Purpose:

-         To observe expression of a series of genes in an individual phenotypes

-         To demonstrate a small part of the range of human variation

-         To understand the genetic basis for human diversity

Introduction:

            Many of you are already familiar with many of the genetic traits of humans, such as baldness, eye color, color blindness and blood types. One often forgets that more familiar characteristics, such as size and position of the eyes, number and shape of fingers, total body size and body proportions, may also be genetically determined. (although such traits as body size may be profoundly influenced by the environment) The tremendous number of genetic traits makes humans extremely variable. With the exception of identical twins, it is highly improbable that any two persons will have the same (or even similar) combinations of genetically determined traits.

            In this exercise you will inventory yourself for a series of genetic traits listed in the data table. These are known to be single-gene traits, expressions of two alleles at one gene locus.

Procedure;

-         Divide into groups of two to four students.

-         Go through the traits listed in the data table

-         Score your own phenotype for each trait.

-         Write the symbols for all your possible phenotypes in the space provided

-         If you know your parents genotype, write them in the space provided

-         We will tally and make a second data table for the class data

Data table 1

Questions:

1)      Is it true that dominant phenotypes are always the most common in the population? Explain your answer.

2)      What determines how often a phenotype occurs in a population?

3)      Is it possible to determine the genotype of a person showing a dominant phenotype? A recessive genotype? Why or why not?

Conclusion:

            What did you learn?

Problems with the lab?

Improvements?

Problem: How can you determine the number of moles of water in a hydrated compound?

Answer:( Leave room)

Procedure;

1)      Measure to the nearest 0.001 gram the mass of a clean, dry crucible and cover. Record in data table.

2)      Add about 4.00 grams of blue hydrate to the crucible. Measure the mass of the crucible, cover and hydrate (CuSO₄) to the nearest 0.001 gram and record in data table.

3)      Record your observations of the hydrate. (Color, texture, appearance etc.)

4)      Place the triangle on the ring stand and place the crucible into the middle of the triangle> (as demonstrated)

5)      Cover the crucible with the cover slightly tilted to allow water to escape.

6)      Begin heating at a low heat, then gradually increase the flame. Heat fro 10 minutes.

7)      When heating is complete remove the crucible using tongs. (Beware HoT!)

Place the lid on the crucible and allow contents to cool.

      Measure the mass of the cooled crucible, cover and anhydrous salt. Record in data table.

9)      Observe the anhydrous CuSO₄and  then add a couple of drops of water slowly to the salt, record your observations before and after adding the water.

10)  Return the anhydrous salt to the front and clean your equipment and lab station.

11)  Wash your hands before leaving the laboratory.

Calculations:

1)      Calculate the number of moles of anhydrous CuSO₄ left after heating.

2)      Calculate the number of moles of water removed by heating.

(Hydrated CuSO₄   -  Anhydrous CuSO₄  =  water driven off)

3)      Determine the formula for the hydrated CuSO_4. 

4)      Determine the percent error if the formula for the hydrate is Copper II sulfate pentahydrate.

Conclusion:

            What did you learn?

            How could you determine the formula for this hydrate?

            Sources of error in the experiment

            Problems and Improvements.

Data Table:

Parts of the Bunsen Burner:

            Below is an illustration of a common laboratory Bunsen burner. While details vary among burners, every burner has four main parts: the base, a vertical tube or barrel, a gas inlet near the base and an adjustable opening at the bottom of the barrel to introduce air to the gas mixture.

Procedures:

            To light your gas burner, hold a lighted match a  littler to one side and just above the barrel of the burner. Turn on the main gas supply. Adjust the air flow until you have a quiet steady flame with a sharply defined inner cone. This will result in the highest possible flame temperature. Test the temperature of the different parts of the flame.

1)      Inset a piece of copper wire and time how long it takes to turn red hot. (No longer than one minute) in positions 1, 2 and 3.

2)      Record results in data table one.

A yellow smoky flame means too little air, adjust the air.

If the flame rises off the burner, the gas pressure is too high, reduce the gas pressure.

If the flame sinks into the barrel the pressure is too little, adjust the gas pressure up.

Glass Manipulation:

WARNING!! Glass does not show that it is hot. Do not handle hot glass or put it down on cold surfaces. Always put hot glass on to the asbestos wire gauze pad to cool. Always allow the glass to cool before attempting to pick it up

            Hold the glass between you fingers and rotate it in the flame. As the glass becomes soft apply a gentle pressure upwards, allowing the glass to sag into a 90^o bend. Fire polish the ends and show to your teacher so he can sign you lab book.

            Repeat the above procedure but this time do not let the glass sag as far and try to achieve a 120^o, fire polish the ends and show to your teacher for credit.

            Lastly, rotate a piece of tubing in the flame until quite soft. Do not let this one sag. Instead, when it is soft pull it apart and draw the glass into a thin tube and let cool.

With a triangular file, separate the thin tube in the middle with a clean break. These will be used as eyedroppers in subsequent laboratories. Show these to your teacher for credit.

Conclusion:

            What did you learn?

            Why could you bend glass?

            Problems and Improvements?

Questions:

                1) What is an exothermic reaction?

                2)  What is an endothermic reaction?

                3) Define the term calorie.

Procedures:

1)      Get  two Styrofoam cups for a calorimeter. Place them inside of one another to double their insulating properties.

2)      Using the graduated cylinder, measure out 50 ml of tap water into the newly constructed calorimeter.

3)      Insert a thermometer and leave in the water for at least 2 minutes. Record the temperature of  the water and record in your lab book.

4)      Measure out 5.00 grams of ammonium nitrate on a piece of paper. Be sure to Tare the scale.(that means you must take into account the weight of the paper)

5)      Dump the ammonium nitrate into the calorimeter with the 50 ml of water.

6)      After two minutes reinsert the thermometer and measure the new temperature of the water. Record in lab book.

7)      Repeat procedures 2 through 6 only instead of using ammonium nitrate, measure out 5.00 grams of calcium Chloride.

      Dispose of all liquids in the sink.

9)      Clean up after yourselves and wash your hands.

Data table:

Calculations:

1)      Calculate the amount of heat absorbed or released  from the reactions. Volume of water X change in temperature = calories

2)      Calculate what fraction of a mole of reactant you used in each reaction.

3)      Calculate your expected amount of heat by multiplying the fraction of a mole of reactant times the heat of formation of the compound. (The heat of formation of ammonium nitrate is 87.27 kc/mole and for calcium chloride it is 179.6 kcal/mole)

4)      Using this data calculate your percentage error for the two reactions. (% error = actual amt – theoretical amt/theoretical amt. X 100%)

Conclusion:

                Explain your percentage error. What were some sources of error in this lab?

                What did you learn?

                Why did  the water change temperature?

                Problems ?

                Improvements?

Pre-lab Questions:

1)      What is a covalent Bond?

2)      What is a dipole?

3)      What two factors determine whether a molecule is polar or not?

Procedures:

1) Using the gummy candy and toothpicks construct ball and stick models of the following compounds.

Data Table

Questions:

1)      Explain how you used the molecular shapes to predict molecular polarity. Support your answer with examples from this lab.

2)      List the advantages and disadvantages of ball and stick models to construct molecules.

3)      Based on your rwesults predict the type of bonding, molecular geometry and molecular polarity of the following molecules. HI, SH₂, NH₃ and CO_2.

Conclusion:

 What did you learn?

Do molecules really look like toothpicks and candy?

Problems and Improvements

          Elements in the same family will combine in the same ratio with ions of the same charge. They will also exhibit similar properties such as color, solubility etc. In this lab we will combine several compounds that have negative ions in the same family and one negative ion will be of another family. Look for a different ratio of ions and different properties of the precipitate.

Procedures:

1)   Take the large plastic bottle labeled Silver nitrate (AgNO₃) and place one drop of the solution in well number 1, two drops in well number 2, 3 in well 3,…. Till you come to well number 11 and place 11 drops of AgNO₃ in it. Then starting with well number 11 add 1 drop of potassium iodide (KI), then 2 drops into well #10, 3 drops in well #9, 4 drops in well #8… till finally you put 11 drops into well number 1. Each well will now have 12 drops total.

2)   Observe the wells. Write your observations into the data table. The well that has the most precipitate will be the well that has the closest ratio of ions to combine together. Using this information determine the ratio of ions in the compound.

Example: If well #4 had the most precipitate, with 4 drops of AgNO₃ and 8 drops of KI, the ratio of ions would be 1 of AgNO₃  to 2 of KI, making the formula for the compound, AgI₂. Or if well #6 had the most precipitate then, 6 drops of AgNO₃  to 6 drops of KI, then the ratio would be 1 to 1 and the formula would be AgI.

          3) Rinse out the well plate and dry with paper towel

4)   Repeat steps 1 , 2, and 3 with the other three solutions, potassium chloride, potassium bromide and potassium sulfide with the silver nitrate for a total of four trials. Record your observations in the data table.

5)   Wash your hands and clean up your lab area after you finish. Several of the compounds are toxic or will turn your hands black. Be Careful.

Data Table:

Questions:

1)   Which negative ion is in a different family and how could you tell from your data?

2)   What happened to the other ions?

3)   Why do families of elements exhibit these traits?

4)   Could you do this experiment using families of positively charged ions?

Conclusion:

-         What did you learn?

-         Why did things happen?

-         Problems?

-         Improvements?

          Elements in the same family will combine in the same ratio with ions of the same charge. They will also exhibit similar properties such as color, solubility etc. In this lab we will combine several compounds that have negative ions in the same family and one negative ion will be of another family. Look for a different ratio of ions and different properties of the precipitate.

Procedures:

1)   Take the large plastic bottle labeled Silver nitrate (AgNO₃) and place one drop of the solution in well number 1, two drops in well number 2, 3 in well 3,…. Till you come to well number 11 and place 11 drops of AgNO₃ in it. Then starting with well number 11 add 1 drop of potassium iodide (KI), then 2 drops into well #10, 3 drops in well #9, 4 drops in well #8… till finally you put 11 drops into well number 1. Each well will now have 12 drops total.

2)   Observe the wells. Write your observations into the data table. The well that has the most precipitate will be the well that has the closest ratio of ions to combine together. Using this information determine the ratio of ions in the compound.

Example: If well #4 had the most precipitate, with 4 drops of AgNO₃ and 8 drops of KI, the ratio of ions would be 1 of AgNO₃  to 2 of KI, making the formula for the compound, AgI₂. Or if well #6 had the most precipitate then, 6 drops of AgNO₃  to 6 drops of KI, then the ratio would be 1 to 1 and the formula would be AgI.

          3) Rinse out the well plate and dry with paper towel

4)   Repeat steps 1 , 2, and 3 with the other three solutions, potassium chloride, potassium bromide and potassium sulfide with the silver nitrate for a total of four trials. Record your observations in the data table.

5)   Wash your hands and clean up your lab area after you finish. Several of the compounds are toxic or will turn your hands black. Be Careful.

Data Table: