Danny's Super Duper Study Set

Topics 4-7 Bio 151

Intron

Non-coding region of mRNA

Exon

Coding region of mRNA

Ribosome

Small and Large subunit, contains EPA sites

tRNA

transfer RNA, brings amino acid to ribosome

E site

Exit site, tRNA released from ribosome

P site

Peptide site, amino acid added to the polypeptide chain

A site

codon and tRNA join the ribosome

Spliceosome

Splices the mRNA together via introns and exons

Poly A tail

On 3’ end, lots of adenines

5’ Cap

On 5’ end

Missense mutation

A point mutation that changes the codon sequence, and therefor the amino acid sequence. Changes the primary structure of the protein.

Nonsense mutation

A point mutation that moves the stop codon earlier in the mRNA, so that the translation stops early. Changes the primary, secondary, and tertiary structure of the protein on a case-by- case basis.

Frameshift mutation

A point mutation that changes the reading frame of the mRNA by inserting/ deleting a nucleotide to change the start codon by 1 nucleotide. Changes the entire amino acid sequence. Affects primary, secondary, and tertiary structure.

Silent mutation

A point mutation that does not cause a change in the amino acid produced during translation, but does cause a difference in the codon.

C Terminus

The ending of a protein, free carboxyl group

N Terminus

The beginning of a protein, free amino group

Sequence Specific Binding Proteins

Bind to specific sequences in DNA, often true of transcription factors which help with the binding of RNA polymerase.

Note: RNA polymerase is not a sequence specific protein

Transcription factors

Sequence specific binding proteins which help RNA polymerase bind more tightly to the DNA. (because RNA polymerase has low affinity to promoter regions)(Often, RNA polymerase won’t bind unless there’s a transcription factor)

Positive control/ regulation

Enhance transcription by increasing polymerase affinity

Negative control

Inhibit transcription by blocking polymerase binding

LAC operon

segment of DNA in bacteria that regulates expression of lactose metabolism genes

beta galactosidase

An enzyme that cleaves lactose into 2 glucose molecules

Sigma 70

Transcription factor that brings in RNA polymerase. Low affinity for promoter.

CAP

CAP binding increases transcription when cAMP is bound. No glucose= more cAMP=more CAP= less transcription

Regulatory transcription factor

specific to a gene, upregulate the production of that gene