BIOL340 #2 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED GRADED A++ LATEST UPDATE
Co-translational translocation
The simultaneous translation and translocation of a protein into the ER.
Post-translational transport
Protein is completely synthesised on free ribosomes and is transported to its eventual
destination AFTER complete synthesis
sorting signals
A short amino acid sequence in a protein that directs the protein to its correct location;
also known as a traffic signal.
- signal peptide: at terminus
- signal patch: patch within folded protein
Transport through nuclear pores
proteins moving from the cytosol into the nucleus are transported through the nuclear
pores that penetrate the inner and outer nuclear membranes
- continuous bidirectional selective transport
Nuclear localisation signals (NLS)
specifically recognised by nuclear import receptors that bind to NLS and nuclear pore
complex simultaneously
RanGTPase
, imposes directionality on nuclear import
Transport across mitochondria
- POST-TRANSLATIONAL
- requires signal sequences and protein translocators (multi-subunit protein complex)
- has to cross 2 membranes
- binds to receptor than TOM complex recognises and TIM complex translocates and
cleavage occurs to produce mature mitochondrial protein
transport across chloroplasts
- POST-TRANSLATIONAL
- has multiple membranes to be crossed (cytosol, stroma, thylakoid lumen)
- two signal sequences required
- TOC complex recognises and TIC binds and allows entry, ATP-dependent
translocation into stroma, cleavage of signal sequence, signal sequence to enter
thylakoid
transport across peroxisomes
- single membrane
- selective import from cytosol or via ER
- short signal sequence direct targeting signal receptors
- driven by ATP hydrolysis
- 23+ proteins involves
- Pex5 carries cargo into peroxisome before being recycled
Endoplasmic Reticulum (ER)
The transportation system of the cell. It moves lipids and proteins around the cell
COMPLETE SOLUTIONS VERIFIED GRADED A++ LATEST UPDATE
Co-translational translocation
The simultaneous translation and translocation of a protein into the ER.
Post-translational transport
Protein is completely synthesised on free ribosomes and is transported to its eventual
destination AFTER complete synthesis
sorting signals
A short amino acid sequence in a protein that directs the protein to its correct location;
also known as a traffic signal.
- signal peptide: at terminus
- signal patch: patch within folded protein
Transport through nuclear pores
proteins moving from the cytosol into the nucleus are transported through the nuclear
pores that penetrate the inner and outer nuclear membranes
- continuous bidirectional selective transport
Nuclear localisation signals (NLS)
specifically recognised by nuclear import receptors that bind to NLS and nuclear pore
complex simultaneously
RanGTPase
, imposes directionality on nuclear import
Transport across mitochondria
- POST-TRANSLATIONAL
- requires signal sequences and protein translocators (multi-subunit protein complex)
- has to cross 2 membranes
- binds to receptor than TOM complex recognises and TIM complex translocates and
cleavage occurs to produce mature mitochondrial protein
transport across chloroplasts
- POST-TRANSLATIONAL
- has multiple membranes to be crossed (cytosol, stroma, thylakoid lumen)
- two signal sequences required
- TOC complex recognises and TIC binds and allows entry, ATP-dependent
translocation into stroma, cleavage of signal sequence, signal sequence to enter
thylakoid
transport across peroxisomes
- single membrane
- selective import from cytosol or via ER
- short signal sequence direct targeting signal receptors
- driven by ATP hydrolysis
- 23+ proteins involves
- Pex5 carries cargo into peroxisome before being recycled
Endoplasmic Reticulum (ER)
The transportation system of the cell. It moves lipids and proteins around the cell
