Question

Summarized Chapter 17 Gene expression: From Gene to Protein and Chapter 18 Regulation of Gene Expression. What they were about? Why they are important? And how they link to other chapters, at least 1/2 page in length for both chapters.

Answer 1

Most genes contain the info required to make functional molecules called proteins. The trip from genes to proteins is complex and strongly controlled within each cell. It consists of 2 major steps: transcription and translation. Collectively, transcription and translation are known as gene expression.

During a process of transcription, information stored in a gene's DNA is reassigned to a similar molecule called RNA (ribonucleic acid) in the cell nucleus. Both RNA and DNA thus are made up of a chain of nucleotide bases (A, T G and C), but they have slightly different chemical properties. The type of RNA that contains the information for making a protein is called messenger RNA (mRNA) because it transmits the message from the DNA out of the nucleus into the cytoplasm.

Translation, the 2^nd step in attainment from a gene to a protein, takes place in the cytoplasm. The mRNA interacts with a specialized complex called a Ribosome, which "reads" the sequences of mRNA bases. Each sequence of 3 bases in mRNA called a codon, generally codes for one particular amino acid. A type of RNA called transfer RNA (tRNA) gathers the protein, one amino acid at a time. Amino acids assembly continues until the ribosome encounters a “stop” codon (a sequence of three bases that does not code for an amino acid) thus forming a protein.

The flow of information from DNA to RNA to proteins is sometimes called the “central dogma.”

Gene regulation for an cellular processes is the step that control the rate and mode of gene expression. Complex sets of interaction between genes,RNA, proteins and other components of expression system determines at what time and where specific genes are activated and the amount of protein or RNA produced.