How organism Reproduce?
Reproduction:- Re= again ; production = to produce.
A biological process by which an organism produce another organism similar to itself.
Not essential for life of individual like respiration.
Function/ importance:-
Necessary for continuing of species.
Do organism create exact copies of themselves?
No. They produce similar but not exact copies (Identical copies) of themselves because their DNA is not same.
We know chromosomes in nucleus a cell contain information for inheritance of features in the form of DNA molecules
DNA :- Deoxyribo Nucleic acid
DNA is the information source for making proteins.
If the information is changed , different proteins will be made.
Thus, different proteins will lead to altered body designs.
Write basic event in reproduction.
Creation of DNA copy.
How cell build copies of DNA?
By using chemical reactions.
Mechanisms:- Semi Conservative mode of DNA replication.
Enzyme involved:-
DNA polymerase
Helicase and gyrase.
DNA ligase
Primate etc.
After DNA replication, other cellular apparatus creates and two cells divides to give rise to two cells.
Since no biochemical reactions is absolutely reliable, so some variation generates each and every time in DNA replication and so organism can't be identical and so NO organism can't be identical.( Case of sexual reproduction)
Advantage of Variation:-
Organism will be capture of adopting changing environment.
Natural rule of Selection:-
Only useful variations will be selected by nature and other will be eliminated.
Types of reproduction:-
Two types:-
Asexual reproduction
Sexual reproduction
Asexual reproduction:-
Uniparental
Simple and fast process
Produce identical offsprings and are called clones.
No role in evolution
Does not involve formation of gametes.
Fusion of gametes takes place.
Involves mitosis.
Sexual reproduction:-
Biparental
Complex and slow process
Produce similar offsprings with some variation
Important role in evolution.
Involves formation of gametes.
Fusion of gametes takes place.
Involves meiosis and mitosis.
Modes of asexual reproduction used by single celled organisms:-
Six types:-
1. Fission
2. Fragmentation
3. Budding
4. Regeneration
5. Spore formation
6. Vegetative propagation.
Fission:- splitting of parental cell into two or more daughter cells.
Two types:-
Binary fission
Multiple fission
Binary fission:- seen in Amoeba, Paramecium (protozoan) and bacteria.
Parental cell split into two daughter cells.
It can be simple/ irregular, longitudinal, transversal depending upon the plane of division.
In Leishmania splitting of parent cell take place in longitudinal plane w.r.t. flagellum at its end.
Multiple fission:-
Seen in malarial parasite, Plasmodium.
Splitting of a parent cell into numerous daughter cells, each of which grow into an adult.
Fragmentation:- seen in lower multicellular organisms which have relatively simple body organisation.
Seen in Spirogyra.
In this parent body breaks into two or more fragments and each fragment grows into a new individual.
Regeneration:-
Mode of asexual reproduction in which missing part of ab organism is repaired by proliferation of cells.
Seen in Planaria.
All these changes takes place in an organised sequence referred to as development.
Budding:-
Seen in Hydra .
In this mode of asexual reproduction, a bud is develops as an outgrowth due to repeated cell division at one specific site
These buds develop into tiny individuals and when fully mature, detach from parent body and become new independent individuals.
Vegetative propagation:-
Mode of reproduction in which new plants are formed from vegetative parts of plants like root , stem etc.
Advantage:-
Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds.
Method is useful for propagation of seedless plants like banana , rose and Jasmine.
All plants produce are genetically similar to parent plant to have all its characteristics.
Example:- Buds produced in notches along the leaf margin of Bryophyllum fall on the soil and develop into new plants.
Spore formation:-
Seen in Rhizopus, Chlamydomonas, Sponges, Penicillium.
On bread, thread like structure grows which is nothing but Rhizopus.
It contain two parts:-
Hyphae
Blob on a stick.
Blob are sporangia which contain cells or spores.
Spores developes into new Rhizopus individuals.
The spores are covered with thick walls that protect them.
When it comes in contact with moist surface the wall ruptures and begin to grow.
Tissue culture:-
New plants grown by separating cells from growing tip of a plant.
The cells are then places in an artificial medium where they divide rapidly to form a group of cells called callus.
The callus is then transferred to another medium containing hormones for growth and differentiation.
The plant let's are placed in soil so that they can grow into mature plants.
Using tissue culture,many plants can be grown from one parent in disease free conditions.
Technique is commonly used for ornamental plants.
Sexual reproduction:-
Involves two parents.
When reproduction takes place as a result of fussion of male and female gametes , this is called sexual reproduction.
Fusion of two gametes results in formation of zygote.
Sexual reproduction in flowering plants:-
Pistil/ Carpel :-
Comprises of
- Stigma
-style
-ovary
Group of Pistil is called Gynoecium.
Female reproductive part .
Stamen:-
Comprises of
- Anther
-Filament
Group of stamen is called androecium.
Male reproductive part.
Petals:-
Coloured attractive modified shoot.
Attract pollinators such as insects.
Group of petals is called corolla.
Sepals:-
Green coloured modified shoot.
Perform photosynthesis.
Group of sepals is cay calyx.
Note:- Stamens and Carpels are reproductive parts of flower which contain germ cells.
Types of flower:-
Two types :-
Unisexual
Bisexual.
Unisexual:-
Contains either stamen or pistils.
Example:- Papaya, Watermelon.
Bisexual:-
Contains both Stamens and Carpels.
Stamens is male reproductive part and produces pollen grains (yellow)
Carpel is female reproductive part and placed centrally.
It consists 3 parts
-Stigma:- Terminal and sticky
-Style:-middle , elongated
-Ovary:-bottom part , swollen.
Contain ovules
Each ovule contain an egg cell.
Fertilisation:-
The process of fusion of male germ cell produce by pollen grain and female gamete present in ovule is called fertilization.
Pollination:-
The transfer of pollen grains from.anther to stigma of same flower or of different flower is called pollination.
Types of pollination:-
Two types
Self pollination
Cross pollination
Self pollination:-
Transfer of pollen from anther to stigma of same flower.
Seen in bisexual and cleistogamous flowers ( Flowers which donot open)
Cross pollination:-
Transfer of pollen grains from anther to stigma of different flowers.
Seem in some bisexual and all unisexual flowers.
What happens after pollination?
After pollination, the pollen grains reaches to ovary through pollen tube
It than reaches to ovule and finally to egg.
On reaching egg, it get fused with it to form zygote.
This is called fertilization.
Post fertilization events:-
Zygote divides many times to form an embryo within ovule.
Ovule develops a tough coat and is gradually converted into seed.
Ovary ripen to form fruit.
Meanwhile, petals , sepals, stamens, style and stigma may shrivel and fall off.
Germination:-
Seed contains future plant or embryo which develops into a seedling under appropriate conditions.
This process is known as germination.
Reproduction in Human beings:-
General process of growth:-
Increase in size (height).
Increase in body weight.
Acquire teeth {Deciduous (milky) and permanent (second set)}
Changes after puberty:-
Thick hair growth in new body parts such as armpits and genital area between thighs.
Thin hair appear on legs , arms and face.
Skin become oily and pimple develops.
Aspects of sexual maturation:-
In girls :-
breast size begin to increase;
Menstrual begin;
Voice become high pitch.
In boys:-
Penis become large and erect
Voice begin to crack.
Thick hair growth on face.
Puberty:- the period in which rate at which general body growth behind to slow down, reproductive tissues begin to mature is called puberty.
Why does the body show sexual maturation at this age?
For creation of germ cells to participate in sexual.
Note:- if animals are to participate in the process of mating, their state of sexual maturity must be identified by other individual.
For transfer of germ cells between two people there is a need of specialised organs for sexual act.
In male , it is penis.
In female, it is vagina.
Male reproductive system:-
Male reproductive system comprises of :-
1.Primary sex organ:-
-Testis ( 1 pair, produce sperm and testosterone)
2.Secondary sex organ/ accessory sex organ:-
-Epididymis
-Seminal vesicle
-Prostate gland
-Cowper's gland.
3.Duct ( Help in conduction of sperm)
-Vas deferens
-Urino genital duct (Common passage for urine and sperm conduction)
4.External genital
-Penis (Help in insemination)
Ques:- testes are located outside the abdominal cavity in scrotum . Why?
Because sperm formation require a 2°lowet temperature than the normal body temperature.
Name the hormones that regulate formation of sperms and also bring changes in appearance seen in boys at the time of puberty.
Testosterone
Define sperm.
Tiny body that consists of genetic material a long tail that help them to move towards the female germ cell.
What is the role of seminal vesicle and prostate gland? Also write role of Cowper's gland.
Seminal vesicle:-
Secretion contain prostaglandins.
Activate sperm
Cause construction in femal reproductive gland.
Prostate gland:-
Provide nutrition to sperm
Protect sperm from acidic medium of vagina.
Provide basic pH for sperm (7.4)
Cowper's gland:-
Secrete mucus.
Help in lubrication during copulation.
Sperm + secretion from three gland:- semen.
Female reproductive system:-
It consists of:-
1. Primary sex organ
-Ovary ( produce egg and female sex hormone)
2. Uterus , Fallopian tube , vagina.
3. Glands :- Mammary gland.
4. External genitalia:- Valva
Ovary:- When a girl is born, the ovary already contain thousands of immature eggs.
On reaching puberty, some of these starts maturing.
One egg is produced every month by one of ovaries in alternate manner.
Fallopian tube:-The egg is carried from ovary to womb through oviduct.
It comprises of Infundibulum, ampulla and Isthamus.
Site of fertilization.
Uterus:-
Two fallopian tubes unite into an elastic bag like structure called uterus .
Site of Implantation of zygote.
After implantation, it get divided to form foetus.
Placenta:-
During pregnancy mother's uterus prepare itself every month to receive and nurture growing embryo.
Lining thickens and is richly supplied with blood to nourish the growing embryo.
The lining is called placenta.
Vagina and Cervix:-
The uterus opens into vagina through cervix.
From where embryo get Nutrition?
From mother's blood through placenta
Development of Embryo:-
Placenta contains villi on embryo's side of tissue.
On the mother's side are blood spaces which surround the villi.
Villi provide large surface area for glucose and oxygen to pass from mother to embryo.
Waste generated by developing embryo also be removed by transferring them into mother's blood through placenta.
Gastation period:-
The development of child inside the mother's body take approx nine months
This period is called gastation period.
What happens when egg is not fertilised?
If the egg is not fertilised, it lives for about one day.
So after that it slowly breaks down and comes out through vagina as blood and mucous..
This cycle takes place every month and is known as menstruation.
It usually last for about two to eight days .
Note:- Since the ovary release an egg every month , the uterus prepare itself every month to receive a fertilised egg.
Thus it's lining becomes thick and spongy for nourishing the embryo if fertilization has taken place.
Reproductive health:-
It is a state of complete Physical, mental and social well being in all aspects of reproduction.
Parent should have adequate knowledge on the following:-
-knowledge of reproductive process and organs.
Care of mother and child.
What point to be remembered to ensure good care of mother and child?
Proper nutrition diet to pragnent woman as well as lactating woman.
Proper age difference between children.
Planning a body at right age of mother ( between 20-35 years) . Restrict the number of children not to add over population.
Avoid unwanted pregnancy.
Family planning:-
Necessary to limit the huge increase in polulation.
Overpopulation can give rise to serious problems like lack of food, employment and education which in turn affect the economy and also survival of population.
Knowledge on STD ( Sexually Transmitted disease)
Transmission of disease via sexual connection.
This include:-
Bacterial infection (Gonorrhoea , Syphilis)
Viral infection (Warts, AIDs)
AIDs :- Acquired immuno-deficiency syndrome
HIV :- Human Immunodeficiency Virus.
Precautions from STD spread:-
Use Condom
Wash before and after intercourse.
Ways to prevent unwanted pregnancy:-
Condom:- Balloon like elastic covering that tightly fits over the penis.
Collect ejaculated sperm during intercourse
Oral contraceptive pills:-
Does not allow ovulation to occur.
Surgical method:-
Vasectomy:- Removal of a small portion of vas deferens.
Tubectomy:- removal of a small portion of fallopian tube.
Copper-T :-A loop or copper T are placed in uterus to prevent pragnency.
Side-Effect:- cause irritation in uterus.
Thank you :-)
