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7.1 DNA structure and replication

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Additional higher level » Topic 7: Nucleic acids » 7.1 DNA structure and replication

Description

Nature of science:
Making careful observations—Rosalind Franklin’s X-ray diffraction provided crucial evidence that DNA is a double helix. (1.8)

Understandings:

Nucleosomes help to supercoil the DNA.
DNA structure suggested a mechanism for DNA replication.
DNA polymerases can only add nucleotides to the 3’ end of a primer.
DNA replication is continuous on the leading strand and discontinuous on the lagging strand.
DNA replication is carried out by a complex system of enzymes.
Some regions of DNA do not code for proteins but have other important functions.

Applications and skills:

Application: Rosalind Franklin’s and Maurice Wilkins’ investigation of DNA structure by X-ray diffraction.
Application: Use of nucleotides containing dideoxyribonucleic acid to stop DNA replication in preparation of samples for base sequencing.
Application: Tandem repeats are used in DNA profiling.
Skill: Analysis of results of the Hershey and Chase experiment providing evidence that DNA is the genetic material.
Skill: Utilization of molecular visualization software to analyse the association between protein and DNA within a nucleosome.

Theory of knowledge:

Highly repetitive sequences were once classified as “junk DNA” showing a degree of confidence that it had no role. To what extent do the labels and categories used in the pursuit of knowledge affect the knowledge we obtain?

Utilization:
Syllabus and cross-curricular links:
Biology
Topic 2.6 Structure of DNA and RNA

Aims:

Aim 6: Students could design models to illustrate the stages of DNA replication.

Guidance:

Details of DNA replication differ between prokaryotes and eukaryotes. Only the prokaryotic system is expected.
The proteins and enzymes involved in DNA replication should include helicase, DNA gyrase, single strand binding proteins, DNA primase and DNA polymerases I and III.
The regions of DNA that do not code for proteins should be limited to regulators of gene expression, introns, telomeres and genes for tRNAs.

Directly related questions

16N.1.SL.TZ0.15: Which is a valid comparison between prokaryotic and eukaryotic DNA?
16N.2.HL.TZ0.7c:
Growth in living organisms includes replication of DNA. Explain DNA replication.
17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
17M.1.HL.TZ1.27: The diagram shows how pre-mRNA is processed into mature mRNA. Which structures are indicated by...
17M.2.HL.TZ1.2a.i: Nucleosomes help to regulate transcription in eukaryotes. State the components of a nucleosome.
20N.1.HL.TZ0.27: Which are two proteins that assist in the unwinding and separation of DNA strands during...
17N.3.HL.TZ0.03a:
The Hershey and Chase experiment supported DNA as the hereditary material. Describe the experiment.
17N.1.HL.TZ0.27:
Which letter (A–D) indicates where a new nucleotide would attach?
21M.1.HL.TZ1.27: Which statement applies to tRNA? A. There is at least one type of tRNA that combines with each...
21M.1.HL.TZ1.26: Which regions of DNA code for the production of specific proteins? A. Telomeres B. Genes for...
21M.1.HL.TZ2.26:
The graph shows results of an experiment by Hershey and Chase in 1952 in which bacteria were infected with a mixture of virus particles labelled with either ³²P or ³⁵S. A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining on the outside of the cells.

[Source: Republished with permission of ROCKEFELLER UNIVERSITY PRESS, from Independent functions of protein and nucleic acid in growth of bacteriophage. Hershey, A.D. and Chase, M., 1952. (Journal of General Physiology, 36(1), p.47). Society of General Physiologists, Rockefeller Institute for Medical Research, Rockefeller Institute; permission conveyed through Copyright Clearance Center, Inc.]

What do curves X and Y represent?
21N.1.HL.TZ1.26:
Rosalind Franklin produced X-ray diffraction images of DNA.

[Source: © King’s College, London. KCL Department of Biophysics KDBP/1/1.]

Which previously unknown aspect of DNA was deduced from these images?

A. Chromosomes are made of DNA.

B. Deoxyribose sugar is attached to a phosphate group.

C. The base A pairs with T and C with G.

D. The DNA molecule is a double helix.
21N.1.HL.TZ1.27:
What is the difference between the DNA of adult identical (monozygotic) twins?

A. Order of genes

B. Sequence of nucleotides

C. Methylation pattern

D. Ratio of complementary base pairs
22M.2.HL.TZ2.5a.i: Describe the structure of nucleosomes.
22M.1.HL.TZ1.26: The image shows a replication fork. Which row identifies X, Y and Z in the diagram?
22M.2.HL.TZ2.5a.iii:
There are multiple tandem repeats of nucleotide segments of DNA found in the non-coding DNA between genes. Outline how tandem repeats are used for DNA profiling.
22M.1.HL.TZ2.26:
The diagram shows the structure of a nucleosome.

[Source: Zephyris. Nucleosome 1KX5 colour coded. Available at https://en.wikipedia.org/wiki/Nucleosome#/media/File:Nucleosome_1KX5_colour_coded.png
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license (https://creativecommons.org/licenses/by-sa/3.0/deed.en).]

What is the structure labelled T?

A. 5' end of RNA

B. 5' end of uncoiled DNA

C. N-terminal tail of one DNA strand

D. N-terminal tail of one histone
18N.1.HL.TZ0.26: Current understanding of DNA is an example of the accumulated discoveries of many scientists....
18N.2.HL.TZ0.3a: State one similarity and one difference between the structure of genes and short tandem repeats.
18N.2.HL.TZ0.3b: Outline the role of short tandem repeats in DNA profiling.
18M.1.HL.TZ1.27: What does eukaryotic DNA have that is missing from prokaryotic DNA? A. Uracil B. Promoter...
18M.2.HL.TZ2.2b.iii: State one function for a region of DNA that does not code for proteins.
18M.2.HL.TZ2.2b.i: State one role of nucleosomes in eukaryotic cells.
18M.2.HL.TZ2.2b.ii: Outline how Hershey and Chase’s experiment provided evidence for DNA as the genetic material.
19M.1.HL.TZ1.27:
The diagram shows the arrangement of introns and exons in a segment of pre-mRNA. Pre-mRNA is immature mRNA containing introns and exons.

Which is a mature mRNA molecule derived from the pre-mRNA by splicing?

[Source: © International Baccalaureate Organization 2019]
19M.1.HL.TZ2.11:
Hershey and Chase used a bacteriophage (a virus that infects bacteria) to investigate the chemical nature of genes. The diagram shows a bacteriophage.

[Source: Graham Knott and Christel Genoud, ‘Commentary: is EM dead?’, Journal of Cell Science (2013),
126: 4545–4552, reproduced with permission. http://jcs.biologists.org/content/126/20/4545.figures-only
doi: 10.1242/jcs.124123 http://www.biologists.com/journal-of-cell-science]

The sulphur in the protein and the phosphorus in the DNA of the bacteriophage were radioactively labelled. The data obtained after bacterial infection and centrifugation are shown in the table.

What did Hershey and Chase conclude from their experiment?

A. DNA was mainly outside the bacterial cells.

B. Viruses infect bacterial cells with proteins.

C. Viral DNA was found within the bacterial cells.

D. Neither protein nor DNA were chemicals making up genes in viruses.
19M.1.HL.TZ1.26: What contribution did the X-ray diffraction conducted by Rosalind Franklin make to our...
19M.1.HL.TZ2.12: What are the functions of DNA primase and DNA polymerase I in DNA replication?
19M.1.HL.TZ2.13: A nucleotide containing dideoxyribose is shown. What is the reason for the use of...
19M.1.HL.TZ2.14: What applies to DNA base sequences? I. Some genes do not code for proteins. II. Promoters are...
19M.2.HL.TZ1.7a: Outline the roles of helicase and ligase in DNA replication.
19M.2.HL.TZ2.2a.iii:
DNA has regions that do not code for proteins. State two functions of these regions.

1.

2.
19N.1.HL.TZ0.26: What is a function of DNA polymerase I? A. Adds nucleotides in a 5’ to 3’ direction to elongate...

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DP Biology Questionbank

7.1 DNA structure and replication

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