What happens in cells (and what do cells need)?

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Question 3
Medium

Protease is an enzyme produced in the human digestive system. It breaks down proteins.

a.

The diagram below shows the steps in protein digestion.

Diagram showing the steps of protein breakdown by protease. Step 1 shows a long protein chain composed of amino acid sub-units. Step 2 shows protease enzyme molecules approaching the protein chain, with a dotted line pointing to them labeled '........................ molecules'. Step 3 shows the protease enzymes binding to the protein chain. Step 4 shows the digested chain. A dotted line points to the remaining peptidic backbone labeled '........................ molecule', and another dotted line points to the released individual sub-units labeled '........................ molecules'..

Complete the labels in the diagram.

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b.

Trypsin is a protease found in the small intestine where the pH is alkaline (around pH 8).

Draw a curve on the axes below to show the effect pH will have on the rate of reaction for the digestion of proteins by trypsin.

An empty grid with a vertical axis labeled 'Rate of reaction' and a horizontal axis labeled 'pH' ranging from 4 to 12 in increments of 1.

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c.

Casein is a protein found in milk that gives milk its cloudy, white appearance.

When protease breaks down casein, the solution turns clear.

A group of students investigate how temperature affects the enzymes that break down proteins found in milk.

Describe an experiment that the students could use to investigate the effect of temperature on the breakdown of the protein in milk.

In your description include:

  • how the independent variable could be changed
  • the observations that should be made
  • two variables that need to be controlled.
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What happens in cells (and what do cells need)? Questions

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  2. /Biology
  3. /What happens in cells (and what do cells need)?