Sexual ReproductionMale ReproductiveFemale ReproductiveFertilisationExternal and Internal fertilisationTest-tube babyReproductive system of male and female frogMetamorphosisAsexual ReproductionBinary fissionBuddingViviparous and oviparous AnimalsDolly the clone
SEXUAL RERODUCTIONSexual Reproduction: The reproduction in whichthe both male reproductive organs and femalereproductive organs involved to give birth to newindividual is called sexual reproduction.Like plants, the the reproductive parts in animalsalso gametes that fuse to form a zygote. It is thezygote which develops into a new individual.
MALE REPRODUCTIVE ORGANGSThe male reproductive organs include a pairof testes, two sperms ducts and a penis. Thetestes produce male gametes called sperms. Millions of sperms are produced by the testes.
FEMALE REPRODUCTIVE ORGANS IN HUMANS [OVIDUCTS]
FEMALE REPRODUCTIVE ORGANS The female reproductive organs are of ovaries, oviducts[fallopian tubes] and the uterus. Theovary produces female gametes called ova[eggs]. A single matured egg is released into oviduct by on of the ovaries every month. Uterus is the development of the baby takes place. Like the sperm, an egg is also a single cell.
HUMAN OVUM An ovum (plural ova, ovum meaning egg or egg cell) isa haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the youngovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization.
SPERMSperm were first observed in 1677 by Antonie van Leeuwenhoek using a microscope. The sperms are produced by testes. Though sperms are verysmall in size, each has head, a middle piece and a tail. Each sperm is a single cell with all usual cell components.
FERTILISATION The first step in process of reproduction is the fusion of asperm and an ovum. When sperms come in contact with anegg, one of the sperms may fuse the egg. Such fusion of the egg and the sperm is called Fertilisation
PROCESS OF FERTILISATION IN HUMAN BEINGS Fertilization involves the fusion of the male and the female gamete. The male and the female gametes are released from the male and the female reproductive organs.Sperms or male gametes are released from the male reproductive organ i.e., the penis. These sperms then enter the female body through the vagina. Then, they travel through the fallopian tubes where they meet the eggs. Hence, the process of fertilization takes place in the fallopian tubes. During fertilization, the haploid nucleus of the sperm and that of the ovum fuse with each other to form the zygote. This zygote divides to form an embryo which in turn develops into a foetus.
INTERNAL FERTILISATION AND EXTERNAL FERTILISATION The fertilisation which takes place inside the female body is called Internal fertilisation. Fertilisation in which the fusion of maleand female gamete takes outside the body is called External fertilisation. Example: frog, fish, starfish etc.
ZYGOTE A zygote is always synthesized from the union of two gametes, and constitutes the first stage in a unique organisms development. Zygotes are usually produced by a fertilization event between two haploid cells— an ovum (female gamete) and a sperm cell (male gamete)—which combine to form the single diploid cell. Such zygotes contain DNA derived from boththe parents, and this provides all the genetic information necessary to form a new individual. Fusing nuclei
TEST-TUBE BABYIn some women oviducts are blocked. These women are unable to bear babies because sperms cannot reach the egg for fertilisation. In such cases, doctors collect freshly released egg and sperms and keep them together for a few hours for IVF. In case fertilisation occurs, the zygote is allowed to develop for about a week and then it is placed in the mother’s uterus.Complete development takes place in the uterus and the baby is born like other babies. Babies born through this technique are called test-tube baby In vitro fertilization (IVF) is a process by which egg cells are fertilized by sperm outside the womb, in vitro.
EMBRYOFertilisation results in the formation of zygote which begins to develop into embryo. The zygote divides repeatedly to give rise to a balls of cells. The cells then begin to form groups that develop into different tissues and organs of body. This developing structure is termed an embryo. The embryo gets embedded in the walls of uterus for development.
FOETUSThe stage embryo in which all body parts can been seen is called Foetus. UTERUS Foetus in the uterus
A female frog sitting on a mass of its own spawn [eggs]
REPRODUCTION IN FROGS During spring or rainy season, frogs and toads move to ponds andslow flowing streams. When the male and female come together in water, the female lays hundreds of eggs. A layer of jelly holds theeggs together and provides protection to the eggs. As the eggs are laid, the male deposits sperms over them. Each sperm swimsrandomly in water with the help of its long tail. The sperms contact with the eggs this results in fertilisation. Though the animals lay hundreds of eggs and release millions of sperms, all the eggs do not get fertilised ,this is because the eggs get exposed in water movement, wind and rainfall. Also, there are other animals in pond which may feed on eggs
METAMORPHOSIS Metamorphosis is a biological process oftransforming a larva into an adult. This involves relatively sudden and abrupt changes in the animal’s structure. Frogs and insects are examples of organisms showing metamorphosis.
ASEXUAL PRODUCTION Asexual reproduction is a mode of reproduction that does not involve thefusion of the male and the female gamete. It requires only one parent, and the offsprings produced are exact copies of their parents.
BINARY FISSON It is a type of asexual reproduction in which a single cell divides into two halves. Organisms that reproduce through binary fissionare bacteria and Amoeba. In Amoeba, the division of cells can take place in any plane. It involves the division of its nucleus into two nuclei, which is followed by the division of its body into two halves. Each half of the body receives a nucleus. BINARY FISSON IN AMOEBA DIVIDING NULEUS DAUGHTER AMOEBAE
BUDDING Budding involves the formation of a new individual from the bulges, known as buds formed on the parent body. This method ofreproduction is common in Hydra. In Hydra, the cells divide rapidly at a specific site and develop as an outgrowth, called the bud. These buds, while being attached to the parent plant, develop into smaller individuals. When these individuals become mature enough, they detach from the parent’s body and become independent individuals. Budding in Hydra
OVIPAROUS ANIMALS AND VIVIPAROUS ANIMALSAnimals which lay eggs outside their bodies are known as oviparous animals. All birds, frogs, lizards, crocodiles etc. belong to this group. Animals which give birth to young ones are knownas viviparous animals. Animals like lions, tigers, dogs, and humans belong to this group.
DOLLY, THE CLONE Dolly was the first cloned mammal, and is genetically identical to its parent sheep.Cloning is creating an exact copy of a biological entity. A clone is created by inserting the complete genetic material of a regular body cell from a donor into a recipient. Sheep are viviparous animals, and so propagate their offspring sexually. Sir Ian Wilmut from Roslin Institute in Edinburgh, Scotland created Dolly.
WORLD’S FIRST CLONED BUFFALO WAS IN INDIA! Scientists at India’s National Dairy Research Institute, in the Indian state of Haryana, produced the first cloned buffalo back in February 6 2008,using DNA from the ear of an adult female—though unfortunately, it died of pneumonia soon after its birth.