SEX DETERMINATION

 SEX DETERMINATION: Sex determination deals with the occurrence of sex in the next generation, or it can also be spoken as- occurrence of  sexes of organisms. Earlier it was believed that women plays a great role in determining the sexuality of an organism but later on scientifically it has been found that it is not the female but Male who are the determiner of sex for the next generation. 

Higher Organisms  are 2n, means they are diploid. We have 23 pairs of chromosomes ie. 46 number of chromosomes. Out of 23 pairs or 46 number of chromosomes, 22 pairs or 44 number of chromosomes are called autosomes and one pair or 2 chromosomes are only sex chromosomes.

23 pairs of chromosomes an organism has 50% come from the mother side and other 50% come from the Father side.

Sexually reproducing organism produces gametes and the gametes are produced after Meiosis division or reduction division. Male gametes are called Sperms and female are called egg or ova.

Due to sexual reproduction both the both the gametes  ie. Sperm and an egg unite together to form Zygote. Zygote leads to the formation of an embryo or the future organism.

Dihybrid Cross

 Dihybrid Cross: For conducting Dihybrid cross, Mendel selected 2 pairs of contrasting characters. Earlier Mendel took one pair of contrasting character for conducting his monohybrid experiment. For the dihybrid experiment, Mendel completed his experiment in the following way -

1st pair - Height             contrasting characters          Tall( TT )         and      Dwarf( tt )

2nd pair Seed shape        contrasting characters         Round( RR )    and      Wrinkle( rr )

For dihybrid experiment Mendel took dominant characters in one side and crossed it with the recessive characters in the following way-

                                       Tall Round     x    Dwarf Wrinkle

                                             TT RR                  tt rr

Ratio that he obtained from the dihybrid cross is 9:3:3:1

While doing this experiment Mendel formulated his another most important Law, "which is Law of  Independent Assortment".

Mendel found that the parental characters of Dihybrid experiment assort out independently in F2 generation.

That means -Tall Round(TT RR )  when crossed with Dwarf Wrinkle ( tt rr ) the F1 generation became Tall Round with the genotype (Tt Rr ), but in the F2 generation parental characters ie. TTRR and ttrr reappear.

Some Important Terminology:

Phenotype: Visible expression means can be seen, like tall or dwarf.

Genotype: Genetic constitution of individual, which cannot be seen. Like tall may be TT OR Tt. These  TT or Tt which are found through genetic study, known as Genotype.

Homozygous :      The organism carrying similar alleles for a trait, eg TT or tt.

Heterozygous :     The organism carrying different  alleles for a trait eg Tt

F1 Generation  :    The first Filial generation

Gametes         :    Reproductive unit, ( Sperm and Egg in case of human beings)

Dominant allele :   The parental character that occurs in the next generation.

Recessive allele:   The character which is unable to be expressed and remain suppressed is called Recessive allele 

MONOHYBRID EXPERIMENT AND LAWS

For doing monohybrid experiment Mendel took one pair of contrasting characters from his selected seven pairs of contrasting characters.As Maendel took one pair so it is known as Mono and crossing as hybrid.From the crossing the ratio that is obtained, he named it as monohybrid ratio and it is 3:1

   7 pairs of characters that Mendel took

First experiment in monohybrid cross he took the pair Height. Height has two contrasting characters one is tall and other is dwarf. For tall he gave the symbol TT which is dominant and dwarf is recessive so he used the small letters of dominant ie. tt.

From the monohybrid cross Mendel formulated two laws ie. Law of Dominance  and Law of segregation.

Law of Dominance- Mendel stated the law in this way- One factor in a pair may express itself and prevent the expression of other. The factor that  expressed itself was described by Mendel as dominant factor and unexpressed one is the recessive factor.

That means that character from father and mother come through gametes. Gametes unit to form zygote and later on leads to the formation of an organism. Sometimes character of father is dominant and sometimes mother's character. The dominant character is expressed in the F1 generation. F1 means first filial generation ie son or daughter.

Law of Segregation:  Segregate means  to separate. In the F1 generation we found that the character is tall and it comes from Tt . But these two allele never get mixed up or are contaminated, they simply remain together and has a tendency to get separated. And this separation occur in the F2 generation, where we find the parental characters to  reappear ie. TT and  tt. This is segregation.

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HEREDITY

 

Higher Organisms  are 2n, means they are diploid. We have 23 pairs of chromosomes ie. 46 number of chromosomes. Out of 23 pairs or 46 number of chromosomes, 22 pairs or 44 number of chromosomes are called autosomes and one pair or 2 chromosomes are only sex chromosomes.

23 pairs of chromosomes an organism has 50% come from the mother side and other 50% come from the Father side.

Sexually reproducing organism produces gametes and the gametes are produced after Meiosis division or reduction division. Male gametes are called Sperms and female are called egg or ova.

Due to sexual reproduction both the both the gametes  ie. Sperm and an egg unite together to form Zygote. Zygote leads to the formation of an embryo or the future organism.

As the chromosomes come from two organisms to form zygote, therefore the organism that is formed shows variation .

Variation is a change due to which the species have equal chances of surviving in the environment they remain.

Chromosomes are the hereditary vehicles. It is long, slender thread like structure. Genes are present in the chromosome and it contains genetic materials. Chemical nature of gene is called DNA. Characters of father or mother that occurs in gametes are the DNA that is present there. Characters are also known by another name called Traits.

Gregor Johan Mendel is known as Father of Genetics .He did experiment on garden peas and blended his knowledge of science and mathematics to get the result of his experiment. He was the first person to give the information that the characters are transmitted from father to son. For doing his experiment  Mendel took 7 Pairs of contrasting characters. For example Height is a character which have two contrasting characters like Tall and Dwarf( Dwarf means short). When we say the person has height means he may be tall or short but it doesn’t mean that the height is tall.

With the garden peas Mendel conducted many experiment, which are known as  Monohybrid , Dihybrid  and Poly hybrid experiment. 

Monohybrid Experiment or Mono hybrid cross: For conducting the monohybrid experiment Mendel took one pair of contrasting character. One pair means mono and crossing them is the hybridization (or hybrid), the ratio of mono hybrid experiment is 3:1 .

Dihybrid Experiment or Dihybrid cross: For conducting the dihybrid Mendel took two pairs of contrasting characters. The ratio of Dihybrid cross is 9:3:3:1 .

From these above crosses Mendel formulated his famous laws, which are known as –

Law of Dominance, Law of segregation and Law of Independent assortment

Some Important Terminology:

Phenotype: Visible expression means can be seen, like tall or dwarf.

Genotype: Genetic constitution of individual, which cannot be seen. Like tall may be TT OR Tt. These  TT or Tt which are found through genetic study, known as Genotype.

Homozygous : The organism carrying similar alleles for a trait, eg TT or tt.

Heterozygous :  The organism carrying different  alleles for a trait eg Tt

CONTROL AND COORDINATION:

Nervous system is a system of highly specialized nerve cells , nerve fibres and organs that continue and control the activities of different parts of the body. This is done by converting external and internal stimuli of environmental changes into the form of electrical impulse( a process called transduction) and transmit them into a specialized called effectors(muscles, glands etc.) to react accordingly.

Between the receptors and effectors are the conducting cells of nervous system, called neurons. Neurons are the structural and functional unit of the nervous system that forms a complex network of communications by spreading throughout the organism.

Reflex action:(Marshal Hull, 1833) is an immediate involuntary action of any organ or part of the body in response to the particular stimulus. The function or action occurs immediately, without the involvement of will or consciousness.

Reflex arc: The nervous pathway taken by nerve impulse in a reflex action is called reflex arc.

Examples of reflex action:

1) Blinking of an eyelid when a moving object approaches the face.

2) Sneezing is a reflex action to the stimuli in nose.

3) Salivation occurs at the sight of food.

4) An  immediate removal of hand when it touch hot bodies.

Importance of reflex action:

1) It enables the animal to respond immediately to a harmful stimuli so that the no harm is caused to it.

2) It relieves the brain of too much work as the responses of routine nature take the form of reflex actions. If the animal is to exercise its will every time a wave of peristalsis occurs in the intestine, then the brain would soon become exhausted.

VIDEO NO - 1

VIDEO NO - 2

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POST FERTILIZATION CHANGES (In Humans):

 

POST FERTILIZATION CHANGES: Fusion of male and female gamete leads to the formation of zygote. Zygote divides rapidly by mitotic division as it moves through the isthmus of oviduct towards the uterus. This is called cleavage and the cells that are formed are called blastomeres. From single cell zygote there is the formation of 2 cells, 2 to 4 cells, and then 8 cells. 8 cells then leads to the formation of 16 cells. This condition of 16 to 32 solid ball of cells is called Morula.

Morula – It is the solid mass of cell comprising of 16 – 32 cells formed from the zygote by mitotic divisions (after 5^th cleavage). It takes approximately 3 days. A morula can be differentiated from blastula in the absence of cavity. It looks like a mulberry shaped ball of cells. The morula reaches the uterus about 4-6 days after fertilization.

In mammals due to the presence of insignificant amount of yolk, cleavage division cut the ovum into complete daughter cells. This type of cleavage in mammalian egg is termed as holoblastic.  Cleavage in the mammalian egg takes place during its passage through the fallopian tube to the uterus.

The outer layer of cells become flattened and is termed as Trophoblast, which absorbs fluids from the uterus. These fluid absorbed by the trophoblast gets collected in a cavity called blastocoels, or blastocyst cavity. As the quantity of fluid increases , the morula increases rapidly and assumes the shape of a cyst, which passes further into the uterus.

The blastocytes has over 100 cells. The portion of the blastocytes where the embryonal knob located lies against endometrium.

Implementation is the attachment of the blastocysts in the uterine wall. It takes place about seven days after fertilization.

Role of Zona Pellucida : The function of zona pellucida is to prevent the implementation of the blastocyst at an abnormal site.

The trophoblast of the invading blastocyst develops the rudiment of chorion, an extra embryonic membrane, which later forms placenta. The chorionic cells secretes a hormone named human chorionic gonadotrophin ( hCG), which resembles and takes over the job of pituitary LH during pregnancy.

Finally transformation of the blastula into gastrula takes place. Gastrula has three primary germ layers. In this stage morphogenetic movements takes place.

          

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FERTILIZATION IN HUMANS:

FERTILIZATION IN HUMANS: The sperms present in the semen travel a long distance, from the uterus to the Fallopian tube. The sperms swim in the fluid medium of  the female genital track which is also partly helped by uterus.

Sperms swims at the rate of 1.5 to 3 mm per minute. A single ejaculation of sperms contains about 200 to 400 million of sperms in some 3ml. of fluid secretion. The sperms remains active for 24 to 48 hours after that it exhausts its energy and dies. 

Increased levels of GnRH stimulates the anterior pitiitary gland which then secretes the FSH and LH .FSH stimulates sertoli cells to secretes some factors which helps in spermatogenesis.

The motile sperms swim rapidly the cervix, enter the uterus and reaches the ampullary - isthamic junction of the oviduct, where the fertilization takes place.

A sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane to block the entry of the additional sperms.

The enzyme of the acrosome of sperm help to dissolve zonna pellucida and plasma membrane of the ovum and sperm head is allowed to enter into the cytoplasm of the ovum. This includes completion of Meiosis II to form secondary oocytes and II polar body.

The activated spermatozoa undergo acrosomal reaction and release various chemicals, like hyaluronidase that acts on the ground substance of follicle cells, corona penetrating enzyme that dissolves corona radiate, and zona lysine or acrosin that help to digest the  zona pellucida.All these chemicals are contained in the acrosome, located at the tip of sperm head and are collectively termed  sperm lysins. Fertilization of egg with only one spermatozoan is known as monospermy.

Numerous physical and chemical changes occur in response to egg- sperm binding. First egg become activated and undergoes depolarization of its membrane. Second the egg exhibits cortical reaction and shows zona reaction, which makes egg impervious to any other sperm.

As the fertilizing sperm enters the ovum it usually looses its flagellum. The sperm entry stimulates the egg to complete its second meiotic division.

Ultimately diploid zygote is formed by the fusion of a sperm with an ovum.

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LUNG CAPACITY

Comparative study on capacity of lungs of normal people and smokers under different age: 

Lungs are the vital organ of the body. Lungs occurs in pair and are spongy and it is located on the either side of the chest. The lungs are covered by a thin tissue layer called pleura. A thin layer of fluid is also present which acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath. Air enters our lungs through nostrils, then trachea and bronchi and helps in the exchange of gases. Lungs are also important organ for the purification of blood. Lung volume  and the lung capacity refer to the volume of air in the lungs at different phases of the respiratory cycle. The average lung capacity of an adult human male is about 6 litres of air. The average human respiratory rate is 30 -60 breaths per minute at birth, then decreasing to 12 -20 breaths per minute in adults.

This is a survey based project which was undertaken to know the lung capacity of people in different age groups. Along with the different age groups, another division was made in each group that is of addiction like smoking, alcoholic etc  to find if there is any variation in lung capacity.

OBJECTIVE:

1)      To find the lung capacity of people under different age groups.

2)      To compare the lung capacity of normal and healthy people with that of smokers and addicted.

RESEARCH QUESTIONS:

1)      Lung capacity of smoker is less or more?

2)      Why the smokers have less stamina?

3)      Why smokers and addicted people become tired very quickly ?

4)      How lung capacity can be increased?

5)      Is the physical work efficiency of a normal and healthy person related to lung capacity?

METHODOLOGY

Ø  For doing this Project we have taken long polythene tube/bag of 100 cm

Ø  Then we conducted survey with the polythene tube

Ø  We asked people to blow air  at a single instance

Ø  Next we took the measurement of the inflated portion of the polythene tube

Ø  Then finally we took out the volume from the measurement that we obtain

Ø  In this way we took the measurement of number of people under  different age group.

1)      First of all we took out the circumference

Then the radius taken out by using formula 2πr

Then the volume formula was used = 2 πr²h

Suppose a person blown air of 65 cm then

Circumference of polythene = 22 cm

Then the radius will be = 3.5 or 7/2

Now putting the value

The volume formula 2πr²h

=2 x 3.14 x3.5 x 3.5 x 65

=38.5 x 65

=2502.5 cm³

^{LUNG CAPACITY OF NON SMOKERS}

Age group : 16 to 30 years (group A)

SL	Date	Name	Age	Volume	Cm
1	19/8/19	Biban Jidung	17	2502.5cm3	65cm
2	19/8/19	Joshwa	17	2733.5cm3	71cm
3	19/8/19	Bijit Naiding	17	2645.5cm3	69cm
4	19/8/19	Vivek Patwary	16	2541cm3	66cm
5	19/8/19	Pallav Jyoti Gogoi	16	2618cm3	68cm
6	19/8/19	John Hanse	22	2425.5cm3	63cm
7	19/8/19	Pale Saithuvai	29	2695cm3	70cm
8	19/8/19	Rolin Saithuvai	24	2387cm3	62cm
9	19/8/19	Lavi Saithuvai	22	2541.5cm3	66cm
10	19/8/19	Rahul Thapa	26	2579.5cm3	67cm

Age group : 31 to 45 years (group B)

SL	Date	Name	Age	Volume	Cm
1	21/8/19	J.T Lian Vaichai	42	2117.5cm	55cm
2	21/8/19	Bongthoi Thinphun	38	2156.5cm	56cm
3	21/8/19	D.S lian	40	2310cm	60cm
4	21/8/19	Sanga Saithuvai	32	2271.5m	59cm
5	21/8/19	L.T lily	36	2425.5cm	63cm
6	21/8/19	Payal Dutta	31	2194.5cm	57cm
7	21/8/19	Sanju Pradhan	43	2271.5cm	59cm
8	21/8/19	Rohan Enghi	34	2348.5cm	61cm
9	21/8/19	Roshan Nath	39	2464cm	64cm
10	21/8/19	Ricky Singh	32	2040.5cm	53cm

 Age group: 46 to 60 (group C )

SL	Date	Name	Age	Volume	Cm
1	23/10/19	S.N Thang	52	1809.5cm3	47cm
2	23/10/19	Abisheck Rai	56	1617cm3	42cm
3	23/10/19	Mycle Rai	48	1540cm3	40cm
4	23/10/19	Rahul Saithuvai	49	1694cm3	44cm
5	23/10/19	Ajit Pradhan	46	1886.5cm3	49cm
6	23/10/19	Krish Chowdhury	59	1501.5cm3	39cm
7	23/10/19	William Saithuvai	54	1655.5cm3	43cm
8	23/10/19	Roshan Paslin	56	1578.5cm3	41cm
9	23/10/19	Rohit Phancho	52	1617cm3	42cm
10	23/10/19	Manju Phancho	51	1694cm3	44cm

 

 LUNG CAPACITY OF  SMOKERS 

Age group : 16 to 30 years (group D )

SL	Date	Name	Age	Volume	Cm
1	25/11/19	Redian Hasnu	21	2156cm3	56cm
2	25/11/19	Roshan Rai	23	1848.5cm3	48cm
3	25/11/19	Pronesh Kemprai	26	1809.5cm3	47cm
4	25/11/19	Lian Neibom	19	2002cm3	52cm
5	25/11/19	John Lama	28	1732.5cm3	45cm
6	25/11/19	Jacob Saithuvai	29	2040.5cm3	53cm
7	25/11/19	Ankit Nag	25	2194.5cm3	57cm
8	25/11/19	Ayan Rai	21	1963.5cm3	51cm
9	25/11/19	Arjun Mogor	23	2117.5cm3	55cm
10	25/11/19	Bishnu Raya	26	2271.5cm3	59cm

 

Age group : 31 to 45 years (group E )

SL	Date	Name	Age	Volume	Cm
1	25/11/19	Rahul Nath	33	1809.5cm3	47cm
2	25/11/19	Aman Kemprai	35	1732.5cm3	45cm
3	25/11/19	Joiring Hojai	32	1848cm3	48cm
4	25/11/19	Bishnu Rai	33	1694cm3	44cm
5	25/11/19	Utam Sharma	44	1771cm3	46cm
6	25/11/19	Ram Rai	41	1655.5cm3	43cm
7	25/11/19	Simanta Nath	34	1578.5cm3	41cm
8	25/11/19	Vivek Sharma	36	1617cm3	42cm
9	25/11/19	Joyjit Warisa	35	1655.5cm3	43cm
10	25/11/19	Rohit Kemprai	38	1655.5cm3	43cm

 Age group: 46 to 60 (group F )

SL	Date	Name	Age	Volume	Cm
1	23/10/19	S.N Thang	52	1809.5cm3	47cm
2	23/10/19	Abisheck Rai	56	1617cm3	42cm
3	23/10/19	Mycle Rai	48	1540cm3	40cm
4	23/10/19	Rahul Saithuvai	49	1694cm3	44cm
5	23/10/19	Ajit PraSdhan	46	1886.5cm3	49cm
6	23/10/19	Krish Chowdhury	59	1501.5cm3	39cm
7	23/10/19	William Saithuvai	54	1655.5cm3	43cm
8	23/10/19	Roshan Paslin	56	1578.5cm3	41cm
9	23/10/19	Rohit Phancho	52	1617cm3	42cm
10	23/10/19	Manju Phancho	51	1694cm3	44cm

 

 Average lung capacity of different age groups that we have surveyed

(group A to C are normal people and from group D to F are smoker of drug addicted)

GROUP A (age group  16 to 30 years age) ─2568.05cm³

GROUP B (age group  31 to 45 years age) ─2259.9cm³

GROUP C  (age group 46 to 60 years age─ 1661.2cm³

GROUP D  (age group  15 to 30 years age)─2013.6cm³

GROUP E  (age group  31 to 45 years age )─1701.7cm³

GROUP F  (age group 46 to 60 years age)─1362.9cm³

So it can be concluded that the lung capacity of smokers, addicted etc. is much less than the lung capacity of the people in their age group.

Lung capacity can be increased through Pranayam and Yoga

 

 

Special thanks to my students:

Prescott Telengsing

Suhas Nandi Purkayastha

Dimpal Gogoi