biomolecules & biochem

BIOMOLECULES & BIOCHEMISTRY

In recent years, it has become increasingly evident that an understanding ofbiology requires a thorough understanding of chemistry. More and more biologicalresearch is devoted to understanding the chemistry of biomolecules. Biomoleculesinclude the proteins, carbohydrates, lipids, nucleic acids, and the building blocks ofwhich they are made. Understanding the relationship between structure and function iscritical to understanding biology at the organismal level. Similarly, understanding thestructure of biomolecules and how that structure relates to their function is critical tounderstanding biology at the molecular level.

OBJECTIVES

L Learn the structure and chemical characteristics of the most common functional groups foundin biomolecules

L Understand the relationship between the redox state, the chemical structure and energycontent.

L Learn the chemistry and recognize the structures of the building blocks of proteins,carbohydrates, lipids, and nucleic acids.

L Perform and Understand condensation and hydrolysis reactions using models of monomersfound in protein, carbohydrates, and lipids.

L Perform and Interpret biochemical assays for proteins and carbohydrates.

PART 1: COMMON FUNCTIONAL GROUPS FOUND IN BIOMOLECULES

There are eight common functional groups found in biomolecules. In today’s lab wewill explore six of them. Use the molecular model kits provided to build the moleculeson page 2. These molecules contain 5 of the 6 functional groups that will be disucssedin lab. Count how many of each atom and each bond you will need. Collect thesepieces on a tray. PLEASE, TAKE ONLY THE AMOUNT OF MATERIALS YOU NEED.

Key to pieces:Carbon - BlackHydrogen - WhiteOxygen - RedNitrogen - BluePhosphorus - Brown

Single bonds - short gray rodsDouble bond - long flexible rods (use 2)

06Feb17 12:18 pm Biomolecules & Biochemistry - 1

NOTE: Sections 1a - 1d (pg 2-3) apply to the molecules enclosed by the box only. The Aminogroup will be covered in Section 3

1a. The C!H Functional Group

This functional group, commonly called a hydrocarbon, is made of a singlecarbon atom covalently bonded to a single hydrogen atom. A single pair of electrons isshared between the carbon and the hydrogen. Chemical bonds represent storedenergy. When a bond is broken, the stored energy is released. In order to make thebond, energy must be provided. Count the number of C!H groups in each molecule.

Which molecule has the most C!H groups? _________

Which has the least? ___________.

Arrange the molecules in order of decreasing number of C!H groups.


1b. The -OH Functional Group

This functional group, commonly called a hydroxyl or alcohol, is made of a singleoxygen atom covalently bonded to a hydrogen atom. A single pair of electrons isshared between the oxygen and the hydrogen. Due to the high electron affinity of theoxygen atom, this functional group has polar characteristics. The oxygen has a partialnegative charge while the hydrogen has a partial positive charge. As a result of thecharge separation, this group tends to form hydrogen bonds. When the group isbonded to a carbon atom (the bond is between the carbon and the oxygen), thehydrogen retains its partial positive charge while the partial charge on the oxygenbecomes less localized. The hydrogen atom is acidic in nature and will be releasedinto solution as a proton under the proper conditions. W hen the group is ionized in thisway, the oxygen is left with a full negative charge.

Which molecules have -OH groups?__________________________________

1c. The -C=O Functional Group

This functional group, commonly called a carbonyl, is made of a single carbonatom covalently bonded to a single oxygen atom. The bond is a double covalent bond. The two atoms share two pairs of electrons, hence the name double bond. Todifferentiate the atoms in this group from others in the molecule to which it is attached,the oxygen is referred to as the carbonyl oxygen and the carbon as the carbonylcarbon. The carbonyl group can have polar characteristics. The oxygen can have apartial negative charge again due to its high electron affinity. The partial positivecharge is not localized on any single atom. As a result of this characteristic, thecarbonyl oxygen can form hydrogen bonds. This is especially important in forming thesecondary structures of proteins, a topic to be covered at a later date.

Which molecules have -C=O groups? _________________________________

1d. The -C=O Functional GroupW

OH

This functional group, commonly called a carboxyl or carboxylic acid, is made of acarbonyl group with a hydroxyl group bonded to the carbonyl carbon. This grouppossesses the characteristics of the two groups of which it is made. It can form H-bonds with other molecules through the hydroxyl and carbonyl oxygen. The hydroxylgroup is acidic.

Which molecules have carboxyl groups?____________________________


Methane Methanol Methyl Aldehyde Methanoic Acid Carbon Dioxide

PART 2: OXIDATION, REDUCTION, AND THE ENERGY CONTAINED INMOLECULES

You should still have the molecules arranged in the order specified in Part 1a. If not, rearrange the molecules from most to least number of C!H functional groups.

We will begin by reviewing the definitions of OXIDATION and REDUCTIONand their relationship to energy. Oxidation is defined as the loss of electrons. Reduction is defined as the gain of electrons. The process of oxidation results in anoverall loss of energy while reduction results in a gain of energy. In other words, amolecule that has undergone oxidation contains less energy than it did prior to theoxidizing event. Similarly, a molecule that has undergone reduction contains moreenergy than it did prior to the reducing event.

In biomolecules, oxidation is most often accomplished by replacing thehydrogen in C!H groups with a hydroxyl group (!OH). The C!OH can be furtheroxidized by removing the hydrogen attached to the oxygen and a hydrogen attached tothe carbon. These two single bonds are replaced with a double bond between thecarbon and the oxygen.

In general, the degree of oxidation (or reduction) of an atom can be determined bycounting the number of hydrogens directly bonded to an atom (in this example, theatom is a carbon atom). In the reaction example above, the carbon contained in themolecule on the left (reactant) is more reduced than the carbon in the molecule on theright (the product)(1 hydrogen bonded to the carbon vs. none). So the diagramedreaction is described as an oxidation. The reverse reaction would be described as areduction. Returning to the molecules you have made, they are in descendingorder based on the number of C--H groups. Based on the discussion above, you cannow see that they are also in descending order based on energy and degree ofreduction. Draw in the structure of each molecule under its name. (see pg. 2)

Highest Energy Lowest EnergyMost Reduced Least ReducedLeast Oxidized Most Oxidized

You are responsible for the names of all the molecules and identifying their relativelevel of oxidation, reduction, and/or energy


PART 3 - PROTEINS

Proteins are strings of covalently bonded amino acids. They primarily serve asstructural components and enzymes. The functional structure of proteins is dependenton their amino acid sequence. Interactions between amino acids produce complexthree-dimensional molecules. In this exercise you will examine the structure of aminoacids and the covalent bond that links them together. You will also examine a commonbiochemical assay for proteins.

3a. Amino Acid Structure

There are twenty essential amino acids. Each amino acid has the same chemicalbackbone. Amino acids differ chemically due to their side chains (referred to asfunctional or "R" groups). These functional groups can be polar (hydrophilic), non-polar(hydrophobic), acidic, or basic.

Examine the structures of the amino acids on the next page. Get enough molecularmodel pieces to construct both amino acids.

Referring to the diagrams:

Part a - Amino GroupPart b - Carboxylic Acid GroupPart c - Functional or "R" Group

Examine the models by taking note of the following points and answering somequestions.

1. Note that the name "amino acid" comes from the amino group and the [carboxylic]acid group.


2. Note that all amino acids have the same "amino - carbon - acid" backbone. As aresult, all amino acids have both basic (due to the amino group) and acidiccharacteristics.

• The amino group is basic since it can accept a proton (becoming NH3 + ) under

the proper conditions. • The acid group can donate a proton (becoming COO- ) under the proper

conditions. • Molecules with regions that are acidic and other regions that are basic are

termed: AMPHOTERIC• In addition, amphoteric molecules like amino acids will carry a double charge

at certain pH’s. • For example, at physiological pH’s

• The amino group of amino acids will be positively (+) charged • The acid group of amino acids will be negatively (-) charged.

3. In addition to the acidic/basic qualities of the backbone, many amino acids haveacidic or basic R-groups. These can also be charged at certain pH’s.

4. Note the differences in the functional or R-groups. Of the molecules youconstructed, which R-groups would have polar characteristics? Non-polarcharacteristics?

__________________________________________________________________

__________________________________________________________________


3b. Linking Amino Acids Together to Make Peptides and Proteins - The Peptide BondAmino acids are joined together to form peptides (longer chains are referred to

as proteins). This is accomplished through a general reaction called DEHYDRATIONor CONDENSATION. The reaction involves the removal of water, hence the name. When joining amino acids, the amino group contributes a hydrogen while the acid groupcontributes an alcohol group (-OH).

The reaction is mediated by a specific enzyme. The reaction is diagramed below. Perform a dehydration reaction on your two amino acid models.

The bond that forms between the amino nitrogen and the carbonyl carbon is called aPEPTIDE BOND. The reaction can be reversed by adding water to the peptide bond. This reaction is called HYDROLYSIS. It is also enzyme-mediated. Use your model toreverse the reaction.


3c. The Biuret Test - An Assay for Protein

Biochemical assays test for the presence of certain types of molecules. Theassay usually tests for a specific functional group known to be part of the molecule. Assays can be qualitative, testing for presence or absence, or quantitative, providing anumerical value to the amount of material present. Qualitative tests can be sensitiveenough to give some indication as to the amount of the material present (e.g., none vs.a small, medium, or large amount). Such distinctions are subjective. They may dependon how long the assay was allowed to proceed or the conditions under which the assaywas conducted.

The Biuret Test is a qualitative test for proteins. It specifically tests for thepresence of two CONH groups joined together by a carbon atom. This is the peptidelinkage.

Biuret's reagent is blue in color. It turns pink to purple in the presence of peptidelinkages. A pink color indicates less protein than a purple color.

Procedure for Performing Biuret TestYou will test five unknown materials marked A through E for the presence of protein.

1. Secure 5 test tubes and a test tube rack. Mark each tube with two lines, one 3 cmfrom the bottom of the tube and one 4cm from the bottom. Mark each tube with oneletter, A - E.

2. Add unknown material (A-E) to the corresponding tube up to the 3cm line.


3. Add CuSO4 (Biuret's Reagent) up to the 4cm line.

4. Observe the color change. Record the results below.

Unknown Color

A

B

C

D

E

QUESTIONS:

1. The unknown materials are Water, Starch, Glucose, Egg Albumin (a source of pureprotein), and a Nutrient Supplement (containing carbohydrate and protein). Basedon your test results try to identify the unknowns. If you aren't sure, list all thepossibilities for each unknown.

Unknown A:_________________________________________________________

Unknown B:_________________________________________________________

Unknown C:_________________________________________________________

Unknown D:_________________________________________________________

Unknown E:_________________________________________________________

2. Which unknowns did not contain any protein? How do you know this?

________________________________________________________ ___________

________________________________________________________ ___________


PART 4 - CARBOHYDRATES

Carbohydrates are large macromolecules made by linking simple sugars(MONOSACCHARIDES). Carbohydrates are often referred to asPOLYSACCHARIDES since they are made of strings of monosaccharides. Monosaccharides can also be joined in pairs to form disaccharides. Commondisaccharides are: Sucrose (table sugar) and Lactose (milk sugar). Carbohydrates havea variety of uses. Their primary function is energy storage. Examples of carbohydratesused as energy sources are glycogen and starch. Both of these molecules arepolymers of glucose. Carbohydrates serve structural role in plants. Cellulose, theprimary constituent of plant cell walls, is also a polymer of glucose. Certainmonosaccharides (ribose and deoxyribose) are structural components of the nucleicacids, DNA and RNA, and the energy transfer molecule, ATP.

4a. The Structure of Monosaccharides

Monosaccharides are usually represented as rings containing 5 or 6 carbonmolecules. The ring structures are highly variable. You will examine two commonmonosaccharides, glucose and fructose. Both are six carbon sugars. Glucose has 5carbons in its ring and 1 outside the ring. Fructose has 4 carbons in its ring and 2outside.

NOTE: In the above diagrams the vertex of anylines represents a carbon atom. Glucose withcarbon atoms shown is diagramed here.


Retrieve the ready-made glucose and fructose models from the table at the frontof the lab. DO NOT DISASSEMBLE THESE MOLECULES. YOU MAY ONLY MAKETHOSE CHANGES SPECIFIED IN THE LAB INSTRUCTIONS. ALWAYS RETURN THEMOLECULES THE WAY YOU FOUND THEM.

Now examine the molecules using the instructions that follow.

1. Orient the molecular model of each sugar with the flat drawing on the preceedingpage. Notice that the hydrogen and hydroxyl groups are not in the same plane asthe ring of carbon molecules. The 3-Dimensional orientations of these groups areimportant to the function of the sugar. Changing the orientation of any groupchanges the chemical nature of the molecule.

2. Count the number of carbons, hydrogens, and oxygens in each molecule. Recordthe information in the table below.

Atom GLUCOSE FRUCTOSE

Carbon

Hydrogen

Oxygen

What is the ratio of Carbon to Hydrogen to Oxygen in both molecules ?_______

All Carbohydrates have this same ratio of one carbon molecule to one watermolecule - Cn (H2 O)n . The name "Carbohydrate" literally means hydrated(water-soaked ) carbon. For each atom of carbon in a carbohydrate there is onemolecule of water.

4b. Linking Monosaccharides to Make Disaccharides and Polysaccharides

As with amino acids, monosaccharides are joined together by a DEHYDRATIONREACTION. The resulting bond is called a GLYCOSIDIC BOND. It is sometimesreferred to as an OXYGEN BRIDGE. The position of the hydrogen and hydroxyl groupsinvolved in the bond vary with the types of sugars being joined and the orientation of thesugars. For example, glycogen, starch, and cellulose are all made of polymers ofglucose. Glycogen and starch are both storage forms of glucose, the latter found onlyin plants while the former is found only in animals. Cellulose is the main structuralcomponent of plant cell walls. The only structural difference between these functionallydifferent molecules is the orientation bonds between the glucose molecules. Again aswith amino acids, the separation of joined monosaccharides is achieved using aHYDROLYSIS REACTION.

Using the models, perform a DEHYDRATION reaction as diagrammed below. Then reverse the process by performing a HYDROLYSIS reaction.


Glucose and Fructose aligned for Dehydration Reaction

+ H2O

Glucose and Fructose joined by Glycosidic bond (Oxygen bridge) to form Sucrose


4c. Biochemical Assays for Monosaccharides and Polysaccharides

The Benedict's test is a qualitative assay for certain monosaccharides. TheBenedict's test will show a positive result in the presence of any monosaccharide that isalso a reducing sugar. Reducing sugars readily contribute electrons causing reduction. Reducing sugars become oxidized in the process. In the Benedict's test, copper (II),Cu2+ ,is used as an electron acceptor. It is reduced to copper (I), Cu 1+, in the presenceof a reducing agent. The reduction of copper (II) to copper (I) is monitored by a colorchange. Copper (II) is blue. The solution will change from blue to green to yellow-green to orange to reddish-orange (rust) as the copper (II) is converted to copper (I). The amount of color change is dependent on both the amount of reducing sugarpresent and the amount of time the assay is allowed to proceed.

The Iodine test is a qualitative assay for the presence of the polysaccharidestarch. Iodine, in the presence of starch, will turn a solution bluish-black. The morestarch, the darker the color.

Procedures for Performing the Benedict's TestYou will test five unknowns for the presence of reducing sugars.

1. Secure 5 test tubes and a test tube rack. Mark each tube with one of the unknownletters (A,B,C,D,E).

2. Add 2ml of Benedict's solution to each tube..

3. Add 1ml of unknown material to the corresponding tube. MIX THOROUGHLY

4. Place the tubes in one of the boiling water baths provided. THE TUBES ARE TO BELEFT IN THE WATER BATH FOR EXACTLY 3 MINUTES.

5. Record the color of each tube in the table below. Use the following key to assign aqualitative value to each result.

Blue: !Brownish/Green: +Brownish/Orange: ++Red/Orange: +++

Unknown Color Value

A

B

C

D

E

6. Which unknown is a reducing sugar ? _____________________________________


Procedures for Performing the Iodine TestYou will test five unknowns for the presence of starch.

1. Secure 1 ceramic spot plate.

2. Add 1 drop of each unknown to a separate depression in the spot plate.

3. Add 1 drop of iodine (in the dropper bottle labeled “Lugol’s) to each unknown sampleand record the results below

Unknown Color

A

B

C

D

E

3. Which unknown(s) gave a positive Iodine Test result ?______________________

4. Based on your results from the 3 assays (Biuret, Benedict's and Iodine) identify eachunknown.

Unknowns: Water, Starch, Egg Albumin, Glucose, Nutrient Supplement

Unknown

A

B

C

D

E


PART 5 - LIPIDS

Lipids, or fats, are hydrophobic molecules with a variety of structures andfunctions. Triglycerides, waxes, and steroids are all examples of lipids. We will look attriglycerides and their relatives in this portion of the lab exercise.

5a. The Structure of Triglycerides and their Relatives

Triglycerides are composed of a GLYCEROL backbone with three FATTYACIDS attached through an ester linkage. An ester linkage is diagrammed below.

Retrieve the 3 FATTY ACIDS that were assembled in last week’s lab. AS WITH THEOTHER PRE-ASSEMBLED MOLECULES, MAKE ONLY THOSE CHANGESSPECIFIED IN THE LAB INSTRUCTIONS. ALWAYS RETURN THE MOLECULESTHE WAY YOU FOUND THEM.

1. Use the diagram on the next page to construct a GLYCEROL molecule.

2. Fatty acids can be attached to glycerol via dehydration reactions. Glycerol with 1fatty acid attached is called a MONOGLYCERIDE, with 2 fatty acids, aDIGLYCERIDE, and with 3 fatty acids, a TRIGLYCERIDE. Fatty acids can beSATURATED or UNSATURATED. In saturated fatty acids each carbon is bound to4 other elements via single bonds. In unsaturated fatty acids, some carbons arebound to adjacent carbons by double bonds. Fatty acids with one double bond arecalled MONOUNSATURATED. If two or more double bonds are present, the fattyacid is called POLYUNSATURATED. Examine a saturated and unsaturated fattyacid chain. Other than presence of a double bonded carbon, what is different aboutthem?


3. Orient the glycerol (molecule on the left) and 3 fatty acids (molecules on the right) asdiagramed below.

4. Perform 3 dehydration reactions, as diagramed below, to make a triglyceride. Notethat each dehydration reaction forms an ester linkage between the glycerol and thefatty acid.

5. Would you characterize this molecule as hydrophobic or hydrophilic? Why? (Hint: the carbonyl oxygen is not partially charged in this bonding pattern)

________________________________________________________ ___________

________________________________________________________ ___________

6. Perform a hydrolysis reaction toremove the first fatty acid. Youshould now have the moleculediagrammed to the right. This is adiglyceride.


7. Perform a dehydration reaction to attach the phosphocholine molecule where fattyacid #1 was attached to the glycerol. (see diagram below)

8. The molecule you have just created is called a PHOSPHOLIPID. Its technical nameis PHOSPHOTIDYLCHOLINE. Note that the phosphate group and the choline groupare charged. The phosphate has a negative charge while the choline has a positivecharge.

9. Can you characterize this molecule as exclusively hydrophobic or hydrophilic? Why?______________________________________________________________

_______________________________________________________ ___________

10. Which portions of the molecule are hydrophobic? hydrophilic? _______________

__________________________________________________________________

11. Which portions of the molecule will combine with water? Which parts will not?

__________________________________________________________________

__________________________________________________________________

12. Molecules with hydrophobic and hydrophilic regions are called AMPHIPATHIC. Phospholipids will spontaneously form bilayers when placed in a water. They formthe matrix of cell membranes a topic to be discussed later.


PART 6 - NUCLEIC ACIDS

Nucleic acids serve numerous functions within the living cell. In addition to theirfamiliar roll as information-carrying molecules, nucleic acids also serve as energycarriers, phosphate-group donors and modifiers of protein structure and function.

The nucleic acid building block is the nucleotide. Nucleotides are composed of aphosphate, a five-carbon sugar (ribose or deoxyribose), and one of 5 nitrogen bases. The general structure is diagramed below.

In the above molecule the sugar is deoxyribose. This is a variation of the 5-carbon sugar ribose. The difference is the replacement of an alcohol group on the 2'carbon with a hydrogen. The phosphate group is attached to the 5' carbon which isoutside the ring structure. The nitrogen base is attached to the 1' carbon. There are 5different nitrogen bases as listed in the figure.

Nucleic acids take the form of single nucleotides, nucleoside triphosphates andextended nucleotide polymers attached 5' to 3'. Nucleosides are nucleotides withoutthe phosphate group. Two important nucleoside triphosphates are ATP (AdenosineTriPhosphate) and GTP (Guanosine TriPhosphate). ATP is diagramed below


Both ATP and GTP can act as phosphate-group and energy donors. The terminalphosphate group is removed via a hydrolysis reaction, converting the nucleosidetriphosphate to a nucleoside diphosphate (ATP º ADP + Pi where Pi = an inorganicphosphate group). Pi is also indicated as a capital P enclosed in a circle. The terminalphosphate bond is considered a high-energy bond and, upon hydrolysis, can provide 7-11 Kcal/mole of energy to drive chemical reactions with a +ÄG. In addition thephosphate group can act as a structural modifier changing the functional state ofproteins. This structural modifier role is also evident in the role of the entire GTPmolecule in regulating so-called G-proteins which are involved in cell signaling.Nucleic Acid polymers are used to store and transfer informationthroughout the cell. Nucleotides are joined via their 5' phosphategroups and 3' alcohol groups. A small polymer is diagramed at theright. This polarity (direction) of the diagramed strand is 5' to 3'. Polymers can also be 3' to 5'. DNA molecules are composed of twopolynucleotide stands of opposite polarity (i.e., one strand is 5' to 3'and the other strand is 3' to 5').

Nucleic acids can be single strands of nucleotides as in the diagram to the right or they can be composed of twostrands of nucleotides. When two nucleotide strands are involved,they interact to form a helical structure resembling a twisted ladder. The phosphates and sugars form the backbone while the nitrogenbases form the rungs. Find the DNA model in the lab. Referring tothe model, the sugar/phosphate backbone is represented by theribbon (phosphates) and the small squares marked with a "D" (fordeoxyribose). The nitrogen bases are represented by the coloredrectangles marked with the first letter of one of the four bases foundin DNA (Uracil is only found in RNA). The two strands are heldtogether by hydrogen bonds between the nitrogen bases. Thebases pair very specifically due to their hydrogen bonding groups. Adenine hydrogen bonds only with Thymine and Cytosine onlyhydrogen bonds with Guanine. Find the nitrogen based models(Adenine, Guanine, Thymine and Cytosine). A diagram is providedbelow. Notethat the A-Tpair has two H-bonds while theG-C pair hasthree.


DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are central to a cell'sability to store, transfer, duplicate, and use genetic information. These processes areaccomplished by template synthesis. Template synthesis uses an existing strand as aguide to produce a duplicate molecule. The two strands of a DNA molecule are notexact copies, rather they are said to be COMPLEMENTARY since base pairingdepends on each base pairing with its complementary base (e.g., A/T C/G). DNA'sprimary function is storage of information, while RNA is used in the transfer ofinformation into a functional form and to regulate the expression of genetic information.

DNA and RNA are measured not by physical length but by the number ofnitrogen bases in the polymer. Single stranded molecules are measures in “bases”. For example the diagram on the previous page is 4 bases in length. Double strandedmolecules are measured in base pairs (bp), the number of A-T and C-G pairs in themolecule.

The production of exact copies of DNA (Replication) is critical to the survival ofcells and organisms. This process is accomplished with a series of enzymes thatseparate the two strands of the DNA helix and produce exact copies of each strandusing the existing stands as templates. The result is a helix that is a duplicate of theoriginal helix. Each helix contains one strand of DNA from the original molecule andone newly synthesized DNA strand. This method of replication is termed SEMI-CONSERVATIVE since each new molecule conserves one strand from the originalmolecule.

Transfer and conversion of the information stored in DNA is accomplished viatwo processes: Transcription and Translation. Transcription involves the conversion ofa section of DNA code into single-stranded RNA code for transport out of the nucleus.The RNA code can function as transcribed. These “functional” RNA molecules come ina variety of forms that are generally referred to as“ncRNAs”. The “nc” stands for non-coding because the RNA does not code for a Protein. The rest of the RNA transcriptsare in the form of “mRNA”. The “m” stands for “messenger”. Translation of mRNAs iscarried out by a cellular organelle called the RIBOSOME. The Ribosome converts thatRNA code into an amino-acid sequence, a protein.

In the next several exercises you will, on paper, accomplish the tasks ofreplication, transcription, and translation. (A Key is provided at the end of the labexercise)

1. REPLICATION - Write out the complementary sequence for the sequence givenbelow. What is the size (in bp) of the resulting double-stranded molecule?

T T C G G C C C C A G G T A T


2. TRANSCRIPTION - Write out the complementary RNA sequence for both strands ofDNA in problem #1. Begin by copying the DNA sequences in the space provided. Remember, RNA does not contain Thymine. It is replaced by Uracil. So each "A" inDNA is paired with a "U" in the RNA transcript. Thymine in DNA is still paired withAdenine in RNA. The G/C pairings also remain the same.

DNA:

RNA:

DNA:

RNA:


3. TRANSLATION. Assume that the RNAs you made above are mRNAs and translatethem using the Genetic Code (Use your textbook or other reference book to find acopy of the genetic code). The genetic code matches 3-letter RNA words (calledCODONS) into amino acids. Using the code, translate both RNA transcripts fromthe previous exercise (#2 on the preceding page) into amino acid sequences. It ishelpful to circle the codons before translating. Begin at the left end of each RNAtranscript and circle 3 letter codons until you reach the end of the transcript. Usethe code to translate the RNA codons into amino acids. As a point of reference, theaverage protein is 400 amino acids long. Therefore, the RNA transcript would be1200 nucleotides in length.

RNA:

AMINOACID:

RNA:

AMINOACID:

KEY TO NUCLEIC ACID EXERCISES:

Original sequence is in BOLD: T T C G G C C C C A G G T A TA A G C C G G G G T C C A T ASize = 15bp

T T C G G C C C C A G G T A T RNA: A A G C C G G G G U C C A U A

A A G C C G G G G T C C A T ARNA: U U C G G C C C C A G G U A U

A A G C C G G G G U C C A U AAmino Acids: Lys Pro Gly Ser Ile

U U C G G C C C C A G G U A U Amino Acids: Phe Gly Pro Arg Tyr


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