Biology Cell Types and Chromosome Structure

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Questions and Answers

What phase of the cell cycle is primarily focused on the replication of chromosomes?

Growth Stage 1 (G1)

Growth Stage 2 (G2)

Metaphase

Synthesis Stage (S) (correct)

During which phase of mitosis do chromosomes condense and spindle fibers begin to form?

Prophase (correct)

Telophase

Metaphase

Anaphase

What occurs during the G2 phase of interphase?

Cell size decreases and energy levels drop.

Chromosomes are replicated.

Preparation for mitosis is finalized, including organelle production. (correct)

Spindle fibers form and chromatin condenses.

Which of the following accurately describes the state of chromatin at the end of interphase?

Loosely coiled, allowing for DNA copying. (D) Signup and view all the answers

What is the role of spindle fibers during metaphase?

To align chromosomes along the equator of the cell. (B) Signup and view all the answers

Which event is not a characteristic of prophase?

Synthesis of DNA occurs. (B) Signup and view all the answers

Which of the following phases has the longest duration in the cell cycle?

Interphase (C) Signup and view all the answers

What happens to the centrioles during metaphase?

They move to opposite ends of the cell. (B) Signup and view all the answers

What is the number of chromosomes in a human cell?

46 chromosomes (A) Signup and view all the answers

During which phase of the cell cycle is DNA duplicated?

S phase (B) Signup and view all the answers

Why is mitosis important for an organism?

To replace damaged tissues and produce new cells (D) Signup and view all the answers

Which phase of the cell cycle is the longest?

Interphase (A) Signup and view all the answers

What happens to chromosomes during mitosis?

They duplicate and then separate (C) Signup and view all the answers

What is the primary reason cells divide?

To grow, repair, and maintain proper size (B) Signup and view all the answers

How many chromosomes do dogs typically have?

78 chromosomes (B) Signup and view all the answers

Which statement is true about sex cells compared to somatic cells?

They have half the number of chromosomes as somatic cells (B) Signup and view all the answers

What is the primary difference between prokaryotic and eukaryotic cells concerning their genetic material?

Prokaryotic cells have DNA floating in the cytoplasm while eukaryotic cells have DNA in the nucleus. (B) Signup and view all the answers

What structure do eukaryotic chromosomes consist of?

Linear DNA coiled around histone proteins. (D) Signup and view all the answers

What happens to sister chromatids during cell division?

They separate, with one going to each new cell. (C) Signup and view all the answers

Why does DNA change from chromatin to chromosome during cell division?

To ensure more efficient division of genetic material. (D) Signup and view all the answers

Which statement about prokaryotic cells is correct?

They have circular chromosomes and may have plasmids. (D) Signup and view all the answers

In which cellular process does mitosis occur?

After cells have completed DNA replication. (C) Signup and view all the answers

What is the function of the centromere in a chromosome?

It holds sister chromatids together until they are separated. (D) Signup and view all the answers

Which type of cells are characterized by having membrane-bound organelles?

Eukaryotic cells. (C) Signup and view all the answers

What occurs during anaphase?

Sister chromatids separate. (B) Signup and view all the answers

Which force is involved in the separation of sister chromatids during anaphase?

Repulsion force and attractive force. (A) Signup and view all the answers

What happens during telophase?

Nuclear membranes form around sets of chromosomes. (A) Signup and view all the answers

Which structure disappears at the end of telophase?

Spindle fiber. (C) Signup and view all the answers

What is the main distinction between cytokinesis in animal and plant cells?

Animal cells form a furrow, while plant cells form a cell plate. (B) Signup and view all the answers

Which of the following statements is true regarding daughter cells after cytokinesis?

They are genetically identical to the parent cell. (C) Signup and view all the answers

What primarily occurs to chromosomes during telophase?

They begin to uncoil. (A) Signup and view all the answers

Which of the following best describes spindle fibers?

They assist in the movement of chromosomes during cell division. (D) Signup and view all the answers

Study Notes

Cell Types

Two categories: Eukaryotic cells (have membrane-bound organelles) and prokaryotic cells (lack membrane-bound organelles).
Eukaryotic cells are found in multicellular organisms like plants and animals, while prokaryotic cells are found in unicellular organisms like bacteria.
Differences in organelles, genetic material, and chromosome structure distinguish the two.

Chromosome Structure

DNA is located in the nucleus and controls all cellular activities, including cell division.
Chromatin is long, thread-like DNA in a non-dividing cell.
Chromosomes are doubled, coiled, short DNA in a dividing cell, made of two parts:
- Chromatid: two identical "sister" chromatids attached at the centromere.
- Centromere: the area in the middle where sister chromatids are attached.
During cell division, sister chromatids separate and one goes to each new cell.

Number of Chromosomes

Constant for all members of a species: humans have 46 chromosomes (23 pairs), dogs have 78 (39 pairs), goldfish have 94 (47 pairs), and lettuce has 18 (9 pairs).
Constant throughout an individual's life.
Constant for each cell in the body except sex cells, which only have half sets.

Cell Division

Cells divide to allow organisms to grow, repair damaged tissue, and ensure efficient nutrient uptake.
Mitosis is the division of the nucleus into two nuclei, each with the same number of chromosomes.
Mitosis occurs in all somatic (body) cells, ensuring each new daughter cell has a complete set of chromosomes.

The Cell Cycle and Mitosis

The cell cycle has three stages: Interphase, Mitosis, and Cytokinesis.
Interphase: The cell carries out normal functions and prepares for division.
- G1 phase: The cell increases in size, synthesizes new proteins, and organelles.
- S phase: The cell duplicates its DNA.
- G2 phase: The cell prepares for mitosis by producing organelles and molecules needed for division.
Mitosis: The nucleus divides into two equal parts.
Cytokinesis: The separation of two nuclei and cell contents into two daughter cells.

Stages of Mitosis

Prophase: Chromosomes condense, spindle fibers form, and chromosomes are captured by spindle fibers.
Metaphase: Chromosomes line up along the equator of the cell, attached to spindle fibers.
Anaphase: Sister chromatids separate, pulled toward opposite poles by shortening spindle fibers.
Telophase: Two new nuclear membranes form around the chromosomes, the spindle fibers disappear, chromosomes uncoil, and the cell begins to divide.

Cytokinesis

Cytokinesis is the division of cytoplasm after telophase.
Animal cells form a cleavage furrow to divide.
Plant cells form a cell plate to divide.
Both daughter cells are genetically identical to the parent cell.

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Description

Explore the fundamental differences between eukaryotic and prokaryotic cells, as well as the intricate structure of chromosomes. This quiz covers the organization of DNA, chromatin, and the process of cell division. Understand how these concepts are crucial for the functioning of living organisms.