Summary

Summary Biotechnology notes and experiments

0 purchase

Course
Biology

Institution

Experiments Included ( answered thoroughly with additional notes ): 1 Describe the role of anaerobic respiration in yeast during the production of ethanol for biofuels. 2 Describe the role of anaerobic respiration in yeast during bread-making. 3 Investigate and describe the use of pectinase in f...

[Show more]

Preview 1 out of 1 pages

View example

Uploaded on September 18, 2023
Number of pages 1
Written in 2023/2024
Type Summary

biotechnology
experiments
biotechnology notes and experiments

Institution Secondary school
Biology
School year 4

$4.79

Add to cart

Add to wishlist

100% satisfaction guarantee
Immediately available after payment
Both online and in PDF
No strings attached

Biotechnology - Notes on notes!

1 Describe the role of anaerobic respiration in yeast during production of ethanol for biofuels.

When yeast cells are reproducing rapidly, the oxygen is used up. The yeast has to switch to using anaerobic
respiration to ensure it can survive. With fossil fuels being non-renewable and contributing to global warming, biofuels
are increasingly being considered as a possible alternative for the future. Bioethanol production uses yeast
to anaerobically ferment carbohydrate. When ethanol is made by fermentation, sugar is converted into ethanol and
carbon dioxide if conditions are anaerobic. Single-celled fungi, called yeast, contain enzymes that are
natural catalysts for making this process happen. In some countries, such as Brazil, the source of sugar is sugar cane
- which yeast can directly ferment into ethanol. (In other countries, plants such as maize are used. Because maize
contains starch rather than sugar, the enzyme amylase must first break down the starch into sugar before the yeast
can ferment it into ethanol). The ethanol produced by yeast only reaches a concentration of around 15 per cent before
the ethanol becomes toxic to the yeast. In order to make it sufficiently concentrated to be burnt as a fuel, the ethanol
must be distilled. https://www.bbc.co.uk/bitesize/guides/z8sb2p3/revision/4

2 Describe the role of anaerobic respiration in yeast during bread-making.

Yeast is a live, single-celled fungus. There are about 160 species of yeast, and many of them live all around us.
However, most people are familiar with yeast in its mass-produced form: the light brown granules that come in 8g foil
packets at the supermarket. This organism lies dormant until it comes into contact with warm water. Once reactivated,
yeast begins feeding on sugars in foods such as flour, and releases carbon dioxide that makes bread rise (although at
a much slower rate than baking powder or soda). Yeast also adds many of the distinctive flavors and aromas we
associate with bread. Yeast, on the other hand, is a live, single-celled fungus. There are lots of different types of flour
used in bread, but the most commonly used in raised bread is wheat flour. This is because wheat flour contains a
protein which, when combined with water, forms gluten. As you knead the dough, the gluten becomes more and more
stretchy. This gum-like substance fills with thousands of gas bubbles as the yeast goes to work during rising.

Starch, a carbohydrate that makes up about 70% of flour by weight, also gets in on the act. When starch granules are
attacked by enzymes present in flour, they release the sugars that yeast feeds on. Starch also reinforces gluten and
absorbs water during baking, helping the gluten to contain the pockets of gas produced by the yeast.

Sometimes, a baker will let the dough rise several times, allowing the gluten to develop more completely and the
yeast to add more of its flavors. When the dough is finally cooked—either in an oven, over a fire, or in a steamer,
depending on what kind of bread you’re baking—the yeast inside it continues feeding, and the pockets of gas in the
dough continue to expand. As the temperature of the cooking dough rises, the yeast eventually dies, the gluten
hardens, and the dough solidifies – and you end up with …Bread!
https://www.exploratorium.edu/cooking/bread/bread_science.html Check this practical: https://www.exploratorium.edu/cooking/bread/activity-
yeast.html

3 Investigate and describe the use of pectinase in fruit juice production.

Enzymes are an integral component of modern fruit juice manufacturing and are highly suitable for optimising
processes. Fruit juices are extracted using an enzyme called pectinase. Pectin is a substance which helps to stick
plant cells together. Fruits like apple or orange contain a lot of pectin. The braking down of pectin makes it much
easier to squeeze juice from the fruit. Pectinase is widely used in order to: (a) extraction of juice from raw material
(b) processing efficiency (pressing, solid settling or removal) (c) generate a final product that is clear and visually
attractive. http://igbiologyy.blogspot.com/2012/12/27-use-of-enzymes-in-food-industry.html
Check this practical: https://www.youtube.com/watch?v=Q3bJStyn80o

4 Investigate and describe the use of biological washing powders that contain enzymes.

Biological washing powders contain protease and lipase to remove protein stains and fat/grease from clothes. The
enzymes break down proteins or fats on the fabric, forming water-soluble substances that can be washed away.
Example: Blood contain the red protein Haemoglobin (Hb). The Proteases in biological washing powder break Hb
molecules into smaller molecules, which are not coloured and which dissolve in water and can be washed away.
This makes the washing powder more effective than detergent alone, especially at lower temperatures. This save
energy (no need to boil water), but if the temperature is too high, the enzyme will be denatured.
https://biology-igcse.weebly.com/use-in-biological-washing-powders.html

5 Investigate and explain the use of lactase to produce lactose-free milk.

When the enzyme lactase is mixed with milk which contains lactose, the lactase enzymes break the lactose down into
simple sugars that can be consumed by people who have intolerances to lactose The following link shows haw
lactase can be used to break lactose down into glucose and other monosaccharide sugars:
https://www.youtube.com/watch?v=P7e9Mj9ATpQ

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller brianblack. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $4.79. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

69052 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 15 years now

Start selling