Question

1. Define the steps of gene expression. Be sure to specifically speak to the following: (USLO5.1)

DNA Replication

Transcription

Translation

2. Discuss vertical versus horizontal transmission.

Answer 1

# Gene expression is the process by which the genetic code - the nucleotide sequence - of a gene is used to direct protein synthesis and produce the structures of the cell. Genes that code for amino acid sequences are known as 'structural genes'.

The process of gene expression involves two main stages:

Transcription: the production of messenger RNA (mRNA) by the enzyme RNA polymerase, and the processing of the resulting mRNA molecule.

Translation: the use of mRNA to direct protein synthesis, and the subsequent post-translational processing of the protein molecule.

The 9 steps of gene expression :-

chromosome changes

- DNA unpacking

control of transcription

- regulatory proteins and control sequences

control of RNA processing

- addition of cap and tail

splicing

flow through nuclear envelope

breakdown of mRNa

control of translation

control after translation

- cleavage/modification/activation of proteins

breakdown of protein

#

Signal NUCLEUS Chromatin DNA unpacking invoivin DNA demethylation and histone acetylation Gene DNA available for transcription Gene Transcription Exon RNA へ へ11,Primary transcript 7心Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasmm radation of mRNA Translation 000099000 Polypeptide Cleava Chemical modification Transport to cellular destination Active protein Degradation of protein ded protein

2. Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction) .

Vertical gene transfer Horizontal gene transfer Chromosome Transformation sduction Genome replication and cell division