The structure and function of macromolecules

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The structure and function of macromolecules
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????????????????? (macromolecules) ?????????????
??????? 4 ?????????????????????????????????
?????? Carbohydrate ?????????????? C, H,
O Protein C, H, O, N Lipid C, H,
O Nucleic acid C, H, O, N, P
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Building models to study the structure of
macromolecules
Today, scientists use computer
Linus Pauling (1901-1994)
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???????????????? macromolecules
?????? Condensation ???????????????????????
macromolecules ??? monomers ?????????????????
???????????? H2O ???? ??????????????????
????????? dehydration Hydrolysis
????????????????????? macromolecules ?????????
?????????????????????????????????????????????????
???????????? macromolecules ??????????????????????
?
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The synthesis of a polymer
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The Breakdown of a polymer
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Carbohydrates

• Carbohydrates ?????????????????? ?????? ???
  polymer ?????????
• ????????? carbohydrates ??????? 3 ?????
  ????????????????????????????????????????? ??????
• Monosaccharide
• Disaccharide
• Polysaccharide

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Monosaccharide ???????????????????????
????????????? C, O ??? H ????????? (CH2O)n
????????????? C ????????????? ????? Carbonyl
group ??? hydroxy group ?????????????? C
Carbonyl group
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The structure and classification of some
monosaccharides
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Linear and ring forms of glucose
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???????????????? (Disaccharides)
?????????????????????????????????????? 2 ???????
???????????? condensation Covalent bond
??????????? ???????? Glycosidic linkage
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Examples of disaccharides synthesis
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• Polysaccharide ???? carbohydrate
  ???????????????? ?????????? monosaccharides
  ?????????????????? glycosidic linkage
• ??????? polysaccharide ???????????
• 1. ??????? monosaccharide
• 2. ??????? Glycosidic linkage
• ???????? polysaccharide ?????? starch, glycogen,
  cellulose ??? chitin

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Storage polysaccharides
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Starch 1-4 linkage of ? glucose monomers
Cellulose 1-4 linkage of ? glucose monomers
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Cellulose ?? glucose ??????????????????????????
???? ????????????? ?1-4 glycosidic linkage
????????????????????????? cellulose ????????????
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The arrangement of cellulose in plant cell walls
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Chitin, a structural polysaccharide
Chitin forms the exoskeleton of Arthropods
Chitin is used to make a strong and flexible
surgical thread
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Chitin ??????????????????? Cellulose
????????????? ????????????? N-acetylglucosamine
???????????????????????
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• ?????????? carbohydrate
• Sugars
• ??????????????????????????????????????????????????
  ??
• ribose ??? deoxyribose ????????????????? nucleic
  acid
• Polysaccharide
• ??????????????????????????????????
  ????????????????????????????? starch
  ???????????????????????????????? glycogen
• Cellulose ??? chitin ???????????????????????????

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Lipids Diverse Hydrophobic molecules
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• Lipids ????????????????? polymer
• Lipids ??????????? ????????????????????? lipids
  ?????????? nonpolar covalent bonds ???????????
• Lipids ??????
• ????? (Fat)
• Phospholipid
• Steroid
• ??????? (Wax)

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Fats ????????????????????

• Fats ??????????????? polymer ?????????????????????
  ????????? ????????????????????????????????????????
  ?????????????????? Dehydration
• Fats ?????????? Glycerol ??? ???????? (Fatty
  acid)

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???? tail ??? fatty acid ??????? hydrocarbon
???????????????????????????????? 16-18 ?????
???????????????? fats ??????????? (hydrophobic)
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Triglycerol ????? 1 ??????? ?????????? Glycerol
1 ??????? ??? ???????? 3 ???????
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• ??????????????????? 2 ????? ??????
• Saturated fatty acid (???????????????????)
• Unsaturated fatty acid (??????????????????????)
• ??????????????????? ???? ??? ?? saturated fatty
  acid ?????????????? ??????????????????????????????
  ????
• ??????????? ?? unsaturated fatty acid
  ?????????????? ??????????????????????????????????

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Saturated fat and fatty acid
Unsaturated fat and fatty acid
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• Phospholipids
• ????????????????????? cell membrane
• ?????????? glycerol 1 ??????? fatty acid 2
  ??????? ??? phosphate group (phosphate group
  ??????? -)
• ??????????????????? ????????????????????
  (hydrophilic) ?????????????????????? (hydrophobic)

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The structure of phospholipid
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Phospolipid in aqueous environments
????????? phospholipids ??????? phospholipids
??????????? ??????????????????????
?????????????????????????? ????????????????
???????? micelle
Micelle
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??? cell membrane ?????????????? Phospholipids
?????????????? 2 ???? ??? hydrophilic head
??????????????????????????? ???? hydrophobic tail
???????????
Phospholipid bilayer
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• Steroids
• ???? lipids ?????????? ?????????????????????????
  4 ??
• Steroids ????????? ?????? functional group
  ?????????????????????????
• Cholesterol ???? steroid ????????????????????
  cell membrane

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Cholesterol, a steroid
Cholesterol ??????? precusor ???????????????????
steroid ????????????? ???? hormones
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• Protein
• ???? polypeptide ??? amino acid
  ???????????????????????????????????????????????
• ???????????????????? ????????????? (conformation)
  ?????????????????????
• ????????????????????? 10,000 ????
  ????????????????????????????????????????

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Amino acid ???????????????????????? carboxyl
??????? amino ??????????????????????????????????
??????????????????????????????????? hydrogen
??????? R group 1 ?????????????????
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• Amino acid ??????????????????????????????? R
  group
• R group ???????????????? ????????? amino acid
  ?????????? 20 ???? ???????????????????????????????
  ?????????????????

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Amino acid ????? Nonpolar
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????? Polar
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????? Electrically charged
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Making a polypeptide chain
Amino acid ???????????????????? covalent bond
???????? peptide bond
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• ????????????? amino ???????? N-terminus
• ????????????? carboxyl ???????? C-terminus

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??? polypeptide ?????????? amino acid ???? 20
???? ???????????????????? ??? polypeptide
???????????????????????????????????????????????
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• ????????????????????????????????? (conformation)
  ?????????????????????
• ??????????????????????????? polypeptide 1
  ?????????????? ???????????????????????????????????
  ??? side chain ??? amino acid
• ?????????????????????????????????????? amino acid
  ???????????????

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A proteins function depends on its specific
conformation
Ribbon model
Space filling model
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???????????????????????????????? Primary
structure Secondary structure Tertiary
structure Quaternary structure
????????????????????????? polypeptide ??????? 1
???
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The primary structure of a protein

• Primary structure ??? ???????? amino acid
  ???????????????????????
• Primary structure ?????????????????????????????
  (DNA)

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??????????????????? amino acid
???????????????????????????????????????????
???????????????????????????????????????
???????????? ??? sickle-cell anemia
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A single amino acid substitution in a protein
causes sickle-cell disease
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The secondary structure of a protein

• Secondary structure ???????????????????????????
  H-bond ??????????? carboxyl??????? amino

• Secondary structure ?????????????????????????
  ?Helix ??? ? Pleated sheet

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???????????? ???????????? ?????????????? ?
Pleated sheet ?????????????????????????????????
Spider silk a structural protein
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Tertiary structure of a protein
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• Tertiary structure ?????????????? polypeptide
  ??????????????? ??????????????????????????????????
  ?????????????? R group ?????????? ???? R group
  ????????????????
• ????????????????????
• H-bond
• ionic bond
• Hydrophobic interaction
• Van der Waals interaction
• ???????????????????????????? covalent bond
  ?????????? ???????? disulfide bridges ???????????
  sulhydryl (-SH) ???????????? cysteine
  ??????????????

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The Quaternary structure of proteins
??????????????????????????????????? polypeptide
??????? 1 ??????????? ??????? tertiary structure
??? polypeptide ????????????????
???????????? Collagen ???? fibrous protein
?????????? polypeptide 3 ?????????????
??????????????????????????????????????????
connective tissue
Polypeptide chain
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Hemoglobin ?????????? polypeptide 4
???????????????????????????????????????????
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The four levels of protein structure
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Denaturation and renaturation of a protein
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• ???????????????????????????????????????????
  ???????????????????????????????? ???? pH ????????
  ???????? ??????? ?????????????????????????????????
  ? amino acid ????? polypeptide ????????
  ????????????????????????? Denaturation
• ?????????????????????? denaturation ????
  ?????????????????????????????? ????????
  Renaturation

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A chaperonin in action
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X-ray crystallography
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• ????????????????
• ??????????????????????????????????????? oganelles
• ???????????????????????????????? ???? keratin
  ????????????????? ???? ?? ???????
• Haemoglobin ??????????????????????
• Hormones ????? ?????????????????????????????????
• Acin ??? myosin ???????????? ?????????????????????
  ??????????
• Enzymes ??????????????????????????????????????
• ???

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Nucleic acid (Informational polymer)
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1. Nucleic acid ??????????????????????????????????
???????????????????????????

• Nucleic acid ?? 2 ???? ??????
• Ribonucleic acid (RNA)
• Deoxyribonucleic acid (DNA)

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DNA ??????????????????????????????? mRNA
??????????????????????????????????????????????????
????
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• ??????????????????????????? DNA ?????????????
• ?????????? DNA ???????????????????????????????????
  ??????
• DNA ???????????????????????? ????????????????????
  ???? ??????????????? ???? ???????????????????????
• ??????????????? nucleotide ?? DNA
  ??????????????????????????????????????????????????
  ??
• ??????????????????????????????????????????????????
  ?????????????? nucleotide ????????????????????????
  ???????

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2. ?????? nucleic acid ?????????? polymer ???
nucleotides
????? nucleotide ?????????? 3 ????
?????? Nitrogen base Pentose sugar Phosphate
group
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Nitrogen base ??????????? 2 ?????
??????????????????? ??????
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?? DNA ??? RNA ????????? 4 ???????????? DNA
????? A, G, C, T RNA ????? A, G, C, U
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?????? pentose ?? RNA ??? ribose ?? DNA ???
deoxyribose
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????????????????????????? 5 (5) ?????????
pentose ?????? phosphate group ????? ????????
pentose nitrogen base phosphate group ???
nucleotide
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The components of nucleic acids
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• Nucleotide ????????????????????????? ????????????
  polynucleotide ????????? phosphate ??? pentose
  ?????????????????? ??? nitrogen base
  ?????????????????????? nucleic acid
• Bond ????????????????????? nucleotide 2 ???????
  ???????? Phosphodiester linkage

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• ???????? nitrogen base ????? DNA ???? mRNA
  ????????????????
• ???????? base ??????????????????????????? amino
  acid ??? polypeptide ?????????

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3. ?????????????????????????????????????
????????? DNA ????????????????

• RNA ????????????? polynucleotide ?????????????
• DNA ????????????? polynucleotide 2
  ?????????????????? ????????????????????????
  ???????? double helix

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• ????????????? DNA ???????????????????????? ???
  ???????? 5 ??? DNA ????????????????????????????
  3 ?????????????? ???????????????? H-bond ???????
  A ??? T ??? G ??? C (??????)
• ?????????????????????? base ???????? complementary

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The DNA double helix and its replication
???????????????????????? DNA ?????????????
??????????????????????????? ???????? DNA
??????????? ???????? DNA replication
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????????????????????????????????????????????
nucleotide ?????????????????????????????????????
?????????????????????????????????????
???????????????????????????????????????????????