frq exam 4 bio

calculate the minimum number of nucleotides required in the coding region of the LDS2B mRNA molecule to produce and terminate the 565-amino acid polypeptide

1701. I got that by multiplying 565 by three then adding an additional two sets of three to account for the start and stop codons

prokaryotes gene expression

-Primarily controlled at the level of transcription -Operons -Inducible operons -Repressible operon

initiation in prokaryotes, DNA replication

- Pull apart parent strands through helicase - Makes replication fork - Topoisomerase - relieves the strain on the DNA strands around the replication bubble - Single strand binding proteins- bind a stabilize single stranded DNA - Primase - produces an RNA primer which allows DNA polymerase III to bind

DNA polymerase III prokaryotes, DNA replication

- Moves in the 3' to 5' meaning it synthesizes DNA in the 5' to 3' direction - Takes nucleotides and adds them to the growing chain

Provide TWO reasons that the number of nucleotides in the mature mRNA may differ from the number of base pairs in the gene

reasons include the 5' cap and polyA tail adding nucleotides that are not included in the gene, the gene could have promoters/regulatory sequence that do not get transcribed, RNA could also be genetically modified, which would potentially add nucleotides. - introns are removed from mRNA but remain in the gene structure - alternative splicing mixes different exons

eukaryotes gene expression

- Chromosome level DNA methylation Histone acetylation Epigenetic inheritance - Transcription level Enhancers Alternative splicing poly-A tail RNAi (RNA interference) - Translation level Phosphorylation of proteins Acetylation of proteins Methylation of proteins - Differential gene expression Cell division Cell differentiation and morphogenesis

prokaryotes transcription

- DNA undergoes replication and transcription and translation in an undivided compartment -- All three can occur simultaneously - Transcription initiation machinery is simple since DNA is not associated with any histone proteins - NO TRANSCRIPTION FACTORS -RNA polymerase can recognize and bind to the promoter region

Eukaryotes DNA replication

- Has multiple origins of replication - Unidirectional replication - Inside the nucleus of the cell - 4+ types of polymerases

prokaryotes DNA replication

- Initiation, elongation, termination - Replication begins at the *single origin of replication* -*Different from eukaryotes* - *Circular loop (plasmid)* - Only 1 or 2 types of polymerases - *Replication occurs in two opposing directions at the same time* - Takes place in the cytoplasm (no nucleus) - Replication takes place at a much faster rate compared to eukaryotic cells - Replication is occurring continuously - Two strands of DNA are pulled apart ---*Forms the replication bubble* ---Bubble expands until it hits the termination site ---The two detach and form 2 genetically identical plasmids

Eukaryotes transcprtion

- Replication and transcription occur in the nucleus - Translation occurs in the cytoplasm ---RNA therefore must travel across the nuclear membrane before it undergoes translation ---Transcription and translation are physically separated - pre-mRNA must be processed before being translated ---5' cap and poly A tail must be added and introns spliced -Transcription initiation machinery is very complex since the genetic material is associated with proteins - TRANSCRIPTION FACTORS ARE NEEDED ---RNA polymerase cannot recognize the promoter region directly unless the promoter is pre-occupied by transcription initiation factors - Promoter region contains a TATA box (DNA sequence that indicates where a genetic sequence can be read and decoded; type of promoter sequence which specifies to other molecules where transcription begins)

prokaryotes translation

-Transcription and translation are continuous processes occurring both in the cytoplasm - mRNA does not need to be processed ---No caps needed because everything happens in the cytoplasm

Eukaryotes trnalsation

-mRNA processing must occur -5' cap (has a methyl group) ---Ribosomal binding site -Poly a Tail ---Long ---Prevents degradation of mRNA in the cytoplasm -----Need extra protection for journey from nucleus to cytoplasm -Translation occurs in the cytoplasm