MBG: BLOCK 2: TOPIC 2: CHROMOSOME STRUCTURE AND FUNCTION

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Questions and Answers

What is a karyotype primarily used for?

Studying protein synthesis

Identifying the function of individual genes

Analyzing the number and structure of chromosomes (correct)

Determining a cell's metabolic rate

Which structure is crucial for the proper segregation of chromosomes during cell division?

Telomere

Nucleosome

Histone

Kinetochore (correct)

What is the primary role of telomerase in chromosome maintenance?

Facilitating DNA replication

Elongating telomeres (correct)

Repairing chromosomal breaks

Condensing chromatin

Which of the following best describes heterochromatin?

Tightly packed and generally transcriptionally inactive Signup and view all the answers

What characterizes a chromosome territory within a cell?

The distinct spatial region occupied by a specific chromosome Signup and view all the answers

Which of the following is NOT a consequence of changes in telomere length?

Enhanced DNA repair activities Signup and view all the answers

In karyotype analysis, what does the term 'banding pattern' refer to?

Distinct light and dark stripes on chromosomes Signup and view all the answers

Which region of the chromosome is involved in the assembly of the spindle fibers during cell division?

Centromere Signup and view all the answers

Which structural change of homologous chromosomes is listed alphabetically via abbreviation?

Deletion Signup and view all the answers

What does the abbreviation 'hsr' indicate in cytogenetics?

Homogeneously staining region indicating gene amplification Signup and view all the answers

In which circumstance would the receptor chromosome be listed before the donor chromosome?

When there is a three-break rearrangement Signup and view all the answers

What is indicated by a semicolon in the listing of aberrations?

Two or more chromosomes altered Signup and view all the answers

Why is the notation involving square brackets important in karyotyping?

It provides the number of cells for each clone or line Signup and view all the answers

What is the main reason for the evolution of nomenclature in cytogenetics?

New findings and ongoing studies in genetics Signup and view all the answers

What does the abbreviation 'dic' refer to in cytogenetic nomenclature?

Dicentric chromosome Signup and view all the answers

What is the purpose of using a detailed system for chromosome band descriptions?

To provide a clearer view of chromosomal changes Signup and view all the answers

What does a break suspected at the interface of two bands require in terms of numbering?

The higher band number Signup and view all the answers

Which of the following best characterizes the use of oncology microarrays in genetics?

Techniques used for comparative analyses reflecting new findings Signup and view all the answers

What is the primary function of Nucleolar Organizer Regions (NORs)?

Site of ribosomal RNA gene production Signup and view all the answers

How are chromosomes classified based on their centromere position?

Metacentric, submetacentric, and acrocentric Signup and view all the answers

What does the term 'banding resolution' refer to in chromosome analysis?

The level of detail in identifying bands on chromosomes Signup and view all the answers

What staining technique is primarily used to visualize centromeric regions of chromosomes?

Q-banding Signup and view all the answers

Which statement about G-banding is correct?

It darkly stains A-T rich regions. Signup and view all the answers

In karyotyping, what is the correct order of reporting?

Chromosome number, sex chromosome complement, abnormalities Signup and view all the answers

What does the nomenclature '7q34' represent?

The fourth region of the long arm of chromosome 7 Signup and view all the answers

Which of the following is NOT a staining technique used in chromosome analysis?

PCR amplification Signup and view all the answers

What does DAPI staining primarily identify?

AT-rich regions Signup and view all the answers

Why must final reports include the level of banding resolution?

Due to variability in observed banding patterns Signup and view all the answers

Which chromosomes are identified as acrocentric?

13, 14, 15, 21, 22, and Y Signup and view all the answers

What is primarily analyzed in oncology microarrays?

Gene expression levels across a variety of samples Signup and view all the answers

Which type of chromosome has its centromere located in the middle?

Metacentric Signup and view all the answers

Study Notes

General/Background

Chromatin: DNA and associated proteins in the nucleus, forms chromosomes.
Chromosome: A highly organized structure of DNA and proteins that contains genetic material.
Chromatid: One of the two identical copies of a chromosome, joined at the centromere.
Chromosome Territories: Regions within the nucleus where chromosomes occupy specific positions.
Histone: A protein that associates with DNA to form nucleosomes.
Nucleosome: The basic unit of chromatin structure, consisting of DNA wrapped around a core of eight histone proteins.
Centromere: A constricted region of the chromosome where spindle fibers attach during cell division.
Kinetochore: A protein complex assembled at the centromere, which connects to microtubules during cell division.
Neocentromere: A newly formed centromere at a different location on a chromosome.
Telomere: Repetitive DNA sequences at the ends of chromosomes, protecting them from degradation.
Karyogram: A visual representation of chromosomes arranged in order by size and shape.
Karyotype: The characteristic chromosome complement of an individual or species.
Autosome: Any chromosome that is not a sex chromosome (X or Y).
Repetitive DNA: DNA sequences that are repeated many times in the genome.
Pseudoautosomal Regions: Regions on the X and Y chromosomes that share homologous sequences.
Banding/Banding Pattern: Distinctive patterns of light and dark bands on chromosomes, revealed by staining techniques.
Euchromatin: Less condensed, gene-rich regions of chromosomes.
Heterochromatin: Highly condensed, gene-poor regions of chromosomes.
Locus (loci): The specific location of a gene on a chromosome.
Allele: An alternative form of a gene.

Chromosome Structures and Function

Types of DNA sequences: Different DNA sequences influence chromosome structure; repetitive DNA and gene-rich regions play a specific role.
Chromosome structure and histone variants: Histone variants contribute to the formation of different chromosome structures.
Chromosome Condensation:
- Components: Histones, topoisomerases, and other proteins are involved in chromosome condensation.
- Consequences of protein change: Alterations in protein availability or modifications impact condensation levels.
Centromere:
- Function: Attaches to spindle fibers during cell division, ensuring proper chromosome segregation.
- Location: Constricted region of the chromosome.
- Gene Content: Centromere contains unique repetitive DNA sequences and a few genes involved in centromere function.
- Importance: Essential for proper chromosome segregation and cell division.
Kinetochore:
- Function: Attaches to microtubules, mediating chromosome movement during mitosis and meiosis.
- Location: Attached to the centromere.
Kinetochore, chromosome condensation, and centromere positioning:
- A tightly regulated process, involving kinase activity and the Anaphase Promoting Complex (APC).
Telomere:
- Function: Protect chromosome ends from degradation and fusion, and regulate cell lifespan.
- Length: Telomeres shorten with each cell division; telomerase enzyme adds nucleotides to the ends to prevent depletion.
- Telomerase activity: Can be regulated by various factors, influencing cell ageing and proliferation.
- Consequences of telomere change: Changes in telomere length affect cellular processes such as cell division, aging, and cancer development.
Telomere Associated Proteins:
- They protect telomeres and regulate telomerase activity.

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Test your understanding of chromatin, chromosomes, and their structures with this quiz. Dive into essential concepts such as chromatids, histones, and the function of nucleosomes. This quiz will help reinforce your knowledge of cell division and genomic organization.