Biotechnology
2011-2012
Study Guide Exam #1
Mr. Heward
1. List the properties of the following subatomic particles: protons, neutrons, and electrons.
Subatomic Particle Location in Atom Charge Mass
Proton
Neutron
Electron
Nucleus
Nucleus
Orbiting the
Nucleus
Positive
Neutral
Negative
2. Label the parts of the following entry from the periodic table.
Atomic number = # of protons
6
C
12.011
Element Symbol
Atomic Mass = # of protons + # of neutrons
1 amu
1 amu
Negligable
3. Compare and contrast covelent, ionic and hydrogen bonds.
A covalent bond is a bond between two atoms that share a pair of electrons. These bonds can be polar if the electrons are not shared equally as when oxygen or nitrogen bond with hydrogen.
An ionic bond is a bond between oppositely charged ions. The cation has a positive charge because it lost an electron to the atom that became the negatively charged anion.
A hydrogen bond is a weak bond that forms between two polar covalent molecules.
Hydrogen bonds are important in establishing the secondary and tertiary structure of proteins and holding the two strands of a DNA double helix together.
4. Complete the following table
Element
Element
Symbol
H
C
N
Atomic #
1
6
7
# of electrons in the valence shell
1
4
5
Valence (the # of unpaired electrons in the valence shell)
1 Hydrogen
Carbon
Nitrogen
4
3
Oxygen O 8 6 2
5. What is a mole and how do you calculate the molecular weight of a substance?

A mole is 6.02 x 10 23 units of a substance. This allows you to convert from atomic mass or molecular weight to grams. Carbon 12 has an atomic mass of 12. One mole of carbon
12 would have a mass of 12 grams.
6. What is the mass of one mole of NaCl?
58.443
7. Describe the pH scale and explain how to calculate it.
The pH scale is used to measure the acidity or alkalinity of the substance. The pH scale ranges from 0 - 14. Values below 7 are considered acidic and values above 7 are considered basic. pH = -log[H + ]
[H + ][OH ] = 10 -14
8. What is the pH of a solution with an [OH-] of 10 -3 ?
[H + ] = 10 -11 pH = 11
9. Explain hydrolysis and dehydration synthesis and their relationship to monomers and polymers.
Polymers are made from repeated units called monomers. Monomer are joined together by dehydration synthesis. Removing a hydroxyl group (-OH) from one monomer and a hydrogen (-H) from the other allows the two monomers to form a new covalent bond that joins them together. Hydrolysis is the reverse process.
10. What is the monomer of a carbohydrate? What are the functions of carbohydrates?
List examples of carbohydrates.
Monosaccharides are the monomers of carbohydrates. Monosaccharides are composed of
Carbon Hydrogen and Oxygen in a 1:2:1 ratio.
Carbohydrates are primarily used as an energy source and for short term energy storage.
Some carbohydrates are used as structural components.
Monosaccharides
Glucose
Polysaccharides
Starch - sugar storage in plants
Ribose
Deoxyribose
Glycogen - sugar storage in animals
Cellulose - structural molecule in plants

11. What are lipids and what are their functions?
Lipids are hydrophobic molecules. They function as energy storage molecules, chemical signals, and cell membrane components. Lipids include fats, oils, waxes, steroids and phospholipids.
12. What is the monomer of a protein? Describe the 4 levels of organization in proteins.
What are the functions of proteins?
The monomer of a protein is an amino acid. There are 20 amino acids. Proteins have four levels of structure. The primary level is the sequence of amino acids in the polypeptide chain.
The secondary structure of the protein is maintained by hydrogen bonds between the backbone of the polypeptide. Secondary structures include alpha helices and beta pleated sheets.
The tertiary structure of the protein is the overall shape of the folded polypeptide. The tertiary structure is maintained by interactions (hydrogen bonds, covalent bonds, hydrophobic interactions, and van der Waals forces) between the side chains.
The quarternary structure of a protein is formed when two or more polypeptides combine to form the final functional protein.
13. Know how to calculate the protein concentration in a sample using a standard curve from known concentration samples.
14. How would you make a 400 uL of 300 ug/mL BSA using a 10 mg/mL stock solution of BSA?
12uL of BSA stock solution and 288 uL of H
2
O
15. What is the monomer of a nucleic acid? Describe the structure of a DNA molecule.
The monomer of nucleic acids is the nucleotide which has three parts: sugar, phosphate and a nitrogenous base. There are 5 nitrogenous bases: adenine, thymine, cytosine, guanine, and uracil.
The DNA double helix is composed of two anti-parallel strands twisted together like a spiral staircase. The sugars and phosphates form the backbone of the molecule and the nitrogenous bases form the steps on the staircase. The bases always pair in the same

fashion: guanine with cytosine and adenine with thymine and the two strands are held together by hydrogen bonds between the bases.
16. Describe DNA replication.
DNA replication is a process that involves separating the two strands and then using each strand as a template to build a complementary strand.
17. What is the role of each of the following proteins in replication? o Helicase - the enzyme that breaks the hydrogen bonds and separates the two strands. o Topoisomerase - an enzyme that relieves the coiling tension that forms in the double helix as helicase separates the two strands. o Single-stranded Binding Protein - proteins that bond to the single-stranded pieces of DNA to keep them from reattaching before the complimentary strands can be built. o Primase - an enzyme that attaches an RNA primer to the DNA o DNA Polymerase - an enzyme that builds a new strand of DNA by adding in the complimentary bases. o Ligase - the enzyme that seals the gaps in the sugar-phosphate backbone of a newly synthesized DNA strand.
18. Describe the Polymerase Chain Reaction (PCR). Include in your description the three main steps: denaturing, annealing, extending.
PCR is artificial DNA replication. It occurs in three steps: Denaturing, Annealing, and
Extending.

Denaturing - High temperatures are used to melt the DNA (break the hydrogen bonds that hold the two strands together)
Annealing - The solution is cooled off so that the primer will bind to the complimentary sequence on the DNA strand
Extending - The solution is heated up to an intermediate temperature to allow the heat tolerant DNA polymerase to build the complimentary strand.
19. Describe the Central Dogma of molecular biology.
DNA
→
RNA
→
Protein
A gene is transcribed from a DNA molecule to an mRNA molecule. The mRNA molecule is then translated into a protein by a ribosome.
20. Explain the process of transcription. What is the primary enzyme involved?
Transcription is the process of copying a DNA message to an mRNA molecule.
Transcription is accomplished by RNA polymerase.
21. How is mRNA processed in Eukaryotes before it leaves the nucleus?
In Eukaryotes RNA is processed before it leaves the nucleus. A cap is added to the 5’ end and a poly-A tail is added to the 3’ end. Eukaryotic genes usually have introns that are cut out and the exons are spliced together.
22. Explain the process of translation. Identify the roles of mRNA, tRNA and the ribosome.
Translation is the process by which an mRNA message is used to make a protein. The ribosome is responsible for translation. The ribosome has three active sites the E site, P site, and A site. The mRNA message is read beginning with the start codon in the P site and a tRNA molecule carrying methionine pairs up with the start codon (complimentary base pairing). The next codon in the message is located in the A site and a tRNA molecule will bring in the next amino acid. A new peptide bond forms between the amino acids and the ribosome shifts one codon downstream on the mRNA molecule. The first tRNA molecule enters the E site and then leaves the ribosome. The second tRNA molecule enters the P site and a vacancy opens up in the A site. The process repeats until a stop codon is encountered.
23. What is a codon? What is an anticodon?
A codon is a group of three adjacent bases on an mRNA molecule. The start codon in a gene sets the reading frame for translation and every three bases after the start codon are read as codons.
An anticodon is a group of three bases on a tRNA molecule that are used for complimentary base pairing with the codon. This complimentary pairing is the key to translation.
24. Be able to transcribe and translate a gene using a codon table.