Quiz: Cell Cycle and Chromosome Dynamics — 5 perguntas

1. Which term describes the division of the cytoplasm that occurs after nuclear division, resulting in two separate cells?

A. Meiosis

B. Cytokinesis

C. Karyokinesis

D. Mitosis

Answer: (B)

Explicação

Cytokinesis is the process of dividing the cytoplasm after nuclear division, leading to two distinct cells. Mitosis and meiosis refer to nuclear division, while karyokinesis is the division of the nucleus itself, which is part of mitosis or meiosis. The definition provided explicitly describes cytokinesis.

2. Which chromosome abnormality is primarily caused by nondisjunction during cell division?

A. Crossing over between homologous chromosomes

B. Deletion of chromosome parts

C. Translocation of chromosome segments

D. Aneuploidy leading to abnormal chromosome numbers

Answer: (D)

Explicação

Nondisjunction is the failure of chromosomes to separate properly during cell division, which primarily causes aneuploidy, an abnormal number of chromosomes. Among the options, aneuploidy is directly caused by nondisjunction, making it the correct answer. Translocation and crossing over are different types of chromosome abnormalities that involve chromosome segments but are not caused by nondisjunction. Deletion involves loss of chromosome parts, not the failure of chromosome separation.

3. How does programmed cell death (apoptosis) differ from necrosis?

A. Apoptosis is a regulated process that removes cells without causing inflammation, while necrosis is uncontrolled and causes inflammation.

B. Both apoptosis and necrosis are regulated processes that do not cause inflammation.

C. Necrosis is a regulated process that prevents inflammation, unlike apoptosis which causes inflammation.

D. Apoptosis causes inflammation, whereas necrosis does not.

Answer: (A)

Explicação

The source states that apoptosis is a regulated process that removes damaged or unnecessary cells without causing inflammation, whereas necrosis is uncontrolled and often results in inflammation. This fundamental difference makes option 0 the correct answer.

4. Who is credited with discovering the regulatory role of cyclin-dependent kinases in cell cycle control?

A. Timothy J. Hunt

B. Harold Varmus

C. Paul M. Nurse

D. Leland H. Hartwell

Answer: (C)

Explicação

Paul M. Nurse is credited with discovering that cyclin-dependent kinases (Cdks) require binding to cyclins to become active and regulate the cell cycle, an essential breakthrough in understanding cell cycle control.

5. What is the centromere in chromosome structure?

A. A protein complex that packages DNA into nucleosomes

B. The DNA sequence that codes for a specific gene

C. The region where sister chromatids are joined and spindle fibers attach

D. The end region of a chromosome that protects the genetic material

Answer: (C)

Explicação

The centromere is the region where sister chromatids are joined, serving as the attachment point for spindle fibers during cell division. This is essential for proper segregation of chromosomes. The other options describe different chromosome features: a gene-coding sequence, a protein complex involved in chromatin structure, and chromosome telomeres, respectively.