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Protein synthesis

1. (a) (Linear) sequence / order / arrangement / pattern of amino acids;

(b) Description of H bond / attraction between dipoles e.g +and /

weak electrostatic bond

Between H and !

"n amine and carbo#$l groups

%eference to t&e &eli# / secondar$ structure / ' s&eet/ strand !

(Bond between)R groups in coiling / tertiar$ stucture / D s&ape a#

(c) Long c&ain / long strand / fibrils / reference to linear molecule

%epeating sequence of amino acids!

an$ parallel strands lie side b$ side /eq!

%eference to a &eli# / (pleated) s&eet!

*ollagen &as triple &eli#! a# [8]

2. (a) central * wit& % and H attac&ed b$ single bonds !

H,and *H attac&ed to carbon b$ single bonds !

-accept H+and /or *

(b) (i) %ibosomes !

B %oug& 0% !

* 1olgi apparatus !

(ii) (%ises b$ 23 units in 23 minutes)

%ate 4 23 5 23 ! -accept ot&er correct figures

4 2 !

unit per min !

-allow unit mark if figures from incorrect cur6e

(c) %adioacti6it$ will continue to drop in (all) organelles !

%eference to &alf life (of isotope) / natural drop in radioacti6it$ o6er time !

o6ed out of cell / e#oc$tosis / secreted !

s protein / named e#ample !

%adioacti6it$ will not reac& 7ero !

Because some8 amino acids / proteins8 incorporated !ma# [11]

3. amino acids / pol$peptides / peptides !

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peptide ! -not dipeptide -accept peptide / &$drogen / disulp&ide / ionic if peptide

or pol$peptides gi6en abo6e

condensation / pol$merisation !

() &eli# / (alp&a) &eli# !

&$drogen / H !

4. Award marking points only in correct context

2 *onsists of amino acids &eld toget&er b$ peptide bonds (in eit&er) !

, "nsulin is globular and collagen is fibrous !

H$drogen bonds &old8 secondar$ structure / (alp&a) &eli# / beta strands8 in

s&ape (in eit&er) !

9 % groups determine8 tertiar$ / D8 s&ape (in eit&er) !

3 %eference to named t$pe of bonding in tertiar$ structure !

Insulin

: %elati6el$ small protein / 32 amino acids !

; %eference to8 alp&a &eli# / beta s&eet !

< =wo pol$peptide c&ains / c&ain and B c&ain !

> %eference to disulp&ide bonds !

2? %eference to binding site for cell membrane receptor !

Collagen

22 %elati6el$ large protein / o6er 2??? amino acids !

2, pol$peptide c&ains / triple &eli# ! -ignore alp&a &ere

2 H$drogen bonds between c&ains !

29 %egular amino acid sequence / repeating sequence !

23 olecules form (micro)fibres / cross'linking between molecules ![10]

5. (a) 2. (m%) is a cop$ of D !

,. (cop$ of) part of D / eq !

. (cop$ of) one strand / sense strand !

9. m% is complementar$ (to D) / m% made up ofcomplementar$

bases !

3. m% strand8 built / formed (looking for idea t&at m% strand is put

toget&er during t&e process) / reference to en7$me !:. carries genetic code to8 c$toplasm / out of nucleus / to ribosome !

(b) 2. genetic information / base sequence / code8 in m% determines

amino acid sequence !

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,. codons / base triplet on m% !

. determines amino acid !

9. (codons) pair wit&8 complementar$ triplet / anticodons8 on t% !

3. reference to start / stop codons / sequences / binding sequences !

:. occurs on ribosomes !

6. @equence / order !Aeptide !

*ondensation / pol$merisation !

H$drogen / H !

(di)sulp&ide / co6alent ! -accept sulp&ur

% groups / side c&ains / sulp&ur / @H groups / t&iol groups !

;. (b) (i) m% is made !

"t is complementar$ to D % D code is copied !

(ii) =$r Leu A&e @er ! !

-one error 4 2 mark8 , errors 4 ? mark

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(ii) 1*= =11 *11 1*= =1 =11!!

-all correct 4 , marks8 one error 4 2 mark8 more t&an one error 4 ?

marks

(c) %eference to start codon!

%eference to stop codon!

%eference to post transcription modification!(d) 2. ccurs on / inC ribosome!

,. =wo t% molecules (&eld in position in ribosome)!

. 0ac& carr$ing a specific amino acid!

9. nticodons on t%!

3. %eference to binding of t% to complementar$ bases on m%!

:. Aeptide bonds form between amino acids!

;. %ibosome mo6es along m%!