Hoorcolleges Training, ageing and disuse
Hoorcollege 1
ageing population: keep them healthy and fit
when we age / disease we lose muscle mass: cachexia → become inactive → circle
more vulnerable to disease → mortality higher
ageing high risk of falls, injuries, fractures
bonus point for every WG with your statement!
protein turnover = synthesis
most important in muscle: actin and myosin
in many conditions we need power and endurance (sustainable power)
how can you attain both? or how can you improve power or endurance?
we have to trigger the body to improve
disease people needs to trigger to body like athletes
muscle peak power
max sustainable power
cross section: muscle fiber (muscle cell) can be as long as the muscle belly, are bundled in
collagen (bundle) & kept together to connective tissue and this makes a connective with
capillaries and nerves. every fiber has a connection with an axon and capillary for O2.
myofibril bestaat uit myofilamenten
- sarcomeer in parallel and in series
muscle fibers are multinucleated → every couple of micrometer → very much protein
synthesis per micrometer
number of muscle fibers per muscle: some 800.000 and some 1.5 miljoen at athletes
max force is proportional to cross sectional area
# muscle fibers is set after birth , not everyone the same amount of fibers
length force relation: we can only changing the number of sarcomeres in serie and parallel
strength: sarcomeres parallel
power: volume, sarcomeres parallel = cross section and sarcomere in series (the more in
series the faster, the higher the force at a certain velocity)
different types: type 1 (slow, efficient, not high power), type 2a, type 2x (fastest, high power)
- type 1: tour de france, exercising for hours
- type 2: most seen (hockey very high type 2)
- type 2x: sprint, you can hardly get them.
*zero force = isometric
power: so it is about muscle volume, optimum muscle fiber length, physiological cross
sectional area and type (myosin composition) = important for potential generate power (90%
determined by these)
,Skeletal muscle has the ability to hypertrophy and increase the number of sarcomeres in
series in response to immobilization at extended length
mitochondrial density determines endurance, we need energy supply after a couple seconds
of exercising. (60-70% of endurance determined by density)
myofibrils are surrounded by t tube and SPR and in between also mitochondria
type 1: more mitochondria, you need oxygen via capillaries. They have many capillaries.
oxygen transport via myoglobin (binds oxygen, transport oxygen from sarcolemma to the
core) there is many myoglobin
endurance: it is a about mitochondria density, slow myosin heavy chains (are more efficient,
certain force with less ATP), capillary density and myoglobin concentration
what happens with disuse, age and train? = all about in this lecture
balance between protein synthesis and degradation (with every training you have both)
Adaptation of muscle size is a change in balance of protein synthesis and degradation
synthesis:
myonuclei: synthesis starts in nucleus (recipes for protein in DNA)
transcription: copy of DNA → mRNA → translation → protein → posttranslational modification
(3d structure)
blue spot =myonuclei lying inside of the membrane → subsarcolemmal localisation,
Myonuclei lying beneath the sarcolemma
and there are other cells between myofibers in collagen→ fibroblasts produce collagen,
stemcells, endothelial cells, adipose cells, so many more cells than only myofiber
#nuclei/ mm fiber length increase = increase in cross sectional area (FCSA)
you need nuclei in order to get bigger
blue = nuclei → for a bodybuilder is a lot of nuclei
stemcells: satellite cell (inside of membrane) → what do we have these (third lecture)
slide 35 stemcell can proliferate (copy its dna) → two cells → fuse with myofiber → myonuclei,
could also be one nuclei and one remain stemcell
nucleus contain DNA → helix, two strands, molecules combi of atomes. First you have to
decouple the strands.
1 strands (DNA) has the code for the messenger RNA. = transcription: copy DNA strand
(mRNA) =complementary to DNA strand. 3 nucleotide = codes for a aminoaccids. the order
of nucleotides determines the order of the amino acids and thus determines the
characteristics of the protein
,DNA is very densely packed. DNA is wrapped around the nucleosome and these are
wrapped around each other. when you want to read the DNA you have to unwind this, and
after this you can decouple the double stands.
not the number of gene count for your performance (vlieg heeft al evenveel)
the order determine the protein
C-G
A-T/U
- sense/ coding strand = you makes this strand complementary
- anti sense (opposite coding) = the same as RNA (U instead of T)
DNA = double stranded helix, H bonds between strand
RNA = all single strand, H bonds within strands (mRNA = message protein, tRNA (transfer),
rRNA (ribosomal))
histome octomer = DNA can be packed together, wrap it up
nuclei acids made up of chains of nucleotides
nucleotides consist of:
- nitrogenous base (on the 2nd) = G, T, A , or C
- a sugar / (deoxy) ribsose (on the 5th H)
- hydroxylgroup (on the 3rd H)
binding between strands is at the base sides.
bases only bind to a specific other base due to chemical structure
see slide 5’ (phosphate group) and 3’ (hydroxyl)
translation is reading from 3’ to 5’ → RNA is from 5’ to 3’
you read it from 5’ to 3’ (transcription)
- 5’ is defined as the nucleic acid of which the 5 carbon is attached to a phosphate
group and not to another nucleic acid.
- 3’ is defined as the nucleic acid of which the 3 carbon is attached to a hydroxyl and
not to another nucleic acid
transcription: information transcripted from DNA to mRNA
translation: information in mRNA translated into primary sequence of protein
codes for protein in nuclei: unwind the DNA at a certain base to generate a specific protein,
the enzyme binds at this place (polymerase), read the DNA from 3’ to 5’ = pre messenger.
- blue structures are taken = introns
- the systems knows where to cut, it depends on enzymes on the DNA
you got 5’’ cap (is methylated) at the ends to protect the structures and an 3’ poly A
(nucleolus where there is the coding of the mRNA and tRNA)
Three types of RNA:
1. Messenger RNA (mRNA) - carries the code for the protein
2. Transfer RNA (tRNA) - carries amino acids from amino acid pool to mRNA
, 3. Ribosomal RNA (rRNA) - joins with ribosomal proteins in the ribosome where amino
acids are joined to form the protein primary structure.
mRNA transported via nuclei ports → cytoplasm → translated to protein
it needs a ribosomal complex (small and big components bind to messenger)
tRNA: aminoacid are broad to ribosome complex), 3 nucleotides and will be picked up by
tRNA and make the chain longer and longer till it drops off (tRNA) and you got you protein
● needs to determine which protein needs to be generated
● initiation: promoter (region) bind and it will start reading
● training: change chemistry in muscle cell = change in nucleus → proteins bind to DNA
● these are the following: rna polymerase = read the DNA , general transcription
factors and mediator complex = transcription pre initiation complex = favorable
condition for reading a gene
● the polymerase can only read the DNA when this complex is there
nucleosomes wrap DNA, polymerase cannot bind and the promoter cannot be reached to
open the DNA. you need transcription factors that bind particular regions and unwrap DNA.
in the introns there are regions that facilitate the binding of the transcription factor. so introns
are not completely useless.
see slide 50 for complements
the polymerase reads it from 3’ to 5’ → so mrn is again from 5’ to 3’
polymerase pick up the propriate nucleotide
it starts at promotor where the RNA polymerase is activated, which is done by activators
→ repressors does repress it (inactive)
exons = coding regions protein (5’ to 3’)
promotor end with a tata box
introns = non coding regions
enhancer = enhance reading, maybe present in the code itself, but can also be far away
from the protein code as a proximal upstream or downstream enhancer
different splicing = different exons in and out
transcription summary:
- Each cell nucleus contains all genes for that organism but most genes are only
expressed as needed
- Transcription regulated by transcription factors
- Proteins produced by their own genes
- transcription factors promoting transcription ‐ activators
- transcription factors inhibiting transcription – repressors
regulation by TF:
- transcription factors are already present in nucleus but they are not moving to the
nucleus there are in cytoplasm??? under particular conditions → they can be
