Mar 4th Flashcards
What is gametogenesis?
The formation and genetic/phenotypic maturation of gametes.
How many chromosomes do gametes have compared to somatic cells?
Gametes are haploid, meaning they have half the number of chromosomes as somatic cells.
How many phases are there in gametogenesis?
4 phases
Which phase of gametogenesis is identical in both males and females?
The first phase.
What are the four phases of gametogenesis?
1️⃣ Migration of extraembryonic primordial germ cells (PGCs) to the gonads
2️⃣ Increase in PGCs by mitosis
3️⃣ Reduction of chromosomal material by meiosis
4️⃣ Structural and functional maturation (oogenesis/spermatogenesis)
What are primordial germ cells (PGCs)?
They are the earliest recognizable precursors of gametes.
Where do PGCs migrate to during early embryonic development?
They migrate into the gonads.
Where do PGCs originate?
Outside of the gonads, in the hindgut.
Is crossing over random?
No, it occurs at “hot spots” based on protein configurations that organize chromosomes early in meiosis.
Where does crossing over occur in sex chromosomes (X & Y)?
Within a small region of homology between the X and Y chromosomes.
What role does histone hypermethylation play in recombination?
It marks specific sites where DNA strands break and are repaired after crossing over.
What is the function of cohesion?
It holds sister chromatids together during cell division.
What is condensin’s role in cell division?
It is important for chromosomal compaction and is necessary for both mitotic and meiotic divisions.
Where does spermatogenesis occur?
testes
How long does spermatogenesis last?
It is an indefinite process, continuously producing sperm.
How many gametes are produced per cycle in spermatogenesis?
Four sperm cells per cycle.
What is spermatogenesis?
The process of producing spermatozoa from male primordial germ cells via mitosis and meiosis.
What are the initial cells in spermatogenesis called and how do they become spermatocytes
- Spermatogonia
- through mitosis
What are spermatogonia?
Diploid stem cells that give rise to two daughter cells.
What happens to the two daughter cells produced by spermatogonia?
One remains a stem cell at the basement membrane, and the other becomes a primary spermatocyte.
What occurs in the first meiotic division of spermatogenesis?
The primary spermatocyte duplicates its DNA and divides into two haploid secondary spermatocytes.
What happens in the second meiotic division of spermatogenesis?
The secondary spermatocytes divide into four haploid spermatids.
What are the four phases of spermatogenesis?
- Spermatocytogenesis – Formation of primary & secondary spermatocytes.
- Spermatidogenesis – Formation of spermatids from secondary spermatocytes.
- Spermiogenesis – Maturation of spermatids into immotile spermatozoa.
- Spermiation – Final maturation into motile spermatozoa.
What is spermatocytogenesis?
The process of forming spermatocytes with half the normal genetic material.