sned halp pls Flashcards
cistron
the genetic unit that carries information for the synthesis of a single enzyme or protein molecule
regulatory gene in lac operon
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.
why is lac operon’s regulation called negative regulation
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
Why are some untranslated sequence of bases seen in mRNA, coding for polypeptide? Where exactly are they present on mRNA?
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)
Lac operon, lactose present in medium
- Lactose binds to the repressor molecule
- As a result, repressor molecule cannot bind to the operator site
- RNA polymerase is able to pass over the operator site
- Thus it is able to transcribe structural genes z y and a
Miller and Urey conclusion
Life originated abiotically in the primitive ocean due to reaction among inorganic molecules
Gases formed in the spark chamber in miller urey experiment
CH4, NH3, H2, H2O
Which cells does the HIV attack first when it enters the body?
Helper cells and macrophages
Major components of biogas
Methane, carbon dioxide, nitrogen gas
In agarose gel electrophoresis, why are some bands of DNA further ahead than the others?
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
How are DNA fragments visualised in agarose gel electrophoresis?
The agarose gel is stained with ethidium bromide and viewed under UV radiation
Name and explain the selective markers in pBR322 vector
ampR and tetR act as selectable markers. These are used to identify the transformed hosts and eliminate the non-transformed host
What does Z represent in the species-area relation
log S = log C + ZlogA
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
Define clones
Clones are morphologically and genetically similar organisms
In present times, the origin of life is not possible from inorganic compounds due to?
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.
Gene therapy definition
Direct modification of the content, organization, or expression of defective genetic information in cells or organisms to provide functional genes and gene products
Somatic cell therapy
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
Germline therapy
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
Gene therapy for treatment of SCID
- In SCID, a gene known as ADA (Adenosine deaminase) gene that codes for the enzyme adenosine deaminase is mutated.
- 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.
- Inserted gene either integrates into the chromosome of the host at different sites away from the mutated gene
- or replaces the defective gene and produces functional enzymes.
Molecular diagnosis with recombinant DNA technology
- DNA fragments that recognise specific genes can act as probes to identify the genetic information of any organism
- The region coding for a particular gene is first isolated and then characterised
- The nature of the genetic difference is determined in the corresponding DNA from an individual showing symptoms of disease
- Used for diagnosis of infectious diseases, cancer, genetic disorders
Molecular diagnosis with PCR
- 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
- PCR is routinely used to detect HIV in suspected AIDS patients and to detect mutations in genes of suspected cancer patients
ELISA: Molecular diagnosis
- Used for immunodiagnosis of viral infections and other microbial agents
- More sensitive and specific than other serological tests
- Sandwich ELISA and Indirect ELISA
Transgenic animals: Chemical safety testing
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.
Transgenic animals: Study of diseases
- 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.
Fossil
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
5 eras + Dominant plant life + Dominant animal life
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
Biogeography
The science concerned with the geographical distribution of plant and animal life
Function of ecosystem
- Helps in circulation of energy
- Helps in transfer of minerals or conversion of minerals from one form to another
- Balance among organisms
When does the sperm induce changes in the ovum during the process of fertilization?
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.
