1. Write an essay on protein structure and synthesis
Protein synthesis is a cellular process leading to the production of proteins. This term is also synonymous to protein translation. It begins with a sequential process of transcription of DNA into mRNA, which is then used as input for translation after exon-intron splicing. The addition of successive tRNA molecules based on the code of mRNA matched up by base-pairing through their anti-codons in the ribosomes creates the nascent protein. After the protein chain has
been synthesized, post-translation modification occurs, e.g. phosphorylation, motifs added to the protein. This may happen at various levels: secondary (alpha-helix, ...view middle of the document...
2. Give an account of chromosome structure.
The DNA molecule is structured into a thread-like shape in the nucleus of each cell which is the chromosome. Chromosomes are composed of 50 % DNA (deoxy-ribonucleic acid) and 50 % proteins. The genetic material or DNA is wrapped around the histone protein to form a nucleosome. About 200 base pairs (bp) of DNA coil around one histone. The next level of organization of the chromatin is the 30 nm fibe, a solenoid structure with about 6 nucleosomes per turn. The stability of this structure requires the presence of the last member of the histone gene family, histone H1. The final level of packaging is characterized by the 700 nm structure seen in the metaphase chromosome. The condensed piece of chromatin has a scaffold that can be detected during metaphase. This is the result of looping and condensation of the DNA in the chromosome.
Chromosomes are too elongated and tenuous to be visible in the cell’s nucleus and cannot be seen even with the help of a microscope when the cell is not dividing. During cell division by mitosis however, the DNA which makes up the chromosome becomes tightly wrapped and condenses into short structures (~ 5 µm) that they become visible under a microscope.
Every chromosome has a constriction point called the centromeres. Centromere contains 1-10 million base pairs of DNA in human beings. Most of this is repetitive DNA: short sequences ( e.g., 171 bp) which are repeated over and over in tandem arrays. This centromere divides the chromosome into two groups or “arms.” The short arm of the chromosome is called as the “p arm” while the long arm of the chromosome is labeled the “q arm.” The location of the centromere on each chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.
3. Write an essay on signalling in eukaryotes
Signal transduction is the process by which an extracellular signaling molecule activates a membrane receptor, and in turn alters intracellular cascades creating a celullear response. It happens in stages. First, a signalling molecule activates a receptor on the membrane. Second, a second messenger that will perpetuate the signal into the cell will bne activated to elicit a physiological response. Examples of such process involve cAMP, calcium signaling, and kinases.
4. Write an essay on the uses of polymerase chain reaction in molecular biology
The polymerase chain reaction (or PCR) is a molecular technique for the amplifyication of a single or a few copies of DNA strands across several orders of magnitude, generating thousands to even millions of copies of a particular DNA strand with the specific primers and a thermo-resistant polymerase enzyme. This powerful technique is being applied in medicine, eg, detection of gene mutation in cancers and tailoring of therapies; infectious diseases,eg detection of pathogens and infections; agriculture, analysis of...