Proteins & Genes Flashcards
Transcription
(What it does & where it occurs?)
- DNA –> mRNA
Transcription occurs to make a protein from the genes within DNA
- DNA is first transcribed into an
mRNA molecule
- The ‘m’ is for “messenger”
It occurs in the nucleus of
eukaryotes and in the cytoplasm
of prokaryotes
RNA
Has similar similar shape as DNA but single helix
- Has nitrogenous bases that are mostly similar to DNA
- Uracil, in place of Thymine,
pairs with Adenine
Pairs :
Uracil & Adenine
Guanine & Cytosine
Transcription - Initiation Process
- RNA polymerase
- Transc. bubble
- Re-wound
- RNA polymerase locates a promoter region of the DNA
- Promoter will be ahead of a particular gene - A transcription bubble forms where DNA is partially separated or unwound
- The DNA is re-wound behind the RNA polymerase
Transcription - Elongation Process
-1 side –> temp.
- RNA poly. –> form mRNA
- One side of DNA becomes the template strand
- RNA polymerase adds nitrogenous bases to form mRNA
Transcription - Termination Process
- mRNA is set free
Transcription - Post Processing
- Stabilizing
- Caps
- Introns & Extrons
Post-processing occurs in the nucleaus of eukaryotes before migrating to cytoplasm
During the process :
1. Stabilizing proteins are added to
prevent degradation
2. Caps are added to the ends of
mRNA
3. Introns are spliced out (removed);
exons stay put in mRNA
Genetic Code
Conists of nitrogenous base pairs that code in triplets
- Each possible triplet codes for an amino acid
Translation (Protein Synthesis)
(What it does and where it occurs?)
- mRNA –> proteins
Consists of using mRNA to build proteins
Takes place in cytoplasm
- Ribosomes help the synthesis
process
Composed of large and small
subunits
Translation - Initiation Process
- tRNA –> start codon
tRNA interacts with start codon to begin process
- The ‘t’ is for “transfer”
Translation - Elongation Process
- tRNA enter –> bring AA
- condons –> which AA is needed
- AA attrcted to chain –> tRNA leaves
More tRNAs come in, bringing amino acids with them
- Codons tell tRNAs which amino
acids are needed
- As amino acid is attached to
growing chain, tRNA leaves
Translation - Termination Process
- S codon –> ribsosome –> release P & mRNA
Stop codon tells ribosome to release protein and mRNA
Gene Regulation - Prokaryotes
Proteins must be synthesized at the
right times & in the right amounts
(gene expression)
Prokaryotes regulate transcription to
control gene expression
- Because transcription and translation occur in the same place
Gene Regulation Eukaryotes
Ep.Transcrip.Translat.P.Transl.
Proteins must be synthesized at the
right times & in the right amounts
(gene expression)
Eukaryotes have multiple ways to
regulate gene expression
- Epigenetic: when DNA is unwound
- Transcriptional: when RNA is transcribed
- Translational: when RNA is translated to
protein
- Post-translational: occurs after protein is made
