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Mitosis cell division in which the nucleus divides into nuclei containing the same number of chromosomes interphase (Mitosis) The time between cell divisions. Dna is found as thin threads of chromatin in the nucleus. Dna replication occurs during the s phase of interphase. Organelles, other than the nucleus, and centrioles, duplicate during interphase. Phophase (Mitosis) The chromatin condenses into chromosomes. Each chromosome consists of two chromatids joined at the centromere. The centrioles move to the opposite end of the cell, and the nucleolus and the nuclear envelop disappear. Microtubules form near the centrioles and project in all direction. Some of the microtubules end blindly and are called astral fibers. Others, known as spindle fibers, project towards an invisible line called the equator and overlap with fibers from the opposite centrioles. Metaphase (Mitosis) The chromosomes align in the center of the cell in association with the spindle fibers. The spindle fibers attach to kinetochores in the centromere of each chromosome. Anaphase (Mitosis) The chromatids seperate, and each chromatid is then referred to as a chromosome. Thus, when the the centromeres divide, the chromosome number is double, and there are two identical sets of chromosomes. The chromosomes, assisted by by the spindle fibers, move toward the centrioles at each end of the cell. Separation of the chromatids signals the beginning of anaphase, and by the time anaphase has ended, the chromosomes have reached the poles of the cell. Cytokineses begins during anaphase. Telophase (Mitosis) Migration of each set of chromosomes is complete. The chromosomes unravel to become less distinct chromatin threads. The nuclear envelope forms the endoplasmic reticulum. The nucleoli form, and cytokineses continues to form two cells. Completion: Cell division has produced two daughter cells, each with DNA that is identical to the DNA parent. Meiosis I The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell. Early Prophase I The duplicated chromosomes become visible chromatids. Middle Prophase I Homologous chromosomes synapse to form tetrads. Crossing over may occur at this stage. Metaphase I Tetrads align at the center of the cell. Random assortment of homologous chromosomes occurs. Anaphase I Homologous chromosomes move apart to opposite sides of the cell. Telophase I New nuclei form, and the cell divides. Meiosis II the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two. Prophase II Each chromosme consists of two chromatids. Metaphase II Chromosomes align along the center of the cell. Anaphase II Chromatids separate and each is now called a chromosome. Telophase II New nuclei form around the chromosomes. The cells divide to form four daughter cells with a haploid number of chromosomes. Interphase Phase between cell divisions. G 1 phase:growth of cell. S phase: DNA is replicated. G 2 phase: centrioles replicated. Major difference between Meiosis and Mitosis? Crossing Over Point Mutation Error at one point in the base pairing Frame shift mutation Additional base added during base pairing. Transposition Change of position of bases from one location to another. Male Structures Male perineum-located between symphysis pubis and the coccyx. Scrotom- 2 chambered sac that contains the testes. Testes-where the sperm is produces, 300-400 lobules for each of the testes. Seminiferous tubules-700 feet long stretched out. This is where sperm is produced. Ducts of the Epididymus, Epididymus- Where sperm is stored. Vas Deferens-goes up to the abdominal cavity. Sperm is carried through the Vas Deferens. Seminal Vesicle-produces the seminal fluid. Seminal fluid contains fructose. Gives sperm the energy to swim. Prostate Gland, Ejaculatory duct: creates prostate fluid which neutralizes the acidity., Urethra, Bulbourethral gland:creates a fluid and lubricates the urethra so sperm can easily flow out. Female Structures Ovary-where the egg is produced and held there by ligaments. (Ovarian ligament, suspensory ligament, and broad ligament). Ovarian Epithelium-Tunica albuginea-dense white fibrous collagenous tissue. There is an outer called the cortex. It contains eggs and follicules. The center area is called the medulla and is a passageways for blood, lymphatic vessels and nerves. Fallopian Tube-transport canal for the eggs to the uterus. Infundibulum- adjacent to the ovaries and the opening of the fallopian tubes. Fimbria is fingerlike processes. Three layer of the fallopian tube serous (Outer) muscular layer (middle layer, and mucousa (innermost). The Fimbria moves the egg towards the uterus and it implants to the uterus. The uterus has three layers: perimetrium (outer), Myometrium (middle layer, it is the muscular layer and contracts to push baby), Opening to the uterus is cervix, Vagina has 2 layers (outerlayer of smooth muscle and inner layer of epithelial cells that are one layer thick, moist. Spermatogenesis 1. Spermatogonia are the cells from which sperm cells arise. The spermatogonia divide by mitosis. One daughter cell remains a spermatogonium that can divide again by mitosis. One daughter cell becomes a primary spermatocyte. 2. The primary spermatocyte divides by meiosis to form secondary spermatocytes, 3. The secondary spermatocytes divide by meiosis to form spermatids. 4. The spermatids differentiate to form sperm cells. Sertoli Cell (Nurse)- assist in the process of making sperm. Sperm has a head, midpiece, and tail (flagella). The sperm cell is released into the lumen and stored in the epididymus. It takes 2 weeks for a sperm to mature. Sertoli Cell (Nurse) Assist in process of making sperm. 1) Form tight junctions with one another. They form a blood testes barrier. Which limits the blood that can get into the into the developing sperm. When sperm goes from Diplod to Halfploid, it helps protect them because they are a foreign material. 2) Nourish the sperm. Eggs Maturation It can take an egg 35 year to mature. A female has all eggs in her 4th prenatal month (5 million eggs), by birth (2 million). At birth Meiosis 1 has begun but it stays in prophase 1. Eggs are down to 200,000 to 300,000 when puberty begins. Only 300-400 will go through process of maturation. The follicule around the egg is what mature. When one egg getss picked it develops granulosa cells. It is now called a primary follicule, The granulosa cells become stratified. There is protective coating called the zona pellucida. Granulosa cells develop fluid filled spaces. It is now a secondary follicle. When the multiple fluid spaces become one, it is a graafian follicule. It is going to sweel the perimeter of ovary and egg will be expelled. Right before ovulation it goes through the rest of Meiosis. The second cell degenerates. The one that degenerates is called the 1st polar body. When egg bursts out it takes the zona pellucida and some of the granular cells. After ovulation it precedes to Meiosis. It goes through the fallobian tube and if the sperm doesn't find it, it degenerates. If the egge is found by sperm it will immediately finish Meiosis 2. There is a second polar body then. Only one cell is left and that is the one the sperm fertilizes. Corpus lutem what is left behind. It is an important part of fertilization occurs. It stays for 3-4 months and produces progesterone. If egg isn't fertilized it degenerates to a corpus albicans. Then degenerates totally. Male Hormones Gonadotropin releasing hormone-released from the hypothalamus. It is constant. It stimulates the anterior pititary to produce LH and FSH. Luteinizing Hormone-stimulates the cells of the Leydig to produce testosterone. Follicle stimulating hormone-stimulates the sertoli cells to stimulate sperm cell fomation and inhibits the production of GnRH. Testosterone-has a stimulatory effect on the sustentacular cells of the seminiferous tubules, and on the development of sex organs and secondary sex characteristics. Female Hormones Gonadotropin releasing hormone-realeased in hypothalamus. It is produced in cycles. It stimulates the Anterior Pituitary to produce LH and FSH. LH- target hormone for the ovaries. It acts to mature the follicle. It stimulates ovulation. The follicle itself is producing estrogen. Estrogen-Endometrial Cell Division, stimulates the mammary ducts, secondary sexual characteristics, Increases LH and FSH, with progesterone it decreases LH & FSH. The Corpus Luteum releases progesterone. Progesterone- Endometrial Hypertrophy, development of mammary glands, secondary sexual characteristics, with estrogen decreases LH and FSH. FSH- causes follicle to to begin development. Fertilization( Egg, Zygote, Embryo, Fetus) produces Human Chorionic Gouadotropin-it maintains the Corpus Luteum. No fertilization-No HCG, No Corpus Luteum, No Progesterone. Protactile-stimulates milk secretion (after birth) from the mammary glands. The Posterior Pituitary produces oxytocin that contracts smooth muscle of the uterus (myometrium) during childbirth. 3 stages of development during pregnancy Zygotic(0-2 weeks), Embryonic Stage(2-8 weeks)-formation of all organs, heartbeats, formation of all limbs, facial features are all in place, sex determination. Fetal Stage (8 weeks to birth)-Growth and refinement. It results in a process of perfection of development and development of brain cells. 4 processes of development Cell Division-Multiplication of cells, Morphogenesis- Change in form, Cell growth- cell grows bigger, Differentiation- cells change function Sperm cell until it gets into the Egg. The sperm is attracted to the egg. The sperm contains genetic material. There are enzymes at the cap of the head. They are digestive material that digest the material of the egg. The first one that penetrates the egg, goes inside. This causes penetration causes activation. The membrane is no longer permeable to any other sperm. Activation causes:Biochemical changes, change in electrical potential across the membrane, release of calcium through egg. Sets up a secondary membrane. Stimulate egg cell to go through the rest of Metaphase 2. After the egg goes through metaphase 2 Increase in oxygen for cellular respiration (energy), Increase in permeability and phosphate (ATP and make nucleotides), the head seperates from the mid piece and tail. The head ruptures and spills out the genetic material. Grouping of genetic material (mens and womens). There are two nuclei. Nuclei fuse together in a process called fusion. The fusion of the two nuclei is actually fertilization. Cell division In about 24 hours a single cell is going to become two, 4 cells (2 days), after four days we are going to have a solid cluster of 32 identical cells called Morula. After four days we start to get morphogenesis (change of form). They actively transport sodium into the center of the cluster of cells. Through osmosis water comes in to follow sodium. It gets a fluid filled center and there is cell growth. It is now called a blastocyst. The fluid filled center is a blastocele. Shortly after we get differentiation into two types of cells. They are the embryonic cells (going to make up the individual), trophoblastic (placenta and support tissues). After about 7 days, the blastocyst is going to implant itself on to the endometrium. The trophoblasts are going to invade the endometrium as finger like projections. Get nutrients to the baby and get rid of wastes. This is the end of the zygotic state. embryonic stage formation of placenta, formation of germ layers, formation of digestive tract Formation of Placenta Frontal section of the uterus and uterine tube showing development, 7 days after fertilization. Implantation of the blastocyst and the trophoblast begin to invade the uterine wall (8-12 days). As maternal blood vessles are encountered by the trophoblast, lacunae is formed and filled with maternal blood.. Cytotrophoblast cords surround the synctiotrophoblast and lacunae, and embryonic mesoderm enters the cord (1 month). Formation of germ layers Morula- a mass of cells, Blastocyst hollow ball with inner cell mass Embryonic disk:two layers of cells between two cavities (ectoderm and endoderm) Gastrula Three germ layers. The ectoderm turns inward causing the Primitive streak which is where spinal cord is going to be. The cells in this space differentiate and become mesoderm. Formation of germ layers to for fetus Three layers are going to turn inward making a circle. Ectoderm is the outer tube (nervous system, sensory, and skin itself), mesoderm-muscles, skeleton, connective tissues, cardiovascular tissues, and tissues of the lymphatic system. endoderm-digestive system There are some organs that are a combination of mesoderm and endoderm. cell death cells are dying to create form. ex. webbing between fingers and toes. These cells start to die so the baby gets it's form. Fetal Circulation Nutrients and oxygen come in from the umbilical vein, enters the inferior vena cava through and opening called the ductus venosus to the right atrium through the formen ovale to the left atrium. The majority of blood goes in to the left atrium when this contacts. From the left atrium, to left ventricle, to the aorta, to the body. There is some from the forman ovale that goes to the right ventricle, it goes to the pulmonary artery but goes through the ductus arterioles, and exits from the umbilical arteries and exits from the internal iliac arteries. Postnatal stages Newborn (0 to 1 month), Infant (1 month to 2 years): 3 months: have some eye/hand coordination, hold head up, should be able to smile 6 months: laughing, sit, should be able to grasp things, head should be able to follow an object, 9 months: recognize thing, reach for objects 12 months: standing and sometimes walking. Child (2 years to puberty):social development. Adolescent (puberty to 20) physical and behavioral changes. Adult (20 and on) characterized by deterioration. Theories of aging Teleomeres, Free radicals, restricted calorie intake. Many one cell organisms, bacteria, and cancer cells don't die. Genetics study of heredity DNA Hereditary material of cells and controls cells activities. Chromosomes-contain thousands of genes. Genes Functional unit of heredity. A portion of DNA. Dominant and Recessive Dominants mask the effects of recessive genes Genotype Actual set of alleles a person has for a given trait Phenotype Persons appearance Homozygous AA-homozygous dominant, aa-homozygous recessive. Heterozygous Aa Mendel's First Law: Law of Segretion When gametes are formed two distinct factors separate and pass into separate gametes. Each gamete then processes only one factor for each characteristics. Each new plant thus recieves one factor from each parent. Mendel's Second Law: Law of Independent Assortment Alleles at different loci assort independently and do not effect alleles at a different loci. Exceptions to Mendels Laws Multiple alleles- more than 2 alleles for a given trait within the population. Incomplete dominance-Alleles do not mask each other. Exceptions to mendels second law- in many cases alleles at one loci do not effect alleles at another.