Protein Turnover Flashcards
Why are proteins in a continual state of turnover
Cannot be stored
What % of total body protein is turned over daily
1-3%
Why is protein turnover a high energetic cost
Take up approximately 20% of BMR
What do proteins do each day
- Form new muscle cells
- Form synthetic pathways
- Form plasma proteins, immune cells and haemoglobin
- Form new enzymes in the gut and digestive system
What does protein turnover involve
Protein synthesis and protein degradation
What is the rate of protein turnover
300g/day
What is the importance of nitrogen balance
Used to track how much nitrogen (protein) enters the body and how much nitrogen is excreted from the body e.g. We lose approximately 35 – 100 g of protein per day; hence we need this to survive
Which proteins have a very fast (minutes) half life
Enzymes in the liver
What is half life
How long it takes before half the total amount of protein is broken down
Why is it useful for liver enzymes to have a fast half-life
So toxic/ waste products are metabolised quickly and effectively- preventing accumulation
Which proteins have a slow half life
Mitochondrial proteins, myofibrillar proteins
Why is useful for skeletal muscle protein to have slower half life
Prevents muscle wastage
What upregulated the proteins in skeletal muscle
Cardio-respiratory and resistance raining
What is required for muscle growth
Protein synthesis exceeding breakdown
Which polymerase transcribes the info in the gene to form mRNA
RNA pol II
How many possible codons are there
64
What are the two main pathways for protein degradation
Lysosomal pathway and ubiquitin pathway
What are the lysosomal pathway and the ubiquitin pathway used for
Pathways are used to rid the body of damaged or abnormal proteins
They are essentially replaced by a newer and better versions
Describe the ubiquitin pathway
Proteins can be tagged for degradation by the addition of a chemical marker called ubiquitin.
Ubiquitin-tagged proteins are taken to the proteasome, or “recycling center” of the cell, and broken down into their component parts.
Describe the lysosomal pathway
Protease enzymes degrade the proteins in the lysosome
What is the ubiquitin protein
Protein that takes abnormal or damaged proteins for degradation
What does the lysosome degrade
Extracellular proteins, cellular proteins and membranes
Which intracellular protein is damaged and therefore degraded after exercise
Dystrophin
How many stop codons are there
3
How many start codons are there
1 -AUG
