Unit 7 Flashcards
What is the protein and region that it binds to so they can increase gene expression?
Enhancer region and activator protein
What is the protein and the region it binds to for gene expression to decrease
Silencer and repressor protein
Roles of non-coding DNA
- allows alternate splicing (due to introns)
- promoter-proximal elements regulate transcription
- do not code for polypeptides
- activators bind to enhancers to increase transcription
- repressors bind to silencers to decrease transcription
Where do regulatory proteins bind to? What is their role?
promoter-proximal region, they regulate the levels of transcription.
Parts of the tRNA and where they’re located.
- Acceptor stem (ACC bases), carries amino acid - top of tRNA molecule
- D arm, associates with tRNA activating enzyme - left of tRNA
- T arm, associates with ribosome - right side of tRNA
- Anticodon, associates with mRNA molecule via complementary base pairing - bottom of tRNA.
What are the steps, in order, of tRNA activation?
1) tRNA activating enzyme binds with ATP molecule and amino acid.
2) two phosphates are cleaved, charging the amino acid
3) tRNA is recruited, where the amino acid is then bound to it
4) a charged tRNA molecule is produced.
Explain the initiation stage of translation
small ribosomal subunit binds to mature mRNA strand, where it goes down 5’-3’ direction, until it reaches the start codon (AUG), where the charged tRNA molecule (containing methionine) binds to, due to complementary base pairing. Then the large ribosomal subunit aligns itself with the tRNA (on the P site).
Explain the elongation stage of translation
A new charged tRNA molecule aligns to A site, binding to the codon with its anticodon. Due to the charge in the amino acid in the P site, a peptide bond forms between them. The tRNA in the P site is now uncharged. The ribosome moves along one codon (5’-3’ direction), causing the uncharged tRNA to be in E site, and is released. The charged tRNA holding the polypeptide is now in the P region. This is repeated indefinitely.
What are the different sites present in ribosomes structure, and their function.
A Site: where new charged tRNA molecules bind to with their anticodons to codons, due to complementary bases.
P Site: where tRNA holding amino acids form peptide bonds to the growing polypeptide.
E Site: where uncharged tRNAs exit the ribosome.
Describe what Hershey and Chase’s experiment showed (4).
Hershey and Chase wanted to determine whether proteins or DNA were the main genetic code (1), they injected viruses with radioactive isotopes of phosphorous in DNA and sulphur in proteins (1). The viruses injected their genetic material into E. Coli where it then was left to synthesise it’s proteins. They blended the E. Coli and only found traces of radioactivity in the pellet of the E. Coli infected with phosphorous after centrifuging it as the cell’s internal contained the genetic code, the supernatant contained of the E. Coli infected with sulphur contained radioactive protein as it was left on the cell’s exterior.
Explain DNA profiling
Non-coding satellite DNA contains regions called short tandem repeats; sequences of several nitrogenous bases that are repeated a specific number of times. It uses restriction enzymes to excise the tandem repeats and then use gel electrophoresis to separate the bases. Individuals typically have unique tandem repeats at one specific loci.
How does gel electrophoresis work?
Splits up longer strands of DNA from longest to smallest as smaller strands can move greater distances. allowing the colours to be easily seen as each lengths’ strand has a different coloured dideoxynucleoside bound to it.
Example of how external conditions can change gene expression
Human and melanin production based off sunlight exposure.
Explain tertiary protein structures
Tertiary protein structures occur from interactions between non-adjacent R-groups. These can be ionic bonds, disulphide bridges, hydrogen, hydrophobic,
Explain secondary protein structures
Secondary proteins occurs from hydrogen bonds forming between non-adjacent amine and carboxyl groups, they can be alpha helices or beta pleated sheets.
