PEPERIKSAAN IJAZAH SARJANA MUDA SAINS
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE
SESI AKADEMIK 2019/2020 : SEMESTER I
ACADEMIC SESSION 2019/2020 : SEMESTER I
SIC2008 : BIOMOLEKUL
BIOMOLECULE
Dis 2019/Jan 2020 Masa: 2 jam
Dec 2019/Jan 2020 Time: 2 hours
ARAHAN KEPADA CALON: INSTRUCTIONS TO CANDIDATES: Jawab SEMUA soalan.
1. (a) Pertimbangkan formula struktur berikut. Examine the following structural formulas.
(i) Kelaskan karbohidrat A-F kepada gula penurun dan gula bukan penurun.
Classify carbohydrates A-F above into reducing and non-reducing sugars.
(6 markah/marks) (b) Sebatian aldotetrosa boleh membentuk empat stereoisomer. Lukiskan
semua stereoisomer tersebut menggunakan unjuran Fischer.
An aldotetrose can form four stereoisomers. Draw all the stereoisomers in Fischer projection. Classify them as D and L isomers.
(6 markah/marks) (c) Takrifkan epimers dan berikan SATU (1) contoh.
Define epimers and give ONE (1) example.
(d) Jawab semua soalan dibawah dengan merujuk kepada dibawah unjuran Fischer mannosa.
Answer all the questions below by referring to the below Fischer projection of mannose.
(i) Lukis unjuran Fischer bagi L-mannosa Draw the Fischer projection of L-mannose.
(ii) Bina unjuran Haworth bagi β-D-mannopyranosa Construct the Haworth projection of β-D-mannopyranose
(iii) Tandakan konfigurasi mutlak bagi C-3 dan C-5 dalam D-mannosa Assign the absolute configuration for C-3 and C-5 in D-mannose
(5 markah/marks)
2. (a) D-glukosa boleh membentuk dua isomer glukosida selepas tindak balas dengan metanol dalam kehadiran pemangkin HCl seperti ditunjukkan di bawah. Cadangkan mekanisme tindak balas berikut.
D-glucose can form two isomers of glucosides after reaction with methanol in presence of catalytic HCl as shown below. Suggest a mechanism for the following reaction.
(b) Takrifkan mutarotasi. Terangkan, mengapa laktosa menunjukkan mutarotasi tetapi sukrosa tidak.
Define mutarotation. Explain why lactose shows mutarotation but sucrose does not.
(6 markah/marks)
(c) Tuliskan reaksi dan mekanisme untuk pembentukan osazona apabila D- erythrosa bertindak balas dengan lebihan fenilhidrazina. Gunakan
unjuran Fischer.
Write a reaction and mechanism for the formation of osazone when D-erythrose reacts with excess of phenylhydrazine. Apply Fischer projections.
(8 markah/marks)
3. (a) Dua jenis asid nukleik adalah asid deoksiribonukleik (DNA) dan asid ribonukleik (RNA).
The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Tulis struktur pirimidina dan purina yang terdapat dalam DNA dan RNA.
Write down the structures of pyrimidine and purine bases present in DNA and RNA.
(b) Bebenang deria suatu segmen DNA mempunyai jujukan bes seperti di bawah: The sense strand of a segment of DNA has the following sequence of bases:
5’ … GGATCGCCTTAGAAT … 3’
(i) Berikan jujukan mRNA hasil daripada segmen ini. Give the mRNA sequence produced from this segment.
(ii) Andaikan bes pertama mRNA ini adalah permulaan kodon. Cadangkan urutan asid amino yang boleh diterjemahkan daripada sintesis ini.
Assume that the first base in this mRNA is the beginning of a codon. Suggest the order of amino acids translated from this synthesis.
(4 markah/marks) 4. (a) Jawab soalan di bawah berdasarkan jadual berikut:
Answer the questions below, based on the following table: Asid amino Amino acid pK1 (-COOH) pK2 (-NH3+) pKR (rantai sisi/side chain) Glisina Glycine 2.34 9.60 - Lisina Lysine 2.18 8.95 10.79 Asid glutamik Glutamic acid 2.19 9.67 4.25
(i) Kira takat isoelektrik (pI) untuk glisina, lisina dan asid glutamik. Calculate the isoelectric point (pI) for glycine, lysine and glutamic acid.
(ii) Lukis struktur asid glutamik apabila ia terlarut di dalam larutan akueus yang mempunyai keadaan seperti berikut:
Draw the structure of glutamic acid when it is solvated under an aqueous solution in each of the following conditions:
pH = 1 pH = 13 pH = pI
Tentukan cas keseluruhan untuk asid amino berkenaan pada pH yang dinyatakan.
Determine the net charge of the amino acid at the stated pH.
(6 markah/marks) (b) SDS-PAGE (elektroforesis gel bagi natrium dodecil sulfat polyakrilamida) digunakan untuk memisahkan protein, DNA dan RNA.
Terangkan dan illustrasikan prinsip disebalik gel elektroforesis SDS-PAGE.
SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) is used to separate macromolecules like proteins, DNA and RNA. Describe and illustrate the principles behind SDS-PAGE gel electrophoresis.
(6 markah/marks) 5. (a) Satu peptida telah dianalisa secara berturutan.
A peptide has been analysed sequentially.
(i) Hidrolisis sepenuhnya bagi peptida tersebut dengan 6 M HCl memberikan Tyr, Asn, Pro, Arg and Gly.
Complete hydrolysis of the peptide with 6 M HCl gave Tyr, Asn, Pro, Arg and Gly.
(ii) Degradasi Edman untuk peptida tersebut memberikan terbitan PTH untuk Pro.
Edman degradation of the peptide gave the PTH derivative of Pro. (iii) Tindak balas peptida tersebut dengan karboksipeptidase
memberikan Asn pada mulanya.
Reaction of the peptide with carboxypeptidase gave Asn initially. (iv) Pembelahan peptida tersebut dengan kimotripsin memberikan
(v). Hidrolisis HCl bagi Serpihan B memberikan Asn dan Gly. HCl hydrolysis of Fragment B gave Asn and Gly.
Dengan menggunakan segala maklumat daripada langkah (i) – (v), tentukan turutan asid amino untuk peptida tersebut.
Use all the information from (i)-(v) to determine the amino acid sequence of the peptide.
(7 markah/marks) (b) Tindak balas suatu tripeptida dengan fenil isothiosianat menghasilkan sebatian A dan suatu dipeptida. Tindak balas dipeptida itu dengan fenil isothiosianat menghasilkan sebatian B dan histidina. Kenal pasti dan lukis struktur asid amino dari sebatian A, sebatian B dan struktur permulaan bagi tripeptida tersebut.
Treatment of a tripeptide with phenyl isothiocyanate yields compound A and a dipeptide. Treatment of the dipeptide with phenyl isothiocyanate yields compound B and histidine. Identify and draw the structure of amino acids from compound A, compound B and the structure of starting tripeptide.
HN N O S Compound A NH N O S Compound B H H (5 markah/marks) (c) Cadangkan sintesis dipeptida berikut dengan menggunakan kaedah
Merrifield fasa pepejal.
Outline the synthesis of the following dipeptide via the Merrifield solid phase method.
Gly-Ala
6. (a) Berikan reagen atau hasil (A) – (H) bagi tindak balas berikut: Give reagents or products (A) – (H) for the following reactions:
OH O NH2 (racemic) H3O+ (B) NH4Cl, (A) H O 1. PBr3, Br2 2. (D) (C) EtO OEt HN O O O 1. NaOEt 2. (F) (G) (H) OH O Br (E) (8 markah/marks) (b) Proses pembuatan sabun dari lemak dipanggil saponifikasi. Proses ini
melibatkan pemanasan triasilgliserol dalam lemak haiwan dengan kehadiran larutan beralkali.
The process of making soap from fat is called saponification. This process involves the heating of triacylglycerols in animal fats in an alkaline solution.
H2C HC H2C O R1 O O R2 O O R3 O Triasilgliserol Triacylglycerol
(i) Tulis persamaan kimia secara umum untuk saponifikasi lemak dengan KOH. Seimbangkan persamaan kimia tersebut.
Write the general chemical equation for the saponification of fat with KOH. Balance the equation.
(2 markah/marks) (ii) Kira purata jisim molekul bagi triasilgliserol dalam 1.5 kg lemak daging lembu tulen jika ia memerlukan KOH sebanyak 289.8 g untuk saponifikasi yang lengkap. (Jisim atom relatif: H=1, C=12, O=16, K=39)
Lampiran Attachment
Table: Codon assignments of base triplets
First base (5’-end)
Middle base Third base (3’-end)
U C A G
U U Phe Phe Leu Leu
C Ser Ser Ser Ser A Tyr Tyr Stop Stop G Cys Cys Stop Trp
C U Leu Leu Leu Leu
C Pro Pro Pro Pro A His His Gin Gin G Arg Arg Arg Arg
A U Iie Iie Iie Met
C Thr Thr Thr Thr A Asn Asn Lys Lys G Ser Ser Arg Arg
G U Val Val Val Val
C Ala Ala Ala Ala A Asp Asp Glu Glu G Gly Gly Gly Gly
20 asid amino biasa dalam protein The 20 common amino acids in proteins
HO2C NH2 H NH NH H2N Arginine (Arg) R HO2C NH2 H HN N Histidine (His) H HO2C NH2 H H2N
Lysine (Lys) K Aspartic acid (Asp) D
HO2C
COOH NH2
H
Glutamic acid (Glu) E HO2C NH2 H HOOC HO2C OH NH2 H Serine (Ser) S HO2C NH2 H Threonine (Thr) T HO H HO2C NH2 H Asparagine (Asn) N O H2N HO2C NH2 H Glutamine (Glu) Q O NH2 HO2C SH NH2 H Cysteine (Cys) C Glycine (Gly) G HO2C NH2 Proline (Pro) P HO2C NH H HO 2C NH2 H Alanine (Ala) A HO2C NH2 H Valine (Val) V HO2C NH2 H Isoleucine (Ile) I HO2C NH2 H Leucine (Leu) L HO2C NH2 H Phenylalanine (Phe) F HO2C NH2 H Tyrosine (Tyr) Y OH HO2C NH2 H Tryptophan (Trp) W NH HO2C SeH NH2 H Selenocysteine (Sec) U TAMAT END
