Wednesday 30 December 2015
Tuesday 29 December 2015
Monday 28 December 2015
Tuesday 22 December 2015
B Sc II students:
Read this article to learn about the Cycas: Occurrence, Morphological Features and Economic Importance !
Division : Cycadophyta
Order : Cycadales
Genus : Cycas
Class : Cycadopsida
Family : Cycadaceae
Occurrence:
Sixteen species of Cycas are found in the tropical and subtropical parts of the earth. The name Cycas has been derived from a Greek word Kykas = Cocopalm. It is an evergreen plant. In India Cycas is represented by six species— C. revoluta, C. pectinata, C. siamensis, C. beddomei, C. rumphiand C. circinalis.
Cycas revoluta is the most commonly cultivated species of Indian gardens. It also occurs in China, Africa, Nepal, Sri Lanka and Japan. Its natural habitat is in open, sunny, well-drained situations. It is a palm-like tree with size varies from 1-2 meters. As it yields ‘sago’, from the mucilage in its main trunk. It is popularly called ‘sago palm’. Leaflets are 6-8 mm broad with revolute margins.
Morphology:
Cycas sporophyte is an evergreen palm-like tree that attains a height of 0.4 to 2.0 mt. Sporophyte is dioecious i.e. male and female plants are separate. Both the plant body is differentiated into roots, stem and leaves (Fig. 9.2).
(i) Roots:
Roots are of two types, i.e., normal tap root and coralloid root. Tap root is positively geotropism, non-green, without root hair. It helps in anchorage and absorbs water and minerals. Coralloid roots are lateral branches of tap root. It grows first horizontally (diageotropic) then, repeatedly divide dichotomously, come out of the soil surface (apogeotropic) in the form of coral like mass.
These are devoid of root hair and root cap. Its anatomy is similar to normal tap root, but its cortex is differentiated into three zones i.e., Upper cortex, Middle cortex and Lower cortex Middle cortex carries BGA (Anabena cycadcearum, Nostoc) symbiotically. Coralloid root helps in nitrogen fixation as well as respiration (due to lenticels).
(ii) Stem:
The stem is erect, columnar, woody and un-branched. It is covered with alternate whorls of leaf bases of foliage leaves and scale leaves. The stem apex bears a crown of leaves and sex organs at maturity.
(iii) Leaves:
Leaves are dimorphic i.e. 2 types, assimilatory or foliage leaves and scaly leaves or cataphylls. Both the leaf types are born at the stem apex in alternate spirals. Foliage leaves are large (1 -3 m), green, pinnately compound. Petiole has 2 rows of spines. Rachis bears 80-100 pairs of pinnae or leaflets.
Leaflets are sessile, elongated, tough, and lanceolate in shape with a spiny apex, revolute or smooth margins. Young leaves have circinate vernation like those of ferns and always covered with brown hairs called ramenta (Fig. 9.3). Scale leaves are small, dry, brown, triangular leaves covered with ramenta. They are non- photosynthetic and protect the stem apex (Fig. 9.3).
Economic Importance of Cycas:
1. Cycas plants are highly valued for their ornamental looks, and hence grown in homes and garden as an ornamental plant.
2. A starch called ‘sago’ is obtained from the stem pith of Cycas revoluta. That is why this species of Cycas is also known as “Sago Palm”. Sago starch is used in the preparation of “Sabbodana”.
3. In Sri Lanka, the starch obtained from the seeds is used in cakes.
4. Soft young leaves of Cycas are used as vegetable also in some parts of the world.
5. Seed of some species of Cycas are used as fodder for animals.
6. Boiled seeds of Cycas rumphi are eaten by inhabitants of Andaman.
7. Its leaves are used for making mats, hats, L rooms and baskets.
8. Extract of young Cycas leaves is used in the treatment of many skin diseases, blood vomiting and stomach disorders.
9. The decoction of seeds is used as purgative.
10. Tincture prepared from its seeds is used in some areas in headache, nausea, bad throat etc.
11. The terminal buds of Cycas circinalis are used to treat ulcerated wounds and swollen glands.
Source: http://www.biologydiscussion.com/articles/cycas-occurrence-morphological-features-and-economic-importance/5720
Thursday 17 December 2015
B Sc III Blood group inheritance
Source : http://webcache.googleusercontent.com/search?q=cache:http://www.nzblood.co.nz/give-blood/about-blood/inheritance-of-blood-groups/&gws_rd=cr&ei=-qpzVr7zGIaSuAS95afQAw
Blood groups are inherited from both parents. The ABO blood type is controlled by a single gene (the ABO gene) with three types of allelesinferred from classical genetics: i, IA, and IB. The gene encodes aglycosyltransferase—that is, an enzyme that modifies thecarbohydrate content of the red blood cell antigens. The gene is located on the long arm of the ninth chromosome (9q34).
Source : http://webcache.googleusercontent.com/search?q=cache:http://www.nzblood.co.nz/give-blood/about-blood/inheritance-of-blood-groups/&gws_rd=cr&ei=-qpzVr7zGIaSuAS95afQAw
Blood groups are inherited from both parents. The ABO blood type is controlled by a single gene (the ABO gene) with three types of allelesinferred from classical genetics: i, IA, and IB. The gene encodes aglycosyltransferase—that is, an enzyme that modifies thecarbohydrate content of the red blood cell antigens. The gene is located on the long arm of the ninth chromosome (9q34).
The IA allele gives type A, IB gives type B, and i gives type O. As bothIA and IB are dominant over i, only ii people have type O blood. Individuals with IAIA or IAi have type A blood, and individuals with IBIBor IBi have type B. IAIB people have both phenotypes, because A and B express a special dominance relationship: codominance, which means that type A and B parents can have an AB child. A couple with type A and type B can also have a type O child if they are both heterozygous (IBi,IAi) The cis-AB phenotype has a single enzyme that creates both A and B antigens. The resulting red blood cells do not usually express A or B antigen at the same level that would be expected on common group A1 or B red blood cells, which can help solve the problem of an apparently genetically impossible blood group.[22]
| Blood group inheritance | |||||||
| Blood type | O | A | B | AB | |||
|---|---|---|---|---|---|---|---|
| Genotype | ii (OO) | IAi (AO) | IAIA (AA) | IBi (BO) | IBIB (BB) | IAIB (AB) | |
| O | ii (OO) | O OO OO OO OO | O or A AO OO AO OO | A AO AO AO AO | O or B BO OO BO OO | B BO BO BO BO | A or B AO BO AO BO |
| A | IAi (AO) | O or A AO AO OO OO | O or A AA AO AO OO | A AA AA AO AO | O, A, B or AB AB AO BO OO | B or AB AB AB BO BO | A, B or AB AA AB AO BO |
| IAIA (AA) | A AO AO AO AO | A AA AO AA AO | A AA AA AA AA | A or AB AB AO AB AO | AB AB AB AB AB | A or AB AA AB AA AB | |
| B | IBi (BO) | O or B BO BO OO OO | O, A, B or AB AB BO AO OO | A or AB AB AB AO AO | O or B BB BO BO OO | B BB BB BO BO | A, B or AB AB BB AO BO |
| IBIB (BB) | B BO BO BO BO | B or AB AB BO AB BO | AB AB AB AB AB | B BB BO BB BO | B BB BB BB BB | B or AB AB BB AB BB | |
| AB | IAIB (AB) | A or B AO AO BO BO | A, B or AB AA AO AB BO | A or AB AA AA AB AB | A, B or AB AB AO BB BO | B or AB AB AB BB BB | A, B, or AB AA AB AB BB |
The table above summarizes the various blood groups that children may inherit from their parents.[23][24] Genotypes are shown in the second column and in small print for the offspring: AO and AA both test as type A; BO and BB test as type B. The four possibilities represent the combinations obtained when one allele is taken from each parent; each has a 25% chance, but some occur more than once.
| Blood group inheritance by phenotype only | ||||
| Blood type | O | A | B | AB |
|---|---|---|---|---|
| O | O | O or A | O or B | A or B |
| A | O or A | O or A | O, A, B or AB | A, B or AB |
| B | O or B | O, A, B or AB | O or B | A, B or AB |
| AB | A or B | A, B or AB | A, B or AB | A, B or AB |
Historically, ABO blood tests were used in paternity testing, but in 1957 only 50% of American men falsely accused were able to use them as evidence against paternity.[25] Occasionally, the blood types of children are not consistent with expectations—for example, a type O child can be born to an AB parent—due to rare situations, such as Bombay phenotype and cis AB.[26]
Source https://en.wikipedia.org/wiki/ABO_blood_group_system
Wednesday 9 December 2015
Tuesday 8 December 2015
B Sc II Economic Importance of Gymnosperms:
Economic Importance of Gymnosperms:
1. Ornamental value:
A number of gymnosperms are grown as ornamental plants, e.g., Cycas, Araucaria, Thuja etc.
2. Food Value:
i. ‘Sago’ starch obtained from pith and cortex of stem of C. revolute, C. rumphi etc.
ii. ‘Seed starch’ obtained from seeds of Cycas rumphii, Dioon edule etc. It is prepared into flour and cooked before eating.
iii. Seeds of Pinus gerardiana (chilgoza) are edible.
iv. ‘Kaffir bread’ prepared from the stem pith of Encephalartos.
v. Young leaves of Cycas cooked as vegetables.
3. Medicinal value:
i. Ephedrine (alkaloid) extracted from Ephedra used in treating asthma, cough, cold, bronchitis etc.
ii. Tincture of Ephedra is a cardiac stimulant.
iii. The juice extracted from young leaves of Cycas revoluta is used for curing blood vomiting and flatulence.
4. Industrial Use:
i. Gum-Cycas gum used as adhesive, antidote for snake bites and using malignant ulcers.
ii. Tannins – Tannins extracted from bark of Araucaria, Pinus, Sequoia etc. used in leather industry.
iii. Canada balsam – It is turpentine obtained from Abies balsamea and used as a mounting medium in biological preparations.
iv. Amber (fossil resin) – obtained from Pinus succinifera. Wood of Pinus is used for doors, poles, beams, railway wagon flooring etc.
v. Plywood prepared from Podocarpus.
vi. Papers like newsprints, writing and printing papers are being prepared from the wood pulp of Pinus, Picea,Abeis, Gnetum etc.
vii. The leaves of cycads are used for preparing baskets, mats, hats, brooms etc.
viii. The fibres obtained from the leaves of Cycas and Macrozamia are used for stuffing pillows and making mattresses.
5. Source of oils:
i. Oils extracted from seeds of C. revoluta, Macrozamia reidlei, Pinus cembra and Cephalotaxus drupacea are used as edible oils.
ii. Red cedar wood oil extracted from the heart wood of Juniperus virginiana is used for cleaning microscopic preparations and for oil immersion lenses.
iii. Oils obtained from Cedrus deodara, Ciyptomeria japonica and Cupressus serm-perivirens are used in preparations of perfumes.
Source: http://www.biologydiscussion.com/gymnosperm/gymnosperm-classification-and-economic-importance/5726
Sunday 6 December 2015
B Sc. II
Salient features of Gymnosperms
1. Gymnosperms (gymnos - naked, sperma = seed) are naked - seeded plants. Here the ovules are not enclosed and thus the seeds remain naked.
2. Most of the gymnosperms are evergreen, woody perennials with shruby or tree like habit. They show xerophytic characters.
3. The main plant body is a well differentiated sporophyte consisting of root, stem and leaves. Gametophyte is reduced and is dependent on sporophyte.
4. Plants possess well developed root system.
5. Leaves are of two types i.e. foliage leaves and scale leaves.
6. Vascular bundles are conjoint, collateral, open and endarch.
7. Xylem consists of only tracheids.
8. Vessels are absent except in Gnetum.
9. Companion cells are absent.
10. Secondary growth takes place both in roots and stems.
11. Reproductive parts are generally in the form of compact and hard cones or strobili. The cones are generally unisexual.
12. In male cones, many microsporphylls are arranged on a central axis. Microsporophyll's bear micro sporangia containing microspores or pollen grains.
13. Archegonia lack neck canal cells.
14. Pollination is of anemophilous type.
15. The ovules are covered by single integument and are orthotropous type. The ovule is a modified mega sporangium borne directly on the surface of megasporophyll.
16. Endosperm is formed before fertilization.
17. Polyembryony is exhibited by many members of gymnosperms.
18. Embryo is formed inside the ovule. The ovule gets transformed into seed.
19. Epigeal mode of germination is seen.
20. Plants show distinct alternation of generation.
Courtesy: http://www.preservearticles.com/2011122118741/six-important-features-of-gymnosperms.html
Friday 4 December 2015
Tuesday 1 December 2015
B. Sc. III Curriculum (Theory) Semester -VI
B. Sc. III (Theory)
Semester -VI
Paper XIX
(Genetics and Biotechnology)
(45 L)
Unit : 1
1. Mendelism: (04)
i. Introduction
-G.J. Mendel
ii. Mendelian
principles –Law of Dominance , law of segregation, law of
independent
assortment, back cross and test cross
2. Interaction of genes: (07)
i. Allelic
interaction: incomplete dominance, co dominance, lethal genes and blood group
inheritance
ii. Non allelic
and non epistatic -comb shapes in fowls
iii. Non
allelic and epistatic:
a)
Complementary genes or duplicate recessive epistasis (9:7)
b)
Supplementary genes or recessive epistasis (9:3:4)
c) Dominant
epistatic genes or dominant epistasis (12:3:1)
d) Duplicate
genes or duplicate dominant epistasis (15:1)
3. Sex determination: (04)
i. Chromosomal
theory of sex determination
ii. Mechanism
of sex determination in man (xx -xy), Drosophila (xx and xy),birds (zz-zw),
grasshopper (xx-xo) and genic balance theory in Drosophila
iii. Sex
determination in plants – Melandrium
Unit : 2
1. Sex linked inheritance: X, XY and Y linked
inheritance: (07)
i)
Colourblindness and hemophilia in man ii) Holandric genes
iii) White eye
colour in Drosophila iv) Gynandromorphs
2. Structure and function of gene: (08)
i. Fine
structure of gene (Seymour Benzer)
ii. One gene
one enzyme hypothesis
iii. Genes and
related diseases – phenylketonuria, and alkaptonuria
iv. Detection
of genetic diseases –amniocentesis Genetic counseling
Unit: 3
Biotechnology: (15)
1. Concept of
genetic engineering and recombinant DNA technology
2. Restriction
endonucleases, their properties and uses
3. Cloning
vectors -plasmids and phage vectors
4. Techniques
of genetic engineering -isolation of desired gene, gene cloning,
transfer of
gene into plants
5. Applications
of genetic engineering
*****
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