A level Biology AQA Unit 8

An automated DNA sequencing machine mixes template DNA with four other components (shown in the headings of the table). Which line of the table shows the functions of these components in the sequencing machine?

• A

• B

• C

• D

Automated sequencing uses fluorescent dyes to identify different bases in a section of DNA, as shown in the table. The diagram shows sample results for bases 120 – 130 of a certain gene. Which of the statements below are true? (click all that apply).

• The order of bases in the sequence is AAATCTGGTTT.

• The base order in mRNA transcribed from this sequence is UUUAGACCAGA.

• A substitution mutation affecting a base pair somewhere in this sequence could potentially affect any one of five amino acids in the resulting protein.

The β-globin gene codes for a polypeptide in haemoglobin. An individual with the disease sickle cell anaemia has two copies of a recessive allele of this gene. A genetic test can distinguish between the normal and sickle cell alleles.

· A restriction digest of normal DNA gives a 7.6 kbp fragment that contains the normal β-globin allele.

· The same restriction digest gives a 13 kbp fragment if the sickle cell allele is present instead of the normal β-globin allele.

After restriction digestion, the fragments are separated by electrophoresis. A fluorescent DNA probe is used to show the location of the fragments on the gel.

The diagram shows results for three individuals. Which individual(s) suffer from sickle cell anaemia?

• 1

• 2

• 3

The polymerase chain reaction (PCR) is a laboratory technique used to amplify DNA.

Which statement(s) correctly describe aspects of this process?

• When the temperature is at 55^oC single-stranded DNA anneals to primers.

• DNA copy number increases with each thermal cycle on a logarithmic scale.

• The enzyme Taq polymerase is used because it catalyses transcription in a bacterium that lives in hot water.

The chemotherapy drug cytarabine is an anti-metabolite similar to the nucleotide cytosine. The drug kills cancer cells by stopping them making and repairing DNA. At which stage in the cell cycle will cytarabine be incorporated into DNA?

• G₁

• G₂

• S

• M

The two strands of DNA are held together by:

• Hydrogen Bonds
• Phosphodiester Bonds
• Glycolsyl Bonds
• Glycosidic Linkages

What determines the code, or information, of a DNA molecule?

• the shape (structure) of the nitrogen bases
• the order (sequence) of the nitrogen bases
• the color of the nitrogen bases
• the frequency (number) of nitrogen bases

Tags

NGSS.HS-LS3-1

A process in which DNA has the unique ability to make an exact copy of itself.

• Replication
• Translation
• Transcription

Tags

NGSS.HS-LS3-2

Replicate the following strand of DNA: 
AATCATGGA

• AATCATGGA
• TTAGTACCT
• UUAGUACCU
• GGATAUCUA

Transcribe the following DNA strand: CTG AAT

• GAC TTA

• CTG AAT

• GAC UUA

• CUG AAU