Molecular Basis of Inheritance- DNA structure and packaging

Chapter 6 : Molecular basis of Inheritance

Prepare for the test from this chapter next week..(on wednesday)

structure of DNA, its packaging, Griffith, Hershey and Chase, Messelson's Experiment, DNA replication, transcription, transcription units, translation, genetic code,Lac operon, Human genome project .

Some previous year questions from Ch- 6 .. Molecular basis of inheritance

Some previous year questions from Molecular basis of inheritance..

Structure of DNA

Q. Name the components a and b in the nucleotide given below:                             D2008     1

Q. Draw a labelled diagram of a nucleosome. Where is it found in a cell?   F2014       2/3

                                             Or 

Q. Draw a neat labeled diagram of a nucleosome Mention what enables histones to acquire a positive 

    charge.      A2012, D2011     2/3

Q. Draw a schematic representation of dinucleotide. Label the following:

            a)the components of a nucleotide           b)5’end 

           c) N-glycosidic linkage                                d) Phosphodiester linkage.  F2010      2/3

Q. Draw a schematic diagram of a part of double stranded dinucleotide DNA chain having all the four 

   nitrogenous bases and showing the correct polarity.   D2012    2/3

Q.  Describe the structure of a RNA polynucleotide chain having 4 different types of nucleotides. D2013 2/3

Q. Explain the two factors responsible for conferring stability to double helix structure of DNA. A2014 2

    It is established that RNA is the first genetic material. Explain giving three reasons.    D2012

Q. The base sequence in one of the strands of DNA is TAGCATGAT.

Q, Give the base sequence of its complementary strand

Q. How are these base pairs held together in a DNA molecule?

Q. Explain the base complementarity rules. Name the scientist who framed this rule.    D 2011    3

Q. Why is DNA considered a better hereditary material than RNA? F 2012, A2008

Q. DNA----------—>DNA-------------àmRNA-------àProtein

Look at the above sequence and mention the events A , B and C.

Q. What does central dogma state in molecular biology? How does it differ in some viruses?    D 2009c   2/3

Q. State any two structural differences and one functional differenc between DNA and RNA    F2002

Experiments

Q Describe  Griffith’s experiment on Streptococcus pneumonia. Discuss the conclusion he arrived at.    

 Q Describe the experiment with Streptococcus pneumonia that demonstrated the existence of some  

    transforming principle.   A2012, F 2013       3

Q Write the scientific name of the bacterium used by Friedrick Griffith in his experiment.

    How did he prove that some transforming principle is responsible for transformation of the non 

      virulent strains of bacteria into the virulent form?

   State the biological nature of transforming principle.

   Name the scientists who proved it.       F2011 (5)

Q.Explain the role of S35 and P32 in the experiments conducted by Hershey and Chase.     D 2009C   2/3

Q. Name the scientists who proved experimentally that  DNA is the genetic material.  Describe their experiment. F2013 , D2012   3/5

Q. Describe Alfred Hershey and Martha Chase experiment. Write the conclusion they arrived at after the experiment. A2014, F2012,D2008, D2009,A2009     5

Q. How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material?    NCERT 

DNA replication

Q.Describe the experiment that demonstrated the semi- conservative mode of DNA replication.F2013   2/3

Q.Describe Meselson and Stahl ‘s experiment and write the conclusion they arrived at. F2014, D2012

Q.Who proposed that DNA replication is semi conservative? How was it experimentally proved by Meselson and Stahl? D2009c

Q. What is semi conservative DNA replication? How was it experimentally proved and by whom? A2008,D2002,F2002

Q. Answer the following questions based on Meselson and Stahl’s experiment:

Write the nameof the chemical substance used as a source of nitrogen in the experiment by them.

Why did the scientists synthesize the light and the heavy DNA molecule in the organism used in the experiment?

How did the scientists make it possible to distinguish the heavy DNA molecule from light DNA molecule? Explain.

Write the conclusion the scientists arrived at after completing the experiment.   A 2011 5

Q. State the dual role of deoxyribonucleoside triphosphates during DNA replication. F 2013  2/3

Q. Draw a labeled schematic sketch of replication fork of DNA. Explain the role of the enzymes involved in DNA replication.    D 2009  2/3

Q.Explain the process of DNA replication that occurs in a replication fork in E.coli.            3  A2013

Why do you see two different types of replicating strands in the given DNA replication fork? Explain. Name these strands. D2011

Name the types of synthesis a and b occurring in the replication fork of DNA shown below:  D2008

Describe the discontinuous synthesis of DNA   D2003  2/3

Name the enzyme involved in the continuous replication of DNA strand. Mention the polarity of the template strand. A2010

Name the enzyme and state its property that is responsible for continuous and discontinuous replication of the two strands of a DNA molecule. D2013

Transcription

Name the parts A and B of the transcription unit given below:    D2008

Draw a labeled schematic diagram of a transcription unit. Explain the function of each component in the unit in the process of transcription.  F 2012   2/3 , A2008  5

Draw a schematic representation of the structure of a transcription unit and show the following in it:

i.Direction in which the transcription occurs       ii. Polarity of two strands

iii.Template strand                                             iv. Terminator gene

Mention the function of promoter gene in transcription.    A2009    

Construct a complete transcription unit with promoter and terminator on the basis of the hypothetical template strand given below. 

    ßATGCATGCATAC—

Write the RNA strand transcribed from the above transcription unit alongwith its polarity.  D2012

Q.Given below is a part of the template strand of a structural gene: TAT CAT TAG GAT

Write its transcribed mRNA strand with its polarity.

Explain the mechanism involved in initiation of transcription of this strand. D2008

Explain the process of transcription in a bacterium. F 2012

Describe the initiation/ elongation/ termination process of transcription in bacteria.   D2010   2/3

Explain the role of RNA polymerase in transcription in bacteria.      F2013.   2/3

Describe  role of RNA polymerase in transcription in bacteria (steps)and in eukaryotes(types).F2008  4+

Name the enzyme responsible for transcription of hn RNA/ tRNA .D2012,A2011   +

Explain the role of DNA dependent RNA polymerase in initiation, elongation and termination during transcription in bacterial cell. How is transcription a more complex process in eukaryotic cells? Explain. F2011    5

Mention the additional processings which hnRNA needs to undergo after splicing so as to become functional .       D2009, F2012

Describe the process of synthesis of fully functional mRNA in a eukaryotic cell.

How is this process of mRNA synthesis different from that in prokaryotes?A2012    5

When and at what end does the tailing of hnRNA take place? A2009                     1

At which ends do capping and tailing of hnRNA occur, respectively? F 2009      1

Genetic Code

Name the scientist who suggested that the genetic code should be made of a combination of three nucleotides. Explain the basis on which he arrived at this conclusion. D2014   2/3

Mention two functions/ specific features  of codon AUG.  Give the sequence of bases it is transcribed from and its anticodon . D2010. A2009, A2013 (2/3)

How many codons will be there in three codons? How many amino acids will this number of bases code for? F2003

Mention the role of the codons AUG and UGA during protein synthesis   D2011

Three codons on mRNA are not recognized by tRNA , what are they? What is the general term used for them? What is their significance in protein synthesis? F2009

Genetic codes can be universal, unambiguous and specific & degenerate. Write about them, giving one example each. A2013 2+, A2011, F2012, A2008

Identify giving reasons the salient features of genetic code by studying the following nucleotide sequenceofmRNA strand and the polypeptide translated from it

AUG UUU UCU UUU UUU UCU UAG

Met- Phe – Ser –Phe – Phe – Ser                                      D2009c

Translation

Mention the role of ribosomes in peptide bond formation. How does ATP facilitate it? A2010

Name the scientist who postulated the role of an adaptor in protein synthesis. Name the adaptor molecule. F2008 , F2014  1+

Q .Name the scientist who called tRNA molecule as adaptor molecule.

Draw the cloverleaf structure of a tRNA charged with Methionine(initiator tRNA)/Tyrosine. (F2014   3+)

Anticodon for this amino acid in its correct site (codon for tyrosine is UCA)

What does the actual structure of tRNA look like?   ( F2012)   A2011  3

State the function of following in a prokaryote: tRNA    rRNA      A2012, (F2014  1+)

Name the major types of RNA s and explain their role in the process of protein synthesis in a prokaryote. F2014

Explain the process of translation in a bacterium. F2012

Where does peptide bond formation occur in a bacterial ribosome and how?  F2014    2

How is the translation of mRNA terminated? Explain.      D2009

Name the aminoacid that initiator tRNA gets linked with.Explain the role of initiator tRNA in initiation of protein synthesis.     D2012

What is the function of aminoacyl tRNA synthetase?   D2002

Explain aminoacylation of tRNA.    A2013    1+

Explain the process of charging of tRNA. Why is it essential in translation? D2008

How are translational unit and untranslated regions in mRNA different from each other? A2013 2

Genetic Maps/ DNA polymorphism

Mention the contribution of genetic maps in human genome project. A2011

Mention how does DNA polymorphism arise in a population. D2014      1

Explain DNA polymorphism as the basis of genetic mapping of human genome.

State the role of VNTR in DNA fingerprinting  A2013   2/3

Name the first two steps in DNA Fingerprinting . Describe them briefly. F2002

Explain thesteps of DNA fingerprinting that will help in processing of the two blood samples A and B picked up from the crime scene.   F2009  5

Lac Operon

Describe how the Lac Operon operates, both in the presence and absence of an inducer in E.coli. A 2014 

Topics for project report

For Project report, please check your topics against your name ... (If not mentioned,  comment your topic in comment box alongwith your name and get approval).

1. Kunika Kumari            Cancer- New Reseach on its Treatment

2. Pooja Singh                            

3. Priya Singh                 Stem cell (Rather Stem cell Therapy- An approach to treat                                                                                                                genetic disorders)

4 Rashi Rathi                   Bombay Blood Group- A special case

5.Riya Sharma             

6.Suchismita Ghosh          Pearl Farming

7. Sunderam Thakur          Thallesemia

8.Suruchi

9. Yukta                             Biofuels from algae

10. Akshat

11.Aman 

12 Anand

13. Anurag                        Insect hormones- A new way to control pests

14.Dhanajay

15. Dushyant                     Human Cloning

16.Mayur                                 

17.Mohit Diwakar                   

18.Mohit Garg                   Problems occuring during pregnanacy/ Gestation period 

19.Rahul                                   

20 Rishabh

21.Sanchay                       Harmful effects of Mobile radiations/ Mobile radiations causing infertility 

22. Siddharth

Some suggestions for topics:

• Mental Health/ Mental disorders - causes and treatment
• Endosymbiotic Theory- Origin of mitochondria and chloroplast
• Life style disorders- ( Blood pressure/ Obesity/ Diabetes)
• Forest fires: Natural disaster-Analysis of Causes, Effects and Solution
• Alternative therapies (Accupressur/ Accupuncture / Homeopathy)- Scientific basis 
• Report on most 'Endangered species of India' with reasons for their extinction and efforts for their conservation.
• Indian Spices- Their source (which plant part is being used), cultivation and medicinal significance (alongwith the name of the chemical responsible for it) .
• Genetically modified crops- Issues involved. ( both benefits and possible harms along with your opinion on whether they should be developed and used.)
• Makhana Cultivation- (crop of immense potential,nutritional benefits,constraints and solutions)
• A genetic/ chromosomal disorder

Important: A hand written report is needed. If your writing is not good you can type your report. In any case print out of a ppt (self made or available online) will not be accepted.

Syllabus for 1st term

Total marks = 50

• Prepare Chapter 1, 2, 3, 4 and chapter 5 (up to Sex determination mechanism including it).

• Practise all the diagrams of plant and human reproduction. (specially schematic representation of spermatogenesis/ oogenesis, seminiferous tubule, testis, sperm, ova, menstrual cycle, microsporogenesis, pollen grain, megasporogenesis, ovule, embryo sac. ). 

• Practise making crosses and punnett squares of the different principles of inheritance very well.

• Practise the questions given in earlier post.

You can enjoy in every upcoming year.... But this year is special for you as you are laying the foundation of your future...  Work hard as you will not get this time again..... Enjoy your studies and utilise this precious time in accomplishment of your dreams..

Practise questions for vacations... Do prepare them well..

Some questions for practice during vacations:

Q.1a) Why does endosperm development precede embryo development in angiosperm seeds?

State the role of endosperm in mature albuminous seeds.

b) Describe with the help of three labeled diagrams the different embryonic stages that include mature embryo of dicot plants.

 Q.2a)Draw a sectional view of seminiferous tubule of a human. Label the following cells in the seminiferous tubule:

i)                    Cells that divide by mitosis to imcrease their number

ii)                   Cells that undergo Meiosis I

iii)                 Cells that undergo Meiosis II

iv)                 Cells that help in the process of spermiogenesis

b) Mention the role of Leydig cells.

Q.3 Explain the ovarian and uterine events that occur during a menstrual cycle in a human female under the influence of pituitary and ovarian hormones respectively.

Q. 4 a) List three different allelic forms of gene “I’ in humans. Explain the different phenotypic   

         expressions, controlled by these three forms.

b) A woman with blood group A marries a man with blood group “O”. Discuss the possibilities of the       inheritance of the blood groups in the following starting with “yes or “no” for each:

i)                    They produce children with blood group “A” only.

ii)                   They produce children some with “O” blood group and some with “A” blood group.

Q5. Aplant with purple flowers was crossed with white flowers producing 50 plants with only purple  flowers . On selfing , these plants produced 482 plants with purple flowers and 162 with white flowers. What genetic mechanism accounts for these results? Explain.

Q6. During his studies on genes in Drosophila that were sex linked, T.H. Morgan found population phenotypic ratios deviated from expected 9:3:3:1. Explain the conclusion he arrived at.

Q7. You are given a red flower bearing pea plant and a red flower bearing snapdragon plant.How would you find the genotypes of these plants with respect to the colour of the flower?

Explain with the help of crosses. Comment upon the pattern of inheritance seen in these two plants.

Q8. Some angiosperms are said to be albuminous whereas few others are said to have a perisperm. Explain each with the help of an example.

Q9. a)How does cleistogamy ensure autogamy?

b)State one advantage and one disadvantage of cleistogamy to the plant.

Q10. How is the child affected if it has grown from the zygote formed by an XX-egg fertilized by a Y carrying sperm? What do you call this abnormality?

  Q11. How does geitonogamy differ from xenogamy? Which one between the two will lead to inbreeding  depression and why?              

May post few more questions later on. So please check by 12 th june..                                                                                                                        

Topics discussed during 9/5/16-13/5/16

Chapter 4- Reproductive Health: Sexually Transmitted diseases(STDs), Assisted Reproductive Technologies(ARTs)

Chapter -5: Principles of Inheritance and Variation
Mendelian Experiments- Monohybrid / Dihybrid crosses, Laws of Inheritance, Dominance, Recesive, Incomplete dominance, Co dominance, Pleiotropic effect, Multiple allelism, Chromosomal Theory of inheritance.