3.2 Chromosomes

Essential Idea

• Chromosomes carry genes in a linear sequence that is shared by members of a species.

Understandings

1. Prokaryotes have one chromosome consisting of a circular DNA molecule.

2. Some prokaryotes also have plasmids but eukaryotes do not.

3. Eukaryote chromosomes are linear DNA molecules associated with histone proteins.

4. In a eukaryotic species there are different chromosomes that carry different genes.

5. Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles of those genes.

6. Diploid nuclei have pairs of homologous chromosomes.

7. Haploid nuclei have one chromosome of each pair.

8. The number of chromosomes is a characteristic feature of members of a species.

9. A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length.

10. Sex is determined by sex chromosomes and autosomes are chromosomes that do not determine sex.

Applications

1. Cairns' technique for measuring the length of DNA molecules by autoradiography.

2. Comparison of genome size in T2 phage, Escherichia coli, Drosophila melanogaster, Homo sapiens and Paris japonica.

3. Comparison of diploid chromosome numbers of Homo sapiens, Pan troglodytes, Canis familiaris, Oryza sativa, Parascaris equorum.

Textbook Reading and/or Activities

Click HERE for a pdf of chapter 3.

• Pages 134-142

  • Challenge Yourself (p.138)

  • Exercises (p.142)

Notes

3.2 Chromosomes

A detailed set of notes, prepared by Bob Smullen, examining all of the IB learning expectations.

i-Biology Notes

A detailed set of notes, prepared by Stephen Taylor, examining U1 - U10 and A4.

i-Biology Study Questions (Not available)

A series of questions, prepared by Stephen Taylor, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Bioknowledgy Notes

A detailed set of notes, created by Chris Paine, examining all of the IB learning expectations.

Bioknowledgy Study Questions

A series of questions, created by Chris Paine, to help check your understanding of the IB learning expectations. This isVERY GOOD practice.

3.2 Notes

A detailed set of notes, prepared by Jacob Cedarbaum, examining all of the IB learning expectations.

3.2 Study Questions (NEW Syllabus)

(OLD Syllabus)

A series of questions, prepared by Jacob Cedarbaum, to help check your understanding of the IB learning expectations. This is VERY GOOD practice. Answers (OLD).

Learning Activities

Make a Karyotype

This short activity, prepared by the University of Utah, will help you better understand chromosomes and how they are organized into homologous pairs based on size and shape.

Karyotyping and Genetic Disorders

Read through and complete this series of activities, prepared by the University of Arizona, to practice compiling karyotypes and diagnosing genetic disorders based on the karyogram.

Karyotype Analysis

More karyotyping and diagnostic practice, prepared by Biology Corner.

Supplemental Reading

1. Image: Pearson Baccalaureate Standard Level Biology 2nd Ed.

2. Use of karyograms to deduce sex and diagnose Down syndrome in humans.

Skills

1. Use of databases to identify the locus of a human gene and its polypeptide product.

Key Vocabulary

• Chromosome

  • Homologous

  • Locus

  • Gene

    • Allele

• Prokaryote

  • Circular chromosome

  • Plasmid

• Eukaryote

  • Linear chromosomes

  • Histone

  • Haploid

  • Diploid

• Autosome

• Sex chromosome

  • Karyogram

  • Karyotype

  • Autoradiography

    • Cairns' technique