Cell Biology Chapter 2 Flashcards
What are the 5 Principles Important to Cell Biology?
Characteristic of carbon Characteristics of water Selectively Permeable Membranes Synthesis by Polymerization of Small Molecules Self-Assembly
What is the Characteristics of Carbon?
Carbon has unique properties that make it suitable as the backbone of biologically important molecules. The carbon atom is the most important atom in biological molecules
What is the Characteristics of Water?
The water molecule has several unique properties that make it suitable as the universal solvent of living systems
What are Selectively permeable membranes?
Membranes define cellular compartments and control the movements of molecules and ions into and out of cells and organelles
What is Synthesis by Polymerization of small Molecules?
Most biological macromolecules are polymers formed by linking many similar or identical small molecules known as monomers
What is Self-Assembly?
Biological macromolecules are often capable of self-assembly into higher levels of structural organization because the information needed to specify the spatial configuration of the molecule is contained in the polymer
What do molecules of importance to the cell biologist have?
A backbone, or skeleton, of carbon atoms linked together convalently in chains or rings
Which is the most important atom in biological molecules?
The Carbon atom
What is the total number of covalent bond per atom and in what conditions?
Bonds per carbon atom is 4 whether carbon atoms form single, double, or triple bonds with other atoms
Carbon atoms are most likely to form covalent bonds with what ?
Other carbon atoms, oxygen, hydrogen, nitrogen, and sulfur
Carbon-containing molecules are what? How is it expressed. Explain the visible portion of sunlight.
Carbon-containing molecules are stable. Stability is expressed as bond energy- the amount of energy required to break 1 mole (6*10^23) of such bonds. The visible portion of sunlight is lower in energy than C-C bonds
What can visible light can’t do what? What is more hazardous and why?
Visible light can’t break the bonds of organic molecules; Higher-energy ultraviolet light is more hazardous; Ultra violet light has an energy that is enough to break carbon-carbon bonds spontaneously
What does the ozone layer do?
The ozone layer filters out much of the much ultraviolet radiation that would otherwise reach Earth’s surface and disrupt the covalent bonds that hold biological molecules together
What are Hydrocarbons? What role do they play?
Hydrocarbons are chains or rings composed only of carbon and hydrogen; play an important role in the structure of biological membranes
What does the interior of every biological membrane look like? What does it project into? What does the feature have?
It is a nonaqueous environment consisteng of the long hydrocarbon “tails” of phospholipid molecules; Projects into the interior of the membrane from either surface; feature of membranes has important implications for their tole as permeability barries
What do Biological Compounds usually contain? What are they a part of?
Contain carbon, hydrogen, and one or more atoms of oxygen, nitrogen, phosphorus, or sulfur; part of functional groups
What are functional groups and what are some important functional groups?
are common arrangements of atoms that confer specific chemical properties on a molecule; Carboxyl and phosphate groups - negatively charged, amino groups - positively charged, hydroxyl, sulfhydroxyl, carbonyl, and aldehyde - uncharged, but polar
What is a covalent bond?
Strong chemical bond in which 2 atoms share 2 or more electrons
What is a polar bond? How do they result and what do polar bonds have?
Electrons are not shared equally between 2 atoms; they result from a high electronegativity of oxygen and sulfur compared to carbon and hydrogen; they have high water solubility compared to C-C or C-H bonds in which electrons are shared equally
Why does water have an indispensable role for life?
It is the universal solvent in biological systems
Water’s most critical attribute and what does it account for?
It’s polarity; accounts for water’s cohesiveness, temperature-stabilizing capacity, and solvent properties
What gives water its polarity? What is it called when the oxygen atom is at one end ? What does it result in?
Unequal distribution of electrons; Is highly electronegative drawing the electrons toward it; results in partial negative charge at this end of the molecule and a partial positive charge around the hydrogen atoms
What does their polarity do? Which molecules are associated with each other? What are those associations called? What does the added effect account for?
makes water molecules attracted to each other; electronegative oxygen of one molecule is associated with the electropositive hydrogens of nearby molecules; called hydrogen bonds, 1/10 strong as covalent bonds, accounts for water’s characteristics
What is water characterized by? What is the combined effect of many hydrogen bonds?
By an extensive network of hydrogen-bonded molecules which make it cohesive; accounts for water’s high: surface tension, boiling point, specific heat, and heat of vaporization
What is the surface tension of water?
The result of the collective strength of vast numbers of hydrogen bonds
What is specific heat? What does it give, what is it much higher than, what is used to break? How does water change temperature?
The amount of heat a substance must absorb to raise its temperature 1C; high specific heat gives water its temperature-stabilizing capacity; the specific heat of water is much higher than most liquids; Heat is first used to break numerous hydrogen bonds in water; water changes temperature relatively slowly, protecting living systems from extreme temperature changes
Without this characteristic of water what is released and what would it cause?
Without this characteristic of water, energy released in cell metabolism would cause cells to overheat and die
What is heat of vaporization? Why is the value high for water?
The amount of energy required to convert 1 gram of liquid into vapor; This value is high for water because of the many hydrogen bonds that must be broken
What is a solvent, why is water able to dissolve a large variety of substances, many of the molecules are what and can form what?
A fluid in which another substance, the solute can dissolve; because of its polarity; are polar and can form hydrogen bonds or ionic bonds with water
Solutes have a what for water and what is it called? What are some small molecules?
have an affinity for water and dissolve in it easily are called hydrophillic -water-loving; sugars, organic acids, some amino acids are hydrophillic
Molecules are not easily soluble in what and what are they called?
Soluble in water such as lipids and proteins in membranes called hydrophobic- water-fearing;
Some molecules have no net charge at what? What are they and why?
at neutral pH, still hydrophillic because they have some regions that are positively charged and some negatively charged
Water molecules will cluster around what and prevent what? Hydrophobic molecules tend to what?
around such regions and prevent the solute molecules from interacting with each other; tend to disrupt the hydrogen bonding of water and are repelled by water molecules
Cells need a what and what are the qualifications?
need a physical barrier between their contents and the outside environment; impermeable to much of the cells contents, not completely impermeable, allowing some materials into and out of the cell, insoluble in water to maintain the integrity of the barrier, and permeable to water to allow flow of water in and out of the cell
What is the cellular membrane and what does it consist of?
is a hydrophobic permeability barrier; consist of phospholipids, glycolipids, membrane proteins, most organisms contain sterols
Membrane lipids are what and have what? Also have what due to what? What else do they have?
are amiphipathic, have both hydrophobic and hydrophillic regions; have a polar head due to a negatively charged phosphate group linked to a positively charged group; also have two nonpolar hydrocarbon tails
Polar heads face where, hydrophobic tails face where, what is the structure called?
face outward toward the aqueous environment; oriented inward; the lipid bilayer
The hydrophobic interior makes a lipid bilayer what? It is quite what and what must be transported?
Readily permeable to nonpolar molecules; quite impermeable to most polar molecules and highly impermeable to all ions; ions transported across
Cellular constituents are mostly what but what diffuses? Transport proteins act as what?
Mostly polar or charged and are prevented from entering or leaving the cell; very small molecules diffuse; act as either hydrophillic channels or carriers;
Transport protein are specific for what? Biological membranes are best described as what?
specific for a particular ion or molecule or class of closely related molecules or ions; described as selectively permeable
Most cellular structures are made of what?
Ordered arrays of linear polymers called macromolecules
Important macromolecules in the cells are? Lipids shares what with macromolecules?
proteins, nucleic acids, and polysaccharides; share some features but are synthesized somewhat differently
What is cellular hierarchy?
Biological molecules and structures are organized into a series of levels each building on the preceding one
Small organic molecules what to form what? What may function on their own and what else do they do? What are components of organelles and what else are they components of ?
polymerize to form biological macromolecules; biological macromolecules and other supramacromolecular structures make up the cell; Supramacromolecular structures are components of organelles and other subcellular structures that make up the cell
The macromolecules responsible for most of the form and order of living systems are generated by what? Repeating units are called what and examples of it?
by the polymerization of small organic molecules; called monomers; glucose present in sugar or starch, amino acids in proteins, and nucleotides in nucleic acids
Major macromolecules polymers in the cell are? Nucleic acids and proteins have a variety of monomers that can be arranged how? What has few types?
Proteins, nucleic acids, and polysaccharides; arranged in nearly limitless ways, the order and type are critical for function; Polysaccharides- one or 2 monomers
Nucleic acids are called what and why? DNA and RNA serve what?
called informational macromolecules because the order of the four kinds of nucleotide monomers in each is non-random and carries important information; serve a coding function containing the information needed to specify the precise amino acids sequences of proteins
Proteins are composed of what? Amino acid sequence determines what? With 20 different amino acids what is possible? Proteins have a wide range of what and what does it include?
nonrandom series of amino acids; determines 3D -> the function of a protein; a nearly infinte variety of protein sequences is possible; range of functions including structure, defense, transport, catalysis, and signaling
Polysaccharides typically consist of what? The order of monomers carry what? Most polysaccharides are what?
consist of single repeating subunits or two alternating subunits; carries no information and is not essential for function; most are structural macromolecules and storage macromolecules
Production of most polymers follow what 6 basic principles?
macromolecules are always synthesized by the stepwise polymerization of monomers
the addition of each monomer occurs by the removal of a water molecules; the monomers must be present as activated monomers before condensation can occur; to become activated a monomer must be couple to a carrier molecule; the energy to couple a monomer to a carrier molecule is provided by ATP or a related high-energy compound; Macromolecules have directionality, the chemistry differs at each end of the polymer
Activated monomers react how? What is a sequential stepwise process?
react with one another in a condensation reaction - removal of water molecule, then release the carrier molecule; the continued elongation of the polymer
Degradation of polymers occurs how?
Via hydrolysis- breaking the bond between monomers through addition of one H+ and one OH- addition of water molecule
The principle of self-assembly has the information needed to specify what?
Information needed to specify the folding of macromolecules and their interactions to form complex structures is inherent in the polymers themselves
Which proteins are sometimes needed to prevent incorrect folding
Molecular charperones
How is every protein or other macromolecule in the cell held together? The complexity of molecular structure can’t be described how?
held together by strong covalent bonds; can’t be described by patterns of covalent bonding alone
Many cellular structures are held together by what?
Noncovalent bonds and interactions: hydrogen bonds, ionic bonds, van der waals interactions, and hydrophobic interactions
Hydrogen bonds involve a what between electronegative atoms and is what?
involve a weak, attractive interactions between an electronegative atom such as oxygen (or nitrogen) and a hydrogen atom that is convalently bonded to a second electronegative atom
What are hydrogen bonds extremely important in maintaining what?
In maintaining the 3D structure of proteins and in holding together the two strands of the DNA double helix
What are ionic bonds, some examples and when do they form?
Strong noncovalent electrostatic interactions between two oppositely charged ions; amino acid +, phosphate -, carboxyl -; they form between negatively charged and positively charged functional groups
Ionic bonds between functional groups on the same protein play an important role in what? Ionic bonds may also influence what?
play an important role in the structure of the protein; influence the binding between macromolecules
What are van deer walls interactions? Why will atoms that are too close together repel one another?
weak attractions between 2 atoms that occur only if the atoms are very close to one another and oriented appropriately; because of their overlapping outer electron orbital
What do hydrophobic interactions describe? Why does water push hydrophobic molecules together?
describe the tendency of nonpolar groups within a macromolecule to associate with each other and minimize their contact with water; to minimize the disruption of water’s hydrogen bonds
Hydrophobic interactions commonly cause what and where could they be found?
cause non polar groups to be found in the interior of a protein or embedded in the nonpolar interior of a membrane
How do many proteins spontaneously fold? The same principles of self-assembly that apply to what also applies to what else? What are capable of self-assembly?
fold into their biological functional state; apply to polypeptides also apply to the assembly of more complex structures; ribosomes and membranes are capable
Some assembly systems depend additionally on what? What are some examples?
information provided by a preexisting structure; membranes and cell walls
