생물공학 기초 1 : 생화학

Molecular Components of Cells

Chemical composition C, H, N, O and small amount of other elements

Molecular building blocks Lipids Carbohydrates Proteins Nucleic acid

• DNA (deoxyribonucleic acid)• RNA (ribonucleic acid)

Subunits of Biological Molecules

Class of Molecules Examples Repeating Unit

Lipid Fats, oils -

Carbohydrate Sugars, starch, cellulose

Monosaccharide

Nucleic acid DNA, RNA Nucleotide

Proteins Enzymes, Antibody

Amino acids

Lipids

Hydrophobic fats, oils (liquid fats), and cholesterol etc. High energy C-H, C-C bonds good energy storage Fats : glycerol + fatty acids

Triglyceride

Lipid

Fatty acid Saturated: tight packing viscous, solid at room temperature Unsaturated: more than one cis-double bond liquid

Phospholipid Glycerol backbone, major cell membrane

two fatty acids (hydrophobic)+ phosphate (hydrophilic)

Energy storage

Lipid : ester bond (-COO-) 나이 들면 살찌는 / 배 나오는 이유 ? 미생물도 에너지 저장 : PHB polyester

* PHB : poly hydroxy butyrate

* biodegradable

* polyester fiber ( 예 :TPA+MA) 와의 차이 ?

FAME(fatty acid methyl ester) : biodiesel

Lipids

Sterols : 식물 ( 예 : 콩 ) 에 많음 Cyclic hydrocarbon compounds Cholesterol( sterol lipid) * Component of animal cell membranes

– Increase membrane fluidity• Starting material for steroid hormones and bile synthesis• (steroid: 부신피질호르몬 )- 피부연고제 , 근육강화 , J.F.Kennedy

Vitamins Vitamin A, D, E, K

Carbohydrates

C:H:O = 1:2:1 Simple sugars (monosaccharide)

Glucoes, fructose, galactose

Disaccharide Simple sugars linked by glycosidic bond Sucrose (glucose+fructose), Lactose (glucose+galactose),

Maltose (glucose +glucose)

Carbohydrates

Polysaccharide Starch, Glycogen, cellulose from glucose Agar, carragreenan (thickener)

Roles of Carbohydrates

Carbohydrates in energy metabolism Plant

• Glucose synthesis by photosynthesis

6CO2 + 6H2O + energy C6H12O6 + 6O2

• Starch for energy storage, cellulose for structural compound Animals

• Intake glucose from food• Glycogen for energy storage

Carbohydrates in molecular recognition Cellular recognition, cell

signaling, cell adhesion e.g. blood typing : sugar chains

in the membrane of RBC

Proteins

Roles of proteins Most of the cellular functions

• Enzymes : chemical reactions• Receptors : signal transduction• Antibody : recognition of foreign molecules and trigger

immune responses• Transporters : e.g. hemoglobin for oxygen• Structural proteins : keratin (hair and nails), actin and

myosin (muscle)

Diversity of organism• Diversity of organization of proteins within an organism

Proteins

Amino acids Building blocks of proteins Hydrophilic backbone + 20

side chains

Polypeptide Amino acid chains linked by

peptide bond

Tree-dimensional structure Determines protein function Determined by amino acid

sequence

Amino Acids and Primary Structure

Amino acids Amino group Carboxyl group R group; 20 Side

chains

Peptide bond Between NH2 and

COOH

Polypeptide A chain of amino acids N terminus and C

terminus

Amino Acids

Primary and Secondary Structure

Primary structure _______________________________________

Secondary structure Core elements of protein architecture Neutralization of partial charges of the peptide

backbone by hydrogen bonding Local folding of polypeptide chain

• _____________ : 60% of the polypeptide chain• Random coils and U-shaped turn

-Helix

Hydrogen bond between carbony O (n) and amid H (n+4)

Directionality on the helix : The same orientation of H bond donor

Side chains point _______

Determine hydrophobic or hydrophilic quality

-Sheet

Laterally packed strands of 5 to 8 residue

Hydrogen bonding between strands sheet, pleated sheet

Parallel or antiparallel

Tertiary Structure

Tertiary structure Overall folding of a polypeptide chain Stabilization

• weak interaction– Hydrophobic interaction between nonpolar side chains– Hydrogen bond between polar side chains and peptide bonds

• Disulfide bond formation

Quaternary Structure

Association of multiple polypeptide chains Lambda repressor : dimer E. coli RNA polymerase : Five polypeptide chains

Disruption of Protein Structure

Factors disrupting protein sturcture Heat, extreme pH, organic solvent, detergent

Denaturation Complete unfolding of amino acid chain Sometimes irreversible : e.g. boiled egg Melting temperature (Tm)

• Denaturation temperature for a given protein• Depending on protein structure

– Proteins from organisms living in thermal vents

Examples of Protein Structure and Function

Keratin Structural protein for hair, wool,

feathers, nails, scales, hooves, horns, skin

Very strong and water insoluble• Hydrophobic alpha helices

– Long -helix with hydrophobic amino acids (A, I, V, M, F)

– Forming fibers by hydrophobic interactions

• Disulfide bonds– The more S-S bonds the

harder the structure– Permanent wave

» Reducing of disulfide bond Generation of new disulfide bond

Protein Engineering

Manipulation of protein’s amino acid sequence to change its function or properties

Chemical manufacturing Develop enzymes more suitable for industrial

applications Increasing enzyme stability

• e.g. bacteriophage lysozyme: introduce S-S bond to increase heat resistance

• Proteases in detergent

Nucleic acids

Nucleotides Building blocks of nucleic acids (deoxy)ribose + phosphate group +

4 bases Bases: adenine (A), guanine (G),

cytosine (C), thymine (T)

Terminology Base Nucleoside : Nucleotide :

Primary Structure : Nucleotides

H

Adenine

Guanine

Cytosine

Thymine (D)

Uracil (R)

RNA DNA

Base

2’-Deoxyribose

Nucleoside

Adenosine

Guanosine

Cytidine

Thymidine

Uridine

Nucleotide

Adenylate

Guanylate

Cytidylate

Thymidylate

Uridylate

Purine

Pyrimidine

Nucleotide Chains

Base pairing C=G, T=A : hydrogen

bonding Complementary base pairs Antipararallel strand in

DNA molecule

Chromosome

Tightly packed complex of DNA and _____ proteins

DNA Replication

Synthesis of a complementary strand using the other strand as a template

_____________

Expression of Genetic Information

Replication

Transcription

DNA

mRNA

Translation

Protein

유전자 조작 ? 단백질 생합성 메커니즘 Gene structure vs function ---