Bio 181 Exam 1
Methyl Group
(--CH3) Affects the expression of genes when on DNA or on proteins bound to DNA. Affects the shape and function of male and female sex hormones. Compound name: Methylated compound Example: 5-Methyl Cytosine, a component of DNA that has been modified by addition of a methyl group.
Carboxyl Group
(--COOH) Acts as an acid (can donate H+) because the covalent bond is between oxygen and hydrogen is so polar. Compound name: Carboxylic acid, or organic acid Example: Acetic acid: which gives vinegar its sour taste
Amino Group
(--NH2) Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms) Compound name: Amine Example: Glycine (an amino acid)
Phosphate Group
(--OPO32-) Contributes negative charge (1--when positioned inside a chain of phosphates; 2-- when at the end). When attached, confers on a molecule the ability to react with water, releasing energy. Compound name: Organic phosphate Example: Glycerol phosphate, which take part in many important chemical reactions in cells
Sulfhydryl Group
(--SH) may be written (HS--) Two --SH groups can react, forming a "cross-link" that helps stabilize protein structure. Hair protein cross-links maintain the straightness or curliness of hair; in hair salons, permanent treatments break cross-links, then re-form them while the hair is in the desired shape. Compound name: Thiol Example: Cysteine, a sulfur-containing amino acid
Hydroxyl Group
(-OH) Polar due to electronegative oxygen. Forms hydrogen bonds with water, helping dissolve compounds such as sugars. Compound name: Alcohol Example: Ethanol
Carbonyl Group
(>C == O) Sugars with ketone groups are called ketoses; those with aldehydes are called aldoses. Compound name: Ketone (is within carbon skeleton) or aldehyde (is at the end of a carbon skeleton) Example: Acetone: the simplest ketone; Propanal: an aldehyde
Which of the following reactions is most likely to be coupled to the reaction ATP + H2O-ADP +Pi ( 'G = -7.3 kcal/mol)?
+Pi-EP ('G = +5 kcal/mol)
During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a 'G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the 'G for the new reaction?
-20 kcal/mol
The hydrolysis of ATP to ADP and inorganic phosphate (ATP + H2O-ADP- +Pi):
-has a ´G of about -7 kcal/mol under standard conditions. -involves hydrolysis of a terminal phosphate bond of ATP. -can occur spontaneously under appropriate conditions.
Ribosome
A cell organelle composed of RNA and protein; the site of protein synthesis.
Peroxisomes
A cell organelle containing enzymes that catalyze the production and breakdown of hydrogen peroxide
Cell Size and Surface Area
A cells efficiency depends on its size. If the larger the cell the less efficient the cell is especially if it has a high surface area to volume ratio.
ionic Bond
A chemical bond resulting from the attraction between oppositely charged ions.
Essential elements
A chemical element required for an organism to survive, grow and reproduce.
Glycosidic Linkage
A covalent bond formed between two monosaccharides by a dehydration reaction.
Cellulose
A major component of the tough walls that enclose plant cells.
Dalton
A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu
Mitochondrion
A membrane‐bound organelle found in most eukaryotic cells; site of cellular respiration where energy is created.
Fluid Mosaic Model
A model that refers to how the lipid bilayer tends to act more like a liquid than a solid.
Which of the following is an example of cooperativity?
A molecule binding at one unit of a tetramer, allowing faster binding at each of the other three.
Which of the following is an example of potential rather than kinetic energy?
A molecule of glucose.
Cytoskeleton
A network of long protein strands in the cytosol that helps support the cell
Starch
A polymer of glucose monomers, as granules within cellular structures known as plastids, which chloroplasts.
Hydrolysis
A process that is essentially the reverse of the dehydrations reaction. This means water breakage.
In cellular respiration, the energy for most ATP synthesis is supplied by:
A proton gradient across a membrane.
a helix
A secondary structure that is a delicate coil held together by hydrogen bonding between every fourth amino acid.
reactant
A starting material in a chemical reaction
Electrons
A subatomic particle with a single negative electrical charge and a mass about 1/2000 that of a neutron or proton. One or more electrons move around the nucleus of an atom.
Protons
A subatomic particle with a single positive electrical charge, with the mass of about 1.7 *10(-24th power) g, found in the nucleus of an atom.
Compound
A substance consisting of two or more different elements combined in a fixed ratio.
Which of the following statements is true regarding enzyme cooperativity?
A substrate molecule bound to an active site affects the active site of several subunits
Protein that spans the phospholipid bilayer one or more times is?
A transmembrane protein.
Pinocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
Cholesterol
A type of steroid, a crucial molecule in animals.
Covalent Bond
A type of strong chemical n=bond in which two atoms share one or more pair of valence electrons.
Hydrogen Bond
A type of weak chemical bond that is formed when slightly positive hydrogen
Electron Shells
AN energy level of electrons at a characteristic average distance from the nucleus of an atom.
Which of the following statements regarding ATP is (are) correct?
ATP serves as a main energy shuttle inside cells, ATP drives endergonic reactions in the cell by the enzymatic transfer of the phosphate group to specific reactants, and the regeneration of ATP from ADP and phosphate is an endergonic reaction.
The primary role of oxygen in cellular respiration is to:
Act as an acceptor for electrons and hydrogen, forming water.
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's:
Activation energy
Hydrophilic
Affinity for water. Substances can be this without actually dissolving.
Gap Junctions
Allow molecules to pass directly from cell to cell.
Protein to be an integral membrane protein it would have to be?
Amphipathic, with at least one hydrophobic region.
Ions
An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.
Atomic nucleus
An atoms's dense central core, containing protons and neutrons.
chemical Bonds
An attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.
Valence Electrons
An electron in the outermost electron shell.
Trace Element
An element indispensable for life but required in extremely minute amounts.
Are part of a prokaryotic cell except?
An endoplasmic reticulum.
Junctions
Anchor cells together so it can remain in a continuous sheet, there are four types, Plasmodesmata, integrins, tight junctions, desmosomers.
Desmosomes
Anchoring junctions that prevent cells from being pulled apart.
Glycogen
Animals store a polysaccharide called this, a polymer of glucose that is like amylopectin but more extensively branched. Vertebrates store this mainly in liver and muscle cells. Hydrolysis of this in these cells releases glucose when the demand for sugar increases.
Chitin
Another important structural polysaccharide, the carbohydrate used by arthropods (insect, spiders, crustaceans, and relate animals) to build their exoskeletons.
Prokaryote
Any cell that does not have membrane-bound organelles.
Eukaryote Cells
Any cell that has membrane-bound organelles such as a nucleus.
Element
Any substance that cannot be broken down to any substance by chemical reaction.
Bacteria Cells
Apart of the prokaryotic family of cells, and is the only living cell that does not have a nucli surrounding by a membrane.
The following question is based on the reaction A + B ↔ C + D shown in Figure 8.1. Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 8.1?
B.
Prokaryotes are classified as belonging to two different domains. What are the domains?
Bacteria and archaea.
How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
By changing the shape of the enzyme's active site.
Which of the following metabolic processes can occur without an input of energy?
C6H12O6 + 6O2 is converted to 6CO2 + 6H2O
Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy?
C6H12O6 is oxidized and O2 is reduced.
Move through the lipid bilayer of a plasma membrane most rapidly?
CO2.
Complementary Base Pairing
Can occur between regions of two RNA molecules or even between two stretches of nucleotides in the same RNA molecule. In fat, base pairing within an RNA molecule allows it to take on the particular three-dimensional shape necessary for its function.
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
Catabolic pathways.
Vacuole
Cell organelle that stores materials such as water, salts, proteins, and carbohydrates
Which of the following statements is representative of the second law of thermodynamics?
Cells require a constant input of energy to maintain their high level of organization.
When you have a severe fever, what grave consequence may occur if the fever is not controlled?
Change in the tertiary structure of your enzymes.
Aquaporins
Channel proteins that facilitate the passage of water
Plasmodesmata
Channels through cell walls that connect the cytoplasms of adjacent cells
Thylakoids, DNA, and ribosomes are all components found in?
Chloroplasts.
Receptor-Mediated Endocytosis
Coated pits contain receptors that attach to specific molecules, engulf and put into vesicle.
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
Competitive inhibition
Nucleotides
Composed of three parts: a five-carbon sugar (a pentose), a nitrogen-containing (nitrogenous) base, and one ore more phosphate groups.
B pleated sheet
Connected by hydrogen bonds between parts of the two parallel segments of the polypeptide backbone.
Lysosome
Contains digestive enzymes necessary for breaking down materials within a cell
Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid? Activity of various enzymes at various temperatures (a) and at various pH (b).
Curves 1 and 4
Where does glycolysis take place in eukaryotic cells?
Cytosol
The following question is based on the reaction A + B ↔ C + D shown in Figure 8.1. Which of the following represents the ΔG of the reaction in Figure 8.1?
D
Bacteria and archaea cells is correct?
DNA is present in both archaea cells and bacteria cells.
DNA in Eukaryotic Cells
DNA located in Nucleus, Mitocondria and Chloroplast.
Disaccharides
Double sugars, consisting of two monosaccharides joined by a covalent bond. Two monosaccharides joined by glycosidic linkage.
Ions diffuse across membranes through specific ion channels?
Down their electrochemical gradients.
Molecular Movement Across Membrane
Due to Osmosis, passive transport or active transport uses energy to go against the gradient.
Van der Waals Interactions
Electrons are not always evenly distributed; at any instant, they may accumulate by chance in one part of a molecule or another. The results are ever-changing regions of positive and negative charge that enable all atoms and molecules to stick to one another.
A chemical reaction that has a positive ΔG is correctly described as:
Endergonic
Which of the following is a statement of the first law of thermodynamics?
Energy cannot be created or destroyed.
Which of these statements regarding enzymes is true?
Enzymes are proteins that function as catalysts, enzymes display specificity for certain molecules with which they interact, the activity of enzymes can be regulated by other molecules, and an enzyme ma be used many times over for a specific reaction
Which of the following is true of enzymes?
Enzymes may require a nonprotein cofactor or ion for catalysis to take place. Enzyme function is reduced if the three-dimensional structure or conformation of an enzyme is altered. Enzyme function is influenced by physical and chemical environmental factors such as pH and temperature. Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
The following question is based on the reaction A + B ↔ C + D shown in Figure 8.1. Which of the following terms best describes the forward reaction in Figure 8.1?
Exergonic, ∆G < 0
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as:
Feedback inhibition.
Glycoproteins
Forms hydrogen bonds with the water molecules surrounding the cell and thus help to stabilize membrane structure
Disulfide Bridges
Further reinforce the shape of a protein. Form where two cysteine monomers, which have sulfhydryl groups (-SH) on their side chains, are brought close together by the folding of the protein.
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through:
Gap junctions.
Observation
Gathering information, either through direct use of the senses or with the help of tools such as microscopes, thermometers, and balances that extend our senses. Can reveal valuable information about the natural world
Monosaccharides
Generally have molecular formulas that are some multitude of the unit CH2O. Glucose (C6H12O6), the most common of these, is of central importance in the chemistry of life.
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
Glycolysis
Which of the following occurs in the cytosol of a eukaryotic cell?
Glycolysis and fermentation
Produces and modifies polysaccharides that will be secrete?
Golgi apparatus.
Functional Groups
Groups in which chemical groups are directly involved in chemical reactions. Each has certain properties, such as shape and charge, that cause it to participate in chemical reactions in a characteristic way.
Unsaturated Fatty Acid
Has one or more double bonds, with one fewer hydrogen atom on each double-bonded carbon.
Pyrimidine
Has one six-membered ring of carbon and nitrogen atoms. The members of this family are cytosine (C), thymine (T), and uracil (U).
Ribose
Has oxygen atoms on the second carbon in the ring
Electrogenic pump
Helps store energy that can be used for cellular work
Predominant Essential Elements in Living Matter
Humans need 25, plants need 17. Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) -- make up 96% of living matter. Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), and a few other elements account for most of the remaining 4% of an organism's mass.
Cohesion
Hydrogen bonds hold the substance together. Contributes to the transport of water and dissolved nutrients against gravity in plants.
Seven Chemical Groups Most Important in Biological Processes
Hydroxyl, carbonyl, carboxyl, amino, sulfate, hydroxyl, phosphate, and methyl.
Denaturation
If the pH, salt concentration, temperature, or other aspects of its environment are altered, the weak chemical bonds and interactions within a protein may be destroyed, causing the protein to unravel and lose its native shape.
Saturated Fatty Acids
If there are no double ones between carbon atoms composing a chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. Such a structure is said to be saturated with hydrogen, and resulting in fatty acid.
Plant cell, DNA may be found?
In the nucleus, mitochondria, and chloroplasts.
Organic Molecules
In this, carbon usually forms sing or double covalent bonds. Each carbon atom acts as an intersection point form which a molecule can branch off in as many as four directions. This enables carbon to form large, complex molecules.
Carbohydrates
Include sugars and polymers of sugars. The simplest ones are the monosaccharides, or simple sugars; these are the monomers from which more complex ones are built.
Where is ATP synthase located in the mitochondrion?
Inner membrane
Messenger RNA (mRNA)
Interacts with the cell's protein-synthesizing machinery to direct production of a polypeptide, which folds into all or part of a protein.
Cholesterol
Is a lipid that gives the cell membrane more structure making it less fluid. Fits in between all the lipids in the cell membrane.
The active site of an enzyme is the region that:
Is involved in the catalytic reaction of the enzyme.
Feature of a carrier protein in a plasma membrane?
It exhibits a specificity for a particular type of molecule.
Which is correct about diffusion?
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
It is lost to the environment.
Water passes quickly through cell membranes because:
It moves through aquaporins in the membrane.
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
Why is glycolysis described as having an investment phase and a payoff phase?
It uses stored ATP and then forms a net increase in ATP.
Deoxyribose
Lacks oxygen atoms on the second carbon in the ring
Purines
Larger with a six-membered ring fused to a five-membered ring. These are adenine (A) and guanine (G).
Avantage of light microscopy over electron microscopy is that?
Light microscopy allows one to view dynamic processes in living cells.
Steroids
Lipids characterized by a carbon skeleton consisting of four fused rings.
Polymer
Long molecule consisting of many similar or identical building blocks linked by covalent bonds, much as a train-consists of a chain of cars.
Microfilaments
Long, thin fibers that function in the movement and support of the cell
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction:
Loses electrons and loses potential energy.
Contains hydrolytic enzymes?
Lysosome.
Bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in?
Lysosomes.
Polysaccharides
Macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages. Some of these serve as storage material, hydrolyzed as needed to provide sugar for cells. Others serve as building material for structures that protect the cell or the whole organism.
Anything that takes up space and has mass.
Matter
Voltage across a membrane called?
Membrane potential.
Tight Junctions
Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid, like grandmas knitting.
Movement of vesicles within the cell depends on what cellular structures?
Microtubules and motor proteins.
Where are the proteins of the electron transport chain located?
Mitochondrial inner membrane
Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
Mitochondrial intermembrane space.
ATP synthesis in eukaryotic cells?
Mitochondrion.
Plant cell organelle contains its own DNA and ribosomes?
Mitochondrion.
Golgi Apparatus
Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell
Dehydration Reaction
Monomers are connected by a reaction in which two molecules are covalently bonded to each other, with the loss of a water molecule.
Ion Diffusion
Movement of ions in and out of the cell due to diffusion.
Which of the following statements describes NAD+?
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
Cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from?
Nearly any eukaryotic organism.
Archaea Cells
No membrane bound organelles inside of the cell apart of the prokaryotic family.
Polynucleotides
Nucleic acids are macromolecules that exists as polymers called this.
Receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?
On the inside surface of the vesicle.
Isotopes
One of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass.
Ionic Bond
Opposite charges, cations and anions attract each other. Any two ions of opposite charge can form this. The ions do not need to have acquired their charge by an electron transfer with each other.
Hydrocarbons
Organic molecules consisting of only carbon and hydrogen. Atoms of hydrogen are attached to the carbon skeleton wherever electrons are available for covalently bonding. Not prevalent in most living organisms.
Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?
Oxidative phosphorylation (chemiosmosis).
Are not embedded in the hydrophobic portion of the lipid bilayer at all?
Peripheral proteins.
Animal cell organelle contains enzymes that transfer hydrogen from various substrates to oxygen?
Peroxisome.
White blood cells engulf bacteria through what process?
Phagocytosis.
Major structural components of the cell membrane?
Phospholipids and proteins.
Difference between pinocytosis and receptor-mediated endocytosis is that?
Pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
Cell with a predominance of free ribosomes is most likely?
Producing primarily cytoplasmic proteins.
Chaperonins
Protein molecules that assist in the proper folding of other proteins.
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
Proteins.
Proton pumps are used in various ways by members of every domain of organisms: bacteria, archaea, and eukarya. According to evolution theory, what does this most probably mean?
Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
Rough Endoplasmic Reticulum
Rough ER (RER) is involved in some protein production, protein folding, quality control and despatch. It is called 'rough' because it is studded with ribosomes
synthesis of proteins that may be exported from the cell?
Rough ER.
Primary objective of cell fractionation is to?
Separate the major organelles so that their particular functions can be determined.
Endomembrane system
Series of interacting organelles between nucleus and plasma membrane that regulates protein traffic and performs metabolic functions in the cell
Covalent Bond
Sharing of a pair of valence electrons by two atoms.
An electron loses potential energy when it:
Shifts to a more electronegative atom.
Phospholipid
Similar to a fat molecule but has only two fatty acids attached to glycerol rather than three.
Molecules pass through a cell membrane most easily?
Small and hydrophobic.
Lliver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?
Smooth ER.
Synthesis of oils, phospholipids, and steroids?
Smooth endoplasmic reticulum.
Enzymes
Specialized macromolecules that speed up chemical reactions.
Motor Proteins
Specialized proteins that use energy to change shape and move cells or structures within cells.
Microtubules
Spiral strands of protein molecules that form a tubelike structure Consist of hollow tubes which provide support for the cell
Describe the Endomembrane system
Starts with the neculeous and how the membrane transitions to the endoplasmic reticulum, then to the round ER or smooth ER where proteins or lipids can be synthesized. Then these proteins or lipids are transported on vesicles to their location.
Hydrophobic
Substances that are nonionic and non polar (or otherwise cannot form hydrogen bonds) actually seem to repel water.
The ATP made during glycolysis is generated by:
Substrate-level phosphorylation.
Hypothesis-Based Approach
Systematic trial and error
Hypothesis
Tentative answer to a well-framed question -- an explanation on trial. A rational account for a set of observations, based on the available data and guided by inductive reasoning.
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
The binding of the substrate changes the shape of the enzyme's active site.
Valence
The bonding capacity of a given atom; usually equals the number of unpaired electrons required to complete the atom's outermost shell.
Energy
The capacity to cause change, especially to the work. ( to move against an opposing force.)
Contractile Vacuole
The cell structure that collects extra water from the cytoplasm and then expels it from the cell
Adhesion
The clinging of one substance to another. Helps counter the downward pull of gravity when hydrogen bonds to the molecules of cell walls.
Cell Fractionation
The disruption of a cell and separation of its organelles by centrifugation.
Unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
Equilibrium Potential
The magnitude of a cell's membrane voltage at equilibrium
Glycolipid
The main function of glycolipids in the body is to serve as recognition sites for cell-cell interactions. The saccharide of the glycolipid will bind to a specific complementary carbohydrate or to a lectin (carbohydrate-binding protein), of a neighboring cell.
Chemical Reaction
The making and breaking of chemical bonds, leading to changes in the composition matter.
Cause of the size limits for certain types of cells?
The need for a surface area of sufficient area to support the cell's metabolic needs
Atomic Number
The number of protons in the nucleus of an atom, unique for each element and designated by a subscript.
For living organisms, which of the following is an important consequence of the first law of thermodynamics?
The organism ultimately must obtain all of the necessary energy for life from its environment.
Valence Shells
The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of an atom.
Quaternary Structure
The overall protein structure that results from the aggregation of these polypeptide subunits.
Tertiary Structure
The overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids
Chemical Equilibrium
The point at which the reactions offset one another exactly. Dynamic equilibrium; reactions are still going on, but with no net effect on the concentrations of reactants and products.
Buffer
The presence of substances called this allows biological fluids to maintain a relatively constant pH despite the addition of acids or bases. A substance that minimizes changes in the concentrations of H+ and OH- in a solution. It does so by accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solutions when they have been deplete.
Which of the following is true for all exergonic reactions?
The reaction proceeds with a net release of free energy.
Monomers
The repeating units that serve as the building blocks of a polymer are smaller molecules.
Secondary Structure
The result of hydrogen bonds between the repeating constituents of the polypeptide backbone (not the amino acid side chains). Most proteins have segments of their polypeptide chains repeatedly coiled or folded in patterns that contribute to the protein's overall shape.
Example of a Hydrogen Bond
The slightly positive hydrogen of one molecule is attracted to the slightly negative oxygen of a nearby molecule. These two molecules are held together.
Extracellular Matrix
The substance in which animal tissue cells are embedded, consisting of protein and polysaccharides. such as providing support, segregating tissues from one another, and regulating intercellular communication
Mass Number
The sum of the number of protons and neutons in an atom's nucleus.
Orbital
The three-dimensional space where an electron is found 90% of the time.
Atomic Mass
The total mass of an atom, numerically equivalent to the mass in grams of 1 mole of the atom. ( for an element with more than 1 isotope, the atomic mass is the average mass of the naturally occuring isotopes, weighted by their abundance.)
Light Microscopy
The use of any kind of microscope that uses visible light to observe specimens
Membrane Potential
The voltage across a cell's plasma membrane.
Some bacteria are metabolically active in hot springs because:
Their enzymes have high optimal temperatures.
Fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
They can move laterally along the plane of the membrane.
Which of the following is (are) true for anabolic pathways?
They consume energy to build up polymers from monomers.
Which of the following statements is true concerning catabolic pathways?
They supply energy, primarily in the form of ATP, for the cell's work.
Smooth Endoplasmic Reticulum
This makes lipids and transports them throughout the cell; it also helps to detoxify drugs.
Primary Structure
This structure of a protein is its sequence of amino acids. As an example, consider transthyretin, a globular blood protein that transports vitamin A and one of the thyroid hormones throughout the body.
Intermediate Filaments
Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments
Gene Expression
Through RNA, controls protein synthesis; this entire process is called this.
Function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is?
To mediate cell-to-cell recognition.
Non Polar Covalent Bond
Two atoms of the same element share electrons equally because the two atoms have the same electronegativity -- the tug-of-war is at a standoff.
In glycolysis, for each molecule of glucose oxidized to pyruvate:
Two molecules of ATP are used and four molecules of ATP are produced.
Hydrogen Bond
When a hydrogen atom is covalently bonded to an electronegative atom, the hydrogen atom has a partial positive charge that allows it to be attracted to a different electronegative atom nearby. Attraction between a hydrogen and an electronegative atom.
Polar Covalent Bond
When an atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally. (H2O).
Peptide Bond
When two amino acids are positioned so that the carboxyl group of one is adjacent to the amino group of the other, they can become joined by a dehydration reaction, with the removal of a water molecule. The resulting covalent bond is called this.
polar covalent bond
a covalent bond between atoms that differ in electronegativity.
Double Bond
a double covalent bond; the sharing of 2 pairs of valence electrons by 2 atoms.
Process called " radiometric dating"
a method for determining the absolute age of rocks and fossils,, based on the half-life of radioactive isotopes.
anion
a negatively charged ion.
Cation
a positively charged ion.
Single bond
a single covalent bond; the sharing of a pair of valence electrons by two atoms.
A series of enzymes catalyze the reaction X _Y _Z _ ± | n Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?
a substrate
nonpolar covalent bond
a type of covalent bond in which electrons are shared equally between 2 atoms of similar electronegativity.
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reactions:
activation energy
How can one increase the rate of a chemical reaction?
add a catalyst
If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is to
add more of the enzyme
A series of enzymes catalyze the reaction X _Y _Z _ ± | n Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. Substance A functions as
an allosteric inhibitor
Radioactive Isotope
an isotope that is unstable ; the nucleus decays spontaneously, giving off a detachable particles and energy.
How does a non-competitive inhibitor decrease the rate of an enzyme reaction?
by changing the structure of the enzyme
Which term precisely describes the cellular process of breaking down large molecules into smaller ones?
catabolism
When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanations for this observation?
cells convert some of the energy of ATP hydrolysis into other forms of energy besides heat
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration
Many different things can alter enzyme activity. Which of the following underlie all types of enzyme regulation?
changes in the activation energy of the reaction, and changes in the active site of the enzyme
Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
cofactor necessary for enzyme activity
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
competitive inhibition
ATP generally energizes a cellular process by
coupling free energy released by ATP hydrolysis to free energy needed by other reactions
A chemical reaction that has a positive 'G is correctly described as
endergonic
Which of the following statements regarding enzymes is true?
enzymes increase the rate of a reaction
Which of the following is not true of enzymes?
enzymes provide activation energy for the reaction they catalyze
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as
feedback inhibition
As temperature decreases, the rate of enzyme-catalyzed reaction also decreases. Which of the following explain(s) why this occurs?
fewer substrates have sufficient energy to get over the activation energy barrier, motion in the active site of the enzymes is slowed, thus slowing the catalysis of the enzyme
Phospholipids
form the basic structure of a cell membrane, called the lipid bilayer.
Peripheral Proteins
found on the surface of the membrane, some of their functions are; some act as receptors, some as enzymes, catalyzing the reaction and since many are cytoskeletons, they give a cell its shape, offers support, and facilitates movement through three main components: micro filaments, intermediate filaments, and micro tubules
The active site of an enzyme is the region that
is involved in the catalytic reaction of the enzyme
An enzyme catalyzes a reaction by
lowering energy of activation of a reaction
neutrons
neutral charge particle
Cholroplasts
organelles used for photosynthesis
Endocytosis
process by which a cell takes material into the cell by infolding of the cell membrane. ingesting of material.
Exocytosis
process by which vesicles release their contents outside the cell
Phagocytosis
process in which phagocytes engulf and digest microorganisms and cellular debris
Integral Proteins
proteins which penetrate the hydrophobic core of the lipid bilayer include transporters, linkers, channels, receptors, enzymes, structural membrane-anchoring domains,
The regulation of enzyme function is an important aspect of cell metabolism. Which of the following is least likely to be a mechanism for enzyme regulation?
removing cofactors
Lipid Rafts
rigid region of membrane involved in signaling and interacting with messenger molecules
Vesicle
small organelle that contains and transports materials within the cytoplasm created by the Golgi body
What name is given to the reactants in an enzymatically catalyzed reaction?
substrates
Which of the following describes some aspect of metabolism?
synthesis of macromolecules, breakdown of macromolecules, and control of enzyme activity
Electronegativity
the attraction of a given atom for the electrons of a covalent bond.
Potential Energy
the energy that matter possess as a result of its location or spatial arrangement (structure)
If an enzyme has been inhibited noncompetitively,
the inhibitor molecule may be chemically unrelated to the substrate.
Which of the following is true for all exergonic reactions?
the reaction proceeds with a net release of free energy
Atom
the smallest unit of matter that retains the properties of an element
Which of the following is (are) true for anabolic pathways?
they consume energy to build up polymers from monomers
Which of the following statements correctly describes catabolic pathways?
they release energy as they degrade polymers to monomers
Integrins
transmembrane protein attaches the extracellular matrix and the cytoskeleton
Molecule
two or more atoms held together by a covalent bond.
Electron Microscopy
uses a beam of electrons to create an image of the specimen
Van der Waals interaction
weak attractions between molecules or parts of molecules that result from transient local partial charges.