Chapter 12

What is gene expression on a molecular level?

The process by which information from a gene is used to synthesize functional gene products, such as proteins.

Why is gene expression important?

Proteins play a crucial role in the structure, function, and regulation of cells, impacting traits and overall physiology.

What are proteins' primary functions in organisms?

Proteins are involved in nearly all cellular processes, including catalyzing reactions and regulating cellular functions.

How does gene expression affect an organism's phenotype?

Many traits result from protein activity, making gene expression directly impact an organism’s phenotype.

What occurs during the initiation stage of transcription?

RNA polymerase binds to the promoter region on DNA, unwinding the DNA and starting RNA synthesis.

What happens during the elongation stage of transcription?

RNA polymerase synthesizes RNA by adding complementary RNA nucleotides as it moves along the DNA.

What signals the termination of RNA synthesis?

RNA synthesis stops when RNA polymerase reaches a termination signal, releasing the RNA transcript.

Where does transcription occur in eukaryotes?

Transcription occurs in the nucleus, with RNA undergoing processing such as splicing.

Where does transcription occur in prokaryotes?

Transcription occurs in the cytoplasm, with RNA being immediately translated without processing.

What are codons?

Sequences of three nucleotides in mRNA that code for specific amino acids.

Why are codons significant?

Codons are the basic unit of the genetic code and direct protein synthesis during translation.

What is the role of mRNA in translation?

mRNA carries the genetic information from DNA to the ribosome for protein synthesis.

What does tRNA do during translation?

tRNA brings amino acids to the ribosome, matching codons in mRNA with anticodons on tRNA.

What is the function of the ribosome in translation?

The ribosome facilitates the assembly of amino acids into a polypeptide chain.

How does the ribosome utilize the mRNA sequence?

The ribosome reads the mRNA sequence and sequentially adds corresponding amino acids to form a protein.

What are conserved genes?

Genes that remain unchanged across species due to their essential functions.

How is a phylogenetic tree constructed?

A phylogenetic tree is constructed by comparing conserved gene sequences across different species.

What do nodes represent in a phylogenetic tree?

Nodes represent the last common ancestor of the branches stemming from that node.

What does the proximity of branches in a phylogenetic tree indicate?

The closer two species' branches are, the more recent their common ancestor, indicating a closer evolutionary relationship.

What is the role of processing in eukaryotic transcription?

RNA undergoes modifications such as splicing and the addition of a cap and tail before translation.