Reproduction at the Organism Level PDF

REPRODUCTION AT THE ORGANISM LEVEL Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonad...

REPRODUCTION AT THE ORGANISM LEVEL Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system. Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system.  Desired Learning Competencies and Time Allotment Desired Learning Competencies Meeting Allotment Actual Number of Meetings Spent Describe the trends and compare 4 various strategies used by organisms in reproduction (plants, animals). Identify key female and male 4 reproductive structures and function. Discuss how the hypothalamic- 4 pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system. Media: Life Cycle of a Pacific Salmon (Downloads) What are some important Biology concepts that were discussed as we traced the life cycle of the Coho salmon? REPRODUCTION is an Important Mechanism of Evolution ◼ Reproduction is the process that creates new individuals of the same kind from previously existing individuals. ◼ Reproduction has allowed life to continue as an unbroken chain from the first cells for billions of years. ◼ Natural selection and reproduction are mechanisms by which evolution occurs. ◼ Animals have many adaptations and diverse ways of reproducing. ASEXUAL REPRODUCTION creates genetically identical offspring. ◼ Asexual Reproduction is the generation of offspring from a single parent that occurs without the fusion of gametes. ◼ Asexual reproduction happens when an animal creates offspring that are genetically identical to itself through the process of mitosis. MECHANISMS OF ASEXUAL REPRODUCTION ◼ Budding – new individuals arise from outgrowths of existing ones (hydra, corals, and sponges) Fragmentation – the breaking of the body into several pieces, followed by regeneration, regrowth of lost body parts (sponges, some flatworms, and certain types of fungi) Fission – the separation of a parent organism into two individuals of approximately equal size (protists and prokaryotes) Parthenogenesis an egg develops without being fertilized (several species of reptiles, birds and sharks, and is especially common in insects) In automixis (a version of parthenogenesis), an animal can merge a polar body with an egg to produce an offspring. In apomixis, reproductive cells replicate via mitosis to create two diploid cells (copy and paste) SEXUAL REPRODUCTION generates diversity among offspring. ◼ Sexual Reproduction is the generation of offspring that have unique combinations of genes inherited from two parents via the gametes (egg and sperm). CONCEPT CHECK 1. How do asexual and sexual reproduction differ from one another? 2-3. Describe an advantage and disadvantage of sexual reproduction. CONCEPT CHECK 4. In your words, describe how evolution and sexual reproduction are dependent on each other. 5. List one reproductive strategy that honeybees utilize. 6. Komodo dragons sometimes lay unfertilized eggs that develop into offspring. Which type of reproduction is this lizard using? Sexual reproductive strategies synchronize the release of gametes ◼ Salmon, sponges, sea urchins, and other animals use external fertilization; that is, they fertilize the eggs outside the body. ◼ Sponges release millions of sperms (production and release of more gametes). ◼ Sea urchins gather in large groups to release both sperm and eggs at the exact same time (synchronization of release). ◼ Animals receive a cue from the environment (phase of the moon, tide, temperature, seasons) that triggers an internal chemical response that signals the time for reproduction.  A moist habitat is Different Reproductive Strategies Enhance Evolutionary Fitness in Animals almost always required to prevent gametes from drying out and to allow the sperm to swim to the eggs. Internal Fertilization unites gametes in a moist, protected environment ◼ Most land animals (reptiles, bird, and mammals) reproduce through internal fertilization which happens when the sperm is transferred inside the female’s body where the protected egg is fertilized. ◼ Internal fertilization is an adaptation that enables sperm to reach an egg even when the environment is dry. Internal Fertilization unites gametes in a moist, protected environment ◼ It typically requires cooperative behavior and compatible reproductive systems. ◼ It is more energy consuming but it enhances the organisms’s reproductive success. ENSURING THE SURVIVAL OF OFFSPRING ◼ Internal fertilization is typically associated with the production of fewer gametes than external fertilization but results in the survival of a higher fraction of zygotes. Internal fertilization is also more often associated with mechanisms that provide greater protection of the embryos and parental care of the young Mammals nurse their offspring and adult birds feed their young. Parental care is in fact widespread among animals, including invertebrates. ENSURING THE SURVIVAL OF OFFSPRING ◼ The amniotic egg is an important evolutionary adaptation of animals which fertilize internally. ◼ The amniotic egg has a food source and a protective membrane. ◼ It permits larger and more developed young at birth.  VARIATION IN PATTERNS OF SEXUAL REPRODUCTION Hermaproditism ◼ each individual has both male and female reproductive systems ◼ any two individuals can mate or any individual can self fertilize ◼ arose as adaptation of animals that have a very limited opportunity to find a mate ◼ Sex reversal Competition for mates results in sexual selection ◼ Sexual dimorphism refers to the difference in physical characteristics between the males and the females of the same species; examples are differences in size, coloration, and body structure. ◼ Sexual selection drives physical traits that stay in the population over successive generations. ◼ Adaptation for sexual selection increase an organism’s fitness and the probability that adaptive genes are passed to the next generation. CONCEPT CHECK 7. What is meant by external fertilization? 8. Why is the amniotic egg considered an important adaptation for reproduction? 9. What is the advantage for an animal to use internal fertilization? CONCEPT CHECK 10-11. Animals use several reproductive adaptations and strategies to ensure evolutionary fitness. Provide two strategies using the land snail as an example. CONCEPT CHECK Brown garden snails, one of several land snails, use their antennae and perhaps their sense of smell to find a mate. Once they find a mate, they perform a courtship ritual that lasts for several hours and includes crawling over and touching each other. One of the pair then shoots a sharp dart into its partner, releasing a chemical that increases the survival of the sperm and leads to more successful offspring production. CONCEPT CHECK As hermaphrodites, each snail carries both male and female reproductive structures. A mating pair exchanges sperm through a genital pore located on the right side of the head, each snail mating with several different partners and collecting sperm in an internal sac. Because each snail is competing with several other mates to fertilize the eggs, the “love dart” provides a reproductive advantage if the dart hits the partner in the proper location. CONCEPT CHECK After the eggs are fertilized, they pass through the snail , exiting with a nutrient-rich jelly coating that will nourish and protect each developing embryo. The eggs are deposited in a damp area where they will stay moist and complete the development cycle. Media: Meet the snails that don’t need Cupid (Downloads) CONCEPT CHECK The image below shows two birds of paradise in their mating ritual, which includes an elaborate dance. 12-13. List two ways that the male and female differ from each other. 14. Identify which bird is the male and which is the female. 15. Explain how this sexual dimorphism enhances reproductive success. END REPRODUCTION AT THE ORGANISM LEVEL Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system. Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system.  Desired Learning Competencies and Time Allotment Desired Learning Competencies Meeting Allotment Actual Number of Meetings Spent Describe the trends and compare 4 various strategies used by organisms in reproduction (plants, animals). Identify key female and male 4 reproductive structures and function. Discuss how the hypothalamic- 4 pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system. Plant Reproduction ◼ is the production of plant offspring, which happens either sexually or asexually Asexual Reproduction in Plants ◼ produces new individual plants that are genetically identical to the parent plant, unless mutations have occurred in the originating cells ◼ can happen thru vegetative reproduction or apomixis Asexual Reproduction in Plants ◼ Vegetative reproduction is an example of asexual reproduction, in which a vegetative portion of the plant (i.e. leaf, stem or root) gets removed from the parental plant and generates a separate individual. ◼ Apomoxis occurs when unfertilized gametes (pollen or ovules) develop into genetically identical spores or seeds. Vegetative Propagation by Stems ◼ Rhizomes are root-like stems that grow horizontally under the ground. New roots and shoots form at the nodes with shoots growing upwards to form new plantlets. Lateral buds grow out to form new rhizomes. Vegetative Propagation by Stems ◼ Some plants, such as strawberries, have long stems that grow along the soil’s surface. They have buds on them. Adventitious (roots that appear on stems and leaves on plants) roots appear at the nodes where the buds are. Vegetative Propagation by Stems ◼ When the nodes touch the soil, new shoots begin that grow into new plants. The runner continues to grow new stems and keeps running. When the connection with the parent plant breaks, the new plant becomes independent. Vegetative Propagation by Stems ◼ Bulbs form lateral buds from the base of the mother bulb, which produce new smaller bulbs or bulbels in subsequent years. Vegetative Propagation by Stems/Roots ◼ Tubers are swollen portions of an underground stem that store food so a plant can lie dormant over the winter, for example, potatoes. Axillary buds, commonly known as ‘eyes’, form over the surface of the tuber and produce shoots that grow into a new plant the following year. Vegetative Propagation by Leaves ◼ Plants like Bryophyllum, Begonia etc., have adventitious buds coming out from the notches of the leaves. These buds develop into new plants. Artificial Vegetative Propagation The grafting process involves joining the shoot system of a plant (known as a scion) to the root system of another plant (known as the stock). To do this, the scion and stock are cut diagonally and then placed facing each other. The cuts are made in such a way that the sizes (diameter) of the scion and stock are very close. They are then taped together and left to heal over time. Artificial Vegetative Propagation ◼ In this method, the healthy branch having leaf buds is planted in the moist soil. The cutting develops roots and grows into a new plant. Example Rose, bougainvillaea, sugarcane Artificial Vegetative Propagation ◼ Layering is a method in which a stem attached to the plant is bent and covered with soil. Young stems that can be bent easily without any injury are preferred. Jasmine and bougainvillea (paper flower) can be propagated this way Artificial Vegetative Propagation ◼ Using tissue culture, sometimes called micropropagation, tiny fragments of plants are treated with plant hormones in a sterile growing medium. The hormones stimulate the growth of a callus, from which a new seedling can grow. This method is used to produce large numbers of identical seedlings. Sexual Reproduction in Plants ◼ Sexual reproduction requires genetic material (DNA) from two parents. The plants have male and female sex cells, called ____________. ◼ The genetic material from the male and female gametes combines to produce offspring. We call this process _____________. The product of sexual reproduction are seeds. Sexual Reproduction in Plants ◼ Sexual reproduction requires genetic material (DNA) from two parents. The plants have male and female sex cells, called gametes. ◼ The genetic material from the male and female gametes combines to produce offspring. We call this process fertilization. The product of sexual reproduction are seeds. Sexual Reproduction in Plants Sexual Reproduction in Plants POLLINATION Sexual Reproduction in Plants P O L L I N A T O R S END REPRODUCTION AT THE ORGANISM LEVEL Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system. Desired Learning Competencies: ◼ Describe the trends and compare various strategies used by organisms in reproduction (plants, animals). ◼ Identify key female and male reproductive structures and function. ◼ Discuss how the hypothalamic- pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system.  Desired Learning Competencies and Time Allotment Desired Learning Competencies Meeting Allotment Actual Number of Meetings Spent Describe the trends and compare 4 2 various strategies used by organisms in reproduction (plants, animals). Identify key female and male 4 reproductive structures and function. Discuss how the hypothalamic- 4 pituitary gonadal (HPG) axis regulates the female reproductive cycle and the male reproductive system. Prompt: ◼ Give me a part of the human body that is part of the reproductive system. Prompt: ◼ Give me a part of the human body that is part of the reproductive system. The Human Reproductive System ◼ is a collection of organs and a network of hormone production in men and women that enable a man to impregnate a woman who gives birth to a child. ◼ During conception, a sperm cell from the man fuses with an egg cell in the woman, creating a fertilized egg (embryo) that implants and grows in the uterus during pregnancy. ◼ Abnormalities or damage to reproductive organs and malfunction of the hormone production and delivery system that governs reproduction are common causes of infertility in men and women. Key Parts and Functions of the Female Reproductive System ◼ Produce the eggs necessary for reproduction, called the ova (ovum is singular for one egg) or oocytes ◼ Incubate and nourish a fertilized egg until it is fully developed ◼ Produce female sex hormones that maintain the reproductive cycle ◼ are two small, oval-shaped glands located on either side of the uterus ◼ home to the female sex cells, called eggs, and they also produce estrogen, the female sex hormone OVARIES: The Female Gonads ◼ are two small, oval-shaped glands located on either side of the uterus ◼ home to the female sex cells, called eggs, and they also produce estrogen, the female sex hormone ◼ extends from the uterus toward each ovary ◼ The dimensions of this tube vary along its length, with the inside diameter near the uterus being as narrow as a human hair. ◼ At ovulation, the egg is released into the abdominal cavity near its funnel-like opening. Cilia on the epithelial lining of this duct help collect the egg by drawing fluid from the body cavity into the duct. FALLOPIAN TUBE/OVIDUCT ◼ extends from the uterus toward each ovary ◼ The dimensions of this tube vary along its length, with the inside diameter near the uterus being as narrow as a human hair. ◼ At ovulation, the egg is released into the abdominal cavity near its funnel-like opening. Cilia on the epithelial lining of this duct help collect the egg by drawing fluid from the body cavity into the duct. ◼ Together with wavelike contractions of the oviduct, the cilia convey the egg down the duct to this part, also known as the womb. ◼ is a thick, muscular organ that can expand during pregnancy to accommodate a 4-kg fetus. ◼ Its inner lining, the endometrium, is richly supplied with blood vessels UTERUS ◼ Together with wavelike contractions of the oviduct, the cilia convey the egg down the duct to this part, also known as the womb. ◼ is a thick, muscular organ that can expand during pregnancy to accommodate a 4-kg fetus. ◼ Its inner lining, the endometrium, is richly supplied with blood vessels ◼ is the lower, narrow part of the uterus ◼ forms a canal that opens to the vagina ◼ Often called the neck or entrance to the womb, it lets menstrual blood out and semen into the uterus CERVIX ◼ is the lower, narrow part of the uterus ◼ forms a canal that opens to the vagina ◼ Often called the neck or entrance to the womb, it lets menstrual blood out and semen into the uterus ◼ is a muscular but elastic chamber that is the site for insertion of the penis and deposition of sperm during copulation ◼ also known as the birth canal and joins the cervix ◼ allows passage of sperm, produces fluid daily to cleanse and lubricate itself and help sperm travel, allows passage of shed endometrium during menstrual period, allows passage of baby and provides sensation VAGINA ◼ is a muscular but elastic chamber that is the site for insertion of the penis and deposition of sperm during copulation ◼ also known as the birth canal and joins the cervix ◼ allows passage of sperm, produces fluid daily to cleanse and lubricate itself and help sperm travel, allows passage of shed endometrium during menstrual period, allows passage of baby and provides sensation Key Parts and Functions of the Male Reproductive System Produces, maintains and transports sperm (the male reproductive cells) and protective fluid (semen) Discharges sperm within the female reproductive tract during sex Produces and secretes male sex hormones responsible for maintaining the male reproductive system is made up of two parts, the shaft and the head. The urethral opening is at its tip and delivers sperm into the vagina during sexual intercourse PENIS is made up of two parts, the shaft and the head. The urethral opening is at its tip and delivers sperm into the vagina during sexual intercourse is the sac-like organ hanging behind and below the penis. It contains the testes, as well as many nerves and blood vessels SCROTUM is the sac-like organ hanging behind and below the penis. It contains the testes, as well as many nerves and blood vessels the oval organs that lie in the scrotum; are the primary male reproductive organ and are responsible for testosterone and sperm production TESTES the oval organs that lie in the scrotum; are the primary male reproductive organ and are responsible for testosterone and sperm production ◼ a C-shaped tube that rests on the backside of each testicle ◼ It transports and stores sperm cells that are produced in the testes. ◼ It also brings the sperm to maturity, since the sperm emerging from the testes are immature and incapable of fertilization. EPIDIDYMIS ◼ a C-shaped tube that rests on the backside of each testicle ◼ It transports and stores sperm cells that are produced in the testes. ◼ It also brings the sperm to maturity, since the sperm emerging from the testes are immature and incapable of fertilization. ◼ is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. ◼ transports mature sperm to the urethra, the tube that carries urine or sperm outside of the body, in preparation for ejaculation. VAS DEFERENS ◼ is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. ◼ transports mature sperm to the urethra, the tube that carries urine or sperm outside of the body, in preparation for ejaculation. ◼ are formed by the fusion of the vas deferens and the seminal vesicles ◼ empty into the urethra EJACULATORY DUCTS ◼ are formed by the fusion of the vas deferens and the seminal vesicles ◼ empty into the urethra ◼ is the tube that carries urine from the bladder to outside of the body. ◼ In males, it has the additional function of ejaculating semen when the man reaches sexual climax. When the penis is erect during sex, the flow of urine is blocked from this part, allowing only semen to be ejaculated. URETHRA ◼ is the tube that carries urine from the bladder to outside of the body. ◼ In males, it has the additional function of ejaculating semen when the man reaches sexual climax. When the penis is erect during sex, the flow of urine is blocked from this part, allowing only semen to be ejaculated. ◼ are sac-like pouches that attach to the vas deferens near the base of the bladder. ◼ Its secretion make up to 80% of the ejaculatory fluid, including fructose. Fructose is an energy source for sperm and helps them move. SEMINAL VESICLE ◼ are sac-like pouches that attach to the vas deferens near the base of the bladder. ◼ Its secretion make up to 80% of the ejaculatory fluid, including fructose. Fructose is an energy source for sperm and helps them move. ◼ is a walnut-sized gland that rests below the bladder and in front of the rectum. ◼ adds additional fluid to ejaculate, which helps nourish sperm. The urethra runs through the center of this gland. Prostate Gland ◼ is a walnut-sized gland that rests below the bladder and in front of the rectum. ◼ adds additional fluid to ejaculate, which helps nourish sperm. The urethra runs through the center of this gland. ◼ are pea-sized structures on the sides of the urethra, just below the prostate. ◼ They create a clear, slippery fluid that empties directly into the urethra. This fluid lubricates the urethra and neutralizes any acids that may remain from one’s urine. Bulbourethral (Cowper’s) Gland ◼ are pea-sized structures on the sides of the urethra, just below the prostate. ◼ They create a clear, slippery fluid that empties directly into the urethra. This fluid lubricates the urethra and neutralizes any acids that may remain from one’s urine. The interplay of tropic and sex hormones regulates mammalian reproduction ◼ In both male and female humans, the coordinated actions of hormones from the hypothalamus, anterior pituitary, and gonads govern reproduction. REPRODUCTIVE CYCLES IN HUMAN FEMALES 1. Menstrual cycle - refers to the changes that occur about once a month in the uterus - also called as the uterine cycle - average 28 days 2. Ovarian cycle - refers to the cyclic events that occur in the ovaries If fertilization does not take place, the falling levels of FSH and LH allow the corpus luteum to degenerate and the concentration of progesterone and estrogen also fall. As a result FSH and LH production is no longer inhibited. The thickened epithelium of the endometrium is shed, producing the menstrual flow. If fertilization occurs, progesterone and estrogen, produced initially by the corpus luteum and later by the placenta, are present in high concentration. LH production and then ovulation are inhibited; follicle development and production of estrogen cease and the uterus lining is maintained. MENOPAUSE ◼the cessation of ovulation and menstruation after about 500 cycles ◼usually occurs between the the ages of 46 and 54 ◼Ovaries lose their responsiveness to FSH and LH, resulting in a declined estradiol production. MENSTRUAL versus ESTROUS CYCLES ◼Only humans and some other primates have menstrual cycles. Other mammals have estrous cycles. ◼In the absence of a pregnancy, the uterus reabsorbs the endometrium and no extensive fluid flow occurs. ◼Mammals with estrous cycle usually copulate only during the period surrounding ovulation. This period, called estrus, is the only time the female is receptive to mating. Hormonal Control of the Male Reproductive System Human Sexual Response ◼ Two types of physiological reactions predominate in both sexes: vasocongestion, the filling of a tissue with blood, and myotonia, increased muscle tension. ◼ Both skeletal and smooth muscle may show sustained or rhythmic contractions, Human Sexual Response ◼ The sexual response cycle can be divided into four phases: excitement, plateau, orgasm, and resolution. ◼ Excitement - the vagina and penis are prepared for coitus (sexual intercourse); vasocongestion is particularly evident in erection of the penis and clitoris; enlargement of the testicles, labia, and breasts; and vaginal lubrication. Myotonia may occur, resulting in nipple erection or tension of the arms and legs. Human Sexual Response ◼ Plateau – the responses in the excitement phase continue as a result of direct stimulation of the genitalia. ◼ Physiological responses include vasocongestion, increase in breathing, and rise in heart rate. Human Sexual Response ◼ Orgasm - characterized by rhythmic, involuntary contractions of the reproductive structures in both sexes; is the shortest phase of the sexual response cycle, usually lasting only a few seconds. ◼ Male – first part is emission, second part is ejaculation ◼ Female - uterus and outer vagina contract, but the inner two-thirds of the vagina does not. Human Sexual Response ◼ Resolution- vasocongested organs return to their normal size and color, and muscles relax. ◼ Following orgasm, the male typically enters a refractory period, lasting anywhere from a few minutes to hours, during which erection and orgasm cannot be achieved. ◼ Females do not have a refractory period, making possible multiple orgasms within a short period of time. END