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MCAT Bio. Ch. 2

TermDefinition
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