Cell Cycle & Mitosis Quiz

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Questions and Answers

What is the primary source of primordial germ cells (PGCs)?

Chorionic cells from the placenta

Endodermal cells in the yolk sac

Epiblast cells formed during the second week (correct)

Mesoderm cells during gastrulation

What type of movement do embryonic cells exhibit during their migration to the gonads?

Ciliary movement

Flagellar movement

Passive diffusion

Amoeboid movement (correct)

Which chromosome configuration indicates a genetically male individual?

XY (correct)

How many homologous pairs of chromosomes do somatic cells contain?

23 Signup and view all the answers

Linked genes tend to be inherited together because they are located on:

The same chromosome Signup and view all the answers

During which developmental stage do primordial germ cells migrate through the primitive streak?

Gastrulation Signup and view all the answers

What layer do primordial germ cells appear in after migrating to the yolk sac?

Endoderm Signup and view all the answers

Which of the following tissues is NOT mentioned as a component of teratomas?

Nerve Signup and view all the answers

What does the term aneuploid refer to in a genetic context?

Having extra or missing chromosomes Signup and view all the answers

Which syndrome is characterized by the presence of 47 chromosomes with an XXY sex chromosomal complement?

Klinefelter Syndrome Signup and view all the answers

What is the estimated percentage of conceptions that end in spontaneous abortion due to major chromosomal abnormalities?

50% Signup and view all the answers

Which of the following characteristics is NOT typically associated with Trisomy 18?

High intelligence quotient Signup and view all the answers

What percentage of infants with Trisomy 18 live beyond one year of age?

5% Signup and view all the answers

Which condition is a result of having an extra copy of chromosome 21?

Down Syndrome Signup and view all the answers

Which of the following is common in individuals with Klinefelter Syndrome?

Presence of Barr body in cells Signup and view all the answers

What is the primary cause of aneuploidy during meiosis?

Disruption of chromosomal separation Signup and view all the answers

What is the role of oocyte maturation inhibitor (OMI) in the development of primary oocytes?

It maintains primary oocytes in an arrested state until puberty. Signup and view all the answers

How many primary oocytes are typically present at the onset of puberty?

40,000 Signup and view all the answers

Which of the following accurately describes the antrum in follicle development?

It is a fluid-filled space formed by coalescing spaces between granulosa cells. Signup and view all the answers

What is the fate of most oocytes during childhood?

They become atretic and do not survive. Signup and view all the answers

What structure surrounds the oocyte and provides support as it matures?

Cumulus oophorus Signup and view all the answers

Which follicular stage is the longest duration found in ovarian development?

Antral or vesicular stage Signup and view all the answers

What is a result of the selection process from the primordial follicle pool each month?

15 to 20 follicles begin to mature, with some dying off. Signup and view all the answers

What happens to the antrum as it develops over time?

It enlarges as more fluid accumulates. Signup and view all the answers

Which phase of the cell cycle is primarily characterized by the synthesis of DNA and the formation of sister chromatids?

S Phase Signup and view all the answers

What occurs during the G1 Phase of the cell cycle?

Growth and accumulation of energy reserves Signup and view all the answers

In which phase do chromosomes become distinguishable?

Prometaphase Signup and view all the answers

Which statement is true regarding cytokinesis?

It results in the formation of a cleavage furrow. Signup and view all the answers

During Metaphase, what structure is formed that helps in aligning the chromosomes?

Mitotic spindle Signup and view all the answers

What happens immediately after Telophase?

Cytokinesis begins. Signup and view all the answers

Which cell type might remain permanently in the G1 Phase and never divide?

Nerve cells Signup and view all the answers

What is the significance of sister chromatids during cell division?

They contain genetic material for the new cell. Signup and view all the answers

What happens to the majority of follicles that develop during an ovarian cycle?

They undergo atresia and degenerate. Signup and view all the answers

What effect does the surge in luteinizing hormone (LH) have on the secondary follicle?

It induces the preovulatory growth phase. Signup and view all the answers

During the completion of Meiosis I, how many daughter cells are formed, and what is their chromosome configuration?

Two daughter cells with 23 double-structured chromosomes. Signup and view all the answers

What is the fate of the first polar body formed during oocyte maturation?

It degenerates and provides no function. Signup and view all the answers

What structures surround the mature vesicular (graafian) follicle?

Theca interna and theca externa. Signup and view all the answers

Which of the following statements is true about the secondary oocyte and the first polar body?

The secondary oocyte receives most of the cytoplasm. Signup and view all the answers

What characterizes the theca interna surrounding the graafian follicle?

It contains steroid-secreting cells and is vascularized. Signup and view all the answers

What occurs when the graafian follicle ruptures?

Ovulation is triggered and the oocyte is released. Signup and view all the answers

Study Notes

Cell Cycle Phases

G1 Phase (Gap 1) is the longest phase, where the cell grows and gathers components for DNA replication.
Cells accumulate energy reserves necessary for chromosome replication during G1.
Some cells, such as nerve cells, may remain permanently in G1 without dividing.
S Phase (Synthesis) involves the synthesis of DNA, resulting in identical pairs of DNA molecules known as sister chromatids.

Mitosis Stages

Metaphase: Chromosomes align at the cell's equatorial plane, becoming distinguishable due to their doubled structure.
Microtubules connect chromosomes to centrioles, forming the mitotic spindle and facilitating chromosome alignment.
Telophase: The nuclear envelope reforms, leading into cytokinesis, where the cell's cytoplasm divides.
Cytokinesis begins with a cleavage furrow, followed by contracting cytoskeletal proteins that split the cell into two daughter cells.

Primordial Germ Cells (PGCs)

PGCs arise from the epiblast during the second week of embryonic development.
They migrate through the primitive streak during gastrulation, eventually reaching the yolk sac wall.
PGCs are essential for gamete formation and are influenced by their migratory pathways.

Chromosome Composition and Inheritance

Humans have 46 chromosomes, comprising 23,000 genes organized into 23 homologous pairs.
Chromosomes are categorized into 22 autosomes and 1 pair of sex chromosomes (XX for females, XY for males).
Linked genes are those situated on the same chromosome, typically inherited together.

Aneuploidy and Birth Defects

Aneuploidy refers to an abnormal number of chromosomes, either due to extra (trisomy) or missing (monosomy) chromosomes.
Chromosomal abnormalities contribute significantly to spontaneous abortions, with an estimated 50% loss rate post-conception.
Trisomy 21 (Down syndrome) exhibits distinct physical traits and can lead to various health issues, including intellectual disabilities and congenital heart defects.

Oocyte Development

Primary oocytes are arrested in prophase until puberty, with around 600,000 to 800,000 present at birth.
Only about 40,000 primary oocytes remain by the onset of puberty, with fewer than 500 ovulated in a lifetime.
Follicles undergo a maturation process, with the antral stage being the longest and most significant phase before ovulation.
Antral follicles form from coalescing fluid-filled spaces between granulosa cells, ultimately developing into mature Graafian follicles just prior to ovulation.

Hormonal Influence on Follicle Maturation

Luteinizing Hormone (LH) triggers the completion of meiosis I in the secondary follicle, producing a secondary oocyte and a first polar body.
The secondary oocyte retains the majority of the cytoplasm, while the first polar body receives minimal cytoplasm and eventually degenerates.
Maturing follicles are surrounded by the theca interna, which is vascularized and aids in steroid secretion, and the theca externa, which merges with the ovarian connective tissue.

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Description

Test your understanding of the cell cycle phases and stages of mitosis. This quiz covers key concepts including G1 phase, S phase, and the process of cytokinesis. Perfect for biology students looking to solidify their knowledge of cellular processes.