoms linked by
nonpolar covalent bonds
• Lipids are grouped together
– Because they are hydrophobic
•
Fats, also called triglycerides
– Are lipids whose main function is energy storage
– Consist of glycerol linked to three fatty acids
3.9 Phospholipids, waxes, and steroids are lipids with a variety of functions
• Phospholipids are a major component of cell membranes
• Waxes form waterproof coatings
• Steroids are often hormones
3.10 Anabolic steroids pose health risks
• Anabolic steroids
– Are synthetic variants of testosterone
– Can cause serious health problems
3.11 Proteins are essential to the structures and activities of life
• A protein
– Is a polymer constructed from amino acid monomers
• Proteins
– Are involved in almost all of a cell’s activities
• As enzymes
– They regulate chemical reactions.
3.12 Proteins are made from amino acids linked by peptide bonds
• Protein diversity
– Is based on different arrangements of a common set of 20 amino
acid monomers
• Each amino acid contains
– An amino group
– A carboxyl group
– An R group, which distinguishes each of the 20 different amino
acids
• Each amino acid has specific properties
– Based on its structure
• Cells link amino acids together
– By dehydration synthesis
• The bonds between amino acid monomers
– Are called peptide bonds
3.13 A protein’s specific shape determines its function
• A protein consists of one or more polypeptide chains
– Folded into a unique shape that determines the protein’s function
3.14 A protein’s shape depends on four levels of structure
Primary Structure
• A protein’s primary structure
– Is the sequence of amino acids forming its polypeptide chains
Secondary structure
• A protein’s secondary structure
– Is the coiling or folding of the chain, stabilized by hydrogen
bonding
Tertiary Structure
• A protein’s tertiary structure
– Is the overall three-dimensional shape of a polypeptide
Quaternary Structure
• A protein’s quaternary structure
– Results from the association of two or more polypeptide chains
3.20 Nucleic acids are information-rich polymers of nucleotides
• Nucleic acids such as DNA and RNA
– Serve as the blueprints for proteins and thus control the life of a
cell
• The monomers of nucleic acids are nucleotides
– Composed of a sugar, phosphate, and nitrogenous base
• The sugar and phosphate
– Form the backbone for the nucleic acid or polynucleotide
• DNA consists of two polynucleotides
– Twisted around each other in a double helix
• RNA, by contrast
– Is a single-stranded polynucleotide
• Stretches of a DNA molecule called genes
– Program the amino acid sequences of proteins
Chapter 4: A Tour of the Cell
4.1 Microscopes provide windows to the world of the cell
• The light microscope (LM)
– Enables us to see the overall shape and structure of a cell
• Light microscopes
– Magnify cells, living and preser ved, up to 1,000 times
• The electron microscope
– Allows greater magnification and reveals cellular details
• Different types of light microscopes
– Use different techniques to enhance contrast and selectively
highlight cellular components
4.2 Most cells are microscopic
• Cells vary in size and shape
• The microscopic size of most cells ensures a sufficient sur face area
• Across which nutrients and wastes can move to ser vice the cell
volume
• A small cell has a greater ratio of sur face area to volume
• Than a large cell of the same shape
4.3 Prokaryotic cells are structurally simpler than eukar yotic cells
• There are two kinds of cells
– Prokaryotic and eukaryotic
• Prokaryotic cells are small, relatively simple cells
– That do not have a membrane-bound nucleus
• Prokaryotic cells are small, relatively simple cells
– That do not have a membrane-bound nucleus
4.4 Eukaryotic cells are par titioned into functional compar tments
• All other forms of life are composed of more complex eukaryotic cells
– Distinguished by the presence of a true nucleus
• Membranes form the boundaries of many
eukar yotic cells
– Compar tmentalizing the interior of the cell and facilitating a
variety of metabolic activities
• A typical animal cell
– Contains a variety of membranous organelles
• A typical plant cell has some structures that an animal cell lacks
– Such as chloroplasts and a rigid cell wall
4.5 The nucleus is the cell’s genetic control center
• The largest organelle is usually the nucleus
– Which is separated from the cytoplasm by the nuclear envelope
• The nucleus is the cellular control center
– Containing the cell’s DNA, which directs cellular activities
4.6 Over view: Many cell organelles are connected through the endomembrane system
• The endomembrane system is a collection of membranous organelles
– That manufactures and distributes cell products
4.7 Smooth endoplasmic reticulum has a variety of functions
• Smooth endoplasmic reticulum, or smooth ER
– Synthesizes lipids
– Processes toxins and drugs in liver cells
– Stores and releases calcium ions in muscle cells
4.8 Rough endoplasmic reticulum makes membrane and proteins
• The rough ER
– Manufactures membranes
• Ribosomes on the sur face of the rough ER
– Produce proteins that are secreted,
inser ted into membranes, or transpor ted in vesicles to other
organelles
4.9 The Golgi apparatus finishes, sor ts, and ships cell products
• Stacks of membranous sacs receive and modify ER products
– Then ship them to other organelles or the cell sur face
4.10 Lysosomes are digestive compar tments within a cell
• Lysosomes are sacs of enzymes
– That function in digestion within a cell
• Lysosomes in white blood cells
– Destroy bacteria that have been ingested
• Lysosomes also recycle damaged organelles
4.11 Abnormal lysosomes can cause fatal diseases
• Lysosomal storage diseases
– Inter fere with various cellular functions
4.12 Vacuoles function in the general maintenance of the cell
• Plant cells contain a large central vacuole,
– Which has lysosomal and storage functions
• Some protists have contractile vacuoles
– That pump out excess water
4.13 A review of the endomembrane system
• The various organelles of the endomembrane system
– Are interconnected structurally and functionally
4.14 Chloroplasts conver t solar energy to chemical energy
• Chloroplasts, found in plants and some protists
– Conver t solar energy to chemical energy in sugars
4.15 Mitochondria har vest chemical energy from food
• Mitochondria carry out cellular respiration
– Which uses the chemical energy in food to make ATP for cellular
work
4.16 The cell’s internal skeleton helps organize its structure and activities
• A network of protein fibers
– Make up the cytoskeleton
• Microfilaments of actin
– Enable cells to change shape and move
• Intermediate filaments
– Reinforce the cell and anchor cer tain organelles
• Microtubules give the cell rigidity
–
And provide anchors for organelles and act as tracks for organelle
movement
4.17 Cilia and flagella move when microtubules bend
• Eukaryotic cilia and flagella
– Are locomotor appendages that protrude from cer tain cells
• Clusters of microtubules
– Drive the whipping action of these organelles
4.19 Cell sur faces protect, suppor t, and join cells
• Cells interact with their environments and each other via their sur faces.
• Plant cells
• Are suppor ted by rigid cell walls made largely of cellulose
• Connect by plasmodesmata, which are connecting channels
• Animal cells are embedded in an extracellular matrix
• Which binds cells together in tissues
• Tight junctions can bind cells together into leakproof sheets
• Anchoring junctions link animal cells into strong tissues
• Gap junctions allow substances to flow from cell to cell
4.19 Eukaryotic organelles comprise four functional categories
• Eukar yotic organelles fall into four functional groups
– Manufacturing
– Breakdown
– Energy processing
– Suppor t, movement, and communication between cells
Chapter 5: The Working Cell
5.1 Energy is the capacity to perform work
• All organisms require energy
– Which is defined as the capacity to do work
• Kinetic energy is the energy of motion
• Potential energy is stored energy
– And can be converted to kinetic energy
5.2 Two laws govern energy transformations
• Thermodynamics
– Is the study of energy transformations
The First Law of Thermodynamics
• According to the first law of thermodynamics
– Energy can be changed from one form to another
– Energy cannot be created or destroyed
The Second Law of Thermodynamics
• The second law of thermodynamics
– States that energy transformations increase disorder or entropy,
and some energy is lost as heat
5.3 Chemical reactions either store or release energy
• Endergonic reactions
– Absorb energy and yield products rich in potential energy
• Exergonic reactions
– Release energy and yield products that contain less potential
energy than their reactants
• Cells carry out thousands of chemical reactions
– The sum of which constitutes cellular metabolism
• Energy coupling
– Uses exergonic reactions to fuel endergonic reactions
5.4 ATP shuttles chemical energy and drives cellular work
• ATP powers nearly all forms of cellular work
• The energy in an ATP molecule
• Lies in the bonds between its phosphate groups
• ATP drives endergonic reactions by phosphorylation
• Cellular work can be sustained
• Because ATP is a renewable resource that cells regenerate
5.5 Enzymes speed up the cell’s chemical reactions by lowering energy barriers
• For a chemical reaction to begin
– Reactants must absorb some energy, called the energy of activation
• A protein catalyst called an enzyme
– Can decrease the energy of activation needed to begin a reaction
5.6 A specific enzyme catalyzes each cellular reaction
• Enzymes have unique three-dimensional shapes
– That determine which chemical reactions occur in a cell
5.7 The cellular environment affects enzyme activity
• Temperature, salt concentration, and pH influence enzyme activity
• Some enzymes require nonprotein cofactors
– Such as metal ions or organic molecules called coenzymes
5.8 Enzyme inhibitors block enzyme action
• Inhibitors interfere with an enzyme’s activity
• A competitive inhibitor
• Takes the place of a substrate in the active site
• A noncompetitive inhibitor
• Alters an enzyme’s function by changing its shape
5.9 Many poisons, pesticides, and drugs are enzyme inhibitors
5.10 Membranes organize the chemical activities of cells
• Membranes
– Provide structural order for metabolism
• The plasma membrane of the cell is selectively permeable
– Controlling the flow of substances into or out of the cell
5.11 Membrane phospholipids form a bilayer
• Phospholipids
– Have a hydrophilic head
and two hydrophobic tails
– Are the main structural
components of membranes
• Phospholipids form a two-layer sheet
– Called a phospholipid bilayer, with the heads facing outward and
the tails facing inward
5.12 The membrane is a fluid mosaic of phospholipids and proteins
• A membrane is a fluid mosaic
– With proteins and other molecules embedded in a phospholipid
bilayer
5.13 Proteins make the membrane a mosaic of
function
• Many membrane proteins
– Function as enzymes
• Other membrane proteins
– Function as receptors for chemical messages from other cells
• Membrane proteins also function in transport
– Moving substances across the membrane
5.14 Passive transport is diffusion across a membrane
• In passive transport, substances diffuse through membranes without work
by the cell
– Spreading from areas of high concentration to areas of low
concentration
• Small nonpolar molecules such as O2 and CO2
– Diffuse easily across the phospholipid bilayer of a membrane
5.15 Transport proteins may facilitate diffusion across membranes
• Many kinds of molecules
– Do not diffuse freely across membranes
• For these molecules, transport proteins
–
Provide passage across membranes through a process called
facilitated diffusion
5.16 Osmosis is the diffusion of water across a membrane
• In osmosis
– Water travels from a solution of lower solute concentration to one
of higher solute concentration
5.17 Water balance between cells and their surroundings is crucial to organisms
• Osmosis causes cells to shrink in hypertonic solutions
– And swell in hypotonic solutions
• In isotonic solutions
– Animal cells are normal, but plant cells are limp
• The control of water balance
– Is called osmoregulation
5.18 Cells expend energy for active transport
• Transport proteins can move solutes against a concentration gradient
– Through active transport, which requires ATP
5.19 Exocytosis and endocytosis transport large molecules
• To move large molecules or particles through a membrane
– A vesicle may fuse with the membrane and expel its contents
(exocytosis)
• Membranes may fold inward
– Enclosing material from the outside (endocytosis)
• Endocytosis can occur in three ways
– Phagocytosis
– Pinocytosis
– Receptor-mediated endocytosis
5.20 Faulty membranes can overload the blood with cholesterol
• Harmful levels of cholesterol
– Can accumulate in the blood if membranes lack cholesterol
receptors
5.21 Chloroplasts and mitochondria make energy available for cellular work
• Enzymes are central to the processes that make energy available to the cell
• Chloroplasts carry out photosynthesis
• Using solar energy to produce glucose and oxygen from carbon
dioxide and water
• Mitochondria consume oxygen in cellular respiration
• Using the energy stored in glucose to make ATP