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MCAT Bio. Ch. 2
| Term | Definition |
|---|---|
| Diploid (2n) Cells Have: | Two copies of each chromosome |
| Haploid (1n) Cells Have: | One copy of each chromosome |
| G1, S, G2 Stages Are Called: | Interphase, during which DNA is uncoiled in the form of chromatin |
| G1 Stage (Presynthetic Gap): | Cells create organelles for energy and protein production which increases their size. |
| Restriction Point In G1 Stage: | DNA is checked for quality and must be passed for the cell to move into the S stage. |
| S Stage (Synthesis): | DNA is replicated. The strands of DNA called chromatids are held together at the centromere. |
| G2 Stage (Postsynthetic Gap): | Further cell growth and replication of organelles in preparation for mitosis, and is another quality checkpoint must be passed for the cell to enter into mitosis. |
| M Stage (Mitosis) | Mitosis and cytokinesis occur |
| G0 Stage: | Cell performs its function without any preparation for division |
| p53: | Plays a role in the two major checkpoints of the cell cycle (G1 to S, and G2 to M) |
| Cyclins And Cyclin-Dependent Kinases (CDK): | Rise and fall during the cell cycle. Cyclins bind to CDKs thus phosphorylating and activating transcription factors for the next stage of the cell cycle. |
| Cancer | Occurs when cell cycle control becomes deranged and allows damaged cells to undergo mitosis without regard to quality or quantity of the new cells produced. |
| Mitosis Produces: | Two genetically identical diploid daughter cells from a single cell and occurs in somatic cells. |
| Prophase (Mitosis) | Chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opp. sides of the cell, and the spindle apparatus begins to form |
| Kinetochore Of Each Chromosome Is: | Contacted by a spindle fiber |
| Metaphase (Mitosis) | Chromosomes line up along the metaphase plate (equatorial plate) |
| Anaphase (Mitosis) | Sister chromatids are separated and pulled to opp. poles |
| Telophase (Mitosis) | Nuclear membrane reforms, spindle apparatus disappears, and cytosol and organelles are split between the two daughter cells through cytokinesis. |
| Meiosis Occurs In: | Gametocytes (germ cells) and produces up to four nonidentical haploid sex cells (gametes) |
| Meiosis I (Meiosis) | Homologous pairs of chromosomes (homologues) are separated from each other |
| Homologues | Chromosomes that are given the same number but are of opp. parental origin |
| Prophase I (Meiosis I) | Same events as prophase of mitosis, EXCEPT that homologues come together and intertwine in a process called synapsis |
| The Four Chromatids In Prophase I (Meiosis I) Are Called: | Tetrad. These chromatids cross over which exchanges genetic material from one chromatid with material from a chromatid in the homologous chromosome |
| Metaphase I (Meiosis I) | Homologous chromosomes line up on opposite sides of the metaphase plate |
| Anaphase I (Meiosis I) | Homologous chromosomes are segregated to opposite poles of the cell. --> Mendel's first law of segregation. The recombining of genes during crossover --> Mendel's second law of independent assortment |
| Telophase I (Meiosis I) | Chromosomes may or may not fully decondense and the cell may enter interkinesis after cytokinesis |
| Meiosis II | Sister chromatids are separated from each other that is functionally identical to mitosis. |
| Sister Chromatids Are: | Copies of the same DNA held together at the centromere |
| Sex Chromosome # = | 23rd pair. XX = female, XY = male |
| X Chromosome: | Carries a sizeable amount of genetic information. Mutations of which can cause sex-linked disorders. |
| Males Are (BLANK) with respect to the unpaired genes on the X chromosome | Hemizygous. Therefore, they will express sex-linked disorder. |
| Women With One Copy Of The Affected Allele Are Called: | Carriers |
| Y Chromosome Carries: | Little genetic information, but contains the SRY (sex-determining region Y) gene which causes the gonads to differentiate into testes. |
| Sperm Develop In The: | Seminiferous tubules in the testes, which are nourished by Sertoli cells |
| Interstitial Cells (Of Leydig) Secrete: | Testosterone and other male sex hormones (androgens) |
| Test Are Located In The : | Scrotum which hangs outside of the abdominal cavity and have a temp 2 to 4 C lower than the body |
| Sperm gains Motility In The: | Epididymis, and are stored there until ejaculation |
| During Ejaculation, Sperm Travel Through The: | Vas deferens to the ejaculatory duct to the urethra and out through the penis |
| Seminal Vesicles Contribute: | Fructose to nourish sperm and produce alkaline fluid |
| Prostate Gland Also: | Produces alkaline fluid |
| Bulbourethral Glands Produce: | A clear viscous fluid that cleans out any remains of urine and lubricates the urethra during sexual arousal |
| In Spermatogenesis, (BLANK) Sperm Are Produced From A Spermatogonium | Four haploid sperm |
| After S Stage, The Germ Cells Are Called: | Primary spermatocytes |
| After Meiosis I, The Germ Cells Are Called: | Secondary spermatocytes |
| After Meiosis II, The Germ Cells Are called: | Spermatids |
| After Maturation, The Germ Cells Are Called: | Spermatozoa |
| Acrosome Of A Sperm Cell | Contains the genetic material, and is a modified Golgi apparatus that contains enzymes to help the sperm fuse to and penetrate the ovum. |
| Midpiece Of A Sperm Cell: | Generates ATP from fructose and contains many mitochondria |
| Ova (eggs) Are Produced In The: | Follicles in the ovaries |
| An Egg Is Ovulated Into The: | Peritoneal sac and is drawn into the fallopian tube or oviduct. |
| Fallopian Tubes Are Connected To The: | Uterus, the lower end of which is called the cervix. |
| Vaginal Lies Below The: | Cervix and is the site where sperm are deposited during intercourse |
| External Female Anatomy Is Known As The: | Vulva |
| Oogenesis: | One haploid ovum and a number of polar bodies are formed from an oogonium |
| Oogonia That Have Already Undergone Replication At Birth And Are Arrested In Prophase I | Primary oocytes |
| Ovulated Egg Each Month Which Is Arrested In Metaphase II: | Secondary OOcyte |
| Polar Body | Cell receiving very little cytoplasm and organelles in cytokinesis portion of oogenesis |
| Zona Pullcida | Surrounds oocytes, its an acellular mix of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding |
| Corona Radiata | Layer of cells that adhered to the oocyte during ovulation |
| Gonadotropin-releasing Hormone (GnRH) From Hypothalamus: | Causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the functions of which depend on the sex of the individual |
| Testosterone | Responsible for the maintenance and development of the male reproductive system and male secondary sex characteristics |
| FSH In Women: | Stimulates development of the ovarian follicles while LH causes ovulation. These hormones also stimulate production of estrogens and progesterone. |
| Follicular Phase Of Menstrual Cycle: | GnRH secretion stimulates FSH and LH secretion, which promotes follicle development |
| Ovulation Is Stimulated By: | A sudden surge in LH. This surge occurs because estrogen stops having negative feedback effects at a certain threshold and begins to have positive feedback effects. |
| Luteal Phase Of Menstual Cycle | LH promotes the ruptured follicle to become the corpus luteum which secretes progesterone that maintains the uterine lining. |
| Menstruation Occurs If: | There is no fertilization. |
| If Fertilization Does Occur: | The blastula produces human chorionic gonadotropin (hCG) which is an LH analogue that can maintain the corpus luteum. |
| Menopause Occurs When: | The ovaries stop producing estrogen and progesterone between ages 45 and 55. |
Created by:
SamB91
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