30th September 2010

Making our own DNA

Today, we went in depth into DNA. We went through that DNA uses a code to form different types of proteins to make different tissues or organs. The DNA code is the same as words as both make use of letters and when one letter is changed, the whole meaning is different. But this DNA code has a special name called condons. Codons are instructions to make different types of proteins. Alot of codons add up to form DNA. Codons makes use of 4 different letters(A, T, C, G)and only has a combination of 3 letters. The letters A, T, C and G have a special name known as Nitrogenou Bases. A stands for adenine, T stands for thymine, C stands for cytosine and G stands for guanine. For example, a single strand DNA may be like:

TAG CCG CGT TAG ACG TGA

DNA comes in a pair but the other half is complimentary of the original one. So A will always go with T and G will always go with C. So the complimentary strand of the single strand DNA above is like that:

ATC GGC GCA ATC TGC ACT

The double stranded DNA will twist into something like a spiral staircase withn a hollow interior. This is called DNA double helix.

After going through the topic, we were tasked to make a DNA model using stickers and 2 wires. We were given a total of 20 stickers. And on 5 stickers per letter(A, T, C, G), we were required to write a letter on both ends of the sticker. Then we pasted the stickers on the wires following the rule: A goes with T and G goes with C. And this is how my DNA looks like.

29th September 2010

Viewing DNA of a fruit

The lesson before this one, Mdm Riza told each of us to bring a either a banana or a strawberry as we needed to conduct a practical which was extracting DNA. On that day itself, although Mdm Riza emphasized to only bring bananas or strawberries, Alot of us bought different variety of fruits. These included apples, guavas, watermelons and others. Before conducting the practical, we were introduced to the topic DNA. We also got to listen to the DNA song.

Here are some things we went through:

- What does DNA stand for?

DNA stands for Deoxyribonucleic acid

-What is the function of DNA?

It contains genetic materials that are used to make protein

Where is DNA found?

Inside the nucleus of every cell.

- What are proteins for?

To make different organs and tissues.

Here are the steps for viewing the DNA of the fruit:

1) Use about 1/4 of the fruit.

2) Place the fruit inside a ziplock bag.

3) Mash it up until there are no big pieces left. (to break down the cell membrane)

4) Add in 1/2 a teaspoon of salt and 2 teaspoon of detergent. (to break down the nucleus wall)

5) Continue mashing it.

6) Let it settle for a while.

7) Pour a bit of it into a cylinder. Make sure no big pieces flow out.

8) Tilt the cylinder to 45 degrees and slowly pour in 10ml of alcohol.

This is how my DNA looks like:

27th September 2010

Viewing our cheek cells under the microscope!
Today, we started off the lesson by going through the notes about cells. We went through some examples of different tissues and organs. Afterwards, we went on to do a practical experiment. The experiment was about viewing our cheek cells under the microscope.

Here are the steps:

1) Using a toothpick, gently scrape the inside of your cheek
2) Spread the specimen on the glass slide.
3) Let it dry for about a minute.

4) Put a drop of iodine over the specimen.

5) Carefully place a piece of cover slip over the specimen.

6) Place the slide on the stage of the microscope

7) Adjust the coarse focus knob and objective lens to make the specimen clear for viewing.

1) Scrape cheek gently

2) Spread over slide

3) add a drop of iodine

4) cover specimen with cover slip

5) Place specimen under microscope

6)What you will expect to see:

21st September 2010

Making a cell using inedible materials



Today, we conducted a practical experiment on creating a cell using inedible materials we we were told to bring the lesson before by Mdm Riza. My groupmates were Ming Ze, Alec, Yi Heng and myself. I brought some strings to represent the ribosome and Golgi apparatus . Ming Ze brought a piece of brown paper that was crumpled into a ball and taped to represent the nucleus. Alec brought an eraser that was coloured green to represent the mitochondrion. And Yi Heng brought a piece of plastic to represent the endoplasmic reticulum. We took some beads and beans to represent the vacuole and other unidentified parts. We took a photo after placing each material into the agar which is the cytoplasm.

19th August 2010

3) (i) Today I learnt that factories make use of the fractionating column to separate crude oil into its simpler hydrocarbons. In order for separation to occur, the substances must have different boiling points.

Process:

- The crude oil is first burned in the furnace.

- The substances that have the lowest melting point and is the lightest will travel to the top of the column.

- The substances with the highest melting point pand is the heaviest will travel to the bottom of the column.

- The substances at the top are in gaseous state while the ones in the centre are in liquid state and the ones in the bottom are in solid-liquid state.

- more complex substances are found at the bottom while

less complex substances are found at the top.

(ii) Today we also went through of how the distillation set-up works.

process:

- The mixture is first heated in a beaker.

- The water evaporates into vapour.

- The vapour condenses in the condenser

- The water droplets flows down the condenser and into the conical flask

-If the temperature on the thermometer increases, it means that you are no longer collecting water.

(iii) Today we also compared some of the differences between fractional distillation and distillation

Some of the points are:

- Fractional distillation separates more than one substances while distillation separates two substances.

- Fractional distillation makes use of a fractionating column while distillation makes use of a Liebig condenser.

- Fractional distillation is used in factories while distillation is used in labs

2) (i) What other substances besides crude oil can be separated using fractional distillation?

(ii) How does the substances in the fractionating column stay in their corresponding segments?

1) I can apply what I learnt today when I need to separate a mixture of two iquids using distillation.

16th August 2010

3) (i) After todays practical experiment, I know how to separate solutions using the method distillation. Mdm Riza showed us experiment on distillation.
The apparatus needed were:
-bunsen burner
-tripod stand
-beaker
-solution of syrup amd water
-conical flask
-condenser
-thermometer
steps:
- The water first boils from the mixture in the beaker and then then turns into a gaseous state after being heated.
- The water vapour then condenses in the condenser.
- It flows down the condenser and then into the conical flask.
(ii) Chromatography is used to separate coloured substances like ink or dye. We conducted an experiment on chromatography by ourselves today.
The apparatus needed were:
- chromatography paper
- test tube holder
- test tube
- solvent
- ink
- cork
-pencil
steps:
- Draw a horizontal line across the breadth of the chromatography paper about 3 cm from the bottom.
- Fill the test tube with a height of 2 cm of solvent
- Place the chromatography paper into the tast tube
- Cover the test tube with the cork
- Place the test tube on the test tube holder and wait for the colour of the ink to change.
(iii) During todays experiment, we used the learning method of predicting, observing and explaining. I think this is a good learning technique as it can let us think of what the topic is before going deeper in depth.
2) (i) Is the syrup left in the beaker after it boils?
(ii) Can we use other types of paper besides chromatography paper to carry out the experiment?
1) Distillation can be used when we don,t have water with us besides sea water to obtain pure water.

26th July 2010

3) - After today's experiments, we learnt that we can find the amount of sugar content in a substance.

- I learnt my lesson today that when we are repeating the steps of the experiment, we must wash the apparatus that had been used as today when I poured the coke into the measuring cylinder I immediately poured in the coke zero after that. As a result, both solutions turned orange when it was heated.

- I also learnt that the higher the calories contained in a particular food, the higher the food's temperature wil be when it is being burn since there is more oil in the food

2) - I wonder what chemicls are mixed to create the Benedict's solution.

- What is the name of the reaction called when the Benedict's solution is mixed with the substance you want to test.

1) - I will be able to find what type of food is healthier for consumption through this experiment.