Reproduction Flashcards
Mitosis
Division and distribution of the cell’s DNA to its two daughter cells such that each cell receives a complete copy of the original genome.Nuclear division is followed by cell division. Before initiation of mitosis the cell undergoes interphase.
Interphase (Mitosis)
Cell spends 90% of its life. Growth period, four parts.
G1
1 of Interphase, initiates interphase, active growth phase, can vary in length, increases in size and synthesizes proteins. Length of G1 determines the length of the entire cell cycle.
S
2 of interphase, period of DNA synthesis
G2
3 of interphase, The cell prepares to divide. Grows and synthesizes proteins.
M
4 of interphase, cell division occurs (Mitosis), resulting in two identical daughter cells.
Prophase (Mitosis)
Chromosomes condense and the centriole pairs separate and move toward the opposite poles of the cell, spindle apparatus forms between them and the nuclear membrane dissolves allowing the spindle fibers to interact with the chromosomes.
Metaphase (Mitosis)
Centriole pairs are at opposite poles of the cell, fibers of the SA attach to each chromatid at the centromere to align the chromosome at the center of the cell forming the metaphase plate.
Anaphase (Mitosis)
Centromeres split so each chromatid has its own distinct centromere, sister chromatids are pulled toward the opposite poles of the cell by shortening spindle fibers
Telophase (Mitosis)
Spindle Apparatus disappears, nuclear membrane forms around each set of chromosomes, each nucleus contains the same number of chromosomes, chromosomes uncoil resuming interphase form
Cytokinesis (Mitosis)
Near the end of telophase cytoplasm divides into 2 daughter cells each with own set of organelles. Cleavage furrow forms and the cell membrane indents along the equator and pinches the cell separating the two nuclei
Meiosis
process by which gametes are produced, produces the haploid number. Involves two divisions of primary sex cells resulting in four haploid cells, gametes.
Interphase (Meiosis)
Parent cells chromosomes are replicated resulting in 2N sister chromatids
First Meiotic Division
Produces two intermediate daughter cells with N chromosomes with sister chromatids. Consists of Prophase I, Metaphase I, Anaphase I, and Telophase I.
Prophase I (Meiosis)
Chromatin condenses into chromosomes, spindle apparatus forms, nucleoli and nuclear membrane disappear. Homologous chromosomes come together, and intertwine by synapsis. Tetrad is formed.
Tetrad
Homologous chromosomes come together and intertwine by synapsis. Because each chromosome consists of two sister chromatids each synaptic pair of homologous chromosomes has four chromatids, called tetrad
Metaphase I (Meiosis)
Tetrads align at the equatorial plane, each pair attaches to a separate spindle fiber by its kinetochore
Anaphase I (Meiosis)
Homologous pairs separate, pulled to opposite poles of cell (disjunction)
Telophase I (Meiosis)
Nuclear membrane forms around each new nucleus. Each chromosome still consists of sister chromatids joined at the centromere.
Second Meiotic Division
Similar to mitosis, but not preceded by chromosomal replication. Chromosomes align at equator, separate and move to opposite poles and are surrounded by a reformed nuclear membrane.
Testes
Male reproductive physiology, located in scrotum. Produces testosterone which regulates secondary male sex characteristics
Scrotum
Male reproductive physiology , where testes are located. Maintains the testes temperature which is lower than body temperature, which is essential for sperm survival.
Spermatogenesis
Sperm production occurs in the seminiferous tubules. Spermatogonia (2N)–> primary spermatocytes (2N) –First Meiotic Division–> 2 secondary spermatocytes (1N)–Second Division–>4 Spermatids (1N) – Meiosis–> spermatozoa
Spermatozoa
Mature sperm, specialized for transporting the sperm nucleus to the ovum. Elongated cell with a head, neck, body, and tail. Nucleus is all in head. Tail is flagellum. Mitochondria in neck and body provide energy.
Acrosome
over the anterior half of the head of sperm, derived from the golgi apparatus and contains enzymes necessary to penetrate the covering of the ovum.
Ovaries
Found in the abdominal cavity, consist of thousands of follicles.
Follicles
Multilayered sac of cells that contains nourishes and protects an immature ovum. Produce estrogen.
Oviduct
Fallopian tubes. Opens into the upper end of the uterus. Immature ovum is drawn into here from the ovary each month.
Uterus
Muscular chamber. Site of fetal development. Lower, narrow end is the cervix.
Cervix
Lower, narrow end of the uterus. Connects with the vaginal canal
Vaginal Canal
Connects with the cervix. Site of sperm deposition during intercourse and passageway through which a baby is expelled.
Oogenesis
Production of female gametes, occurs in the ovarian follicles.
Primary Oocytes
Diploid cells, form by mitosis in the ovary. immature ova.
After Menarche…
1 primary oocyte per month completes meiosis I –> 2 daughter cells of unequal size, secondary oocyte and polar body –> Secondary oocyte expelled from follicle during ovulation–>FERTILIZATION, layers penetrated by sperm–> two 2N cells, mature ovum and polar body.
Mature Ovum
Large cell containing a lot of cytoplasm, RNA, organelles, and nutrients needed by a developing embryo.
Estrogen
Steroid hormone, need for normal female maturation, thickening of endometrium, secreted by ovarian follicles and corpus luteum.
Progesterone
Steroid hormone secreted by corpus luteum during the luteal phase of menstrual cycle, stimulates the development and maintenance of the endometrial walls in preparation for implantation.
Menstrual Cycle
Follicular phase, ovulation, luteal phase, and menstruation
Follicular phase
Begins with the cessation of the menstrual flow from the previous cycles, FSH from the anterior pituitary promotes the development of the follicle which grows and beings secreting estrogen.
Ovulation
Midway through the cycle, mature ovarian follicle bursts and releases an ovum. Caused by a surge in LH caused by peak in estrogen.
Luteal Phase
After ovulation, LH induces ruptured follicle to develop into the corpus luteum, which secretes estrogen and progesterone. Progesterone causes glands of the endometrium to mature and produce secretions preparing for implantation of embryo.
Menstruation
If ovum is not fertilized corpus luteum atrophies. Resulting drop in progesterone and estrogen causes the endometrium to slough off.
If fertilization does occur developing placenta produces hCG, maintaining the corpus luteum and supply of estrogen and progesterone until placenta produces these.
Fertilization (sperm to ovum)
Sperm must penetrate Corona Radiata : enzymes the sperm secretes help penetrate. Acrosome penetrates the zona pellucida by secreting enzymes to digest this layer. Sperm comes in direct contact with ovum cell membrane. Sperm forms acrosomal process whcih extends to the cell membrane and penetrates it fusing the sperm ovums cell membranes together. Sperm nucleus enters the ovum’s cytoplasm, ovum completes meiosis II.
Cortical reaction
Triggered by acrosomal reaction, calcium ions release into cytoplasm initiating series of reactions that form fertilization membrane, and stimulates metabolic changes within the ovum, followed by fusion of sperm nucleus with ovum nucleus forming diploid zygote. First mitotic division of zygote follows.
Fertilization Membrane
Hard layer that surrounds the ovum cell membrane and prevents multiple fertilizations
