adaptations in insects part 1

1.       Cybister

a.       Habit: it feeds on small fishes. It is positively phototropic. It is an active swimmer.

b.      Habitat: aquatic, occurs in deep water.

c.       Role in ecosystem: it is a secondary consumer.

d.      Adaptations:

i.                     Strucrural adaptations: forewings modified into horny elytra, hind wints are membranous, folded beneath the elytra.

ii.                   Feeding adaptations: mouth parts consists of strong mandibles.

iii.                  Respiratory adaptations: antennae are hydrofuge structures and can hold air balls containing oxygen for respiration.

iv.                 Flight adaptations: wing muscles of both sides are not fused together below the scutellum, therefore it is an active flier.

2.       hydrophilus olivaceous:

a.       habit: predacious, carnivorous.

b.      Habitat: aquatic habitat. It lives near vegetation. It is shade loving.

c.       Role in ecosystem: it is secondary consumer.

d.      Adaptations:

i.                     Structural adaptation: forewings modified into horny elytra, hind wings membranous, folded beneath elytra, body stream linexd.

ii.                   Feeding adaptations: mouth parts mandibulate adapted for biting.

iii.                  Respiratory adaptations: ventral surface of the body is with a set of hydrofuge hairy structures. It can hold an air film for respiratory purpose. Antennae are above hudrofuge structures and can hold air balls near the spiracles.

iv.                 Swimming adaptations: it is an active swimmer. Appendages are fringed with hairs.

v.                   Adaptations for defence: it has a metasternal keel for defence.

3.       Laccotrephes maculatus:

a.       Habit: it is phytophagous, positively phototrophic.

b.      Habitat: aquatic; is a bottom dweller and liver in mud.

c.       Role in ecosystem: primary consumer.

d.      Adaptations:

i.                     Structural adaptations: fore wings are chitinized to form hemielytra.

ii.                   Feeding adaptation: first pair of legs are pre-hensile and adapted for catching food. Mouth parts of piercing and sucking type.

iii.                  Respiratory adaptation: respiratory tube consists of 2-spine like processes.

iv.                 Swimming adaptations: body is slender, appendages are fringed with hair.

4.       Ranatra elongata

a.       Habit: it feeds upon sap of plants. It is positively phototropic.

b.      Habitat: aquatic; swims on the surface of water,

c.       Role in ecosystem:  it is primary consumer.

d.      Adaptations:

i.                     Structural adaptation: for wings are chitinized to form hemielytra.

ii.                   Feeding adaptations: mouth parts are of piercing and sucking type.

iii.                  Respiratory adaptation: respiratory siphon present.

iv.                 Swimming adaptation: body is slender, appendages are ringed with hair. Walking legs are prominent and are also adapted for walking on bottom of the aquatic habitat,

5.       Lethocerus indicus (giant water bug)

a.       Habit: it feed rapaciously upon small fishes, tadpole, youngs, frogs, and insects. It is positively phototropic.

b.      Habitat: aquatic habitat; it clings to vegetation submerged in the bottom.

c.       Role in the ecosystem: pest of fishes, it is secondary consumer

d.      Adaptations:

i.                    Feeding adaptations: mouth parts are of piercing and sucking type.

ii.                  Respiratory adaptation:  it has a pair of respiratory siphons at the hind end. It breaths oxygen by piercing the surface film with the apex of the abdomen

iii.                Swimming adaptation:  body is stream lined, dorsoventrally flattened, so it overcomes friction in water easily, appendages are oar-like and fringed with hair.

iv.                 Colonization: it flies readily from one water piece to the another and just occupy a different habitat. But it is restricted flier. This is because wing muscles of both sides fuse together below the scutellum.

6.       Diplonuchus annulatum:

a.       Habit:  it feeds upon plant sap, mainly on hydrilla. It is positively phototropic.

b.      Habitat: aquatic; fresh water.

c.       Role in ecosystem:  it is primary consumer.

d.      Adaptations:

i.                    Structural adaptations: body is oval in shape. Forewings modified into horny hemielytra. Hind wings are membtanous. Folded bjeath the elytra.

ii.                  Feeding adaptations: mouth parts of piercing and sucking type.

iii.                Respiratory adaptation: it has a pair of respiratory siphon at the hind end. It takes oxygen through this siphon.

iv.                 Appendages are oar like and fringed with hair.

v.                   Parental care: the male carries eggs on it back till they are hatched;

adaptations in insects

Adaptations in insescts.

1.       Cybister

a.       Habit: it feeds on small fishes. It is positively phototropic. It is an active swimmer.

b.      Habitat: aquatic, occurs in deep water.

c.       Role in ecosystem: it is a secondary consumer.

d.      Adaptations:

i.                     Strucrural adaptations: forewings modified into horny elytra, hind wints are membranous, folded beneath the elytra.

ii.                   Feeding adaptations: mouth parts consists of strong mandibles.

iii.                  Respiratory adaptations: antennae are hydrofuge structures and can hold air balls containing oxygen for respiration.

iv.                 Flight adaptations: wing muscles of both sides are not fused together below the scutellum, therefore it is an active flier.

2.       hydrophilus olivaceous:

a.       habit: predacious, carnivorous.

b.      Habitat: aquatic habitat. It lives near vegetation. It is shade loving.

c.       Role in ecosystem: it is secondary consumer.

d.      Adaptations:

i.                     Structural adaptation: forewings modified into horny elytra, hind wings membranous, folded beneath elytra, body stream linexd.

ii.                   Feeding adaptations: mouth parts mandibulate adapted for biting.

iii.                  Respiratory adaptations: ventral surface of the body is with a set of hydrofuge hairy structures. It can hold an air film for respiratory purpose. Antennae are above hudrofuge structures and can hold air balls near the spiracles.

iv.                 Swimming adaptations: it is an active swimmer. Appendages are fringed with hairs.

v.                   Adaptations for defence: it has a metasternal keel for defence.

3.       Laccotrephes maculatus:

a.       Habit: it is phytophagous, positively phototrophic.

b.      Habitat: aquatic; is a bottom dweller and liver in mud.

c.       Role in ecosystem: primary consumer.

d.      Adaptations:

i.                     Structural adaptations: fore wings are chitinized to form hemielytra.

ii.                   Feeding adaptation: first pair of legs are pre-hensile and adapted for catching food. Mouth parts of piercing and sucking type.

iii.                  Respiratory adaptation: respiratory tube consists of 2-spine like processes.

iv.                 Swimming adaptations: body is slender, appendages are fringed with hair.

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classification of amino acids

classification of amino acids

chemical reaction during 5'capping.

An overview of polyadenylation of 3’ end: post transcriptional modification, prior to the nuclear export.

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The final RNA processing event, i.e. the polyadenylation of the 3’ end of the mRNA is linked with the termination of the transcription.

The CTD tail of the polymerase is involved in the recruiting of the enzymes necessary for the polyadenylation.
The DNA contains a poly-A signal sequence. Once the polymerase has reached the sequence and transcribed the poly-A signal sequence into the RNA, the poly-A signal sequence (these sequences once transcribed into RNA, triggers transfer of the CPSF and CstF from the CTD tail of the polymerase to the RNA, described in the text later) in the RNA triggers the transfer of polyadenylation enzymes to RNA leading to three events.
1. Cleavage
2. Addition of the “A” residues.
3. Termination of transcription.
The CTD tail of the polymerase carries two protein complexes as it reaches the end of the gene.
1. CPSF (cleavage and polyadenylation specificity factor)
2. CstF (cleavage stimulation factor)

The binding of the CPSF (cleavage and polyadenylation specificity factor) and CstF (cleavage stimulation factor) is followed by the recruitment of other proteins as well. This leads to RNA cleavage and then polyadenylation.
The poly-A polymerase mediates the process of polyadenylation and adds about 200 adenines to the RNA’s 3’ end produced by the cleavage.
The poly-A polymerase uses ATP (adenosine triphosphate) as a precursor and adds the nucleotides using the same chemistry as that of RNA polymerase, but here in the absence of a template. Thus long “A” tail is only present in RNA (and not in the DNA)
After polyadenylation (the final step in post transcriptional modification, prior to the nuclear mRNA transport) the mature mRNA is then transported from the nucleus to the cytosol.
At present, not more is known about the relation of the polyadenylation with the termination of the transcription. Two basic models have been proposed to explain the link between polyadenylation and termination.
· First: the transfer of the enzymes responsible for the polyadenylation from the CTD tail of the polymerase to the RNA triggers a conformational change in the polymerase that reduces the processivity of enzymes leading to spontaneous termination soon afterwards.
· Second: after cleavage of the RNA transcript the polymerase keeps on transcribing the DNA short while, the polymerase senses the absence of the 5’ cap on the second RNA molecule; as a result, the RNA recognizes the transcript as improper and terminates the transcription.

INSECT ENDOCRINE SYSTEM: ENTOMOLOGY (HEXAPODOLOGY)

FIGURE: CEPHALIC ENDOCRINE SYSTEM (diagrammatic)

hypersensetivity

·         It is an exaggerated response of immune system that leads to the damage of the tissue and cells, and is shown by an individual on a second contact with the antigen.

·         Coombs and Gell classified the hypersensitivity reactions in four classes of reactions

Type I hypersensitivity:

·         The type I hypersensitivity is also known as allergic reaction. It is induced by antigens which are referred to as allergens.

·         Allergens are specifically non parasitic antigens capable of stimulating type I hypersensitivity responses.

·         The type I hypersensitivity reactions are IgE mediated reactions.

·         The reaction is stimulated by IgE to high affinity IgE-specific Fc receptors expressed on the mast cells and the basophil cells

·         When activated by the antigens (allergens) the IgE antibodies stimulates the mast cells and basophil cells to release primary mediators: vasoactive amines, stored in the granules (degranulation)

·         The chief mediators are the proteases, heparin and histamines etc..

·         The mediators are responsible for all the normal consequences of an acute inflammatory reaction. I.e. granulocyte chemotaxis, vascular permeability and all sorts of the consequences of inflammations.

·         The type I hypersensitivity is further classified as :

Ø  Anaphylaxis: this type of the type I hypersensitivity is highly rapid, life threatening, severe and are spread to whole body, they are caused due to the re-exposure of the individual to the antigen (allergens)

Ø  Atopy: if the tendency to develop allergic reactions is inherited genetically, they are called the atopic hypersensitivity reactions.

Type II hypersensitivity:

·         The type II hypersensitivity reactions cause the destruction of the host cells and tissues; by lysis or toxic mediators, hence they are also called as cytotoxic or cytolytic reactions.

·         It is an IgM and IgG mediated response.

·         It is caused by the binding of the antibodies to the cell or tissue antigens.

·         They (IgG and IgM) cause cell destruction by Fc-mediated mechanisms, either directly or indirectly activating the complement via the classical pathway.

·         Example of the hypersensitivity class ii reaction is the hypersensitivity shown by an individual who has been transfused blood of blood group other than that of the individual.

·         The antibodies attach to the cell membrane component, leading to complement fixation; this activates the complement chain and leads to either lysis or oposonization of the cell.

·         Lysis of target cell is analogous to that of cytotoxic T cells and involves the release of cytoplasmic granules, containing perforin and granzymes that activates the event leading to the apoptosis.

Type III hypersensitivity:

·         It is mediated by immune complexes of IgG antibodies with soluble antigens.

·         The circulating immunity complexes may accumulate at various tissue sites, where they activate complement and subsequently cause tissue cell lysis.

·         Normally these complements are phagocytized by the monocyte-macrophage system.

Type IV hypersensitivity:

·         Commonly it is known as delayed type of hypersensitivity.

·         Only class of hypersensitivity that is triggered by antigen-specific T cells. (cell mediated immunity reactions)

·         This is mediated by T-cell dependent effector mechanisms involving T_H cells.

·         This reaction has nothing to do with the antibodies.

PCR: polymerase chain reaction.

·         PCR is a very simple process.

·         All that happens in PCR is a short region of DNA molecule, let’s take for example a single gene, and is copied many times by DNA polymerase enzyme.

·         The PCR has a variety of applications in genetics, research and in broader areas of biology.

An outline of polymerase chain reaction:

·         It results in selective amplification of chosen reaction of the DNA molecule.

·         For amplification, a region of DNA is chosen (whose sequences in border regions are known)

·         The border sequences of the DNA fragment to be amplified must be known, because in order to carry PCR, two short oligonucleotides must hybridize to the DNA molecule, one to each strand of double helix.

·         These oligonucleotides are used as DNA primers for DNA synthesis reaction.

·         Amplification is usually carried out by DNA polymerase I enzymes derived from thermus aquaticus (this bacteria inhabits the hot streams)

·         The polymerase is named taq polymerase after the name of bacteria from which it is derived.

·         Taq polymerase is thermostable and can withstand temperature up to 96 ⁰ C.

·         The PCR is a very sensitive technique; it can even start from a single target molecule.

·         The size of DNA that can be amplified by this technique is 10 to 40 Kb.

Components required to carry out polymerase chain reaction (PCR):

·         DNA template (with known end sequence)

·          Primers ( the primers complementary to the known sequence of target DNA molecule,

·          taq DNA polymerase (isolated from bacteria thermus aquaticus) living in hot springs. It can withstand temperature up to 96 ⁰ C),

·          fixed buffer( to maintain favourable environment during the PCR),

·          Divalent cations (Mg²⁺ is used in general. Mn²⁺ can be also used, but at higher concentration it causes mutation),

·          monovalent cations (K⁺ is used in general)

·         Large number of DNA nucleotides

Procedures of PCR:

·         The PCR consists of 20 to 40 thermal cycles.

·         Each cycles has discrete steps

1.       Hold: the cycle starts with a temperature of 96 ⁰ C. the hold lasts for a brief period.

2.       Initializing step: the temperature is raised further to 94 to 96 ⁰ C. (if the DNA polymerase to be used is highly thermostable then the temperature can be raised up to 98 ⁰ C.)

This step lasts up to 1 to 6 minutes.

3.       Denaturation step: at the 94⁰ C to 96 ⁰ C the tubes containing the target DNA is placed in the machine.

At this temperature the DNA melts—the strands get separated by breading of hydrogen bonds. At the end of the denaturation step the result is the 2 separated ssDNA molecules.

4.       Annealing step: in this step the temperature is decreased down to 50 to 60 ⁰ C and primers are added and are carried out for 20 to 40 seconds.

Also the DNA polymerase is added too. The primers pair with the complementary sequences on target DNA molecules.

Note: annealing temperature should always be 2 to 3 ⁰ C less than melting temperature of primers, to prevent the primers from melting down.

At this temperature H-bonds are formed and DNA polymerase binds to end of primers.

5.       Elongation: at this step the temperature is raised to 70 to 75 ⁰ C.

At this temperature taq DNA polymerase acts at its best (best temperature is 72 ⁰ C)

6.       Final elongation: at this step the temperature is maintained from 70 to 74 ⁰ C for 5 to 15 minutes after last cycle of PCR, to ensure that all last DNA are fully extended.

 

Entomology: trap cropping

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• Trap cropping involves planting small areas of crop or other species plants near the protected crop.
• The trap cropping must be done, after closely understanding the seasonal cycle.
• The insects are left to develop in the trap and are killed with pesticides, this process is beneficial, since the pesticides are not spread on the whole of the crop, and thus environment friendly and economically sound too.
• In this practice the trap may be of different species of plant or the same crop but planted in different time.
• For example: an early maturing variety of crop to be protected must be planted on say 8-10 percent of the field. And the main crop is of a late maturing variety. Now the early maturity of the early maturing variety species will attract the pests, they seek food and will lay eggs of the first generation. treatments of insecticides are made in the trap around 7 to 10 days after the emergence of first generation adults, in order to prevent infestations in main planting.

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Bruce effect

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• The Bruce effect was first noted by HILDA M. BRUCE in 1959.

• The Bruce effect is also known as pregnancy block, it is shown by the rodents, it refers to the tendency of the pregnant female rodents to terminate their pregnancy, when they are exposed to the scent of another male, which is not the father of the embryo carried by the female.
• Still now the Bruce effect has not been confirmed in other non-rodent species.
• In 1959 Bruce kept pregnant female mice with males which were not the father of the carried embryo, it was seen that the female blocked their pregnancy, in the presence of an unfamiliar male. This effect blocking of the pregnancy by the female influenced by the scent of the male mice was termed as BRUCE effect, after the name of HILDA BRUCE.

Mechanism of the appearance of the Bruce-effect.

• The male mouse urine contains MHC CLASS I peptides that binds to the receptor in the females mouse’s vomeronasal organ (it is an organ filled with mucous present in the nasal septum), it stimulates the vomeronasal system to act as a pump and the system draws in the substances actively. These chemical signals which are specific to each male are learned by the females. This chemosensory cue is coupled by the vasopressin, with an appropriate physiological response,
• It is seen that, if the vasopressin 1b gene is knocked out in females, then the presence of an unfamiliar male does not trigger pregnancy disruption.
• Exposure to the male urinal pheromones will activate a neuroendocrine pathway, which leads to the pregnancy failure. However, if these pheromones are pre-memorized by the female mice, then noradrenalin is secreted, which lowers down the receptivity of the olfactory bulb to these pheromones. Thus the pregnancy disruption is averted.
• The hormone oxytocin is also important in Bruce effect, if the males are treated by the oxytocin-antagonist hormone, then the females are unable to recognize the urinary pheromones of the their mate, and terminates pregnancy when exposed any male, known or unknown.

Neuroendocrine pathway and role of oestrogen:
è The activation of vomeronasal neuron receptors by the male pheromones induces a complex neuroendocrine pathway. This works as follows.
i. The pheromonal information is carried by the nerves to the accessory olfactory lobe, and then to the corticomedial amygdala lobe and then to stria.
ii. These areas stimulate the hypothalamus.]
iii. The hypothalamus then secretes the dopamine,
iv. The dopamine prevents the secretion of prolactin from the anterior pituitary (prolactin is necessary for maintaining the corpus luteum, in the absence of the prolactin the corpus luteum undergoes luteolysis)
v. Now in the absence of the corpus luteum the progesterone is not released. Since the progesterone is necessary for maintaining the pregnancy.
vi. Thus in the absence of the progesterone the pregnancy fails.
è Role of oestrogen: oestradiol is a metabolic product of testosterone, the oestrogen (particularly the E2) is a crucial chemo-signal regulating the Bruce effect.
Small steroid molecules such as E2 are able to enter the bloodstream directly via the nasal ingestion, after ingestion the E2 travels to the uterus, which has high level of suitable receptors,
Normally E2 is essential for the preparation of the blastocyst and the uterus for implantation.
However the excessive E2 prevents implantation.
Factors governing the Bruce effect.
1. Timing of exposure: after mating the females experience twice daily surges of prolactin. The incidence of Bruce-phenomena depends on the timing of the exposure to the male pheromones, if the pheromone exposure coincides with the prolactin surges, then only there takes place the Bruce-effect.


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Innate immunity: elements of innate immune system

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1. Innate immunity is present from birth.
2. It provides the first line of defense against pathogens
3. It is not specific to any one pathogen, but rather acts against all foreign molecules.
4. It also does not rely to previous exposure to the pathogens.
5. Its response is functional since birth and has no memory.
Elements of innate immunity:
1. Physical barriers:
Physical barriers are the first line of defence against microorganisms. It includes:

• Mucous membranes
• The acidic pH of sweat and sebaceous glands; fatty acids and hydrolytic enzymes inhibit the growth of microorganisms.
• The respiratory tract is lined by cilia (hair like projection) of epithelial membranes; the synchronous movement of cilia propels mucus entrapped microorganisms from these tracts.
• Conjunctiva is also specialized, the tears contains lysozyme, lactoferin, IgA and thus provide chemical as well as physical protection

In spite of these barriers, some microorganisms are able to penetrate the physical barriers. Then it is up to the adaptive and innate immune system to recognize and destroy them, without harming the host.

2. Chemical mediator:
a. Complement: it is a heat labile component of blood plasma that augments phagocytosis. This activity was said to complement the antibacterial activity of the antibody/
It also bridges the innate and adaptive immunity. The complement system is composed of over 30 serum proteins. Activation of complement in response to certain micro-organism results a controlled cascade of enzymatic reactions which targets the membranes of pathogenic organisms and lead to their destruction. A variety of specific and non-specific immunologic mechanisms can convert the inactive form of complement proteins to active forms with the ability to damage the membranes of pathogenic organisms, either destroying the pathogens or facilitating their clearance. Reactions between the complement molecules or fragments of complement molecules and cellular receptor triggers the activation of innate or adaptive immune systems.
b. Cytokines: the term cytokine is a generic term for any low molecular weight soluble protein or glycoprotein released by one cell population which acts as intercellular mediator. Interferon is cytokines made by cell in response to viral infection which essentially induce generalized antiviral state in surrounding cells.
c. Pattern recognition molecule: many molecules involved in innate immunity have the ability to recognize a give class on molecule. I.e. recognize pattern. Pattern recognition molecule that recognizes pattern associated molecular pattern (PAMP) may be soluble circular proteins or cell surface receptors. E.g. Manose-binding lectin (MBL) and C - reactive protein (CRP) are soluble pattern recognition molecules that bind to microbial surface and promote their opsonization.
3. Cellular defence: leukocytes are responsible for both specific and nonspecific immunity. Many specialized cell such as neutrophils, macrophages, monocytes, NK cells, participate in innate host defense mechanism. Once the pathogen invades the physical and chemical barriers, the specialized cells play and important role in protection, phagocytosis is fundamental protective. The phagocytosis is enhanced by the opsonization of pathogens. (opsonization: the process by which particulate antigen are rendered more susceptible to phagocytosis is called opsonization)
After ingestion the foreign particle is trapped in the phagosome (phagocytic vacuole), which fused with lysosome forming phagolysosomes. Now the antimicrobial and cytotoxic substances present within lysosome destroys the phagocytized micro-organism. The destruction of phagocytized micro-organism takes place as follows.
i. Oxygen dependent killing: during this process the phagocytes increase their O­₂ consumption (such as hydroxyl radicals, superoxide anions, hydrogen peroxide) which acts as antimicrobials.
ii. Oxygen independent killing: activated macrophages also synthesize lysozyme, defensin and various hydrolytic enzymes, who act without oxygen requirement
4. Inflammatory barriers:

•   Inflammation is an important non-specific dense reaction to cell injury.
•   The signs of inflammation are pain redness (erythema) swelling (edema) and heat.
•   Pain is caused due to increased vascular diameter which leads to increased blood flow, thus causing heat and redness in the area.
•   These blood vessels become permeable to fluid and proteins, leading to local swelling and an accumulation of blood proteins that aid in defence.
•   The inflammatory responses are mediated by a variety of signaling molecules. Activated macrophages produce chemo attractants (known as chemokine).
•   Some chemokine attract neutrophils, (which are the first cells, which are recruited in large numbers to the site of infection).
•   Other chemokine attract the monocytes and dendritic cells. The dendritic cells pick up antigens from the invading pathogens and carry them to nearby lymph nodes, where they present antigens to lymphocytes to marshal the forces of adaptive immune system.
•   Two principal mediators of inflammatory response are histamine (released by a variety of cells in response to injury of tissues), kinines (present in blood plasma in active form)

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Basic structure of antibodies

1. The antibodies reside in the serum.

2. The early experiments of kabat and Tiselius resolved serum proteins into three major non-albumin peaks i.e. α, β, ϒ

3. Antibodies are heterodimers. They have common structure of four peptide chains.

4. The structure consists of two identical light (L) chains and two identical heavy (H) chains.

5. Molecular weight of heavy chain (H) is about 50,000.

6. The molecular weight of the light chain (L) is about 25,000.

7. H and L chains are also called immunoglobulin.

8. Each light chain is bounded to heavy chain by disulphide bonds, and other non-covalent interactions such as salt linkage, hydrogen bond etc….

9. It is sometimes called as the dimers of dimer.

10. Around first 110 (or so) AA of amino-terminal region of light or heavy chain varies greatly among antibodies of different specificity, these segments of highly variable regions are called V-regions. i.e. V_L in light chain and V_H in heavy chain.

11. The V-region has an area called complementary-determining region called as CDRs. It is this CDR (on both light and heavy chain) that constitute the antigen binding site of antigen molecule.

12. The region of relatively constant region beyond the variable region have been dubbed C regions. I.e. C_L in light chain and C_H on heavy chains, the site for attatchment of the carbohydrates are restricted to the constant region.

Heavy chain sequencing revealed five basic varieties of heavy chain

a. The sequencing of revealed that the sequence of the heavy chain are very similar to the light chain.

b. The amino terminal part constitute of 100 to 110 amino acid shows great variation among myeloma heavy chains, so were named as V- chains.

c. The remaining part of chains revealed 5 basic sequence patterns corresponding to 5 diferent heavy chain constant regions (i.e. µ, δ, γ, ε, α)

d. Each of these five different heavy chains are called an isotype.

e. The length of constant region is , approximately 330 AA in δ, ϒ, α. And approximately 440 AA in µ, ε.

f. The class of antibody is determined by the type of heavy chain present.

ANTIBODY CLASS	AA length	TYPE OF HEAVY CHAIN
IgM	440	µ
IgE	440	ε
IgG	330	ϒ
IgA	330	α
IgD	330	δ

g. A single antibody molecule may have any one type of light chain, i.e. either kappa (Κ) or lambda(λ) light chain.

h. A single antibody molecule has identical pairs of heavy and light chain respectively. i.e. H₂L₂

i. The isotypes were further classified as subisotypes (similarly were the antibodies classified).

j. In humans there are following subisotypes.

1. α à α_1, α₂ (IgA₁, IgA₂)

2. ϒàϒ₁, ϒ₂, ϒ₃, ϒ₄ (IgG₁, IgG₂, IgG₃, IgG₄)

3. The δ, ε, µ has no subisotypes.

CLASS	H-CHAIN	SUBCLASS	LIGHT CHAIN
IgM	µ	none	K or λ
IgE	ε	none	K or λ
IgG	ϒ	ϒ1, ϒ2, ϒ3, ϒ4	K or λ
IgA	α	α1, α2	K or λ
IgD	δ	none	K or λ

tips for preparing and scoring for the summative assessment ii, class x examination 2012

1. there is nothing other than the text book of N.C.E.R.T to be consulted, so don't bang your heads on other books, it will be just a loss of time.
2. go through the lessons line by line from the N.C.E.R.T text book, all the questions are directly from the book.
3. try to write as concise as possible, don't put useless information in your answers, since science has nothing to do with useless essays and facts, try to write only what you know, and don't just guess answers, it will surely harm you.
4. if possible try to include diagrams/figures wherever possible, whether it is asked in the question or not.
5. for the objective questions, you should have a good concept of all the practicals included in your syllabus, coz the objective questions are all practical oriented conceptual questions, they cant be just guessed and answered.

summative assessment ii guess paper (science) for class x -2012

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SA₂RT

 (SUMMATIVE ASSESSMENT II REVISION TEST)

SHELFORD TUTORIALS

1.      What is the ultimate source of energy on earth?[1]

2.      What is the scientific name of the yellow spot?[1]

3.      Define reflection?[1]

4.      Define Darwinism?[1]

5.      Yeast reproduces through budding. (true/false).[1]

6.      Which functional group does –CHO represents?[1]

7.      What do you mean by valence electrons of and atom?[1]

8.      What do you mean by a food web?[1]

                                                    

9.      Differentiate between the food web and the food chain?[2]

10.  What is the power of accommodation?[2]

11.  Draw a ray diagram of a concave mirror, when the object is placed at the focus.[2]

12.  Draw structures of 1,2-dichloro,pentane and cyclohexane.[2]

13.  What is Newlands’ law of octaves?[2]

14.  What is the function of the vas-defrens and epididymis.[2]

15.  Name two ways of vegetative propagation.[2]

16.  Differentiate between implantation and fertilization in humans?[3]

17.   show the difference between the recessive and the dominant alleles?[3]

18.  What do you mean by the acquired and the inherited traits, which of the following is transferred to the next generation ? give reason.[3]

19.  Draw a well labeled diagram of the human eye. Or. What are the corrective measures for the hypermetropia and myopia, describe with figures[3].

20.  What are sign conventions for the convex mirror?[3]

21.  A convex mirror used for rear-view on an automobile has a radius of curvature of 3.00 m. If a bus is located at 5.00 m from this mirror, find the position, nature and size of the image.[3]

22.  Discuss speciation in brief with the help of  an example?[3]

23.  A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?[3]

24.  What were the limitations of Döbereiner’s classification?[3]

25.  Why should we conserve forests and wildlife?  Suggest some approaches towards the conservation of forests.[3]

26.  Explain why the sky appears reddish during the time of sunset and sunrise, name the phenomena responsible for this.[3]

27.  Describe the structure and function of the male reproductive system.[5]

28.  How is the equal genetic contribution of male and female parents ensured in the progeny, also elaborate how the sex of new individuals are determined.[5]

29.  (a)  Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?[2_­­^1/2]

(b)  Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common?[2^1/2]

30.  An object, 4.0 cm in size, is placed at 25.0 cm in front of a concave mirror of focal length 15.0 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? Find the nature and the size of the image. [5]

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