Biology Ch. 1-4 Flashcards
Cell cylce
Cycle of cells life. consists of 4 primary stages: G1, S, G2 (interphase), and MPhase. 90% of cell life is in Interphase
G1 Phase
Presynthetic Gap. Cell creates organelles for energy production of new cell & increase in size for division.
S Phase
Synthesis of DNA. DNA joined at centromeres as sister chromatid. Still only at 46 chromosomes because they are attached.
G2 Phase
Postsynthetic Gap. Checkpoint. Checks to see if there are enough organelles and if DNA was replicated correctly.
M Stage
Mitosis. Contains 4 stages: Prophase, Metaphase, Anaphase, and Telophase.
G1/S Checkpoint
Determines if DNA is good for replication. Also known as a restriction point. Controlled by p53 protein.
G2/M checkpoint
focused on checking cell size and if organelles have been properly replicated.
Metastasis
Cancerous cells spread to lymphatic systems.
Prophase
Condensation of chromatin into chromosomes. Centriole pairs split and move towards opposite poles of cell. Once centrioles reach opposite ends, they make spindle fibers and asters, which attach to cell membrane, from microtubles.
Metaphase
Centriole pairs reach opposite poles of cell. Spindles, with help from kinetochore fibers align chromosomes at middle of cell (Metaphase plate).
Anaphase
Centromeres split allowing sister chromatids to split. Sister chromatids pulled toward opposite poles.
Telophase
Spindle disappears, nuclear membrane reforms. Chromosomes uncoil into chromatin.
Cytokineses
Happens at end of telophase. Separation of cytoplasm and organelles giving each cell ability to survive.
Recombination Crossover
Chromosomes cross over section of chromosome and swap gene codes on the chromosome for greater variance in genome.
Meiosis
Division of cells to produce gametes (4 non-identical sex cells). They are produced by gametocytes. This follows same pattern of Mitosis but twice to create 23 chromosome cells
Primitive gonard and its function
The testes.
1) Seminiferous tubes: produce sperm
2) Interstitial cells of leydig: nourish sperm cells.
Path of sperm ejaculation
Sperm is stored in Epididymis. Once it is time for ejaculation, sperm moves up vas deferens, into the ejaculatory duct, through the urethra and out of the body.
Prostate
Mixes sperm with Seminal fluid which it produces
Bulbourethral
Cleans out urethra before sperm comes.
Spermatogenesis
Follows pathway of Meiosis producing haploid spermatids. Upon maturing they become spermatozoa.
Head of sperm cell
Covered by Acrosome: structure that is derived from golgi, necessary for penetrating ovum.
Oogenesis
Female gamete production (Meiosis). At birth all Oogonia have already undergone DNA replication becoming primary oocytes
Primary oocytes
Sex cells of females that have already undergone DNA replication but stopped at Prophase I
Menarche
a women’s first menstrual cycle. From here, Primary oocytes complete Meiosis I and become secondary oocytes. Secondary only completes Meiosis II if fertilized.
Oocyte Protection: Zona Pellucida
Made of Glycoproteins and compounds for sperm binding.
Oocyte Protection: Corona Radiata
Outside of Zona Pellucida. Layer of cells that adhere to Oocyte during ovulation.
Testosterone
Produced by testes. Helps promote sperm formation. FSH interacts w/ Sertoli cells, triggering sperm maturation. LH interacts w/ interstitial cells for testosterone production. Also produces secondary sexual characteristics such as facial hair, deep voice, increased muscle, etc
Ovaries
Produce estrogen and progesterone from interacting w/ FSH and LH
Estrogen
Comes from FSH stimulation. Reproductive system and secondary sexual characteristics
Progesterone
Comes from Corpus Luteum in response to LH. Involved in maintenance of endometrium.
Menstural cycle
Estrogen and Progesterone levels rise and fall monthly, resulting in growing and shredding of the endometrial lining and egg. 4 Steps/stages: Follicular Phase–> Ovulation–> Luteal phase–> Menstruation.
Follicular Phase
Begins w/ Menstrual flow (shredding of endometrial/period). FSH and LH increase. estrogen is produced and begins to regrow endometrial lining.
Ovulation
Estrogen Levels get so high that LH and FSH levels Spike. High LH levels cause Ovulation. Release of the ovum (egg) from the ovary into abdominal cavity.
Luteal Phase
LH causes ruptured follicle to form corpus lutem. Progesterone is produced to keep ovum ready for implantation. LH & FSH levels drop to unsure only one egg gets out.
Menstruation
If not pregnant, Corpus Luteum losses LH stimulus. Progesterone dies off, uterine lining sloughed off. New cycle begins.
Pregnancy
zygote produces blastocytes that implant to uterine lining and secrete human chronic gonadotropin. This maintains corpus luteum.
Menopause
Ovaries become less sensitive to FSH and LH. Levels of FSH and LH skyrocket causing sever side effects.
Fertilization
Egg and sperm meet. Occurs at widest part of Fallopian Tube called ampulla. Sperm binds to Oocyte and releases Acrosomal enzymes. These allow head to penetrate the corona radiata and Zona Pellucida.
Acrosomal apparatus
Tube like structures formed by sperm to penetrates Ovum’s membrane
Cortical Rxn
Calcium ions are released causing a depolarized ovum membrane, called a fertilization membrane. It can no longer be penetrated by other sperm cells and has increased growth.
Dizygotic twins
2 eggs released during cycle and both are fertilized by 2 different sperm cells
Monozygotic twins
a single zygote splits into two.