Bio Test 1
Which type of microscope would you use to study (a) the changes in shape of a living human white blood cell; (b) the finest details of surface texture of a human hair; (c) the detailed structure of an organelle in a human liver cell?
(a) light microscope; (b) scanning electron microscope; (c) transmission electron microscope
Atomic Mass
(or weight) is approximately equal to its mass number, the sum of its protons and neutrons. •Although all atoms of an element have the same atomic number, some atoms of a given element may differ in mass number.
Cellulose
-A large polysaccharide composed of many glucose monomers linked into cable-like fibrils that provide structural support in plant cell walls -the most abundant organic compound on Earth, forms cable-like fibrils in the tough walls that enclose plant cells -form an unbranched rod -Arranged parallel to each other, cellulose molecules are joined by hydrogen bonds, forming part of a fibril. In wood, layers of cellulose fibrils combine with other polymers, making a material strong enough to support trees hundreds of feet high.
Water balance & plant cells
-A plant cell immersed in an isotonic solution (part 4) is flaccid, and nonwoody plants, such as most houseplants, wilt in this situation. -a plant cell is turgid, and plants are healthiest, in a hypotonic environment
What is cellular respiration?
-A process that converts the chemical energy of sugars and other molecules to chemical energy in the form of ATP the cytoskeleton and related structures
Explanation of water & heat
-A swimmer crossing San Francisco Bay has a higher temperature than the water, but the bay contains far more heat because of its immense volume -When water is heated, the heat energy first disrupts hydrogen bonds and then makes water molecules move fastwe -o Because heat is absorbed as the bonds break, water absorbs and stores a large amount of heat while warming up only a few degrees. Conversely, when water is cooled, more hydrogen bonds form. Heat energy is released when the bonds form, slowing the cooling process. -Evaporative cooling helps prevent land-dwelling organisms from overheating
Diffusion
-A type of passive transport -the tendency for particles of any kind to spread out evenly in an available space, moving from where they are more concentrated to regions where they are less concentrated. Diffusion requires no work; it results from the random motion (kinetic energy) of atoms and molecules.
Microfilaments
-AKA actin filaments, -solid rods composed mainly of globular proteins called actin, arranged in a twisted double chain -make cells contract -also help these cells change shape and move by assembling (adding subunits) at one end while disassembling (losing subunits) at the other
radioactive isotope
-An isotope whose nucleus decays spontaneously, giving off particles and energy. -useful as tracers-biological spies, in effect-for monitoring the fate of atoms in living organisms -uncontrolled exposure to them can harm living organisms by damaging molecules, especially DNA
plasmodesmata
-An open channel in a plant cell wall, through which strands of cytoplasm connect from adjacent walls -the cells of a plant tissue share water, nourishment, and chemical messages.
Chloroplast:
-An organelle found in plants and photosynthetic protists. Enclosed by two concentric membranes, a chloroplast absorbs sunlight and uses it to power the synthesis of organic food molecules (sugars)
Hydrolysis
-Breaking down a polymer chain -cells break bonds between monomers by adding water to them -In the process, a hydrogen joins to one monomer, and a hydroxyl group joins to the adjacent monomer
Dehydration reaction P 39
-Building a polymer chain -A chemical process in which a polymer forms as monomers are linked by the removal of water molecules. One molecule of water is removed for each pair of monomers linked. -Also called condensation
The ionized or dissociated carboxyl group may be written as _____.
-COO - -When an oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group, the entire assembly is called a carboxyl group (-COOH).
A protein's Secondary structure
-Coiling of a polypeptide chain results in a secondary structure called an alpha helix; a certain kind of folding leads to a pleated sheet -Pleated sheets make up the core of many globular proteins
Isomers
-Compounds with the same formula but different structures -the shape of a molecule usually helps determine the way it functions-how it interacts with other molecules
Waxes
-Consist of one fatty acid linked to an alcohol. -They are more hydrophobic than fats, and this characteristic makes waxes effective natural coatings for fruits such as apples and pears. -Many animals, especially insects, also have waxy coats that help keep them from drying out.
Lipids
-Diverse compounds that consist mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds -Lipid molecules are not attracted to water molecules
Cytoskeleton
-Eukaryotic cells contain a meshwork of protein fibers extending throughout the cytoplasm of a cell -These fibers provide structural support (a skeleton) and are involved in various types of cell movement
Electron Shell
-Farther away the more powerful -Energy levels are called electron shells Can have one, two or more shells •the outermost (highest-energy) shell can hold up to 8 electrons (four pairs). •The innermost shell is full with only 2 electrons. So in atoms with more than 2 electrons, the remainder are found in shells farther from the nucleus •It is the number of electrons in the outermost shell that determines the chemical properties of an atom.
Saturated Fat
-Fats with the maximum number of hydrogens -Most animal fats
Unsaturated Fat
-Fatty acids and fats with double bonds, having less than the maximum number of hydrogens -The kinks in unsaturated fats prevent the molecules from packing tightly together and solidifying at room temperature. Corn oil, olive oil, and other vegetable oils are unsaturated fats -Most plant fats
Protein
-From the Greek word proteios, meaning "first place" -a polymer constructed from amino acid monomers -Function is dependent on their shape Structural proteins: found in hair and the fibers that make up tendons and ligaments. - Muscles contain contractile proteins. Defensive proteins, such as the antibodies of the immune system Signal proteins, such as many of the hormones and other messengers that help coordinate body activities by communicating between cells Hemoglobin in red blood cells is a transport protein that delivers O2 to working muscles. Different transport proteins move sugar molecules into cells for energy Storage proteins, such as ovalbumin, the protein of egg white, which serves as a source of amino acids for developing embryos
Eukaryotic characteristics (plant cell)
-Has a rigid, rather thick cell wall (as do the cells of fungi and many protists). -Cell walls protect cells and help maintain their shape -Chemically different from prokaryotic cell walls, plant cell walls contain the polysaccharide cellulose. -An important organelle found in plant cells but not in animal cells is the chloroplast, where photosynthesis occurs. (Chloroplasts are also found in some protists.) -Unique to plant cells is a large central vacuole, a compartment that stores water and a variety of chemicals. -eukaryotic cells contain nonmembranous structures as well: the centriole and cytoskeleton, both of which consist of protein tubes called microtubules -that ribosomes, the sites of protein synthesis, occur throughout the cytoplasm, as they do in prokaryotic cells. -have many ribosomes attached to parts of the endoplasmic reticulum (making it "rough") and to the outside of the nucleus
Abnormal Lysosomes
-If the lysosomes lack an enzyme needed to hydrolyze the compound, the cell will accumulate an excess of the compound. -a lysosomal storage disease -Pompe's disease -Tay-Sachs
DNA does not put its genetic information to work directly
-It works through an intermediary-RNA -DNA's information is transcribed into RNA, which is then translated into the primary structure of proteins
Flagella
-Longer, generally less numerous appendages on protists -are composed of microtubules wrapped in an extension of the plasma membrane -Can propel cell
Vacuoles
-Membranous sacs -come in different shapes and sizes and have a variety of functions
Polysaccharides
-Polymers of monosaccharides linked together by dehydration reactions. -Some polysaccharides are storage molecules, which cells break down as needed to obtain sugar.
Nucleic acids
-Polymers that can serve as the blueprints for proteins -Two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
The Lysosome P 68
-Sacs of enzymes that function in digestion and recycling within the cell -produced in animal cells by the rough ER and Golgi apparatus 1: The rough ER packages the enzymes into transport vesicles. The Golgi apparatus chemically refines the enzymes and 2: releases mature lysosomes. Eukaryotic cell structure-compartmentalization. The lysosomal membrane encloses a compartment where digestive enzymes are provided with an acidic environment, safely isolated from the rest of the cytoplasm. 3. Lysosomes fuse with food vacuoles, break down food, and release nutrients 4. Lysosomes serve as recycling centers for cells. Fuses with a vesicle and dismantles its contents, making organic molecules available for reuse. W the help of lysosomes, a cell continually renews itself.
Cohesion
-Tendency of molecules to stick together is strongest in water -Allows water to resist gravity
Peptide Bond
-The covalent linkage between two amino acid units in a polypeptide; formed by a dehydration reaction -Cells join amino acids together in a dehydration reaction that links the carboxyl group of one amino acid to the amino group of the next amino acid as a water molecule is removed -Dipeptide: made from two amino acids
A protein's Quaternary structure
-The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits
Nucleotide P 45
-The monomers that make up nucleic acids -each nucleotide has three parts. One part is a five-carbon sugar (blue); DNA has the sugar deoxyribose, whereas RNA has a closely related sugar called ribose. Linked to one end of the sugar in both types of nucleic acid is a phosphate group (yellow). At the other end of the sugar is a nitrogenous base • DNA has the nitrogenous bases adenine (A), thymine (T), cytosine (C), and guanine (G). RNA also has A, C, and G, but instead of thymine, it has uracil (U).
Active Site
-The region of the enzyme a substrate fits into -is typically a pocket or groove on the surface of the enzyme
Cilia
-The short, numerous appendages that propel protists -are composed of microtubules wrapped in an extension of the plasma membrane -coordinated oars -Sweep debris
Commonalities in all cells
-They are all bounded by a membrane, called a plasma membrane -All cells have genes made of DNA as their hereditary material. -And all cells contain ribosomes, tiny structures that make proteins according to instructions from the genes.
What are the main functions of the nucleus?
-To contain DNA and pass it on to daughter cells in cell division, to build ribosomes, to copy DNA instructions into RNA
Polar covalent bond
-Unequal sharing of electrons produces what is called -the pulling of shared electrons closer to the more electronegative atom makes that atom partially negative and the other atom partially positive -Because of its V shape and its polar covalent bonds, water is a polar molecule-that is, it has an unequal distribution of charges -Partial charges on atoms
exergonic reactions
-a chemical reaction that releases energy (exergonic means "energy-out"). -reaction begins with reactants whose covalent bonds contain more energy than those in the products
Phospholipids
-a major component of cell membranes, -are structurally similar to fats, but they contain the element phosphorus and have only two fatty acids instead of three. -Phospholipids are very important biological molecules
Resolution
-a measure of the clarity of an image. Resolution is the ability of an optical instrument to show two close objects as separate. For example, what looks to your unaided eye like a single star in the sky may be resolved as two stars with the help of a telescope -The light microscope can resolve objects as small as 0.2 micrometer (mm), about the size of the smallest bacterium
smooth endoplasmic reticulum
-a network of interconnected tubules, called smooth because it lacks attached ribosomes •One of the most important functions of smooth ER is the synthesis of lipids, including fatty acids, phospholipids, and steroids •Certain enzymes in the smooth ER of liver cells help process drugs and other potentially harmful substances -Smooth ER stores calcium ions necessary for muscle contraction by uptake and release of calcium
chemical reaction
-a process leading to changes in the composition of matter -The arrow indicates the conversion of the starting materials, called the reactants (H2 and O2), to the resulting product (H2O) -Does not create or destroy matter, only rearranges
Extracellular matrix P 75
-a sticky layer of glycoproteins in animal cells -helps hold cells together in tissues and can have protective and supportive functions -helps regulate cell behavior/MECHANICAL SUPPORT
Starch
-a storage polysaccharide in the roots and other tissues of plants, consists entirely of glucose monomers -starch molecules coil into a helical shape because of the angles of the bonds joining their glucose units
Amino Acids
-all have an amino group and a carboxyl group -two main types, hydrophobic and hydrophilic
Basal Body
-an anchoring structure , which has a pattern of nine microtubule triplets -When a cilium or flagellum begins to grow, the basal body may act as a foundation for microtubule assembly from tubulin subunits •Basal bodies are identical in structure to centrioles
Steroids
-are lipids whose carbon skeleton is bent to form four fused rings -All steroids have the same ring pattern: three six-sided rings and one five-sided ring -Cholesterol is a common substance in animal cell membranes, and animal cells also use it as a starting material for making other steroids, including the female and male sex hormones
Lipids differ from other large biological molecules in that they _____
-are not truly polymers -Lipids are not all made of the same type of monomer. Their association as a group is related to their behavior rather than their structure
Anabolic steroids
-are synthetic variants of the male hormone testosterone -Use of these drugs often makes the body reduce its output of natural male sex hormones, which can cause shrunken testicles, reduced sex drive, infertility, and breast enlargement in men. •Use in women has been linked to menstrual cycle disruption and development of masculine characteristics. •In teens, bones may stop growing, stunting growth
monosaccharides P 40
-carbohydrate monomers (single-unit sugars) -generally have molecular formulas that are some multiple of CH2O -Its molecular formula is C6H12O6, identical to that of glucose. Thus, glucose and fructose are isomers; they differ only in the arrangement of their atoms -the main fuel molecules for cellular work -Cells also use the carbon skeletons of monosaccharides as raw material for manufacturing other kinds of organic molecules, including amino acids
Plant cell walls composed of
-consist of fibers of the polysaccharide cellulose embedded in a matrix of other polysaccharides and proteins -Rigid molecules called lignin strengthen the cell walls of many plants. These strong cell walls are the main component of wood.
DNA
-double helix, in which two polynucleotides wrap around each other -The two DNA chains are held in a double helix by hydrogen bonds between their paired bases •Most DNA molecules are very long, with thousands or even millions of base pairs. •One long DNA molecule may contain many genes, each a specific series of hundreds or thousands of nucleotides along one of the polynucleotide strands.
Glycogen
-glucose polysaccharide -Most of our glycogen is stored as granules in our liver and muscle cells, which hydrolyze the glycogen to release glucose when it is needed.
Receptor Protein
-has a shape that fits the shape of a specific messenger, such as a hormone, just as an enzyme fits its substrate.
Contractile vacuole (some protists)
-like wheel hubs with radiating spokes -The "spokes" collect excess water from the cell, and the hub expels it to the outside -Vital for freshwater protists
Intermediate filaments
-made of fibrous proteins rather than globular ones and have a ropelike structure -serve mainly for reinforcing cell shape and anchoring certain organelles
Three main kinds of fibers make up the cytoskeleton:
-microfilaments, the thinnest type of fiber -microtubules, the thickest -intermediate filaments, in between in thickness
Golgi apparatus P 67
-named after Italian biologist and physician Camillo Golgi -Consists of flattened sacs looking like a stack of pita bread -Receives and modifies substances manufactured by the ER -One side of Golgi stack serves as a receiving dock for transport vesicles produced by ER -When Golgi receives transport vesicles containing molecules it takes in the materials and modifies them chemically -finished product exported from the cell or become part of the plasma membrane itself or part of another organelle, such as a lysosome
Mitochondria
-organelles that carry out cellular respiration in nearly all eukaryotic cells, converting the chemical energy of foods such as sugars to the chemical energy of a molecule called ATP
Cellulose is a _____ made of many _____
-polymer ... glucose molecules -Cellulose is a polysaccharide, constructed from many monosaccharides
Denaturation
-polypeptide chains unravel, losing their specific shape and, as a result, their function -The function of each protein is a consequence of its specific shape, which is lost when a protein denatures.
Acid Rain
-rain, snow or fog with a pH lower (more acidic) than 5.6, the pH of uncontaminated rain -precipitation results mainly from the presence in the air of sulfur oxides and nitrogen oxides -The effect of acid in lakes and streams is most pronounced in the spring, as snow begins to melt
A protein's tertiary structure
-refers to the overall, three-dimensional shape of a polypeptide -most tertiary structures can be roughly described as either globular or fibrous -Tertiary structure generally results from interactions among the R groups of the amino acids making up the polypeptide.
endergonic reactions
-requires a net input of energy (endergonic means "energy-in"). Endergonic reactions yield products that are rich in potential energy -Energy is absorbed from the surroundings as the reaction occurs, so that the products of an endergonic reaction store more energy than the reactants did ie o Photosynthesis, the process whereby plant cells make sugar, is one example of a strongly endergonic process. Photosynthesis starts with energy-poor reactants (carbon dioxide and water molecules) and, using energy absorbed from sunlight, produces energy-rich sugar molecules.
ATP
-stands for adenosine triphosphate -powers nearly all forms of cellular work, from the generation of light by fireflies to the movements of muscle cells that enable you to pedal a bicycle • Adenosine consists of adenine, a nitrogenous base, and ribose, a five-carbon sugar; triphosphate is a chain of three phosphate groups • All three phosphate groups are negatively charged
The First Law of Thermodynamics
-the law of energy conservation, the total amount of energy in the universe is constant. Energy can be transferred and transformed, but it cannot be created or destroyed. -An electric company does not manufacture energy; it merely converts it to a form that is convenient to use.
The partial charges on a water molecule occur because of _____
-the unequal sharing of electrons between hydrogen and oxygen -Because oxygen is more electronegative than hydrogen, electrons of the polar bond spend more time closer to the oxygen atom, resulting in a slight negative charge on the oxygen atom and slight positive charges on the hydrogen atoms
The scanning electron microscope (SEM)
-to study the detailed architecture of cell surfaces. -The SEM uses an electron beam to scan the surface of a cell or group of cells that has been coated with a thin film of metal. When the beam hits the surface it emits electrons -The electrons are detected by a device that then translates their pattern into an image projected onto a video screen. -3 dimensional
cells
-transfer chemical energy between molecules in chemical reactions and convert chemical energy to kinetic energy -A cell creates ordered structures from less organized starting materials -Cells extract the chemical energy of glucose and other fuels and return heat and the lower-energy molecules of carbon dioxide and water to their surroundings
facilitated diffusion P 88
-type of passive transport because it does not require energy. As in all passive transport, the driving force is the concentration gradient. -When a transport proteins makes it possible for a substance to move down its concentration gradient, the process is called
The transmission electron microscope (TEM)
-used to study the details of internal cell structured -Specimens are cut into extremely thin sections and stained with atoms of heavy metals such as gold. -The TEM aims an electron beam through a section, just as a light microscope aims a beam of light through a specimen -Initially B&W but color is added
A light microscope (LM)
-works by passing visible light through a specimen, such as a microorganism or a thin slice of animal or plant tissue. -Glass lenses in the microscope bend the light to magnify the image of the specimen and project the image into the viewer's eye or onto photographic film or a video screen
All life-forms on our planet share the fundamental features of
1) consisting of cells, each enclosed by a membrane that maintains internal conditions very different from the surroundings; (2) having DNA as the genetic material; and (3) carrying out metabolism, which involves the interconversion of different forms of energy and of chemical materials.
Like the chloroplast, the mitochondrion is enclosed by two membranes
1. The intermembrane space forms one fluid-filled compartment. 2. The inner membrane space mitochondrial matrix
3 Types of of Cell Junctions
1. Tight junctions: bind cells very tightly together, forming a leak-proof sheet. 2. Anchoring junctions: rivet cells together with cytoskeletal fibers, forming strong sheets. Anchoring junctions are common in tissues subject to stretching or mechanical stress, such as skin and heart muscle. 3. Gap junctions: similar in function to the plasmodesmata of plants; they allow small molecules to flow between neighboring cells. ie the flow of ions through gap junctions in the cells of heart muscle coordinates their contraction.
4 Functional Categories of Eukaryotic Organelles P 77
1: Manufacturing -Nucleus -Ribosomes -Rough ER/Smooth ER -Golgi Apparatus The synthesis of molecules & their transport within the cell 2: Breakdown -Lysosomes (in animal cells and some protists) -Peoxisomes -Vacuoles All membraneous sacs. Break down and recycle materials that are harmful or no longer needed 3: Energy Processing -Chloroplasts (in plants and some protists) -Mitochondria 4: Support, Movement & Comm between cells -Cytoskeleton (cilia, flagella, centrioles in animal cells) -Cell walls (in plants, fungi, and some protists) -Extracellular matrix (in animals) -Cell Junctions a common structural theme in the various fibers involved in the functioning of most of these organelles
Internal membranes partition the chloroplast into three major compartments P 71
1: The narrow intermembrane space, between the outer and inner membranes of the chloroplast 2: the space enclosed by the inner membrane, contains a thick fluid called stroma and a network of tubules and interconnected hollow disks formed of membranes • stroma (stro′-muh) A thick fluid enclosed by the inner membrane of a chloroplast. Sugars are made in the stroma by the enzymes of the Calvin cycle 3: The space inside the tubules and disks constitutes a third compartment • Notice that the disks occur in stacks, each called a granum • The grana are the chloroplast's solar power packs-the sites where chlorophyll actually traps solar energy.
A carbon atom has __ outer electrons in a shell that holds __
4, 8
DNA is build from just __ kinds of monomers called ___
4, nucleotides
Endocytosis
A cell takes in macromolecules or other particles by forming vesicles or vacuoles from its plasma membrane.
Organic Compound
A chemical compound containing the element carbon and usually synthesized by cells
Inhibitor
A chemical that interferes with an enzyme's activity • If an inhibitor attaches to the enzyme by covalent bonds, the inhibition is usually irreversible. • Toxins and poisons are often irreversible inhibitors. Inhibition is reversible when weak bonds, such as hydrogen bonds, bind inhibitor and enzyme.
Inhibitor Overview
A competitive inhibitor competes with the substrate for the active site. A noncompetitive inhibitor alters an enzyme's function by changing its shape. Feedback inhibition helps regulate metabolism . Poisons, pesticides, and drugs may inhibit enzymes
The peptide bond is _____
A covalent bond
Hypercholesterolemia,
A disease characterized by more than twice the normal level of cholesterol in the blood
Macromolecule
A giant molecule in a living organism: a protein, carbohydrate, lipid, or nucleic acid
Polymer
A large molecule consisting of many identical or similar molecular units strung together, much as a train consists of many individual cars. The units that serve as the building blocks of polymers are called monomers
Solution
A liquid consisting of a uniform mixture of two or more substances
central vacuole:
A membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, and development.
Which of the following would probably NOT be affected when a protein is denatured?
A primary structure
isotonic solution:
A solution having the same solute concentration as another solution • The solute concentration of a cell and its isotonic environment are essentially equal, and the cell gains water at the same rate that it loses it
Substrate
A specific reactant that an enzyme acts on
A hypothesis is
A tentative answer to some question
chromosome
A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. Chromosomes consist of chromatin.
Double Bond
A type of covalent bond in which two atoms share two pairs of electrons; symbolized by a pair of lines between the bonded atoms
Hydrogen bond
A type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule (or in another part of the same macromolecule).
Theory
A widely accepted explanatory idea that is broad in scope and supported by a large body of evidence
Based on the way nitrogen bases pair, you would expect the percentage of ___ to be equal to the percentage of ____
A....T
Fat
AKA "triglyceride" A large lipid made from two kinds of smaller molecules: glycerol and fatty acids • glycerol is an alcohol with three carbons, each bearing a hydroxyl group • A fatty acid consists of a carboxyl group and a hydrocarbon chain with about 15 carbon atoms
Explain why an enzyme cannot change an endergonic reaction into an exergonic one
Although an enzyme speeds a reaction by lowering the energy of activation, it has no effect on the relative energy content of products versus reactants.
Ionic bond
An attraction between two ions with opposite electrical charges. The electrical attraction of the opposite charges holds the ions together -Full charges
Matter
Anything that occupies space and has mass
Plasmolysis
As a plant cell loses water, it shrivels, and its plasma membrane pulls away from the cell wall
Isotopes of an element will always differ in _____
Atomic mass number Atomic forms of an element with the same number of protons but different numbers of neutrons are isotopes
Levels of organization
Biosphere: Sum of all planet's ecosystem Ecosystem: All organisms in a given area living or nonliving Community: All organisms living together in a certain area Population: Group belonging to one species in same area Organism: Living thing Organ system: Group of organs Organ: Tissues adapted as a group Tissue: Cooperative unit of many similar cells that perform a specific function within a multicellular organism Cell: Basic unit of life w plasma membrane Organelle: Structure w specific purpose within a cell Molecule: a group of two or more atoms held together by covalent bonds Atom: Smallest unit of matter that retains property of an element
Select the hydrocarbon
C3H8 This is a typical hydrocarbon with single bonds; the number of hydrogen atoms is equal to two times the number of carbon atoms plus 2.
Which one of the following molecules is a carbohydrate?
C60H100O50 Correct. Carbohydrates have molecular formulas that are multiples of CH2O
Remaining 4% of elements in human body
Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), and magnesium (Mg)
polypeptide
Chain of amino acids
Which type of potential energy is stored in molecules of food and gasoline?
Chemical
Chemical nutrients vs Energy
Chemical nutrients: Recycle within an ecosystem Energy: An ecosystem gains and loses energy constantly (enters as light, eventually converted to heat which is then lost from the system)
Long fibers of DNA and protein are called a
Chromatin
a protein with quaternary structure is ____
Collagen. A fibrous protein with helical subunits intertwined into a larger triple helix. This arrangement gives the long fibers great strength, suited to their function as the girders of connective tissue in skin, bone, tendons, and ligaments. (Collagen accounts for 40% of the protein in a human body.)
2 types of enzyme inhibitors
Competitive inhibitor: •Resembles the enzyme's normal substrate and competes with the substrate for the active site on the enzyme. -a competitive inhibitor reduces the productivity of an enzyme by blocking substrates from entering the active site. Noncompetitive inhibitor: -Does not enter the active site. Instead, it binds to the enzyme somewhere else, and its binding changes the shape of the enzyme so that the active site no longer fits the substrate -
A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture _____.
DNA
Nucleic acids
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, a phosphate group, and a nitrogenous base. DNA is a double helix; RNA is a single-stranded polynucleotide
The nucleus contains _____
DNA, the genetic material of a cell, and controls the cell's activities by directing protein synthesis
Alphabet of inheritance
DNA: ATCG RNA: AUCG
Natural selection
Differential success in reproduction by different phenotypes resulting from interactions with the environment Evolution occurs when natural selection produces changes in the relative frequencies of alleles in a population's gene pool
Solvent
Dissolving agent
The formation of systems typically results in the appearance of novel characteristics called
Emergent Properties
Bacterial production of the enzymes needed for the synthesis of the amino acid tryptophan declines with increasing levels of____
Feedback inhibition
Eukaryotic organisms that decompose dead organisms and absorb the nutrients are generally found in which kingdom?
Fungi
As ice melts ___ bonds are broken
Hydrogen
feedback inhibition
If a cell is producing more of that product than it needs, the product may act as an inhibitor of one of the enzymes of the pathway
Functional groups P 37
In an organic molecule-the groups of atoms that usually participate in chemical reactions Hydroxyl group: -consists of a hydrogen atom bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of a molecule -Ethanol, shown in the table, and other organic compounds containing hydroxyl groups are called alcohols Carbonyl group: -a carbon atom linked by a double bond to an oxygen atom. -If the carbon atom of the carbonyl group is at the end of a carbon skeleton, the compound is called an aldehyde. -A compound whose carbonyl group is within a carbon chain is called a ketone. -Sugars typically contain a carbonyl group and several hydroxyl groups. Carboxyl group -consists of a carbon double-bonded to an oxygen and also bonded to a hydroxyl group. -The carboxyl group acts as an acid by contributing an H+ to a solution and becoming ionized. -Compounds with carboxyl groups are called carboxylic acids. Amino Group: -composed of a nitrogen atom bonded to two hydrogen atoms. -It acts as a base by picking up an H+ from a solution. -Organic compounds with an amino group are called amines. -Amino acids, the building blocks of proteins, contain both a carboxyl and an amino group. -Under cellular conditions, both groups are usually ionized. Phosphate group: -consists of a phosphorus atom bonded to four oxygen atoms. It is usually ionized and attached to the carbon skeleton by one of its oxygen atoms. This structure is abbreviated as "v" in this text o Compounds with phosphate groups are called organic phosphates and are often involved in energy transfers. Three phosphate groups are found in the energy compound ATP, or adenosine triphosphate.
Diffusion and Passive Transport Overview
In passive transport, substances diffuse (move from higher to lower concentration) across membranes without work by the cell In facilitated diffusion, transport proteins provide passage across membranes for ions and polar molecules Osmosis is the diffusion of water across a membrane from a solution of lower solute concentration to one of higher solute concentration Osmosis causes cells to shrink in a hypertonic solution and swell in a hypotonic solution. In isotonic solutions, animal cells are normal but plant cells are limp. The control of water balance is called osmoregulation
Main difference between D science and H based science
In the first, scientists observe and describe objects and phenomena; in the second, they propose hypotheses, make deductions, and test predictions
Overview of Proteins
Involved in almost all of a cell's activities; as enzymes, they regulate chemical reactions. Protein diversity is based on different sequences of amino acids, monomers that contain an amino group, a carboxyl group, an H, and an R group, all attached to a central carbon. The R groups distinguish 20 different amino acids, each with specific properties. Amino acids are linked together by peptide bonds to form polypeptides (3.12). A protein consists of one or more polypeptide chains folded into a unique shape that determines the protein's function (3.13).
What makes a chemical taste sweet?
It has a shape that binds to "sweet" taste receptors on the tongue, causing a "sweet" message to be sent to the brain
How does a protein's quaternary structure differ from other levels of protein structure?
It involves two or more polypeptide chains. All other levels of protein structure involve only a single polypeptide chain.
Overview of Lipids
Lipids, diverse compounds composed largely of carbon and hydrogen, are grouped together because they are hydrophobic. Fats, also called triglycerides, are energy-storage molecules consisting of glycerol linked to three fatty acids. Other lipids include phospholipids (found in cell membranes), waxes, and steroids. Use of anabolic steroids can cause serious health problems
Hydrocarbons
Methane and other compounds composed of only carbon and hydrogen -nonpolar molecules, owing to their nonpolar C-H bonds
How do mitochondria, smooth ER, and the cytoskeleton all contribute to the contraction of a muscle cell?
Mitochondria supply energy in the form of ATP. The smooth ER helps regulate contraction by the uptake and release of calcium. Microfilaments function as the actual contractile apparatus.
Sweetness Scale
Natural sugars: Lactose: not as sweet Maltose: Same sweetness Glucose: Slightly sweeter Fructose: 4 times sweeter Artificial Sweeteners: Aspartame :150x sweeter Saccharine: 450x sweeter Sucralose: 600x sweeter Neotame: 8000x sweeter
Cofactors
Non protein helpers necessary to some enzymes
This message-transfer process is called signal transduction P 87
Often the binding of the messenger to the receptor triggers a chain reaction involving other proteins, which relay the message to a molecule that performs a specific activity inside the cell
Properties that are common to all organisms: Oscar regulated germany efficiently, really really efficiently
Order Regulation Growth & development Energy Utilization Response to the environment Reproduction Evolution
Levels of life (narrow to broad)
Organism: Particular type of organism Kingdom: the broad taxonomic category above phylum or division: Archaebacteria (ancient bacteria), Eubacteria (true bacteria) Protista, plantae, fungi, animalia Domains: a taxonomic category above kingdom level. Three domains of life are archaea, bacteria, and eukarya
•Because a cell does not perform work when molecules diffuse across its membrane, the diffusion of a substance across a biological membrane is called
Passive transport
The tail end of a phospholipid is pushed away by water, while the head is attracted to water P 86
Phospholipid bilayer •Nonpolar, hydrophobic molecules are soluble in lipids and can easily pass through membrane •In contrast, polar molecules and ions are not soluble in lipids
3 Types of endocytosis
Pinocytosis: Cellular drinking/not specific Receptor Mediated Endocytosis: Very specific, plasma membrane forms a pit lined w receptor proteins that pick up particular molecules Phagocytosis: Cellular eating. The amoeba engulfs its prey by wrapping extensions, called pseudopodia, around it and packaging it within a vacuole. •The vacuole then fuses with a lysosome, and the lysosome's hydrolytic enzymes digest the contents.
Overview of Cell Junctions
Plant cells are supported by rigid cell walls made largely of cellulose. Plasmodesmata are connecting channels between plant cells. Animal cells. The extracellular matrix of animal cells consists mainly of glycoproteins. Tight junctions bind cells to form leakproof sheets. Anchoring junctions rivet cells into strong tissues. Gap junctions allow substances to flow from cell to cell.
The most widely effective solvent for organisms is a material that is _____
Polar solvents, since their molecules have a positive and a negative pole, are excellent solvents for ions and for other polar materials
Enzyme overview
Protein catalysts that decrease the energy of activation (EA) needed to begin a reaction. Each type of enzyme has a unique active site that binds specifically with its substrate. Temperature and pH influence enzyme activity. Some enzymes require cofactors, such as metal ions or organic coenzymes .
Which is smallest in volume in an atom?
Proton
Two atoms of the same element must have the same number of ___
Protons
Which of these is found in amino acids?
R-NH2
Which of these is found in amines?
R-NH2 -NH2 is the amino group
The alpha helix and pleated sheet represent which level of protein structure?
Secondary structure
In what polysaccharide form do plants store sugar to be available later for energy?
Starch
Element
Substance that cannot be broken down to other substances by ordinary means
Buffers
Substances that resist changes in pH by accepting H+when in excess and donating H+ when it is depleted
The overall three-dimensional shape of a polypeptide is called the _____.
Tertiary structure
Entropy
The amount of disorder in a system
Energy of activation (EA):
The amount of energy that reactants must absorb before a chemical reaction will start.
Taxonomy:
The branch of biology that names and classifies species, arranges them into a hierarchy of broader and broader groups
carbon skeleton
The chain of carbon atoms in an organic molecule
cellular metabolism
The chemical activities of cells usually occur in the fluid-filled spaces within membranous organelles
Chromatin:
The combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing
Non polar covalent bond
The electrons are shared equally between the atoms -No charges on atoms
Cristae
The highly folded inner membrane which increases the membrane's surface area, enhancing the mitochondrion's ability to produce ATP
Which one of the following has negligible mass in an atom?
The mass of an electron is only about 1/2000 that of a proton or neutron, it can be ignored when computing the total mass of an atom.
SA/V
The maximum size of a cell is influenced by its requirement for enough surface area to obtain adequate nutrients and oxygen from the environment and dispose of wastes. Large cells have more surface area than small cells, but large cells have much less surface area relative to their volume than small cells of the same shape.
The valence, or bonding capacity, of an atom
The number of covalent bonds an atom can form is equal to the number of additional electrons needed to fill its outer shell
pH
The pH scale measures the degree of acidity, from 0 to 14. Those substances with a pH of less than 7 are considered acids. The higher the H+ concentration, the stronger the acidity, and the lower the pH -10 fold rule, , lemon juice at pH 2 has 10 times more H+ than an equal amount of grapefruit juice at pH 3 and 100 times more H+ than tomato juice at pH 4
Selective Permeability
The plasma membrane allowing some substances to cross more easily than others.
Phosphorylation:
The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation.
Biology's two dimensions
The vertical: the size scale that stretches from molecules to the biosphere The horizontal: spanning across the great diversity of organisms existing now and over life's long history
exocytosis (from the Greek exo,outside, and kytos, cell)
This process exports bulky materials. •The first step of this process, a membrane-enclosed vesicle filled with macromolecules (purple) moves to the plasma membrane. • Once there, the vesicle fuses with the plasma membrane, and the vesicle's contents spill out of the cell.
Molecule
Two or more atoms held together by covalent bonds
A fatty acid containing at least two double bonds is called _____
Unsaturated
Osmoregulation
Water balance o For example, a freshwater fish, which lives in a hypotonic environment, has kidneys and gills that work constantly to prevent an excessive buildup of water in the body.
Coenzyme
When the cofactor is an organic molecule
Aqueous solution
When water is the solvent
Cellular respiration
a chemical process that uses oxygen to convert the chemical energy stored in fuel molecules to a form of chemical energy that the cell can use to perform work -Exergonic
carbohydrate
a class of molecules ranging from the small sugar molecules dissolved in soft drinks to large polysaccharides, such as the starch molecules we consume in pasta and potatoes
Surface tension
a measure of how difficult it is to stretch or break the surface of a liquid
ER overview
a membranous network of tubes and sacs. Smooth ER synthesizes lipids, processes toxins and drugs in liver cells, and stores and releases calcium ions in muscle cells. Rough ER manufactures membranes, and ribosomes on its surface produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles.
A nucleotide is made of which of the following chemical components?
a nitrogenous base, a phosphate group, and a sugar Each nucleotide consists of three parts: an organic molecule, called a nitrogenous base; a sugar; and a phosphate group.
A glucose molecule is to starch as _____.
a nucleotide is to a nucleic acid
Which component of the cytoskeleton is most important in (a) holding the nucleus in place within the cell; (b) guiding transport vesicles from the Golgi to the plasma membrane; (c) contracting muscle cells?
a) intermediate filaments; (b) microtubules; (c) microfilaments
Hydroxyl is to ____ as ____ is to amine.
alcohol ... amino ; Hydroxyl is the functional group of an alcohol as amino is the functional group of an amine.
Although the structures of the functional groups important to life vary in chemical structure, they share one thing in common: They _____.
all are hydrophilic and increase the organic compound's water solubility
Cell Theory
all living things are composed of cells and that all cells come from other cells
Protein molecules are polymers of _____.
amino acid molecules Polymers of amino acids are called polypeptides. A protein consists of one or more polypeptides folded into specific conformations.
Glucose molecules are to starch as __________ are to proteins.
amino acids
ion
an atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons. Acquiring an electric charge(ionic bonding)
Sodium chloride (NaCl) dissolves in water because water molecules _____
are polar
Large, round cells can overcome surface area to volume problems by
becoming smaller, narrower or flatter.
Smooth endoplasmic reticulum stores____
calcium ions in muscle cells
Cholesterol circulates in the blood mainly in particles called___
called low-density lipoproteins, or LDLs
The four main classes of large biological molecules
carbohydrates, lipids, proteins, and nucleic acids
Almost all the molecules a cell makes are composed of ___
carbon atoms bonded to one another and to atoms of other elements
Citric acid makes lemons taste sour. Which of the following is a functional group that would cause a molecule like citric acid to be acidic?
carboxyl
Ribosomes
cell structures that create protein
A scanning electron microscope is used to study __________, whereas a transmission electron microscope is used to study____
cell surfaces . . . internal cell structures
Which one of the following components of a tossed salad will pass through the human digestive tract with the least digestion?
cellulose (in the lettuce) Correct. Cellulose contains glycosidic linkages that cannot be broken by human digestive enzymes.
Which one of the following lists contains only polysaccharides?
cellulose, starch, and glycogen
There are three main types of cellular work which ATP drives:
chemical: the phosphorylation of reactant molecules drives the endergonic synthesis of product molecules mechanical:the transfer of phosphate groups to special motor proteins in muscle Transport: drives transport work by phosphorylating certain membrane proteins
What is the process by which cells link monomers together to form polymers?
dehydration synthesis
Tonicity
describes the tendency of a cell in a given solution to lose or gain water
Carbon atoms are the most versatile building blocks of the molecules used by living organisms because _____.
each carbon atom acts as an intersection point from which a molecule can branch off in up to four directions
Small, nonpolar, hydrophobic molecules such as fatty acids
easily pass through a membrane's lipid bilayer.
The second law of thermodynamics states that____________.
energy tends to become increasingly dispersed and unusable.
The role of the cytoskeleton in movement is clearly seen in ___
eukaryotic flagella and cilia, the locomotor appendages that protrude from certain cells
Sucrose is formed
from two monosaccharides by dehydration synthesis. -->disacchride
Examples of monosacchrides
glucose (dextrose), fructose (levulose) and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch).
A polysaccharide that we use for storing energy in our muscles and livers is _____.
glycogen
Isotope
have the same numbers of protons and electrons and behave identically in chemical reactions, but they have different numbers of neutrons
The active site of an enzyme
is a groove or crevice on the structure of the enzyme.
Energy
is defined as the capacity to perform work
Kinetic Energy
is defined as the capacity to perform work
A functioning protein is
is one or more polypeptide chains precisely twisted, folded, and coiled into a unique three-dimensional shape
Thermodynamics
is the study of energy transformations that occur in a collection of matter
A protein's primary structure
its unique sequence of amino acids
Cholesterol belongs to which class of molecules?
lipids Steroids, such as cholesterol, are lipids characterized by a carbon skeleton consisting of four fused rings
The processes of photosynthesis and cellular respiration are complementary. During these energy conversions, some energy is
lost as heat
Temperature
measures the intensity of heat-that is, the average speed of molecules rather than the total amount of heat energy in a body of matter
Acid
o A chemical compound that dissociates (breaks up) and forms hydrogen ions (H+ ions) in a solution is called an acid The more acidic the solution, the higher its concentration of H+ions -A compound that donates hydrogen ions to solutions
Explain how a protein-secreting cell can synthesize and secrete its product without the protein ever having to cross a membrane
o From the time the protein is made by ribosomes on rough endoplasmic reticulum (ER), it is enclosed within membranes, first in the ER interior, then within the Golgi, and finally in transport vesicles, which fuse with the plasma membrane, releasing the proteins by exocytosis
Hypothesis Based Science
o Observation of discovery science stimulates inquiring minds to ask questions and seek explanations o Inquiry often involves the proposing and testing of hypotheses o Hypothesis: tentative answer to some question, explanation on trial o Deductive reasoning is the logic used to come up with ways to test hypotheses. In deduction reasoning flows from general to specific o If all organisms are made of cells (premise 1)and humans are organisms (premise 2) then humans are composed of cells (deduction about a specific case)
Hypotonic
o a solution with a higher solute concentration. The cell shrivels and can die from water loss • For an animal to survive in a hypertonic or hypotonic environment, it must have a way to prevent excessive uptake or excessive loss of water.
Hypotonic
o a solution with a solute concentration lower than that of the cell. The cell gains water, swells, and may pop (lyse) like an overfilled balloon
Discovery Science
oAbout describing nature oVerifiable observations and measurements oDescribes life at its many levels from biosphere down to cells and molecules oie sequencing of human genome oInductive reasoning •Derives general principles from a large number of specific observations •"all organisms are made of cells" is an inductive conclusion based on the discovery of cells oDetermination that a change in behavior of a male gorilla is a result of the introduction of a new female.
A cell can:
oPerform all activities required for life oRegulate its internal environment oTake in and use energy oRespond to the environment around it oDevelop and maintain its complex organization oAbility to give rise to new cells is the basis for all reproduction and for the growth and repair of multicellular organisms
Lysozyme consists of
of one long polypeptide, represented by the ribbon. Roughly spherical, lysozyme's general shape is called globular.
Heat
or thermal energy, is a form of kinetic energy associated with the movement of molecules or atoms in a body of matter. Light is another kind of kinetic energy that can be harnessed to perform work, such as powering photosynthesis in green plants.
Elements which make up 96% of human body
oxygen (O), carbon (C), hydrogen (H), and nitrogen (N)
What could affect enzyme shape
pH & Temperature
five-carbon sugars ___ the six-carbon sugars __
pentoses hexoses *most common
The lipids that form the main structural component of cell membranes are _____
phospholipids -Phospholipids, by being partially water-soluble, are suitable for holding the cell membrane in place
Protists can be distinguished from the plants and fungi because
protists are eukaryotic and include both unicellular organisms and multicellular algae. Contain nuclei
Membrane Overview
provide structural order for metabolism. The selectively permeable plasma membrane controls the flow of substances into and out of a cell. A phospholipid has a hydrophilic head and two hydrophobic tails. A membrane is a fluid mosaic, with protein molecules embedded in a phospholipid bilayer Functions of membrane proteins include enzymatic activity, signal transduction, transport, and attachment to the cytoskeleton and extracellular matrix
cells take in cholesterol from the blood by ____
receptor-mediated endocytosis
Secretory proteins are
released from the cell through the plasma membrane.
active transport
requires that a cell expend energy to move molecules across a membrane against the solute's concentration gradient-that is, toward the side where it is more concentrated. • ATP supplies the energy for most active transport.
The Endomembrane System P 66
rough ER, smooth ER, endomembrane system, nuclear envelope
Genes
specific stretches of a DNA molecule that program the amino acid sequences (primary structure) of protein
The Second Law of Thermodynamics
that energy conversions reduce the order of the universe and increase its entropy.
Heat
the amount of energy associated with the movement of atoms and molecules in a body of matter
Enzymes
the chemical catalysts that speed and regulate virtually all chemical reactions in cells
In a group of water molecules, hydrogen bonds form between _____
the oxygen atom in one water molecule and a hydrogen atom in another water molecule
Chemical energy
the potential energy of molecules, is the most important type of energy for living organisms. And just as the potential energy of the cyclist can be converted to kinetic energy in the speedy ride downhill, the chemical energy of molecules can be released to power the work of the cell.
Potential Energy
the second form of energy, is stored energy that an object possesses as a result of its location or structure. A cyclist at the top of a hill has potential energy as a result of elevation
The "primary structure" of a protein refers to _____
the sequence of amino acids
Amino acid sequences determine
the specific three-dimensional structures and therefore the functions of proteins
Mass number
the sum of the protons and neutrons in its nucleus. An electron has only about the mass of a proton
Example of an endergonic reaction
the synthesis of glucose from carbon dioxide and water
Energy coupling
the use of energy released from exergonic reactions to drive essential endergonic reactions-is a crucial ability of all cells. ATP molecules are the key to energy coupling.
One characteristic shared by sucrose and maltose is _____
they are all disaccharides
The term "phosphorylation" refers to the
transfer of a phosphate to a substrate - like ADP.
Covalent Bond
two atoms share one or more pairs of outer-shell electrons
Coupling occurs when the energy released by an exergonic reaction is ______.
used to drive an endergonic reaction.
The electron microscope (EM)
uses a beam of electrons. The EM has a much greater resolution than the light microscope. Under special conditions, the most powerful EMs can detect individual atoms. In general, modern EMs can distinguish objects as small as about 2 nanometers (nm)
Water & Ice
water is less dense as a solid than as a liquid due to hydrogen bonds -spaciously arranged molecules in the ice crystal with the more tightly packed molecules in the liquid water
Induced fit
• When a substrate binds to an enzyme, the active site changes shape slightly so that it embraces the substrate more snugly. This may strain substrate bonds or place chem groups of the active site in position to catalyze the reaction
Electronegativity
•An atom's attraction for its electrons, including shared electron •The more electronegative an atom, the more strongly it pulls shared electrons toward its nucleus
The endoplasmic reticulum (ER)
•An extensive network of flattened sacs and tubes -two regions of ER, rough ER and smooth ER, which differ in structure and function
Linus Pauling
•Believed that large doses of vitamin C can help prevent common cold, cancer etc. •Found out how hemoglobin carries oxygen, how abnormal hemoglobin molecule causes sickle cell disease •First described the two fundamental secondary structures of proteins, the alpha helix and the pleated sheet
Explain how ATP transfers energy from exergonic to endergonic processes in the cell
•By phosphorylation: Exergonic processes phosphorylate ADP to form ATP. ATP transfers energy to endergonic processes
Eukaryotic cell
•Forms of life such as plants, animals, and fungi •subdivided by internal membranes into many different functional compartments, or organelles, including the nucleus that houses the cell's DNA. • membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea are composed of eukaryotic cells
Darwin's Two Observations
•OBSERVATION #1: Individual variation. Individuals in a population vary in many heritable traits. OBSERVATION #2: Overproduction and competition, competition is inevitable. INFERENCE: Unequal reproductive success. Darwin inferred that individuals are unequal in their likelihood of surviving and reproducing. Those individuals with heritable traits best suited to the environment will leave the greatest number of healthy, fertile offspring.
Osmosis
•Physical model of the diffusion of water molecules across a selectively permeable membrane -the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two side
rough endoplasmic reticulum P67
•Ribosomes stud the membranes •Two main functions To make more membrane Modify proteins that will be transported to other organelles or secreted by the cell -Part of the synthesis, modification and packaging of a secretory protein 1. As the polypeptide is synthesized by an attached ribosome it passes into the ER where it folds into its thee dimensional shape 2.Short chains of sugars are often linked to the polypeptide making the molecule a glycoprotein (sugar) 3.When the molecule is ready for export from the ER the ER packages it in a transport vesicle 4.This vesicle buds off from the ER membrane. The protein now travels to the Golgi apparatus for further processing 5. From there a transport vesicle containing the finished molecules makes it way to plasma membrane and releases its content from the cell
Atom
•Smallest unit of matter that still retains the properties of an element •Protons & electrons, nuetron •two neutrons and two protons are tightly packed in the atom's central core, or nucleus •Two electrons orbit the nucleus at nearly the speed of light. The attraction between the negatively charged electrons and the positively charged protons keeps the electrons near the nucleus
Microtubules
•Straight, hollow tubes composed of globular proteins called tubulins -provide rigidity and shape in one area may disassemble and then reassemble elsewhere in the cell. -act as tracks for organelle movement within the cytoplasm -main structural components of cilia and flagella
Prokaryotic characteristics P 62
•The DNA of a prokaryotic cell is coiled into a nucleoid region but in contrast to the situation in eukaryotic cells, no membrane surrounds the DNA •Outside the plasma membrane (gray) of most prokaryotes is a fairly rigid, chemically complex cell wall (orange). The wall protects the cell and helps maintain its shape. •In some prokaryotes, another layer, a sticky outer coat called a capsule (yellow), surrounds the cell wall and further protects the cell surface. Capsules also help glue prokaryotes to surfaces, such as sticks and rocks in fast-flowing streams or tissues within the human body. •In addition to outer coats, some prokaryotes have surface projections. Short projections called pili help attach prokaryotes to surfaces. •Longer projections called prokaryotic flagella (singular, flagellum) propel the prokaryotic cell through its liquid environment.
What enables neighboring water molecules to hydrogen bond to one another?
•The molecules are polar, with the negative end (oxygen end) of one molecule attracted to the positive end (hydrogen end) of its neighbor
Atomic number
•The number of protons •Unless otherwise indicated, an atom has an equal number of protons and electrons and thus its net electrical charge is 0
Base
•a compound that accepts hydrogen ions and removes them from solution •The more basic a solution, the higher its OH- concentration and the lower its H+ concentration
Compound
•a substance containing two or more elements in a fixed ratio •Most of the compounds in living organisms contain at least three or four different elements, mainly carbon, hydrogen, oxygen, and nitrogen
Prokaryotic cell
•simpler and usually much smaller than the eukaryotic cell. The cells of the microorganisms we commonly call bacteria are prokaryotic. •A type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea
Eukaryotic characteristics (animal cell)
•the most obvious difference is the variety of structures in the cytoplasm, the fluid-filled region between the nucleus and the plasma membrane. (The term cytoplasm is also used for the interior of a prokaryotic cell.) •These structures, along with the nucleus, are the organelles, and each type has a specific function in the cell o Organelle: A structure with a specialized function within a cell. •A typical eukaryotic cell, with a diameter about ten times greater than that of a typical prokaryotic cell, has a thousand times the cytoplasmic volume but only a hundred times the plasma membrane area of the prokaryotic cell -that ribosomes, the sites of protein synthesis, occur throughout the cytoplasm, as they do in prokaryotic cells -have many ribosomes attached to parts of the endoplasmic reticulum (making it "rough") and to the outside of the nucleus