LECTURE 2: Protein Metabolism

Question 1

list three instances when protein degradation happens (metabolism > synthesis)

Answer 1

1. aa from protein breakdown are not needed
2. ingest aa > rate of protein synthesis
3. starvation/fasting - breaking down of skeletal muscle to use carbon skeletons for energy

Question 2

list three main purposes for protein degradation

Answer 2

1. to degrade damages/faulty proteins
2. energy provision by conversion to carbon skeletons for use in krebs cycle
3. synthesis of other compounds from aa (eg hormones/neurotransmitters)

Question 3

list the four muscle fibre types/myosin heavy chains (MHC) order of slowest to fastest contraction

Answer 3

MHC I
MHC IIA
MCH IIB
MHC IIX

Question 4

what is myosin made up of

Answer 4

6 polypeptides, 2x heavy chains (MHC) + 4x light chains (MLC)

Question 5

what is muscle hyperplasia and its contribution to muscle growth?

Answer 5

increase in no. muscle fibres. has minimal, if any contribution to muscle growth

Question 6

what is hypertrophy and its contribution to muscle growth?

Answer 6

increase in myocite size with more actin and myosin filaments in each myofibril. the biggest contributor to muscle growth

Question 7

list three reasons neural adaptations contribute to most strength gain in first two weeks of a training program

Answer 7

1. improved innervation
2. decreased activation of antagonist muscles
3. increased neural drive (increased innervation, increased no neurons activated, increased firing rate of motor neurons, increased MN synchronisation, increased neural transmission across NM junctions)

Question 8

list five reasons for fatigue in a 30s max effort

Answer 8

1. lower anaerobic ATP resynthesis
2. higher ADP levels due to lower PCr levels
3. higher Pi levels inhibit innervation and excitation-contraction coupling
4. disruption of Ca2+ handling n cells
5. lower neural drive exciting muscles

Question 9

what system is primarily used to resynthesise PCr levels after sprinting?

Answer 9

aerobic system

Question 9

how much PCr is restored within 30s of finishing a spring?

Answer 9

50%

Question 10

what is delayed with blood occlusion or muscle ischemia when taking biopsies for research?

Answer 10

delays return of PCr to muscle via blood

Question 11

list three adaptations of sprint training

Answer 11

1. enzymatic (higher enzyme activity for ATP resynthesis)
2. substrate ( higher substrate levels (eg creatine) available for ATP resynthesis
3. metabolites (greater capacity to clear metabolites)