Ch. 2: Reproduction Flashcards
What the difference between a diploid (2n) and a haploid (n) cell?
diploid - two copies of each chromosome (animals)
haploid - one copy of each chromosome (germ)
What is interphase?
interphase contains stages G1, S, and G2 and is th elongest part of the cell cycle
DNA is in a less condensed form of chromatin
Presynthetic Gap
Explain the G1 stage.
cells create organelles for energy and protein production
must pass restriction point which ensures that there is the proper complemet of DNA
Synthesis of DNA
Explain the S stage.
cell replicates its genetic material so that each chromosome has two identical chromatids bound by a centromere
Explain the G2 stage.
the cell passes a checkpoint that ensures there are enough organelles and cytoplasm for two daughter cells as well as DNA replication proceeded correctly
there is twice the amount of DNA present (46 chromosomes but 92 chromatids)
Mitosis
Explain the M stage.
- prophase
- metaphase
- anaphase
- telophase
- cytokinesis - splitting the cytoplasm and organelles between the daughter cells
Explain prophase.
condesnation of chromatin into chromosomes
spindle fibers form
Explain metaphase.
centriole pairs at opposite sides of the cell
chromosomes align at the metaphase plate/equatorial plate
Explain anaphase.
centromeres split
sister chromatids separate to opposite sides of the cell
Explain telophase.
spindle disappears
nuclear membrane forms around each set of chromosomes
Explain the G0 stage.
cell is living and carrying out functions without preparing for division
What is checked at the the G1/S checkpoint?
ensure that the DNA is good enough for synthesis
controlled by protein p53
What is checked at the G2/M checkpoint?
ensure the check is proper size and the organelles have been properly replicated
What are cylins and cyclin dependent kinases (CDK)?
cyclins bind to CDKs to create a complex
the complex phosphorylates transcription factors that promote transcription of genes for next stage of cell cycle
responsible for cell cycle control
What occurs in the cell cylce with cancer?
What is metastasis?
there is a problem with cell cycle control
common mutation in the gene (TP53) that produces p53 so that the cell cycle doesn’t stop to repair damaged DNA
there will be continous division without regard to quality or quantity of cells produced
Metastasis: spread of cancerous cells through blood stream or lymphatic system
What is meiosis?
occurs in gametocytes and results in four nonidentical gametes (sex cells with one chromatid in each cell)
one round of replication and two rounds of division
What occurs in meiosis I?
homologous chromosomes being separated resulting in haploid daughter cells (reductional division)
What occurs in meiosis II?
similar to mitosis
results in separation of sister chromatids (equational division)
Difference between meiosis I and mitosis?
in meiosis I, synapsis occurs which is when the homologous chromosomes come together and intertwine
crossing over occurs between the four chromatids which is exchanging gentic material between the chromatids
Difference between meiosis II and mitosis?
it mitosis each chromosome is lined up on the metaphase plate by two spindle fibers
in meiosis each homologous chromosomes are lined up acroos from each other at the metaphase plate nad are held by one spindle fiber
Pathway of sperm through the male reproduc
Explain spermatogenesis.
Formation of haploid sperm through meiosis
1. Diploid cells - spermatogonia
2. After S stage develop into primary spermatocytes
3. After first meiosis division results in secondary spermatocytes
4. After meiosis II develops haploid spermatids
5. After maturation germ cells are called spermatozoa
Explain the structure of sperm.
Contain head, mid piece and flagella
Head- contains genetic material and has an acrosome that helps sperm fuse and penetrate ovum
Midpiece- contains many mitochondria and generates ATP
Flagellum - promotes motility
In the male reproductive system, what secretes testosterone?
In the testes the interstitial cells of Leydig
What produces estrogen and progesterone in the female reproductive anatomy?
Ovaries
They also contain the eggs/ova which are produced by follicles in the ovaries
Explain oogenisis.
- At birth all oogonia have already undergone replication and are primary oocytes
- Each month when an egg is ovulated it completes meiosis I to become a secondary oocyte
- The remainder of meiosis II does not occur until fertilization
Oocytes are surrounded by the zona pellucida which protects the oocyte and has compounds needed for sperm binding
What is gonadotropin-releasing hormone (GnRH)?
Form the hypothalamus and promotes follicle stimulation hormone (FSH) and luteinizing hormone (LH)
In males it promotes testosterone causing puberty changes
Can females it causes ovulation and promotes estrogen and progesterone
What occurs in the follicular phase?
GnRH stimulates FSH and LH secretion for follicular development
Estrogen is also released
What occurs in ovulation?
Sudden surge of LH
Surge is triggered when estrogen levels reach a threshold
What happens in the literal phase?
High levels of progesterone and estrogen and this causes negative feedback on GnRH, LH, and FSH (block)
What occurs in menstruation?
When there is no fertilization
Estrogen and progesterone levels drop in block on GnRH production is removed
What occurs in menopause?
Ovaries stop producing progesterone and estrogen
FSH and LH levels rise
