Term
| Describe th structure of an atom: |
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Definition
| It has a centrally located nucleus, which contains protons (positive charge) and neutrons (no charge). Outside the positively charged nucleus are electrons (negatively charged) which orbit the nucleus in shells. Since the number of electrons and protons are equal, the net charge is 0. |
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Term
| How many electrons can occupy the shells? |
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Definition
| The first shell can contain a maximum of 2, the second, 8. The third and up can contain even more, and they posess more energy the farther they are from the nucleus. If the shells are incomplete, or not filled, they are attracted to other electrons to fill the shell to its maximum. |
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Term
| What are valence electrons? |
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Definition
| The electrons in the outermost shell, if complete, that participate in chemical reactions. |
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Term
| Describe the structure of an ion: |
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Definition
| It is an atom or molecule that loses or gains one or more valence electrons and becomes positively or negatively charged. If it loses electrons, there are more protons than electrons and it becomes positively charged (cation) If it gains electrons, there are more electrons than protons, and it becomes negatively charged (anion). |
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Term
| Describe the nature of ionic bonds: |
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Definition
| It is when one or more valence electrons of one atom are completely transferred to a second atom. This is a weak bond, but not the weakest. |
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Term
| Describe the nature of covalent bonds: |
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Definition
| It is when atoms share valence electrons. It is the strongest bond. |
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Term
| What is a nonpolar covalent bond? |
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Definition
| When electrons in identical atoms are shared equally, such as H2 or O2. The electrons are shared equally, so there is no charge given off, making it nonpolar. |
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Term
| What is a polar covalent bond? |
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Definition
| In covalent bonds between two different atoms, the electrons may be pulled more toward one atom than the other, giving it a positive and negative "pole". |
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Term
| What are 3 atoms with a strong pull and tend to form polar covalent bonds? |
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Definition
| Oxygen, nitrogen and phosphorous |
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Term
| Describe the nature of a hydrogen bond: |
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Definition
| When hydrogen forms a polar covalent bond with oxygen or nitrogen it gain a slight positive charge at one "pole". It then gains a slight attraction to the electronegative oxygen or nitrogen nearby. This is the weakest bond out of the 3 bonds (covalent, ionic and hydrogen). |
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Term
| Describe the characteristics of organic molecules: |
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Definition
| Molecules that contain carbon and hydrogen. Since carbon has 4 electrons in its outer shell, it must covalently bond with 4 more electrons to fill its outer shell with 8 electrons. This allows carbon to form chains and rings while allowing it to bond with hydrogen and other atoms. |
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Term
| What are some important functional groups of organic molecules, and what do they form? |
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Definition
Carbonyl group- forms ketones and aldehyde Hydroxyl group- forms alcohols Carboxyl group- forms organic acids (lactic and acetic) |
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Term
| Why are ions and polar molecules soluble in water? |
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Definition
| They are hydrophilic ("loves water") Hydrophilic molecules are water soluble because polar water molecules build up and surround certain ions and polar molecules because they give off a charge. This forms hydration spheres around the ion or polar molecule. These dissociate in water. |
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Term
| What is the meaning of hydrophobic? |
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Definition
| Hydrophobic ("fears water") molecules are not water soluble because they are primarily formed by nonpolar covalent bonds, which give off few charges and can't form hydration spheres. These are repelled by water. |
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Term
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Definition
| A molecule that can release H+ (protons) into a solution. A proton "donor". |
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Term
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Definition
| A molecule that can combine with H+ (protons) in a solution. A "proton acceptor". |
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Term
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Definition
| It is a scale that runs from 0-14, which indicates the H+ concentration of a solution. A solution with a higher H+ concentration than 7 (neutral) is acidic and a lower H+ concentration than 7 is basic. However- the higher the H+ concentration, the lower the pH. The lower the H+ concentration, the higher the pH. (pH 2=acid, pH12=basic). |
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Term
| Identify the different types of carbohydrates, and give an example of each: |
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Definition
Monosaccharide- glucose (simple sugar) Disaccharide- sucrose (double sugar) Polysaccharide- starch (many monosaccharides linked together) |
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Term
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Definition
| Organic molecules that contain carbon, hydrogen and oxygen in the ratio described by its name: carbo (carbon) and hydrate (water, H2O) Its general formula is: CnH2nOn |
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Term
| Identify the different types of lipids, and give an example of each: |
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Definition
Trigyceride- saturated fat Ketone bodies- acetoacetic acid Phospholipid- lecithin Steroid- progesterone Prostaglandin- prostaglandin E1 |
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Term
| How does a dehydration synthesis reaction occur in a carbohydrate? |
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Definition
| A hydrogen atom (H) is removed from one monosaccharide and a hydroxyl group (OH) is removed from another. As a covalent bond is formed between the two monosaccharaides, a water (H2O) molecule is produced. |
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Term
| How does a dehydration synthesis reaction occur in a triglyceride? |
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Definition
| 3 hydroxyl groups (OH) are removed from the glycerol molecule and 3 hydrogen groups are removed from three fatty acids. As a covalent bond forms between the glycerol and 3 fatty acids, a trigyceride is formed and 3 water (H2O) molecules are produced. |
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Term
| How does a hydrolysis reaction occur in a carbohydrate? |
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Definition
| It is the reverse of dehydration synthesis- when the covalent bond between two monosaccharides is broken (due to an enzyme) a water molecule provides the atoms required to complete its structure. |
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Term
| How does a hydrolysis reaction occur in a triglyceride? |
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Definition
| It is the reverse of dehydration synthesis- when the covalent bonds between a gycerol and three fatty acids are broken (due to an enzyme) 3 water molecules provide the atoms needed to compete its structure. |
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Term
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Definition
| After dehydration synthesis, covalent bonds between the hydrogen from the amino end of one amino acid combines with the hydroxyl group of the carboxyl end of another amino acid. |
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Term
| How are peptide bonds formed and broken? |
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Definition
| Peptide bonds are formed by dehydration synthesis and broken by hydrolysis. |
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Term
| Describe the first 2 different orders of protein structure (in order): |
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Definition
1) primary structure- sequence of amini acids in polypeptide chain 2) secondary structure- conformation of the chain created by hydrogen bonding between amino acids (alpha helix or beta plaeted sheet) |
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Term
| Describe the second 2 orders of protein structure (in order): |
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Definition
3) Tertiary structure- 3-dimensional structure of a protein; each protein has its own unique tertiary structure 4) Quaternary structure- formation of a protein by the bonding of 2 or more polypeptide chains |
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Term
| What are some different functions of proteins? |
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Definition
| They contribute to structure of different tissues (collagen, keratin), enzymes, antibodies, receptors in cell membranes, carriers for transport of specific molecules across the cell membrane |
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Term
| How does protein structure grant specificity of function? |
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Definition
| Because there are about 20 different kinds of amino acids that can be used to construct a protein, and each amino acid has a different functional group. This allows for an immense variety of specific functions. |
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Term
| Describe the structure of nucleotides: |
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Definition
| It is composed of a 5-carbon sugar, a phosphate group attached to one end of the sugar, and a nitrogenous base attached to the other end of the sugar |
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Term
| Distinguish between the structure of DNA and RNA: |
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Definition
The same, except- 1) RNA contains ribose insterad of deoxyribose 2) RNA contains the base uracil instead of thymine 3) RNA is composed of a single polynucleotide strand instead of a double strand (in DNA) |
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Term
| Explain the law of complimentary base pairing: |
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Definition
| Adenine can only pair with thymine (through two hydrogen bonds) whereas guanine can only pair with cytosine (through three hydrogen bonds) |
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Term
Describe the structure between the two strands of DNA |
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Definition
| C & G and A & T form hydrogen bonds together, and each complimentary base is covalently bonded to a sugar-phosphate "backbone" which causes it to form a double-stranded DNA molecule. The two strands are like a staircase and the bonded base pairs are like steps. |
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Term
| How does the law of complimentary base pairing occur between the two strands of DNA? |
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Definition
| Even though there are only four bases, of which two can only pair up with two complimentary bases, there are several thousand nucleotides in a gene, leaving an almost infinite number of possible base sequences. |
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Term
| List the components of an atom: |
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Definition
| nucleus, protons, neutrons, electrons |
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Term
| How are the components of an atom organized? |
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Definition
| Centrally located nucleus containing protons and neutrons. Electrons orbit the nucleus in shells (AKA orbitals). |
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Term
| Why are different atoms able to form characteristic numbers of chemical bonds? |
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Definition
| It is determined by the number of electrons needed to fill the outermost shell. ex. hydrogen only needs 1 electron to fill its shell completing it with 2 (the max.) Oxygen needs 4 electrons to fill its second shell with 4, equalling 8 (the max.) |
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Term
Using chemical equations, explain how bicarbonate ion and carbonic acid function as a buffer pair: |
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Definition
It is a reversible reaction:HCO3- + H+ <=> H2CO3. The direction depends on the concentration of molecules on each side. If H+ rises (more acidity), pH goes down and this would be the reaction: HCO3- + H+ -> H2CO3 (carbonic acid). If H+ falls (more alkaline), pH goes up and this would be the reaction: H2CO3 -> H+ + HCO3- (bicarbonate ion). |
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Term
| How can carbon atoms bond with each other, and with the atoms of hydrogen, oxygen and nitrogen? |
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Definition
| They form single or double covalent bonds forming a "backbone" which allows them to bond with other atoms to form organinc molecules. They usually form hyrocarbon chains or rings which attach more reactive functional groups, usually containing oxygen, nitrogen or phosphorous. |
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Term
| Describe the characteristics of a lipid: |
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Definition
| They are all insoluble in polar solvents (such as water). They consist of hydrocarbon chains and rings, which are nonpolar, and therefore hydrophobic. |
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Term
| Relate the functions of phospholipids to their structure: |
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Definition
| They have hydrophilic heads and hydrophobic tails, which causes them the nonpolar tails to group together and the polar head to face water. This alters the interaction of water molecules, decreasing the surface tension of water. This function makes them surfactants. |
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Term
| Explain the significance of the prostaglandins: |
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Definition
| They are produced by and are active in almost all organs, where they serve a variety of regulatory functions. |
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Term
| Write the general formula for an amino acid: |
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Definition
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Term
| How do amino acids differ from one aother? |
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Definition
| They differ by by functional differences in functional groups, indicated in the general formula as "R" meaning "rest of the molecule" or "residue". |
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Term
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Definition
| Subunits of nucleic acids. |
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Term
| What are the 3 types of RNA? |
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Definition
1) rRna- ribosomal RNA (workbench; makes ribosomes) 2) mRNA- messenger RNA- tells how to make a protein 3) tRNA- transfer RNA -taxi |
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