-
The study of ____________________ is interdisciplinary because solutions require many different approaches to solve a problem
biological systems
-
Living systems have seven characteristics in common
they are composed of one or more cells; are complex and highly ordered; can respond to stimuli; can grow, reproduce, and transmit genetic information to their offsprings; need energy to accomplish work; can maintain relatively constant internal conditions (homeostasis); and are capable of evolutionary adaptation to the environment
-
The hierarchical organization of living systems
atoms; molecule; macromolecule; organelle; cell; tissue; organ; organ system; organism; population; species; community; ecosystem; biosphere
-
____________ is concerned with developing an increasingly accurate description of nature through observation and experimentation
science
-
___________ applies general principles to predict specific results
deductive reasoning
-
_____________ uses specific observations to construct general specific principles
inductive reasoning
-
A _____________ is constructed based on observation, and it must generate experimentally testable predictions; rejected if their predictions cannot be verified by observation or experiment
hypothesis
-
______________ involve a test in which a variable is manipulated, and a control in which the variable is not manipulated
experiments
-
______________ attempts to understand a complex system by breaking it down into its component parts; limited because parts may act differently when isolated from the larger system
reductionism
-
A ________ provides a way of organizing our thinking about a problem; may also suggest experimental approaches
model
-
a proposed explanation for some natural phenomenon; a body of concepts that explains facts in an area of study
theory
-
extends the boundaries of what we know
basic research
-
seeks to use scientific findings in practical areas such as agriculture, medicine, and industry
applied research
-
shows how a scientist develops a hypothesis and sets forth evidence, as well as how a scientific theory grows and gains acceptance
Darwin's theory of evolution
-
During the voyage of the H.M.S Beagle, _________ had an opportunity to observe worldwide patterns of diversity
Darwin
-
Darwin proposed ____________ as a mechanism for evolution
natural selection
-
Traits of offspring can be changed by
artificial selection
-
the basic unit of life and is the foundation for understanding growth and reproduction in all organisms
cell
-
encoded in genes found in the DNA molecule, is passed on from one generation to the next; the molecular basis of inheritance explains the continuity of life
Hereditary information
-
The ___________ of macromolecules and their complexes is dictated by and dependent on their ________. Similarity of ___________________ from one life form to another may indicate an evolutionary relationship
function; structure; structure and function
-
Living organisms appear to have had a common origin from which a ___________________ arose by evolutionary change; they can be grouped into three domains comprising six kingdoms based on their differences
diversity of life
-
The underlying similarities in _______________ and _______________ support the contention that all life evolved from a single science
biochemistry; genetics
-
Cells can sense and respond to environmental changes through proteins located on their ___________________. Differential expression of stored genetic information is the basis for different cell types
cell membranes
-
Organisms are open systems that need a constant supply of energy to maintain their stable __________________________. Living things are able to self-organize, creating levels of complexity that may exhibit emergent properties.
nonequilibrium state
-
All matter is composed of
atoms
-
Electrically neutral atoms have the same number of __________ as __________.
protons; electrons
-
Atoms that gain or lose electrons are called
ions
-
Each atom is defined by its _________________; the number of protons in the nucleus
atomic number
-
The sum or the mass of protons and neutrons in an atom
Atomic mass
-
Forms of a single element with different numbers of neutrons, and thus different atomic mass
Isotopes
-
Isotopes that are unstable
Radioactive isotopes
-
Determine the chemical behavior of atoms; the potential energy of electrons increases as distance from the nucleus increases.
Electrons
-
Contain discrete energy levels
Atoms
-
The loss of electrons from an atom
oxidation
-
The gain of electrons
reduction
-
Electrons can be transferred from one atom to another in
coupled redox reactions
-
Atoms tend to establish completely full outer energy levels. Elements with filled outermost orbitals are
inert
-
_______ elements occur naturally in the Earth's crust. ______ of these elements are found in living organisms in grater than trace amounts.
Ninety; Twelve
-
Compounds of carbon
organic compounds
-
The majority of molecules in living systems are composed of C bound to
H, O, and N
-
Molecules contain two or more atoms joined by
chemical bonds
-
Contain two or more different elements
Compounds
-
Ions with opposite electrical charges form
Ionic bonds
-
A molecule formed by a ______________ is stable because it has no net charge; may be single, double, or triple, depending on the number of pairs of electrons shared
covalent bond
-
________ rule is satisfied, at it has no unpaired electrons
Octet
-
Involve equal sharing of electrons between atoms
Nonpolar covalent bonds
-
Involve unequal sharing of electrons
Polar covalent bonds
-
__________ alter bonds
chemical reactions
-
Weak interactions between a partially positive H in one molecule and partially negative O in another molecule; water's structure facilitates
Hydrogen bonds
-
The tendency of water molecules to adhere to one another due to hydrogen bonding. ________ of water is responsible for its surface tension
Cohension
-
Water molecules are_______. _______ occurs when molecules adhere to other polar molecules
adhesion
-
Action results from water's adhesion to the sides of narrow tubes, combined with its cohension
Capillary
-
Water's high specific heat helps maintain
temperature
-
Solid water is less dense than
liquid water
-
makes it a good solvent for polar substances and ions
water's polarity
-
Polar molecules or portions of molecules are attracted to water
hydrophilic
-
Molecules that are nonpolar are repelled by water
Hydrophobic
-
Makes nonpolar molecules clump together
Water
-
Will aggregate to avoid water
Nonpolar molecules
-
Carbon dioxide and water react reversibly to form
carbonic acid
-
The key buffer in the human blood is the
carbonic acid/ bicarbonate pair
-
The backbone of all biological molecules, can form four covalent bonds and make long chains
Carbon
-
Consist of carbon and hydrogen, and their bonds store considerable energy
Hydrocarbons
-
Small molecular entries that confer specific chemical characteristics when attached to a hydrocarbon
Functional groups
-
Carbon and hydrogen have similar electronegativity so C--H bonds are not
polar
-
Oxygen and nitrogen have greater electronegativity, leading to
polar bonds
-
Molecules with the same formula but different structures
structural isomers
-
Differ in how groups are attached
Stereoisomers
-
Mirror-image stereoisomers
Enantiomers
-
Most important biological macromolecules; long chains of monomer units
Polymers
-
Biological polymers are formed by elimination of _____ from two monomers. They are broken down by adding water (__________)
water; hydrolysis
-
The empirical formula of a carbohydrate _______.
CH2O
-
Used for energy storage and as structural molecules
Carbohydrates
-
_____________ contain three to six or more carbon atoms. Examples are glyceraldehyde (3 carbons), deoxyribose (5 carbons), and glucose (6 carbons)
Simple sugars
-
The general formula for six carbon sugars is ________, and many isomeric forms are possible. Living systems often have enzymes for converting isomers from one to the other
C6H12O6
-
________________ account for differences in molecular properties
functional groups
-
______ have the same molecular formulas but different structures
Isomers
-
____________________________ include carbohydrates, nucleic acids, proteins, and lipids
biological macromolecules
-
___________________ are simple sugars
Monosaccharides
-
Sugar isomers have ______________ differences
structural
-
______________ serve as a transport molecules in plants and provide nutrition in animals
diaccharides
-
Plants convert _______ into the disaccharide sucrose for transport within their bodies
glucose
-
_______________ provide energy storage and structural components
polysaccharides
-
Glucose is used to make three important polymers: ________ (in animals), and ______ and _________ (in plants)
glycogen; starch; cellulose
-
A related structural material found in arthropods and many fungi
Chitin
-
_____________________ and _________________ are polymers composed of nucleotide monomers
Deoxyribonucleic acid (DNA); ribonucleic acid (RNA)
-
Cells use __________________ for information storage and transfer.
nucleic acids
-
Nucletic acids are _______________________
nucleotide polymers
-
Nucleic acids contain four different nucleotide bases. In DNA these are _______, _______, ________, and _______. In RNA, _______ is replaced by ______.
DNA: adenine, guanine, cytosine, thymine; RNA: thymine, uracil
-
___ carries the genetic code.
DNA
-
Double helix held together by specific base pairs: adenine with thymine and guanine with cytosine.
DNA
-
The _________________ sequence constitutes the genetic code
nucleic acid
-
___ is a transcript of a DNA strand.
RNA
-
___ is made by copying DNA. This transcript is then used as a template to make proteins
RNA
-
Other nucleotides are vital components of _______________.
energy reactions.
-
____________________ provides energy in cells; NAD- and FAD transport electrons in cellular processes
Adenosine triphosphate (ATP)
-
Most enzymes are __________. ________ provide defense, transport, motion, and regulation, among many other roles; polymers of amino acids
proteins
-
Amino acids are joined by _______________ to make ___________.
peptide bonds; polypeptides
-
Proteins have high levels of ______________.
structure
-
Protein is defined by the following hierarchy:
primary (amino acid sequence), secondary(hydrogen bonding patterns), tertiary (three-dimensional folding), and quaternary (associations between two or more polypeptides)
-
______ and _______ are additional structural characteristics
Motifs; domains
-
Similar structural elements found in dissimilar proteins; can create folds, creases, or barrel shapes
Motifs
-
Functional subunits or sites within a tertiary structure
domains
-
The process of folding relies on___________________; assist in the folding of proteins; example: heat shock proteins
chaperone proteins
-
Some diseases may result in ________ folding.
improper
-
________________ inactivates proteins; an unfolding of tertiary structure, which usually destroys function
Denaturation
-
Some denatured proteins may recover function when conditioning are returned to normal. This implies that ____________________ strongly influences ____________________.
primary structure; tertiary structure
-
__________________ refers to separation of quaternary subunits with no changes to their tertiary structure.
Disassociation
-
Insoluble in water because they have a high proportion of nonpolar C--H bonds
Lipids
-
____ consist of complex polymers of fatty acids attached to glyceral; excellent energy-storage molecules
Fats
-
Lipids exist as ______________, three fatty acids connected to a glycerol molecule.
triglycerides
-
Contain the maximum number of hydrogen atoms
Saturated fatty acids
-
Contain one or more double bonds between carbon atoms
Unsaturated fatty acids
-
Excess carbohydrate is converted to fat for
storage
-
_____________ form membranes; contain two fatty acids and one phosphate attached to glycerol
phospholipids
-
In __________________________, the phosphate heads are hydrophilic and cluster on the two faces of the membrane, and the hydrophobic tails are in the center
phospholipid-bilayer membranes
-
The unifying foundation of cell biology
Cell theory
-
All organisms are composed of one or more _____. They arise only by division of preexisting _____.
Cells
-
__________ is constrained by the diffusion distance. As it increases, diffusion becomes inefficient
cell size
-
________________ allow visualization of cells and components
Microscopes
-
______________ gives better resolution than is possible with the naked eye. Staining with chemicals enhances contrast of structures
Magnification
-
____ exhibit basic structural structure
All cells
-
All cells have centrally located ___, a semifluid cytoplasm, and an ___________________________________.
DNA; enclosing plasma membrane
-
_____________ cells have relatively simple organization; contain DNA and ribosomes, but they lack a nucleus, an internal membrane system, and membrane-bounded organelles. A rigid cell wall surrounds the plasma membrane.
Prokaryotic cells
-
____________________ consist of peptidoglycan.
Bacterial cell walls
-
Composed of carbohydrate cross-linked with short peptides
Peptidoglycan
-
___________ lack peptidoglycan
Archaea
-
Do not contain peptidoglycan, and they have unique plasma membranes
Archaeal cell walls
-
Some prokaryotes move by means of
rotating flagella
-
Rotate because of proton transfer across the plasma membrane
Prokaryotic flagella
-
Cells that have a membrane-bounded nucleus, an endomembrane system, and many different organelles
Eukaryotic
-
Acts as the information center; surrounded by an envelope of two phospholipid bilayers; the outer layer is contiguous with the ER
The nucleus
-
A region of the nucleoplasm where rRNA is transcribed and ribosomes are assembled
The nucleolus
-
In most _______________, DNA is organized into a single circular chromosome
prokaryotes
-
In most ________________, numerous chromosomes are present
Eukaryotes
-
The cell's protein synthesis machinery; translate mRNA to produce polypeptides; found in all cell types
Ribosomes
-
Creates channels and passages within the cytoplasm
The endoplasmic reticulum (ER)
-
A site of protein synthesis; studded with ribosomes, synthesizes and modifies proteins and manufactures membranes
The Rough ER
-
Has multiple roles; lacks ribosomes; it is involved in carbohydrate and lipid synthesis and detoxificaiton
The smooth ER
-
Sorts and packages proteins; receives vesicles from the ER, modifies and packages macromolecules, and transports them
The golgi apparatus
-
Contain digestive enzymes; break down macromolecules and recycle the components of old organelles
Lysosomes
-
A diverse category of organelles
Microbodies
-
Plants use __________ for storage and water balance
vacuoles
-
Have a double-membrane structure, contain their own DNA, and can divide independently
Mitochondria and chloroplasts
-
Mitochondria metabolize sugar to generate ___.
ATP
-
The inner membrane of mitochondria is extensively folded into layers called ______. Proteins on the surface and in the inner membrane carry out metabolism to produce ATP.
cristae
-
__________ use light to generate ATP and sugars
Chloroplasts
-
______________ capture light energy via thylakoid membranes arranged in stacks called _________, and use it to synthesis glucose.
Chloroplasts; grana
-
Mitochondria and chloroplasts arose by
endosymbiosis
-
Proposes that mitochondria and chloroplasts were once prokaryotes engulfed by another cell
The endosymbiont theory
-
Consists of crisscrossed protein fibers that support the shape of the cell and anchor organelles
Cytoskeleton
-
Type of fiber that composes the cytoskeleton;
long, thin polymers involved in cellular movement
Actin filaments or microfilaments
-
Type of fiber that composes the cytoskeleton
hollow structures that move materials within a cell
Microtubules
-
Type of fiber that composes the cytoskeleton
serve a wide variety of functions
Intermediate filaments
-
_____________ are microtubule-organizing centers; help assemble the nuclear division apparatus of animal cells
Centrosomes
-
___________ helps move materials within cells.
The cytoskeleton
-
Molecular motors move vesicles along microtubules. ________ and _______ are two motor proteins.
Kinesin; dynein
-
_________ occurs as actin polymerization forces the cell membrane forward, while myosin pulls the cell body forward
Cell crawling
-
___________ and _______ aid movement
Flagella; cillia
-
___________ have a 9 + 2 structure and arise from a basal body; _________ are shorter and more numerous than flagella
Eukaryotic flagella; cilia
-
__________ provide protection and support; composed of cellulose fibers
Plant cell walls
-
The ______________________, between cell walls, holds adjacent cells together
middle lamella
-
______________ secrete an extracellular matrix.
Animal cells
-
_________________ are the main component of extracellular matrix (ECM) of animal cells.
Glycoproteins
-
____________ give cells identity.
Surface proteins
-
______________ and ___ proteins on cell surfaces help distinguish self from nonself.
Glycolipids; MHC
-
_________________ mediate cell-to-cell adhesion.
Cell connections
-
Cell junctions include _____ junctions, _________ junctions, and _____________ junctions.
tight; anchoring; communicating
-
In animals, _________________ allow the passage of small molecules between cells.
gap junctions
-
In plants, _______________ penetrate the cell wall and connect cells
plasmodesmata
-
The _____________________________ shows proteins embedded in a fluid lipid bilayer; proteins float on or in the lipid bilayer
fluid mosaic model
-
_____________ are sheets of phospholipid bilayers with associated proteins.
Membranes
-
______________ regions of a membrane are oriented inward and ____________ regions oriented outward.
Hydrophobic; hydrophilic
-
_________ consists of four component groups.
Cellular membranes
-
In eukaryotic cells, membranes have four components:
a phosopholipid bilayer, transmembrane proteins (integral membrane proteins), an interior protein network, and cell-surface markers
-
The __________________________, is composed of cytoskeletal filaments and peripheral membrane proteins, which are associated with the membrane but are not an integral part
interior protein network
-
Membranes contain _____________ and ___________ on the surface that act as cell identity markers
glycoproteins; glycolipids
-
__________________________ has provided structural evidence.
Electron microscopy
-
_______________________________ and _______________________________ have confirmed the structure predicted by the fluid mosaic model
Transmission electron microscopy (TEM); scanning electron microscopy (SEM)
-
______________ are composed of two fatty acids and a phosphate group linked to a three-carbon glycerol molecule
Phospholipids
-
Phospholipids spontaneously form
bilayers
-
The phosphate group of a phospholipid is _______ and _____________; the fatty acids are ________ and ___________; and they orient away from the polar head of the phospholipids.
polar and hydrophilic; nonpolar and hydrophobic
-
The _____________ of the lipid bilayer impedes the passage of water and water-soluble substances
nonpolar interior
-
The phospholipid bilayer is
fluid
-
_____________________ of water keeps the membrane in its bilayer configuration; however _____________ and ______________ in the membrane are loosely associated and can diffuse laterally.
Hydrogen bonding; phospholipids and unanchored proteins
-
_________ can change; depends on the fatty acid composition of the membrane
Membrane fluidity
-
________________________ tend to make the membrane more fluid because of the "kinks" of double bonds in the fatty acid and tails
Unsaturated fats
-
Some bacteria have enzymes that alter the fatty acids of the membrane to compensate for ____________________.
temperature
-
__________ and __________________________ perform key functions.
proteins; protein complexes
-
______________ are integral membrane proteins that carry specific substances through the membrane
transporters
-
_________ often occur on the interior surface of the membrane
enzymes
-
__________________________ respond to external chemical messages and change conditions inside the cell;
cell surface receptors
-
_________________ markers on the surface allow recognition of the body's cells as "self".
Cell identity
-
___________________ of the membrane proteins relate to function.
structural features
-
Transport can occur by ____________.
simple diffusion
-
_________________ is the passive movement of a substance along a chemical or electrical gradient. Biological membranes pose a barrier to hydrophilic polar molecules, while they allow hydrophobic substances to diffuse freely.
Simple diffusion
-
Proteins allow membrane diffusion to be _________.
selective
-
________ and large ________________________ cannot cross the phospholipid bilayer.
Ions; hydrophilic molecules
-
_________ is the movement of water across membranes.
Osmosis
-
_______________ uses energy to move materials against a concentration gradient.
Active transport
-
Active transports are classified based on the number of _______ and _____________.
molecules; direction of transport
-
____________ transport a specific molecule in one direction; __________ transport two molecules in the same direction; __________ transport two molecules in opposite directions
uniporters; symporters; antiporters
-
The sodium-potassium pump runs directly on _______.
ATP
-
___________ transport uses ATP indirectly; occurs when the energy released by a diffusing molecule is used to transport a different molecule against its concentration gradient in the same direction.
Coupled
-
____________________ is similar to coupled transport, but the two molecules move in opposite directions
Countertransport
-
________________ moves large quantities of substances that cannot pass through the cell membrane
Bulk transport
-
Bulk material enters the cell in ___________.
vesicles
-
In ______________, the cell membrane surrounds material and pinches off to form a vesicle. In _____________________________, specific molecules bind to receptors on the cell membrane.
endocytosis; receptor-mediate endocytosis
-
Material can leave the cell by ________________.
exocytosis
-
In _________, material in a vesicle is discharged when the vesicle fuses with the membrane.
exocytosis
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