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Reproduction, Mitosis and Meiosis

Learn about the importance and mechanisms of reproduction through mitosis and meiosis in all living things. Explore the differences between sexual and asexual reproduction, cell division processes, advantages and disadvantages of each, and genetic variations.

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Reproduction, Mitosis and Meiosis

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  1. Reproduction, Mitosis and Meiosis

  2. All Living Things REPRODUCE… • Without reproduction all living things would go EXTINCT…

  3. HOW DOES A LIVING ORGANISM REPRODUCE? Living things can reproduce in 2 different ways: SEXUALLY OR ASEXUALLY Similarities: Both types produce an offspring. Asexual reproduction- only one parent is needed for reproduction. Offspring is a clone (genetically the same) of parent. Sexual Reproduction– Two parents are needed for reproduction. Offspring is genetically different than parents.

  4. 5 Types of Asexual Reproduction • Budding – occurs in simple multi–celled animals and unicellular fungi, a small individual grows off the body of the adult. • KINGDOM : ANIMALS Hydra, jellyfish, corals, sea anemone. FUNGI- yeast

  5. 5 Types of Asexual Reproduction • Binary Fission – simple cell division. Most unicellular organisms like bacteria and protists reproduce this way. • KINGDOMS: Protists and bacteria

  6. 5 Types of Asexual Reproduction • Spores- Are reproductive cells that grow into new individuals when conditions are right. Some ferns and fungi reproduce this way. • KINGDOM : Plants and Fungi

  7. 5 Types of Asexual Reproduction • Regeneration/Fragmentation – Occurs in multi-cellular animals. Entire organisms grow from a piece of the adult. • KINGDOM: ANIMALS • EX: Worms and Starfish.

  8. 5 Types of Asexual Reproduction • Vegetative Propagation – Cuttings from plants grow into new individuals, or new runners (root structures) are produced. • KINGDOM: PLANT • EX: Strawberry plants, monkey grass, potatoes.

  9. SEXUAL REPRODUCTION Most multi-cellular organisms reproduce this way, including KINGDOMS ANIMAL, PLANT and FUNGI . Sexual reproduction involves two sex cells. One sex cell is needed from each parent. Thesex cells, also called gametes,areegg cellsin the female and sperm cellsin the male.

  10. SEXUAL REPRODUCTION: allows forvariation. Sexual reproduction always involves the combining of 2 nuclei from 2 different sex cells. Fertilization is the joining of egg and sperm. The cell (fertilized egg) that comes from fertilization is called the ZYGOTE.

  11. ADVANTAGES AND DISADVANTAGES OF ASEXUAL REPRODUCTION • Advantages: • Quicker, no need to look for a mate. • Simpler to produce another just like yourself if you have • desirable traits. • Disadvantages: • No variation of traits, no individuality. • Offspring is a clone of the parent (can be bad if parent has • undesirable traits.

  12. ADVANTAGES AND DISADVANTAGES OF SEXUAL REPRODUCTION Advantage: 1. Allows for genetic variation. There will never be two just alike unless they are identical twins. • TWO different genetic codes from 2 different parents results in variation in a species. For example, no two quarter horses, pine trees, blue whales, dogwoods or humans are exactly alike. • Disadvantages: • Takes more time (gestation). • More energy required to find a mate, etc.

  13. CELL REPRODUCTION Mitosis and Meiosis

  14. Chromosomes • Definition: The structure that DNA is organized in. • They come in pairs, half from each parent.

  15. CHROMOSOME ARRANGEMENT All regular body cells have all the same # of chromosomes. There are 46 chromosomes in human body cells. Chromosomes always come in pairs. (Homologous Chromosomes) There are 46 chromosomes for a total of 23 pairs. 22 of the pairs are similar. The 23rd pair is different. These are the sex chromosomes.

  16. CHROMOSOME ARRANGEMENT HUMAN BODY CELLS HAVE 46 CHROMOSOMES OR 23 PAIRS. Bone cell Nerve cell BULLFROG BODY CELLS HAVE 26 CHROMOSOMES OR 13 PAIR. FRUIT FLY BODY CELLS HAVE 8 CHROMOSOMES OR 4 PAIR.

  17. HOW DOES A CELL REPRODUCE ITSELF? The process is called CELL REPRODUCTION (DIVISION) Cell Reproduction- Simple cell division in which one cell divides into two Multi-cellular organism use cellular reproduction to produce more body cells for growth and repair. Unicellularorganisms use cell reproduction to asexually reproduce period.

  18. Mitosis: • Definition: A type of cell division that results in two daughter cells that are exactly the same as the parent cell. • Results in cells such as internal organs, skin, bones, etc. OR a new organism (clone).

  19. Purpose of Mitosis: • Multicellular: To produce new cells to repair and replace existing body cells. • Unicellular: To produce a new individual through asexual reproduction.

  20. The Process of Mitosis • a cell wants to make a duplicate of itself, it first must copy its DNA (part of a chromosome). (DNA REPLICATION) • The copies then must be separated & sorted into two sides of the cell. • The cell cytoplasm then splits in two (cytokinesis). Exact DNA is passed on to offspring.

  21. End Product of Mitosis • Multicellular: Results in new body cells such as internal organs, skin, bones, blood, etc. Heart (Cardiac) Cells Liver Cells Bone Cells

  22. End Product of Mitosis • Unicellular: a new individual that is a clone of the parent.

  23. Uncontrolled Mitosis Cancer is a disease of the cell cycle. Some of the body’s cells divide uncontrollably and tumors form. While normal cells will stop dividing if there is a mutation in the DNA, cancer cells will continue to divide with mutation.

  24. Heinretta Lacks

  25. Meiosis

  26. Meiosis: • Definition: A type of cell division that results in two daughter cells each with half the chromosome number of the parent cell. • Results in SEX CELLS!

  27. WHY ONLY ½ IN SEX CELLS??????? Sex cells only have ½ the number of chromosomes as body cells. So, when they unite it equals a full 46... They DO NOT have a full # of chromosomes Human sex cells would have - 23 chromosomes Bullfrog gametes would have - 13 chromosomes 4 chromosomes Fruit fly egg and sperm would have -

  28. Purpose of Meiosis • Multicellular: to produce new SEX CELLS that can combine to form an offspring.

  29. Crossing Over

  30. End Product of Meiosis • New sex cells with half the number of chromosomes as body cells.

  31. FERTILIZATION 23 CHROMOSOMES 23 CHROMOSOMES FERTILIZATION How many chromosomes will the human fetus have? 46 is correct!! Just as it is supposed to be.

  32. Sometimes an egg will split into two separate parts soon after it is fertilized. This creates two embryos with the same DNA: IDENTICAL TWINS. Sometimes two eggs are fertilized at the same time. The two embryos are just like regular siblings except that they develop and are born at the same time. These are called FRATERNAL TWINS.

  33. Human Reproduction and Development

  34. Sexual Development • Puberty is a period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. • When puberty ends, reproductiveorgansare fully developed. • Puberty usually begins between the ages of 9 and 15, and usually starts one year earlier in females than in males.

  35. Sexual Development • Puberty begins when the hypothalamussignals the pituitary to produce increased levels of two hormones that affect the gonads. • These hormones are follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

  36. The Male Reproductive System • Release of FSH and LH stimulates cells in the testes (male reproductive organ) to produce testosterone (male hormone). • FSH and testosterone stimulate the development of sperm(male sex cell (gamete).

  37. Head Nucleus Midpiece Mitochondria Tail • A sperm cell consists of: • a head, which contains the nucleus • a midpiece, which contains energy-releasing mitochondria • a tail, which propels the cell forward

  38. The Male Reproductive System • Male Reproductive System Urinary bladder Vas deferens Pubic bone Seminal vesicle Urethra Rectum Penis Prostate gland Epididymis Testis Scrotum

  39. The Female Reproductive System • Puberty in females starts when the hypothalamus signals the pituitary gland to release FSH and LH. • FSH stimulates cells within the ovaries to produce estrogen • The primary female reproductive organ are the ovaries (egg – gamete)

  40. The Female Reproductive System Fallopian tube Ovary Uterus Cervix Urinary bladder Rectum Pubic bone Vagina Urethra

  41. The Menstrual Cycle • The menstrual cycle is controlled by internal feedback mechanisms between the reproductive system and the endocrine system. • The cycle takes an average of 28 days.

  42. The Menstrual Cycle • During the menstrual cycle, an egg develops and is released from an ovary. (ovulation) • The uterus is prepared to receive a fertilized egg. • If the egg is fertilized, it is implanted in the uterus and embryonic development begins. • If the egg is not fertilized, it is discharged and menstruation occurs.

  43. Fertilization and Development of an Offspring • Gametes – reproductive cells (egg and sperm) • When sperm and egg unite, new cell is called zygote • Fertilization occurs in the oviduct (fallopian tubes) • 1st 8 weeks – Embryo • After 8 weeks - Fetus • Development of fetus occurs in uterus

  44. Terminology for Development • Uterus – muscular structure located in female where development occurs • Placenta - an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply • Umbilical Cord – connects baby to placenta of mother • Amniotic fluid – yellowish fluid that surrounds the baby

  45. Mitosis and Differentiation Cell differentiationis how generic embryonic cells become specialized cells http://stemcells.nih.gov/info/scireport/appendixA.asp  Image courtesy of NIH resource for stem cell research http://embryo.soad.umich.edu/carnStages/carnStages.html Image courtesy of Brad Smith, University of Michigan

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