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IGCSE Biology Extended17.1.8—Protein is madeTopic Practice

17.1.8—Protein is made

• Explain how a protein is made, limited to: • the gene coding for the protein remains in the nucleus • messenger RNA (mRNA) is a copy of a gene • mRNA molecules are made in the nucleus and move to the cytoplasm • the mRNA passes through ribosomes • the ribosome assembles amino acids into protein molecules • the specific sequence of amino acids is determined by the sequence of bases in the mRNA (knowledge of the details of transcription or translation is not required)

Question 2(b)

[Maximum number: 4]

Many researchers are studying the structure and function of genes.

Every living cell is able to make proteins.

The process begins in the nucleus.
Describe how proteins are made in a cell.

Question 2(c)(ii)

[Maximum number: 5]

Fig. 2.1 is a diagram of part of a DNA molecule.

Fig. 2.1

Fig. 2.1

Explain how proteins are made by a cell.

Question 2(c)

[Maximum number: 2]

Quinoa, Chenopodium quinoa, is a dicotyledonous plant that produces seeds that resemble those of cereals, such as rice.

State the roles of mRNA and ribosomes in protein synthesis.
mRNA
ribosome

Question 2(b)

[Maximum number: 3]

Fig. 2.1 is a diagram showing a small region of DNA.

Fig. 2.1

Fig. 2.1

Fig. 2.2 shows part of the DNA enlarged to show the sequence of bases.

Fig. 2.2

Fig. 2.2

Fig. 2.3 shows how DNA is involved in protein synthesis.

Fig. 2.3 not to scale

Fig. 2.3 not to scale

Explain how mRNA is involved in protein synthesis.

Question 2(a)(iii)

[Maximum number: 3]

Insulin is a protein made by cells in the pancreas.
Fig. 2.1 shows how insulin is made in a pancreatic cell.

Fig. 2.1

Fig. 2.1

Explain the role of molecule A in protein synthesis, as shown in Fig. 2.1.

Question 3(a)

[Maximum number: 6]

Proteins are biological molecules.
Explain how proteins are made.

Question 5(d)(ii)

[Maximum number: 2]

A gene is involved in the production of the enzyme alcohol dehydrogenase.

Describe the role of ribosomes in the synthesis of proteins such as enzymes.

Question 5(b)(v)

[Maximum number: 2]

The genetically-engineered bacteria produce mRNA that is a copy of the human TPA gene.

Explain the role of mRNA in the bacterium.

Question 29

[Maximum number: 1]

Which of the statements about the production of a protein are correct?

1 The sequence of bases in the gene determines the amino acid sequence used to make a protein.

2 The mRNA molecules are made in the nucleus and they remain there.
3 The ribosomes assemble amino acids together to make a protein.

A

1 and 2 only

B

1 and 3 only

C

2 and 3 only

D

2 only

Question 30

[Maximum number: 1]

What is the role of messenger RNA (mRNA)?

A

assembles amino acids into protein molecules

B

moves a copy of the gene from the nucleus to the cytoplasm

C

controls cell function

D

duplicates chromosomes before mitosis

0 selected