Mitosis and Centromeres Quiz

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Questions and Answers

Which type of chromosome has its centromere located at the terminal position?

Metacentric

Telocentric (correct)

Submetacentric

Acrocentric

What is the shape of a metacentric chromosome at anaphase?

V (correct)

L or J

In polytene chromosomes, what does the dark banding usually represent?

Sites of chromosomal rearrangement

Areas of high transcriptional activity

Inactive chromatin (correct)

Duplicated DNA sequences

Which chromosome type has unequal arm lengths and a submedian centromere position?

Submetacentric Signup and view all the answers

Where are polytene chromosomes primarily found?

Salivary gland cells in larval stages Signup and view all the answers

What role do spindle fibers play during mitosis?

They attach to the centromere via the kinetochore. Signup and view all the answers

What is the function of the kinetochore?

To facilitate the connection of spindle fibers to centromeres. Signup and view all the answers

What occurs during the anaphase stage of mitosis?

Sister chromatids are pulled apart and move to opposite poles. Signup and view all the answers

Which part of a chromosome is known as the P arm?

The shorter segment of the chromosome. Signup and view all the answers

What do telomeres do?

They protect the ends of chromosomes from degradation. Signup and view all the answers

What is indicated by the term 'Nucleolar Organizing Region'?

A region where ribosomal RNA is synthesized. Signup and view all the answers

What structure is involved in the actual events of chromosome segregation?

Centromere. Signup and view all the answers

How are human chromosomes characterized in terms of telomeric repeat sequence?

They are capped by a grey telomeric repeat sequence. Signup and view all the answers

What structure is essential for dividing chromosomes during mitosis?

Mitotic spindle Signup and view all the answers

What is trisomy?

The presence of an extra chromosome Signup and view all the answers

Which stage of mitosis involves the chromosomes lining up at the cell's equator?

Metaphase Signup and view all the answers

Which of the following conditions is an example of trisomy?

Down Syndrome Signup and view all the answers

What type of chromosomes are found in the growing oocytes of most animals?

Lampbrush chromosomes Signup and view all the answers

What is a characteristic feature of Patau Syndrome (Trisomy 13)?

No eyes or nose opening Signup and view all the answers

During which phase of cell division does cytokinesis typically occur?

Telophase Signup and view all the answers

Which syndrome is associated with a karyotype of 47-XXX?

Metafemale Syndrome Signup and view all the answers

What defines chromosomal mosaicism?

Different chromosomal populations within an individual Signup and view all the answers

What are centrioles primarily associated with in animal cells?

Organizing microtubule arrangement Signup and view all the answers

What is a notable difference between centrioles in animal and plant cells?

Centrioles are absent in plant cells Signup and view all the answers

Which of the following features is characteristic of Edward Syndrome (Trisomy 18)?

Short breastbone Signup and view all the answers

Jacob Syndrome is characterized by having which karyotype?

44-XYY Signup and view all the answers

What type of appearance do lampbrush chromosomes exhibit?

Hairy and branched Signup and view all the answers

What is the primary function of the centrosomes during cell division?

To organize the formation of the mitotic spindle Signup and view all the answers

What is a common feature of Turner Syndrome?

Absence of one X chromosome Signup and view all the answers

What structures become visible during prophase of mitosis?

Chromosomes Signup and view all the answers

Which phase of mitosis is characterized by the alignment of chromosomes at the metaphase plate?

Metaphase Signup and view all the answers

What are the daughter cells formed during cytokinesis derived from?

Single diploid cell Signup and view all the answers

In which phase do the spindle microtubules attach to the kinetochores of chromosomes?

Prometaphase Signup and view all the answers

What is the significance of the cleavage furrow during mitosis?

It aids in the cytokinesis process in animal cells. Signup and view all the answers

What important process occurs at the beginning of anaphase?

Cohesion of sister chromatids breaks down Signup and view all the answers

Which of the following describes the cell plate formation during cytokinesis?

It leads to the formation of a new cell wall in plant cells. Signup and view all the answers

What can be concluded from chromosomal aberrations induced by QPE herbicide in Allium cepa root tip cells?

They provide evidence of genotoxic effects. Signup and view all the answers

Study Notes

Centromere and Chromosomes

Spindle fibers attach to the centromere via the kinetochore during mitosis, essential for chromosome segregation.
Chromosomes consist of arms designated as P (short arm) and Q (long arm).
Secondary constriction regions, known as Nucleolar Organizing Regions, are where the nucleolus forms.

Telomeres and Aging

Telomeres protect chromosome ends, with telomeric repeat sequences crucial in cellular aging and replication.

Types of Chromosomes Based on Centromere Position

Metacentric chromosomes: centromere located at the median, producing equal-length arms shaped in a V.
Submetacentric chromosomes: centromere slightly off the center, arms are unequal, shaped like L or J.
Telocentric chromosomes: centromere at terminal ends, resulting in highly unequal arm lengths.
Acrocentric chromosomes: centromere close to one end, producing very unequal arms.

Polytne and Lampbrush Chromosomes

Polytene chromosomes form through multiple DNA replications, resulting in giant chromosomes with distinct light and dark banding patterns found in Drosophila larval salivary glands.
Lampbrush chromosomes appear in growing oocytes of most animals, featuring chromomeres and large chromatin loops, contributing to their "hairy" appearance during Prophase I.

Mitosis Overview

Mitosis encompasses a series of stages: Prophase, Metaphase, Anaphase, and Telophase.
The mitotic spindle, composed of microtubules, is essential for dividing chromosomes and is organized by centrosomes, which contain centriole pairs in animal cells.

Stages of Mitosis

Interphase: chromatin visible, centrosomes present.
Prophase: early spindle formation; nuclear envelope begins disassembly.
Metaphase: chromosomes align at the metaphase plate; spindle microtubules attach at kinetochores.
Anaphase: sister chromatids separate and move to opposite poles.
Telophase and Cytokinesis: nuclear envelope reforms; cleavage furrow forms; daughter cells are created.

Chromosomal Aberrations

Chromosomal aberrations can be induced by environmental factors, evidenced by studies using Allium cepa root tip cells showing trisomy and related conditions.
Trisomy 13 (Patau Syndrome) and Trisomy 18 (Edward Syndrome) exhibit severe congenital features and developmental issues.

Genetic Conditions

Turner Syndrome (45, X) and Klinefelter Syndrome (47, XXY) are examples of aneuploidy affecting phenotype.
Genetic abnormalities can result in unique conditions, such as the Jacob Syndrome (44, XYY), which may be linked to various behaviors.

Chromosomal Mosaicism

Chromosomal mosaicism refers to individuals having two or more cell populations with different chromosomal compositions, potentially leading to variations in phenotype and development.

Cri-du-chat Syndrome

A genetic disorder characterized by a deletion of part of chromosome 5, leading to distinctive physical and developmental challenges.

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Description

Test your understanding of mitosis and the role of centromeres in cell division. This quiz will cover how spindle fibers interact with the centromere through the kinetochore. Improve your knowledge about the critical processes involved in cellular reproduction.