Gene Expression 1.3 Flashcards
At the ribosome, amino acids are linked by…
Peptide bonds to form polypeptides.
Polypeptides can fold to give a ….
3D structure
Polypeptide structures are held together by
Hydrogen bonds
Amino acids can be separated and identified using…
Chromatography
What is the laboratory method used to separate mixtures
Gel electrophoresis
What is RNA
Ribonucleic acid
Made of nucleotide subunits
Single stranded
What base replaces Thymine in RNA
Uracil
Function of mRNA
Formed in the nucleus, from free nucleotides. Transcribed from DNA.
mRNA carries a copy of the DNA code from the nucleus to the ribosome in the cytoplasm.
What is the name of the bases that are ‘read’ at the ribosome?
Codon
Function of tRNA
tRNA molecules carry specific amino acids, bringing the, to the ribosome to build proteins
What are the three bases exposed on the tRNA called?
Anticodon
Where do amino acids attach
To the tRNA amino acid attachment site
What is rRN
rRNA molecules combine with proteins to form the ribosome
What is the phenotype of an organism determined by?
The proteins produced as a result of gene expression. (Also influenced by environmental factors)
Where does transcription start
A region of DNA known as the promoter
What is the enzyme responsible for transcription
RNA polymerase
What does RNA polymerase do
It binds at the promoter and moves along DMA to unwind the double helix. It also breaks the hydrogen bonds between bases.
What happens after RNA polymerase has separated DNA.
RNA nucleotides align with their complementary base partner on the template strand and form a primary transcript of mRNA
Where does the primary transcript gp
Enters the cytoplasm
What are non-coding regions called
Introns
What are coding regions called
Exons
What is RNA splicing
After the mRNA has been transcribed the intones are removed and the remaining exons are spliced together (order unchanged)
What is the transcript called when the exons have been spliced togther
The mature transcript
What is Translation
The synthesis of a polypeptide following the code within the mature mRNA transcript
What is the translation process
- Initiated by a start codon on the mRNA strand
- tRNA molecules become attached to specific amino acids in cytoplasm and transport them to ribosome.
- The 1st tRNA molecule moves to the ribosome by means of base pairing between the anticodon on the tRNA and the complementary codon on the mRNA strand.
- Step 3 repeats until a stop codon is reached
- The amino acids are joined by peptide bonds forming a polypeptide chain
Alternative Splicing
Alternative RNA segments treated as introns and exons
