IB Biology Topic D3.1.14 Spermatogenesis and Oogenesis in Humans Revision Notes (HL)

IB Biology Topic D3.1.14 Spermatogenesis and Oogenesis in Humans Revision Notes (HL) | RevisionDojo

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Spermatogenesis and Oogenesis Are Both Forms of Gametogenesis

Both processes pass through four shared stages.
1. Mitosis: germ-line cells divide to produce more cells.
2. Cell growth: cells increase in size and prepare for meiosis.
3. Meiosis I and II: two divisions reduce the chromosome number from diploid to haploid.
4. Differentiation: cells develop the specialised features they need.
The two processes differ in timing, number of gametes, and cytoplasm distribution.

Definition

Gametogenesis

The process by which cells undergo meiosis to form gametes.

Spermatogenesis Produces Four Small Motile Sperm

Location: the seminiferous tubules of the testes.
Timing: continuous from puberty, producing millions of sperm daily.
Number of gametes: four functional sperm per primary spermatocyte.
Cytoplasm: minimal, so sperm stay streamlined for movement.
Purpose: maximise gamete number to raise the chance of fertilisation.

Stage 1: Mitosis and Cell Growth

Spermatogonia (diploid stem cells) divide by mitosis in the germinal epithelium, the outer layer of the seminiferous tubules.
Some spermatogonia stay as stem cells, while others grow into primary spermatocytes (larger diploid cells).

Hint

Mitosis in the outer layer keeps a constant supply of stem cells, so sperm production never runs out.

Stage 2: Meiosis

Meiosis I
1. Each primary spermatocyte (diploid) undergoes meiosis I.
2. This produces two secondary spermatocytes (haploid).
Meiosis II
1. Each secondary spermatocyte undergoes meiosis II.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Spermatogenesis and Oogenesis Are Both Forms of Gametogenesis

Both processes pass through four shared stages.
1. Mitosis: germ-line cells divide to produce more cells.
2. Cell growth: cells increase in size and prepare for meiosis.
3. Meiosis I and II: two divisions reduce the chromosome number from diploid to haploid.
4. Differentiation: cells develop the specialised features they need.
The two processes differ in timing, number of gametes, and cytoplasm distribution.

Definition

Gametogenesis

The process by which cells undergo meiosis to form gametes.

Spermatogenesis Produces Four Small Motile Sperm

Location: the seminiferous tubules of the testes.
Timing: continuous from puberty, producing millions of sperm daily.
Number of gametes: four functional sperm per primary spermatocyte.
Cytoplasm: minimal, so sperm stay streamlined for movement.
Purpose: maximise gamete number to raise the chance of fertilisation.

Stage 1: Mitosis and Cell Growth

Spermatogonia (diploid stem cells) divide by mitosis in the germinal epithelium, the outer layer of the seminiferous tubules.
Some spermatogonia stay as stem cells, while others grow into primary spermatocytes (larger diploid cells).

Hint

Mitosis in the outer layer keeps a constant supply of stem cells, so sperm production never runs out.

Stage 2: Meiosis

Meiosis I
1. Each primary spermatocyte (diploid) undergoes meiosis I.
2. This produces two secondary spermatocytes (haploid).
Meiosis II
1. Each secondary spermatocyte undergoes meiosis II.

Definition

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anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D3.1.14: Spermatogenesis and Oogenesis in Humans Notes

Spermatogenesis and Oogenesis Are Both Forms of Gametogenesis

Spermatogenesis Produces Four Small Motile Sperm

Stage 1: Mitosis and Cell Growth

Stage 2: Meiosis

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Spermatogenesis and Oogenesis Are Both Forms of Gametogenesis

Spermatogenesis Produces Four Small Motile Sperm

Stage 1: Mitosis and Cell Growth

Stage 2: Meiosis

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics