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76 Cards in this Set
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autosomal cells |
diploid (2n), which means they contain two copies of each chromosome; for humans, diploid cells have 46 chromosomes |
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germ cells |
haploid (n), which means they contain only one copy of each chromosome; for humans, haploid cells have 23 chromosomes |
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four stages of cell cycle |
G1 S G2 M |
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interphase |
first three stage of the cell cycle (G1, S and G2); longest part of cell cycle (90%); |
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G0 stage |
cell is simply living and serving its function without any preparation for division; offshoot of G1 phase |
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chromatin |
less condensed form of chromosomes during interphase; available for RNA polymerase to transcribe genes |
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G1 stage |
presynthetic gap; cell creates organelles for energy and protein production while also increasing in size; must pass a restriction point before it goes onto S stage |
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S stage |
synthesis of DNA; cell replicates its genetic material so two identical chromatids which are bound together at the centromere are formed; *although there are 92 chromatids now, still only 46 chromosomes |
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G2 stage |
postsynthetic gap; includes another quality control checkpoint before going onto M stage |
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M stage |
consists of mitosis and cytokinesis; |
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phases of mitosis |
prophase metaphase anaphase telophase |
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cytokinesis |
splitting of cytoplasm and organelles into two daughter cells |
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p53 |
main protein involved in checkpoint between G1 and S stages (restriction point); if there is any damage to DNA, cell does not go onto S stage until it is fixed; also plays role in G2/M checkpoint |
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cyclins and cyclin-dependent kinases (CDK) |
during cell cycle, cyclins bind to CDKs, creating an activated CDK-cyclin complex which phosphorylates transcription factors which promote transcription of genes required for next stage of cell cycle |
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TP53 |
gene that produces p53; mutation of this gene leads to cancer because cell cycle is not stopped when DNA is damaged |
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metastasis |
distant spread of cancerous cells through the bloodstream or lymphatic systems |
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prophase |
chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus begins to form; kinetochore of each chromosome is contacted by a spindle fiber |
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asters |
microtubules also coming out of centrioles that anchor them to cell membrane |
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metaphase |
chromosomes are aligned at the metaphase or equatorial plate |
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anaphase |
centromeres split so each chromatid has its own distinct centromere; sister chromatids are split and pulled to opposite poles of cell |
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telophase |
reverse of prophase; spindle apparatus disappears; nuclear membrane reforms around each set of chromosomes and nucleoli reappear; chromosomes uncoil |
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reductional division |
takes place during meiosis I; homologous chromosomes are separated, generating haploid daughter cells |
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equational division |
takes place during meiosis II; similar to mitosis because sister chromatids are separated |
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prophase I |
the same events occur as in prophase of mitosis, except that homologues come together and intertwine in a process called synapsis; the four chromatids are referred to as a tetrad, and crossing over exchanged genetic material from a chromatid in the homologous chromosome |
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chiasma |
point of synapsis where chromatid of homologous chromosome in tetrad may break |
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Mendel's second law of independent assortment |
the inheritance of one allele has no effect on the likelihood of inhering certain alleles of other genes; crossing over explains this |
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disjunction |
during anaphase I, homologous pairs separate and are pulled to opposite poles of the cell; accounts for Mendel's first law of segregation; |
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segragation |
separating of the two homologous chromosomes in meiosis |
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ovum |
can only carry the X chromosome (female equivalent of sperm) |
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hemizygous |
this is the term for males with respect to many of the genes on the X chromosome because they only have one copy |
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SRY (sex-determining region Y) |
no-table gene on the Y chromosome which codes for a transcription factor that initiates testis differentiation and, thus, the formation of male gonads |
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two functional components of testes |
seminiferous tubules and interstitial cells (of Leydig) |
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seminiferous tubules |
produce sperm through spermatogenesis |
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Sertoli cells |
nourish sperm |
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interstitial cells (of Leydig) |
secrete testosterone and other male sex hormones (androgens) |
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epididymis |
where sperm is stored until ejaculation once they are formed and gain motility |
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ejaculation |
sperm travel through the vas deferens (or ductus deferens) to the ejaculatory duct to the urethra and out through the penis |
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seminal vesicles |
contribute fructose to nourish sperm and produce alkaline fluid (seminal fluid) |
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prostate gland |
also produces alkaline fluid (seminal fluid) |
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bulbourethral (Cowper's) gland |
produce a clear viscous fluid (seminal fluid) that cleans out any remnants of urine and lubricates the urethra during sexual arousal |
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spermatogonia |
in males, the diploid stem cells |
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primary spermatocytes |
in males, germ cells after S stage |
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secondary spermatocytes |
in males, germ cells after meiosis I |
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spermatids |
in males, germ cells after meiosis II |
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spermatozoa |
in males, germ cells after maturation |
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sperm head |
contains the genetic material of sperm |
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sperm midpiece |
generates ATP from fructose for sperm; filled with mitochondria |
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sperm flagellum |
for motility of sperm |
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acrosome |
cap which covers sperm head; derived from the Golgi apparatus and is necessary to penetrate the ovum |
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follicles |
make up ovaries; multilayered sacs that contain, nourish and protect immature ova (eggs) |
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peritoneal sac |
lines the abdominal cavity; once a month an egg is ovulated through there |
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fallopian tube or oviduct |
egg is drawn into there after peritoneal sac; lined with cilia to propel the egg forward |
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cervix |
lower end of the uterus; connects to the vaginal canal |
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oogenesis |
production of female gametes; one haploid ovum and a variable number of polar bodies are formed from an oogonium |
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primary oocytes |
all oogonia which have already undergone replication before birth; arrested in prophase I; 2n |
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secondary oocyte |
ovulated egg each month which is arrested in metaphase II; does not complete remainder of meiosis II unless fertilization occurs |
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ovum |
oocyte which has been fertilized and undergone meiosis II |
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polar body |
formed because cytokinesis is uneven in oogenesis; cell which receives very little cytoplasm and organelles |
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zona pellucida |
surrounds oocyte itself; acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding |
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corona radiata |
lies outside zona pellucida; layer of cells that adhered to the oocyte during ovulation |
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menarche |
first menstrual cycle |
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pronucleus |
haploid; nucleus of either the sperm or the egg right before they merge |
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zygote |
created when the pronuclei of the sperm and ovum join; diploid |
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gonadotropin-releasing hormone (GnRH) |
produced at the start of puberty when hypothalamus lifts restriction of its production; triggers anterior pituitary gland to synthesize and release follicle stimulating hormone (FSH) and luteinizing hormone (LH) the functions of which depend on the sex of the individual |
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follicle stimulating hormone (FSH) |
in males: stimulates the Sertoli cells and triggers sperm maturation in females: leads to estrogen secretion |
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luteinizing hormone (LH) |
in males: causes the interstitial cells to produce testosterone in females: tells the corpus luteum to secrete progesterone |
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endometrium |
lining of the uterus |
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estrogen |
lead to thickening of the lining of the uterus (endometrium) |
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progesterone |
involved in the development and maintenance of the lining of uterus (endometrium) |
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menstrual cycle events |
follicular phase ovulation luteal phase menstruation |
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follicular phase |
begins when the menstrual flow begins; GnRH secretion stimulates FSH and LH secretion, which promotes follicle development; estrogen is released, stimulating vascularization and glandularization of the decidua |
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ovulation |
stimulated by a sudden surge in luteinizing hormone (LH); surge occurs because estrogen stops having negative feedback effects at a certain threshold and begins to have positive feedback effects |
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luteal phase |
luteinizing hormone (LH) promotes the ruptured follicle to become the corpus luteum, which secretes progesterone that maintains the uterine lining; high estrogen and progesterone levels cause negative feedback to GnRH, LH and FSH |
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menstruation |
as estrogen and progesterone levels drop, the endometrial lining is sloughed off and the block on GnRH production is removed |
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human chorionic gonadotropin (hCG) |
produced by the blastula if fertilization occurs; luteinizing hormone (LH) analogue; can maintain corpus luteum; near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production |
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menopause |
occurs when ovaries stop producing estrogen and progesterone; FSH and LH levels rise |