sned halp pls

Question 1

cistron

Answer 1

the genetic unit that carries information for the synthesis of a single enzyme or protein molecule

Question 1

regulatory gene in lac operon

Answer 1

gene ‘i’ (inhibitor) is the regulatory gene. it codes for the repressor protein which binds with the operator and inhibits the transcription of structural genes.

Question 2

why is lac operon’s regulation called negative regulation

Answer 2

it codes for the repessor protein which binds with the operator site and inhibits transcription of structural genes. it inhibits the expression and is called negative regulation

Question 3

Why are some untranslated sequence of bases seen in mRNA, coding for polypeptide? Where exactly are they present on mRNA?

Answer 3

The untranslated regions are protective against changes in coding sequences. They are also required in the translation process. The untranslated sequences are present in the cap region (5 end) and tail region (3 end)

Question 4

Lac operon, lactose present in medium

Answer 4

1. Lactose binds to the repressor molecule
2. As a result, repressor molecule cannot bind to the operator site
3. RNA polymerase is able to pass over the operator site
4. Thus it is able to transcribe structural genes z y and a

Question 5

Miller and Urey conclusion

Answer 5

Life originated abiotically in the primitive ocean due to reaction among inorganic molecules

Question 6

Gases formed in the spark chamber in miller urey experiment

Answer 6

CH4, NH3, H2, H2O

Question 7

Which cells does the HIV attack first when it enters the body?

Answer 7

Helper cells and macrophages

Question 8

Major components of biogas

Answer 8

Methane, carbon dioxide, nitrogen gas

Question 9

In agarose gel electrophoresis, why are some bands of DNA further ahead than the others?

Answer 9

Fragments separate according to their size due to the sieving effect by the agarose gel, so smaller fragments move farther away than the larger ones

Question 10

How are DNA fragments visualised in agarose gel electrophoresis?

Answer 10

The agarose gel is stained with ethidium bromide and viewed under UV radiation

Question 11

Name and explain the selective markers in pBR322 vector

Answer 11

amp^R and tet^R act as selectable markers. These are used to identify the transformed hosts and eliminate the non-transformed host

Question 12

What does Z represent in the species-area relation
log S = log C + ZlogA

Answer 12

Z is the slope
if Z is between
1. 0.1 to 0.2- explored area is small
2. 0.6 to 1.2- explored area is very large

If value of Z increases–> slope becomes steeper –> more area is explored

Question 13

Define clones

Answer 13

Clones are morphologically and genetically similar organisms

Question 14

In present times, the origin of life is not possible from inorganic compounds due to?

Answer 14

The earth is highly rich in oxygen today which does not provide the suitable environment for evolution because oxygen attacks the chemical bonds and extracts electrons.

Question 15

Gene therapy definition

Answer 15

Direct modification of the content, organization, or expression of defective genetic information in cells or organisms to provide functional genes and gene products

Question 16

Somatic cell therapy

Answer 16

Aims at correcting some grave disease by repairing the gene which is responsible for the disease

E.g. genetic therapy of certain severe immunodeficiency
* The body is unable to produce a protein that is essential for normal immune function because of a defective gene
* By altering or repairing this gene it is possible to cure this disorder

Question 17

Germline therapy

Answer 17

Aims at correcting defects in reproductive cells, thereby not only mitigating disease but also alleviating it in a manner that the corrected genes would be transmitted to the progeny

Question 18

Gene therapy for treatment of SCID

Answer 18

1. In SCID, a gene known as ADA (Adenosine deaminase) gene that codes for the enzyme adenosine deaminase is mutated.
2. For the repair of this effect, a retrovirus containing a functional wild-type ADA gene is injected into the parent’s bone marrow ex-vivo and then again incorporated into the parent’s bone marrow.
3. Inserted gene either integrates into the chromosome of the host at different sites away from the mutated gene
4. or replaces the defective gene and produces functional enzymes.

Question 19

Molecular diagnosis with recombinant DNA technology

Answer 19

1. DNA fragments that recognise specific genes can act as probes to identify the genetic information of any organism
2. The region coding for a particular gene is first isolated and then characterised
3. The nature of the genetic difference is determined in the corresponding DNA from an individual showing symptoms of disease
4. Used for diagnosis of infectious diseases, cancer, genetic disorders

Question 20

Molecular diagnosis with PCR

Answer 20

1. very low concentration of a pathogen when symptoms of a disease aren’t yet visible can be detected by amplification of their nucleic acid by PCR
2. PCR is routinely used to detect HIV in suspected AIDS patients and to detect mutations in genes of suspected cancer patients

Question 21

ELISA: Molecular diagnosis

Answer 21

1. Used for immunodiagnosis of viral infections and other microbial agents
2. More sensitive and specific than other serological tests
3. Sandwich ELISA and Indirect ELISA

Question 22

Transgenic animals: Chemical safety testing

Answer 22

Chemical safety testing :
* Transgenic animals are made more sensitive to toxic substance than non-transgenic animals by introduction of certain genes.
* These transgenic animals are then exposed to toxic substances under study.
* Toxicity testing in such animals takes less time.

Question 23

Transgenic animals: Study of diseases

Answer 23

• Transgenic animals are designed to study the role of genes in the development of certain diseases.
• In order to devise a cure for these diseases, the transgenic animals are used as model organisms.
• Used in research for the development of medicines.
• For example, we have transgenic models for diseases such as Alzheimer’s and cancer.

Question 24

Fossil

Answer 24

The relics of some former living life- plants or animals- embedded in a dug out of the superficial deposits in past geological periods is known as fossils.

The study of fossils is known as palaeontology

Question 25

5 eras + Dominant plant life + Dominant animal life

Answer 25

Cenozoic
Quaternary-
Dominant plant life: Herbaceous plants
Dominant animal life: Age of man
Tertiary-
Dominant plant life: Angiosperms
Dominant animal life: Age of mammals

Mesozoic
Dominant plant life: Gymnosperms
Dominant animal life: Age of reptiles

Palaeozoic
Dominant plant life: Pteridosperms (seed ferns), primitive land plants, calcareous algae
Dominant animal life: Age of amphibians, fishes and algae

Proterozoic and Archaeozoic
Dominant plant life: Probably unicellular organisms
Dominant animal life: Simple marine invertebrates

CMPPA- Can Muppets Palate Professional Anuses

Question 26

Biogeography

Answer 26

The science concerned with the geographical distribution of plant and animal life

Question 27

Function of ecosystem

Answer 27

1. Helps in circulation of energy
2. Helps in transfer of minerals or conversion of minerals from one form to another
3. Balance among organisms

Question 28

When does the sperm induce changes in the ovum during the process of fertilization?

Answer 28

When sperm comes into contact with the ovum’s zona pellucida layer during fertilization, it causes modifications in the membrane that prevent other sperms from entering.
It ensures that an ovum can only be fertilized by one sperm.