beetroot membranes

8/2/2019 Beetroot Membranes

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Conclusion

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In my two graphs the overall trend is when the temperature is

increased the absorbance of the beetroot is increased. At no point in

my two graphs do you see the absorbance decreases when the temperature

is increased. For example if you look at my average absorbance graph

at 25C the absorbance is 0.35, and at 35C the absorbance is 0.53. So

there is an increase in absorbance.

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Acell membraneis made up of many different molecules these include

phospholipids, cholesterol, proteins, glycolipids and glycoproteins.

Each of these all has specific functions in the cell membrane.

Phospholipids make up the basic structure of the membrane, forming abilayer. They have hydrophilic heads and hydrophobic tails, with the

tales being non polar its very difficult for ions and polar molecules

to pass through the membrane, so the phospholipids act as a barrier to

water soluble molecules.

Therefore the only way water-soluble molecules can get through the

membrane is through the protein. Protein in the membrane acts as

hydrophilic passage ways or transport route for ions and polar

molecules to diffuse into the membrane. Protein control what

substances enter and leave the membrane. There is specific protein

types for different substances, these are known as protein carrier

cells.

Cholesterol role is different compared to protein and phospholipids,

its role is to give the membrane support and strength. Cholesterol

determines how fluid the membrane is. It helps to control the

fluidity, stopping it from becoming too fluid or too rigid, preventing

the membrane from bursting. Cholesterol structure is very similar to a

phospholipid, it too has a hydrophilic head and hydrophobic tale,

which allows it to fit neatly in the phospholipids.

Glycolipids and glycoproteins role is to help stabilise the

membrane, with their carbohydrate chains that extend out into thewater surface forming hydrogen bonds with the water molecules.

[IMAGE]

In the experiment the diffusion between the beetroot membrane and the

solution stayed the same in terms of the kinetic energy being the same

having no effect on the leakage of the membrane. So the kinetic energy

of the diffusion never changed and didnt affect the experiment. So

the leakage was at room temp as the beetroot cylinders was only heated
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for 1 minute, so they cooled back down when the leakage occurred. But

the reason why the leakage was different for the beetroots at

different temperature was during the 1 minute they were heated a

molecule in the membrane was permanently damaged.

I believe the molecule that was permanently damaged was the proteins

in the membrane. My reason for this is a protein is affected by

temperature, when temperature is increased the 3D shape of the protein

is changed causing it to become denatured. Proteins are hydrophilic

channels for ions and polar molecules, also allowing certain

substances enter and leave the membrane and if the proteins specific

shape is changed this will cause the cytoplasm and other substances

contained within the membrane to leak out. This has been shown by a

steady increase in anthocyanin (polar molecule) leaked out of plant

cells as the temperature increases. So this is what has caused more

leakage from beetroot cells. The higher the temperature the more the

protein has changed in shape, which is the reason for the absorbance

increasing when beetroot is heated at highertemperatures. At lowtemperatures such as 35C-45C the 3D shape of the proteins isnt

changed too much, so not much leakage takes place. So there was more

diffusion of the anthocyanin in higher heated beetroot cells, but that

was due to the shape of the protein being changed, not the kinetic

energy.

Also during the 1 minute the beetroot membrane was heated the

phospholipids were changed but this was only temporary, once the

beetroot was back at room temperature the phospholipids changed back

to their original form. What happens is at high temperatures the

phoispholipids dont fit together as easily, as the membrane becomes

more fluid. This means there is a slight chance of substances getting

through past gaps between the phospholipids, but most of the time they

still acted as a barrier to ions and polar molecules even if there was

gaps between them. If any anthocyanin did leak out through the gaps of

the phospholipid or if the phospholipid burst when heated it would

have leaked into beaker, which wasnt measured. Only leakage at room

temperature was measured.

Evaluation

Evaluation of procedure

The things that were kept the same to be a fair test are:

1. The beetroot was cut 21mm every time to allow the same surface area

at each different temperature.

2. Using a thermometer to check the temperature at the start of when

the beetroot was put in the boiling water and at the end of the minute
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when taking the beetroot out. This meant an average was taken for each

temperature.

3. Each beetroot was washed before being put in hot water, this was so

the beetroot juice was washed out.

4. Keeping each beetroot in the solution for the same amount of time,

which was 25 minutes.

5. Using the same sized cork borer when cutting up the beetroot.

Limitation described

Effect on result

Suggested improvement

Justification of improvement

Temperature control- the thermometer was used to measure the temp of

the water using a Bunsen burner.

Accuracy of the effect of temperature on beetroot. The temperature may

not be dead on the required temperature, so it could be a random

effect on the results

Use a thermostatic water bath.

A thermostatic water bath is much more accurate as it keeps water at

the required temperature. It could also be said that the results will

be more reliable as a better piece of equipment is used

Cutting of discs- not always cutting the beetroot straight and

sometimes cutting them vertically, causing the surface are to be

different on the beetroot cylinders

Always increasing

Take extra care when cutting the beetroot. Or use a different piece ofequipment rather than a knife such as a mini plastic mitre block or

something similar to a egg slice.

So there is less chance of the beetroot being cut vertically if it is

not rushed. This will make the results much more accurate and

reliable.

Shaking the test tubes unevenly before putting in colorimeter


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It can be a random effect on the results

Shake each test tube a certain number of times before putting in the

colorimeter.

This means each test tube will be equal in the number of shakes

therefore making the results more accurate. This means the results

will be more reliable.

Washing the beetroot- some beetroot cylinders were washed more than

others.

Some beetroot will have juice still inside. It can be a random effect

on the results

Leave the beetroot in distilled water for 6 minutes

This means each set of beetroot in each test tube will be washed forthe same amount of time. This means the results will be more accurate.

Evaluation of evidence

In my average absorbance graph/table there is no anomalous/ odd

results.

But in group 2 absorbance at 65C to 85C the absorbance was 2

abilitrary units. This means there was an error in the colorimeter.

This could have been caused by many of faults during the method.

But I believe it may be due to the cutting of the beetroot discs not

being cut straight, and being cut diagonally which increases the

surface area therefore increase the result.

Another anomalous result was in group 3 at 35C where the absorbance

decreases. I believe this could have been caused by the beetroot not

being left in the water at 35C for one minute and was taken out to

early. Also it may not have been at 35C and the temperature was

lower.

Also I think same reason applies for the anomalous result at 45C in

group 2 and group 1.

Overall the average absorbance results looked good, as there was a

nice pattern, which formed a nice joined line on the graph and seem to

be reliable. The reason why I think this is group 1 absorbance had

excellent results, and group 3 absorbance was good it was only group 2

absorbance that had a lot of anomalous results. There was no mistakes

in group 1 as that was my group, we did every thing the best we could

and being very careful.


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Percentage of errors

The formula that is used to find out due to measuring equipment is:

Minimum measurement

Actual measurement

Errors due to thermometer

25C

So you apply the formula above:

Now add and subtract 4% of 25C (which is 1) to 25C.

1 + 25=26

1- 25=24

85C

Now add and subtract 1.2% of 85C (which is 1.02) to 85C

1.02 + 85= 86.02

1.02 + 85=84.02

Errors due to absorbance

Many instruments contribute to absorbance error, these are::

Lowest point Highest point

Ruler (21mm)

4% 4%

Syringe (10cm3)

5% 5%

Clock (1min) 2%2%

Colorimeter

7% 0.53%

Lowest point Highest point

Compound error

18% 11.53%


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The percentage of error of the thermometer isnt too bad, it doesnt

effect the results that and shows the thermometer is quite reliable.

The absorbance compound error at my highest point had a major effect

on the result, it shows the equipment used for absorbance cause a

massive error, as show on my average absorbance graph. While at the

lowest point shows the compound error is high (17%), and has a major

effect on the result. The percentage of errors of the equipment puts a

question mark on the accuracy and reliability of the results.


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beetroot membranes

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