Can someone please check... - (May/21/2006 )

can someone pls see ifi have these right?

Which of the following statements about muscle fibres are TRUE?
1-When a sarcomere contracts, the width of the A-band remains unchanged.
2-When a muscle contracts, the width of the sarcomeres shrink, and the length of the myofibrils decreases.
3-The length of the thick filaments in a sarcomere corresponds to the width of the A-band.
4-A sarcomere is a portion of a muscle fibre bounded by the Z-lines.
5-According to the Sliding Filament Model, muscles contract when the thin filaments slide towards the centre of each sarcomere.

i think 1, 3 and 4

you are supplied with muscle tissue which has been pre-treated with a chemical "cocktail". Which of the following statements about the treatment is FALSE?
1-KCl and MgCl2 are added to mimic the salt composition of a normal cell.
2-The solution is buffered to a pH = 7.0 which is the intracellular pH of an intact muscle fibre.
3-EDTA is added to "mop-up" Ca and Mg ions which have leaked from the disrupted membranes.
4-The glycerol denatures the actin and myosin proteins.
5-Glycerol destroys the membranes inside the muscle fibres.

I think...3 and 5

you are supplied with a 2 mM solution of ATP. If the molecular weight of ATP is 507 g/mol, how much ATP was used to make 4 L of solution?
1-4.058 g
2-0.3 g
3-4.058 mg
4-45 g
5-2.536 mg

I have no idea how do to this question!!!!

thank you
biology_06er

I don't know about Q1, Q2 I would say 4 and 5

Q3: number of moles=mass/molar mass Rearrange equation to give mass after calculating how many moles of ATP you require (conc*vol)