biochemistry Task 1

Biochemistry

Introduction
DNA is a double-stranded molecule of polynucleotide chains twined/twisted together into a double helix structure. This molecule is the one that forms the genetic material responsible for transfer hereditary genetic information from one cell to another during cell division. RNA is a single-stranded molecule that contains polynucleotide chain used for the transfer of genetic information especially in bacteria cells (Freifelder, 2002).
DNA replication process
DNA replication is a process by which two DNA molecules are formed from one DNA molecule. In simple words, it’s like ‘duplication’ of a DNA molecule. The DNA molecule is copied whereby each of the new molecules contains a single strand of the original ‘parental’ DNA and one of the newly formed DNA strand (Weaver, 2005). The process occurs in a series that contains four steps; Initiation, Elongation, Termination and Proofreading/Correction.

DNA polymerase III
Its function is to help in duplication/regeneration of a new DNA strand from a single DNA strand. However, it can’t initiate the process itself and it is assisted by an enzyme called primase (Weaver, 2005). Primase is a short strand of RNA that provides a starting point for DNA synthesis. DNA polymerase III also can only synthesize a new DNA strand in 5’ to 3’ direction.

Helicase Is a molecular motor protein that opens up or unzips a strand of DNA, creating the replication fork. This now allows the replication process to take place.

DNA polymerase I Its function during replication is to remove any RNA primer left in the lagging strand and replace the primer with DNA.

DNA Ligase Its function is to connect the okazaki fragments, only after the RNA primase has been removed. Connecting/fitting the DNA strand to make a complete strand of DNA without any gaps.

Role of mRNA in transcription and translation
Step 1
A copy of the gene in the DNA is created (replication). The copy, messenger RNA (mRNA) serves as a blueprint for a protein. An mRNA has Uracil (U) nucleotide instead of Thymine (T).
Step 2
Assembling of the mRNA and the two subunits of ribosomes occurs.
Step 3
Different transport RNA (tRNA) has different anticodons that match various codons of mRNA. The amino acid corresponding to the codon is attached to the end of the tRNA.
Step 4
Inside the ribosomes, tRNA associates with mRNA the codon and anticodon have to match in order for the two to interact. If the codon and anticodon do not match, the tRNA falls off the ribosome.
Step 5
In between the amino acids, there forms a peptide bond. The growing protein chain is moved to the tRNA then the ribosome moves one step along mRNA molecule in order for the next tRNA to bind. Lastly, the amino acid chain is folded to form a complex of protein (Freifelder, 2002).
Poisoning from death cap mushroom
The death cap mushroom has a toxin called alpha-amanitin. The toxin is a small circular peptide. This toxin poisons by attacking RNA polymerase. RNA polymerase is very essential in the life of a cell because it is used in transcription. The alpha-amanitin binds on the back of RNA polymerase far from the binding site for RNA and DNA (Money, 2011). The toxin inhibits the function/ mechanism of the enzyme RNA polymerase thus inhibiting the transcription process.
As a cell lives, it requires to synthesize proteins and DNA if this process is hindered the cell dies. The RNA polymerase functions by being flexible; it changes into different shapes as it performs a series of steps to bind DNA, unwind it and building the strands of RNA. The poison blocks the essential flexibility of the RNA polymerase by binding in between two protein subunits.
If this occurs and the cell is no longer able to perform transcription it can now no carry out the process of creating protein (mRNA to transcription to translation creating a protein). Protein is vital to a cells life; it is considered the workhorse of the cell. Protein is responsible for many things such as cell structure, without it a cell could loose it’s shape and not function properly. Enzymes (proteins) catalyze biochemical reactions within the cell With out these enzymes the cell cannot perform vital functions. The list of the functions of protein in a cell is endless; hence without it the cell dies because it no longer can perform proper functions. In Laymen’s terms the cell can no longer feed itself the food it needs to live (proteins), so the cell “starves” to death.

References
Freifelder, D. (2002). Molecular biology. Boston: Jones and Bartlett.
Money, N. P. (2011). Mushroom . New York: Oxford University Press.
Weaver, R. F. (2005). Molecular biology. Boston: McGraw-Hill.
Nucleic Acids [Motion Picture] (1) WGU, Webinar, 2015

References: Freifelder, D. (2002). Molecular biology. Boston: Jones and Bartlett. Money, N. P. (2011). Mushroom . New York: Oxford University Press. Weaver, R. F. (2005). Molecular biology. Boston: McGraw-Hill. Nucleic Acids [Motion Picture] (1) WGU, Webinar, 2015