Bio 1 exam 1
Which of the following bonds can form between atoms of equal electronegativity?
Van der Waals interactions can form between atoms of equal electronegativity. Even nonpolar covalent bonds have temporary regions of partial positive and negative charge, due to the chance movements of electrons. Attractions between such transient positive and negative charges create weak Van der Waals interactions.
Polar attractions are ...
forces between atoms with partial charges. weaker than covalent bonds. important because they are numerous. Polar attractions occur between atoms with partial charges and are weaker than covalent bonds. Still, they're important because so many of them occur in living cells.
A neutral atom has 2, 8, 8 electrons in its first, second, and third energy levels. This information ________.
does not tell us about the atomic mass of the element
Hypothetically speaking, which subatomic particle(s) of an atom could be altered in number without changing the identity of the atom (or which element it is)?
electrons or neutrons--Recall that the identity of an atom depends upon the number of protons (only!). If you missed this, please review the first three sub-sections of section 2.2 (subatomic particles through isotopes) and the second subsection in section 2.3 (ionic bonds).
About _____ molecules in a glass of water are dissociated.
1 in 500,000,000
When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?
*1 liter of 1.0 M NaCl* 1 liter of 0.5 M NaCl 1 liter of 1.0 M glucose 1 liter of 1.0 M NaCl and 1 liter of 1.0 M glucose will contain equal numbers of solute particles.
Why is water an effective solvent?
1) water is sticky: cohesice, adhesive, high specific heat 2) water is a versatile solvent: biomolecules usually bear partial and/or full charges, so most biomolecules dissolve. 3) water is a polar molecule and can hydrogen bond - Water is an effective solvent because it readily forms H+ bonds - When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules. - Water can also dissolve compounds made of nonionic polar molecules. - Even large polar molecules such as proteins can dissolve in water if they have ionic and polar regions.
How many ELECTRONS do each of the following atoms of hydrogen contain?
1, 0, and 2 electrons--A neutral atom of hydrogen (the first of the three atoms) must have the same number of electrons as it does protons or '1'. The second atom of hydrogen has lost this electron leaving only a proton behind, and hence bears a net charge of '+1'. The third atom of hydrogen has gained an electron and now has two, and bears a net charge of '-1'. Fyi the anion 'H-' is known as a hydride ion; the cation 'H+' is simply 'a proton'.
How much does an atom of hydrogen weigh?
1 Dalton
How much does a single proton weigh?
1 Dalton--Remember that 'grams' are used to describe the weight of everyday objects. 'Daltons' are used to give the weight of single atoms, parts of atoms, or molecules.
List 8 characteristics of life as it is known on Earth. Indicate *which of the following possess all 8 characteristics: a human, a bacterium, a virus, and a fictional robot/android.*
1. complex and ordered 2. regulated (homeostasis)/ evolutionary adaption 3. responsive (for maintaining) 4. grows (builds complexity and expands order) 5. well-adapted (evolution) 6. reproduces (that life will discont. w/out) 7. uses engergy (1-3 all need energy to function) 8. carries instructions (more behavioral)
How many ATOMS are in a tank containing 10 moles of (gaseous) H2 molecules?
1.204 times 10 to the 25th power th power Here you must know the term atom, as well as moleculeandmole. If there are ten moles of H2 molecules, then there are ten times Avagadro's number of H2 molecules. But each H2 molecule consists of two H atoms and the question asks for atoms, not molecules, so you must multiple by 2. Start by listing all of the things you know, then work out a dimensional analysis approach that eliminates all of the units except the one you want. 10 moles of H2 molecules ; 2 atoms of H / H2 molecule 2 atoms/1 molecule H2 x 6.02 molecules H2/1 mole H2 x 10 moles H2 = 1.204 x 10^25 H atoms
If a solution has a pH of 3, what is its concentration of protons (hydrogen ions)?
1/1,000 M Be sure you are clear on how the equation for pH works, and what a negative exponent means. Section 3.3.
Based on the scale diagram shown in the textbook, about how many times more protons are found in lemon juice as compared to an equal volume of tomato juice?
100 As discussed in lecture, adjacent pH units are separated by an order of magnitude (a 10-fold difference).
How many electrons are present in a Phosphorus 2+ atom?
13
How many COVALENT BONDS does glycerol (above) contain?
13 Covalent bonds are usually shown as solid lines. But there is a bond holding together each ‒OH (between 'O' and 'H'). You know this must be because O forms 2 bonds, and H one.
How many ATOMS does glycerol (above) contain?
14 Each atom is indicated by its symbol. The molecular formula of glycerol is C3H8O3.
How many atoms are in a dozen glycerol molecules?
168 14 atoms/1 glycerol molecule x 12 glycerol molecules/ 1 dozen glycerol molecules = 168 atoms/ 1 dozen molecules
About how many elements are required for life? Which 4 are most common in living things? Which 7 are next most common? Why are the remaining elements referred to as 'trace elements'?
17-25 elements are required for life CHON: carbon, hydrogen, oxygen, and nitrogen are most common Na, Mg, K, Ca, P, S, Cl are the next most common The remaining elements are referred to as trace elements because they function primarily as cataylsts in enzyme systems. They are required by an organism in only small quantities. lack of some trace elements can lead to serious medical issues.
How many grams of sucrose (C12H22O11) are dissolved in 500 mL of a 100 mM solution?
17.1 g The molecular formula of sucrose is C12H22O11, and the atomic weights of carbon, oxygen, and hydrogen are approximately 12, 16, and 1 Dalton, respectively. Also note that 500 mL is one-half of a L, and 100 mM is one-tenth of a molar. Knowing this you can forego converting all of the units. 342 g C12H22O11 molecules/ 1 mole C12H22O11 100 mM C12H22O11 = 100 millimoles of C12H22O11 / L = 0.1 moles of C12H22O11 / L 342 g/1 mole C12H22O11 x 0.1 mol/L x 0.5 L = 17.1 g of C12H22O111 mole C12H22O11L If you are not comfortable skipping the conversation, simply add equalities to the string of products, until you are left with the unit that you want.
Approximately how much does one mole of glucose (C6H12O6) weigh?
180 g If you missed this question, you may be unclear on one or more of the following: molecule vs. mole, Daltons vs. grams, or atomic weight. Grams and Daltons are both units of weight, but the gram is a very large unit, and a Dalton is very small. The weight given for each element on the periodic table means both Daltons/atom and grams/mole. A 'mole' is not a weight at all, but simply a number; just as a 'dozen' means exactly 12, a mole means 6.02x1023 (a.k.a. Avagadro's number) See section 3.2 for more info. A 'molecule' refers to a group of atoms held together by covalent bonds. A mole of glucose means 6.02x1023 molecules of glucose.
How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H4?
2
How many different ELEMENTS does glycerol (above) contain?
3 The elements are C, O, and H. Glycerol is an alcohol, whose structure is similar to a monosaccharide. It is used to build fats and phospholipids. (See Chapter 5!)
When did life appear on earth?
3-4 billion years ago
How many electrons will a single atom of nitrogen with no charge and no bonds have in its valence shell?
5
How many electrons does glycerol contain?
50 The number of electrons is equal to the number of protons, for neutral atoms and molecules. Since there are no charges in the molecule, we know that the number of electrons is the same.
How many atoms in glycerol (above) have undergone sp3 hybridization?
6 All of the C and O atoms have done so. This is because they are forming only single covalent bonds with other atoms. Please review the 'Rules for Orbital Hybridization' (Chapter 2 slides).
How many Daltons are equal to one gram? (Hint: Pick any atom on the periodic table and use a dimensional analysis approach to convert between these units! For example, 1 mole of H atoms weighs 1 g. Start with this equivalency, and go from there.)
6.02 X 10^23 Daltons Recalling that 'Dalton' is an incredibly small unit of mass and 'gram' is a large one, you should immediately eliminate the first three answers. Here is a dimensional analysis approach which converts grams to Daltons, using the molar mass (weight of one mole) of the atom hydrogen; a similar calculation can be made using the molar mass of any element (go ahead and try it!). 1 g of H atoms/1 mole of H atoms x 1 mole of H atoms/6.02 X 10^23 H atoms x 1 H atom/1 Dalton of H atoms
How much does one molecule of fat with the molecular formula (C51H98O6) weigh?
806 Daltons If you missed this question, you may be unclear on one or more of the following: molecule vs. mole, Daltons vs. grams, or atomic weight. 'Moles' has nothing to do with this question. If you missed it, please review section 3.2.
How many atoms are in a mole of glycerol molecules?
84.28 x 10^23 atoms 6.02 X 1023 glycerol molecules/1 mole of glycerol molecules x 14 atoms/ 1 glycerol molecule = 84.28 x 1023 atoms/ 1 mole of glycerol molecules
We can represent atoms by listing the number of protons, neutrons, and electrons−−for example, 2p+,2n0,2e−2p+,2n0,2e− for helium. Which of the following represents the 18O18O isotope of oxygen?
8p^+, 10n^0, 8e^−
Explain how covalent bonds may be either polar or nonpolar depending on the electronegativities of the bonded atoms. What constitutes a polar or a nonpolar molecule?
<0.5 = nonploar 0.5-1.6 = polar Polar -> if the electrons are shared unequally nonpolar -> electrons are shared equally
dehydration reaction
A chemical reaction in which molecules combine by removing water requires an enzyme requires energy biosynthesis within cells
What is a polymer? Name and describe the chemical reactions that are used to make and break biological polymers, as done in lecture. *Which of the four classes of biological molecules form polymers?* What of the four may be macromolecules?
A polymer is a substance or material consisting of very large molecules, or macromolecules, composed of many repeating subunits dehydration: removes a water molecule. hydrolysis: adds a water molecule. Carbohydrates and nucleic acids are the only polymers. There are four classes of macromolecules that constitute all living matter: carbohydrates, lipids, proteins, and nucleic acids. While they have different structures and functions, they are all composed of long complex chains of molecules (polymers) made up of simpler, smaller subunits (monomers).
Which statement about relative potential energy of electrons is correct?
An electron in the 3 p orbital of the third electron shell has more potential energy than an electron in the 2 p orbital of the second electron shell.
Hydrolysis
Breaking down complex molecules by the chemical addition of water requires an enzyme releases energy digestion within gut
How many covalent bonds do C, H, O, and N usually form? Which atoms among CHON undergo sp3 hybridization, and when do they do it? *How does the position of electrons in s and p orbitals differ from the position of electrons in sp3 hybrid orbitals? What do the orbital shapes have to do with the spacial arrangement of any covalently bonded atoms?*
C normally forms 4 covalent bonds H normally forms 1 covalent bond O normally forms 2 covalent bonds N normally forms 3 covalent bonds Carbon, oxygen, and nitrogen undergoes SP3 hybridication whenever they form SINGLE COVALENT BONDS ONLY Hydrogen does not undergo SP3 hybridization because it only has 1 orbital. the position of electrons in s and p orbitals are______ whereas in sp3 orbitals they orbital shapes have to do with the spacial arrangement of covaalently bonded atoms because____ determines molecular shape: 1. which atoms are bonded (H2O vs. C2) 2. orbitals 3. intramolecular interactions 4. environmental conditions
Summarize the different roles carbohydrates play in organisms, and give examples of each.
Carbs are used for energy and used to build (Polymer) and built by dehydration using energy. Glycogen is mainly used in liver and muscles and humans can only make about a one day supply. Plants have cellulose which plays a major role in the cell wall. Energy source, c source, storage, and structural.
Nitrogen (N) is more electronegative than hydrogen (H). Which of the following is a correct statement about the atoms in ammonia (NH3)?
Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.
Define potential energy. What happens when the potential energy of an electron changes? What is another name for electron shell? Explain the terms valence shell and valence electrons.
Electrons store potential energy The further the orbital is from the nucleus, the higher the potential energy of an electron. electron shell=valence shell= the outermost shell the number of electrons in the outermost shell (valence electrons) determines its reactivity or tendency to form chemical bonds.
Which of the following correctly describes chemical equilibrium?
Forward and reverse reactions continue with no net effect on the concentrations of the reactants and products.
Which of these is the correct equation for the dissociation of water?
H2O + H2O <==> H3O+ + OH-
What makes a substance hydrophilic? What makes a substance soluble? Can a substance be one and not the other? What makes a substance hydrophobic? Give examples as discussed in lecture.
Hydrophilic: "water-loving," water sticks to it, does not equal soluble Solubility is the ability of a solid, liquid, or gaseous chemical substance to disolve in a solvent. - all sodium, potassium, and ammonium compounds - all nitrates: ends in "nitrate" - all common and chlorides (with the exception of some) - all common sulphates (with the exception of some) NOT ALL substances that are hydrophilic are soluble (ex. a towel). ALL substances that are soluble MUST BE hydrophilic (ex. salts, glucose, sucrose, DNA, enzymes) hydrophobic: "water-fearing," water avoids, example would be oils
Which of the following best explains why water is COHESIVE?
It is polar and forms hydrogen bonds with itself. It is essential to clearly understand WHAT a question is asking, before trying to answer it. One trick to doing this is to rephrase the question using your own words. For example, 'cohesion' refers to the tendency of a substance to stick to itself. So this question is asking "Which best explains why water sticks to itself?". Now, test each answer:"Water sticks to itself because it sticks to other molecules." (This doesn't make sense.)'Adhesion' is the tendency of a substance to stick to other molecules; so same as above!"Water sticks to itself because it has a high specific heat." (Also doesn't make sense.)"Water sticks to itself because it is polar and forms hydrogen bonds." (Bingo!)So this question deals with cause and effect, a key relationship in science: because water is polar and can h-bond with itself (cause), it is cohesive (effect). The other three answers are other consequences of water's polarity and h-bonding ability, and not causes of cohesion.
Which of the following statements about sp3 hybridization is CORRECT?
It occurs when certain atoms form hydrogen bonds --.Has nothing to do with hydrogen bonding. It occurs when atoms are not bonded to other atoms.--Actually, it occurs as a direct result of covalent bonding. It occurs with carbon atoms, but not oxygen atoms.--It occurs with carbon, oxygen, and nitrogen (why not H?). So, the shape of biomolecules will greatly depend on this concept! It involves the formation of four new p orbitals.--No: one s and three p orbitals combine, and four new orbitals form. *It involves the formation of four new sp3 hybrid orbitals.--Correct; the four old orbitals are replaced by four new ones—each an sp3 hybrid orbital.*
How many POLAR COVALENT BONDS does glycerol (above) contain?
Just count the highly electronegative atoms (O,N,F) 6, This depends on the electronegativities of the atoms. O has high and C and H both have low electronegativities. So, each bond between carbon and oxygen (C‒O) and between oxygen and hydrogen (O‒H) is a PCB.
How many protons does glycerol contain?
Just take each element's atomic number, multiply by the number of atoms present of that element then add each value up. 50, Remember that each atom's identity is based on its number of protons: H has 1, C has 6, and O has 8. So 3 (6) + 3 (8) + 8 (1) = 50.
List the organisms that are classified as prokaryotes and organisms that are classified as eukaryotes, as shown on the evolutionary tree slide.
Prokaryotes: Bacteria and Archaea eukaryotes: protists, plantae (plants), fungi, animalia (animals)
In the molecule below, how many atoms could make hydrogen bonds with water? -see screenshot-
The 10 atoms that can form hydrogen bonds with water are the 4 oxygens and 2 hydrogens around the phosphorus atom, the 2 oxygens double-bonded to carbon atoms, and the oxygen and hydrogen (the hydroxyl group) bonded to carbon. Your ability to predict hydrogen bonding will be a great help in understanding the central processes of life.
In order for a hydrogen atom to be capable of hydrogen bonding, what is required?
The hydrogen must be covalently bonded to a strongly electronegative atom.--If you had difficulty with this question, please review the third subsection in section 2.3 (hydrogen bonds).
What is the basic structure of a monosaccharide? Explain the terms triose, pentose, and hexose. What type of structure do biological monosaccharides typically have? Give examples of ways in which monosaccharides differ leading to different isomers. Explain the difference between a and b glucose.
Ring and long chain Triose (3), pentose (5), and hexose (6) relate to the number of carbons. Carbon Hydrogen Oxygen Nitogen A is when OH is below the ring and B is when OH is above the ring.
How does the pH of the solution on the right compare with that of the solution on the left? right: all positive left: all negative
The solution on the right is basic relative to the solution on the left. The solution on the right has a lower concentration of hydrogen ions relative to hydroxide ions than does the solution on the left.
Which of the following DOES NOT apply to biological weak interactions?
They can be broken.-- True; for example, when the two strands of a DNA molecule come apart. They can occur between different molecules.--Examples of intermolecular weak interactions include a reactant and it's enzyme, a hormone and it's receptor, and DNA wrapped around histone proteins. They can occur within a single molecule.--An example of an intramolecular weak interaction is the weak interactions that help hold together receptor's 3-D shape. In fact, most proteins contain such interactions. *They do not have functional relevance to cells.-- Obviously they are critical to cellular function!* More than one answer listed here.-- Rather than trying to identify the answer that 'DOES NOT', simply eliminate all of the answers that 'DO APPLY'. This topic was discussed exclusively in lecture.
A covalent bond between an oxygen atom and a hydrogen atom is best described as _____.
a polar covalent bond--A hydrogen atom that is covalently bonded to oxygen COULD go on to form a hydrogen bond, but that doesn't mean it will. Read the questions carefully so that you are clear about what they are saying; then choose the most direct answer to the question.
About how much longer was life a water-based phenomenon, in comparison to the time there has been terrestrial life?
about 6 times as long 3,000,000,000 years / 500,000,000 years = a 6-fold difference
How many PROTONS do each of the following isotopes of hydrogen contain? 1^H 2^H 3^H
all contain same number of protons
Oxygen has an atomic number of 8 and, most commonly, a mass number of 16. Thus, what is the atomic mass of an oxygen atom?
approximately 16 daltons
Define the following terms, using your textbook and lecture notes: atom, element, compound, molecule, isotope, and ion.
atom: the smallest unit of an element, contains protons, neutrons, and electrons. element: cannot be broken down chemically to other substances compound:contains two or more different elements in a fixed ratio. Oxygen, carbon, hydrogen, and nitrogen make up approximately 96% of living matter. molecule: consist of two or more covalently bonded atoms. The attraction of an atom for the electrons of a covalent bond is its electronegativity isotope: of an element differ from each other in neutron number and therefore mass. Unstable isotopes give off particles and energy as radioactivity.(isotopes have diff # of neturons) ion: forms when an atom or molecule gains or loses an electron and becomes charged. (ions have diff # of electrons)
Explain the meaning of the following terms: atomic number, atomic weight, molecular weight, and mass number.
atomic number: # of protons in an atom, neutral atoms have the same number of protons and electrons atomic weight/mass: weighted avergae mass of an atom of an element based on the relative natural abundance of that elements isotopes molecular weight: the sum of all the masses of the atoms in a molecule mass number: total count of protons and neutrons in nucleus atomic mass- atomic number= neutrons
Which of the following weak interactions involves nonpolar molecules or nonpolar parts of molecules?
both van der Walls interactions and hydrophobic interactions--Two of the four weak interactions discussed involve polar/charged molecules, and two of the interactions involve nonpolar/uncharged molecules!
Classify the following substances as HYDROPHILIC, SOLUBLE, BOTH, or NEITHER: (Note that some terms may be used more than once.) · serine (Look up its structural formula in Chapter 5; then evaluate if it is hydrophilic and/or soluble based on the principles discussed in lecture!) · 100% cotton t-shirt · phosphofructokinase (Look it up! What would you expect, based on the discussion from lecture?) · corn oil
both, hydrophilic, both, neither Serine is a type of amino acid, whose structure is pictured in Fig. 5.14. It is rich in O and N which result in polar covalent bonds, making serine a polar molecule; furthermore it is CHARGED, so it will readily attract water and dissolve. (All amino acids have amino and carboxyl chemical groups which are basic and acidic respectively, and ionize at cellular pH.) PFK is a type of enzyme (for another example see Fig. 3.9). Remember that hydrophilic means attracts water; soluble means dissolves in water. For a substance to be soluble, it MUST be hydrophilic, but the opposite is not necessarily true!
Hydrogen bonds ...
can form between H and N. They can also form between H and other highly electronegative atoms, such as O, if the atoms have strong partial charges.
Define the following terms related to chemical reactions: reactant, product, reversible reaction, and chemical equilibrium. Illustrate the meaning of each of these terms using an example reaction.
chemical reactions: -always involve breaking and forming bonds -most are reversible -in isolation, will reach chemical equilibrium reactant: a substance that takes part in and undergoes change during a reaction product: the species formed from chemical reactions reversible reaction: a reaction in which the conversion of reactants to prodicts and the conversion of products to reactants occur simultaneously. chemical equilibrium: *The state of a reaction in which the RATE of the forward and reverse reactions are EQUAL* The point at which the reactions offset one another exactly. This is a dynamic equilibrium; reactions are still going on in both directions, but with no net effect on the concentrations of reactants and products. Equilibrium does not mean that the reactants and products are equal in concentration, but only that their concentrations have stabilized at a particular ratio.
How many atoms in the pictured molecule can form hydrogen bonds with water molecules?
count the H, C, O, and F bonds O and N can make hydrogen bonds, as can each H attached to O or N.
Phosphorus VIOLATES the 'octet rule' in biological molecules by _____.
having more than eight electrons in its valence shell after covalent bonding--The octet rule says that atoms react chemically in order to obtain 8 electrons in their outer shell. However, some atoms like hydrogen and phosphorus are exceptions to this rule. Since P has 5 electrons in its outer shell, we would expect it to form 3 covalent bonds to acquire 3 more electrons. Instead, it forms 5 covalent bonds.Since each covalent bond contains two electrons, P has 10 electrons in its outer shell.
Which of the following types of chemical bonds and interactions are relatively WEAK in cells? Why are 'ionic bonds' not strong within cells? This question is 'right out of the lecture'
hydogen bonds and ionic bonds
In a neutral solution the concentration of _____.
hydrogen ions is equal to the concentration of hydroxide ions definition of neutral solution
know the charges and structures of: water, methane, glucose, hydroxide ion, hydronium ion, hydrogen ion
hydronium ion: 1+, A water molecule that gains a hydrogen becomes a hydronium ion, A water molecule gained an hydrogen ion from another water molecule, This molecule was formed by the transfer of a hydrogen ion from one water molecule to another. hydroxide ion: 1-, A water molecule that loses a hydrogen ion is referred to as a hydroxide ion. hydrogen ion: The arrow is indicating a single proton, a hydrogen ion (H+)
Explain the merits of weak interactions in molecular biology. Distinguish between intermolecular interactions and intramolecular interactions.
intermolecular forces are forces that exist *between molecules* intramolecular forces are forces that *hold atoms* together within a molecule
A(n) _____ refers to two or more atoms held together by covalent bonds.
molecule A molecule is defined as two or more atoms held together by covalent bonds.
Compare and contrast the 3 main subatomic particles in terms of their location, mass, and charge.
neutrons: no charge, 1 dalton mass, in nucleus protons: positive charge, 1 dalton mass, in nucleus electrons: negative charge, less than 1,000, forms cloud around atom
Sulfur is in the same column of the periodic table as oxygen but it is less electronegative than oxygen. Compared to water molecules, how will the H2S molecules behave?
not be able to form hydrogen bonds with each other
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their
number of molecules.
What does the pH of a solution tell you about the [H+] and the [OH−]? Why must cells maintain and control their pH? What is the pH of most biological fluids? Of cells? Explain the importance of buffers in biological fluids, and how they function.
pH = -log[H+] [H^+] x [OH^-] = 10^-14M SO... if pH is 3 10^-3 M H^+ = 10^-3 protons and OH^- = 10^-11 so that it equals 10^-14 As pH goes up, [H^+] (protons) comes down If pH goes from 3 to 4, proton concentration decreases by 10^1 *If [H+] concentration is 10^-7 the ph is 7 and if [H+] concentration is 10^-3 the ph is 3. 10^-7 is less than 10^-3 making a ph of 3 have a higher proton concentration* acids GIVE protons= negative bases DONATE protons= positive the pH of most biological fluids is 6-8 with stomach acid being at 2 & cells at 7 buffers maintain pH and acid-base homeostasis by either donating or accepting protons
Which of the following organisms are classified as eukaryotes? (Please consult the evolutionary tree diagram from the slides and Chapter 1!) What characteristics do ALL of these organisms share (as they are common to all living things)? By what process did this diversity of life on earth originate? Be sure you are aware of the 'three questions' about this process that we discussed in lecture.
plants and protists
proton, electron, neutron: mass, symbol, charge
proton: mass of ~1 amu symbol p +1 charge electron: mass of ~1/2000 amu symbol e -1 charge neutron: mass of ~1 amu symbol n 0 charge The proton and neutron both have masses of about 1 amuamu, whereas the electron mass is only about 5.5×10−4amu5.5×10−4amu.
List, draw, and describe the characteristics of the chemical functional groups most important in biological organisms, as covered in lecture. Cross reference the information in Fig 4.10 with the content covered in lecture. Which functional groups can become charged, and how?
see chart
When pure water reaches a chemical equilibrium between whole water molecules and dissociated ones, which of the following applies?
the reaction continues to run in both directions the concentrations of reactants and products are no longer changing the speed of the forward reaction is equal to the speed of the reverse reaction
Which of the following factors contribute to the tetrahedral shape of the above molecule? (CH4 bond)
the shape of the sp3 hybrid orbitals of the electrons shared between the carbon and hydrogen atoms
Chemical equilibrium is the point in a chemical reaction when _____.
the speed of the forward reaction is equal to the speed of the reverse reaction--Although the concentrations of reactants and products are not equal, at equilibrium their concentrations are no longer changing.
What shapes do carbon backbones form in biological molecules? How do double bonds affect a molecule's shape and flexibility?
they form chains that are straight, branched, and look like closed rings double bonds make a molecule flat and in the same plane which make it unable to spin
How did experiments performed by Wöhler and Miller challenge 'vitalism', the initial foundation of organic chemistry?
vitalism: biomolecules are created by a 'life force', prevailing model for centuries Vitalism is the idea that living matter has something which makes it inherently different from non living matter. Wöhler discovered several elements and chemical analyses of meteorites. Miller found all biochemicals can be made synthetically in a lab by his "lightening-in-a-bottle" experiment. this demonstrated the abiotic synthesis of organic atomopshere compounds
Summarize the characteristics of the strong and weak chemical interactions or bonds that occur in the chemistry of life.
weak chemical interactions: ionic bonds hydrogen bonds van der waals interactions hydrophobic interactions weak bonds are important because they work together and collectively they have strength. weak interactions are both intermolecular and intramolecular and transient/ easily reversible. *ionic bonds are strong in dry environments and weak in wet ones* strong chemical interactions: covalent bonds strong bonds hold atoms together in molecules
Explain how water molecules dissociate.
when two H2O are H-bonded together and one H leaves and bonds with the other (the electron is left behind creating a negative charge) H2O +H2O -> OH- + H3O+ OR H2O -> OH- + H+
