Drug delivery & Tissue engineering Lab Chapter 1. An Overview of Biological Basics.

Drug delivery & Tissue engineering Lab

Chapter 1. An Overview of Biologi-cal Basics

DRUG DELIVERY SYSTEM & TISSUE ENGINEERING

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1. 분자생물학 기초


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The Chemical Nature of Polynucleotides

• Biochemists determined the components of nucleotides during the 1940s

• The component parts of DNA–Nitrogenous bases: • Adenine (A)• Cytosine (C)• Guanine (G)• Thymine (T)

–Phosphoric acid–Deoxyribose sugar

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Nucleotides and Nucleosides

• RNA component parts– Nitrogenous bases• Like DNA except Uracil (U)

replaces Thymine– Phosphoric acid– Ribose sugar

• Bases use ordinary num-bers• Carbons in sugars are

noted as primed numbers•Nucleotides contain phos-

phoric acid (cf. nucleo-sides)


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Purines and Pyrimidines• Adenine and guanine are related structurally to the

parent molecule purine• Cytosine, thymine and uracil resemble pyrimidine

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DNA Linkage• Nucleotides are nucleosides with a phosphate

group attached through a phosphodiester bond• Nucleotides may contain one, two, or even

three phosphate groups linked in a chain

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Trinucleotide

The example trinu-cleotide has polarity– Top of molecule has a

free 5’-phosphate group = 5’ end

– Bottom has a free 3’-hy-droxyl group = 3’ end


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DNA Structure

The Double Helix• Rosalind Franklin’s x-ray data suggested that

DNA had a helical shape• The data also indicated a regular, repeating struc-

ture• DNA was believed to require an irregular se-

quence• Watson and Crick proposed a double helix with

sugar-phosphate backbones on the outside and bases aligned to the interior 2-8


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DNA Helix

• Structure compared to a twisted ladder– Curving sides of the ladder represent the sugar-phosphate

backbone– Ladder rungs are the base pairs– There are about 10 base pairs per turn

• Arrows indicate that the two strands are antipar-allel


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Transcription

http://www.youtube.com/watch?v=teV62zrm2P0


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DNA

Sigma factor

Longer transcriptsShort transcripts

Sigma

RNA

Promoter region Gene(s) to be transcribed(light green strand)

RNA polymerase(core enzyme)

Sigma recognizespromoter andinitiation site

Transcription begins; sigmareleased. RNA chain growthcontinues to termination site

Termination sitereached; chaingrowth stops

Release ofpolymeraseand RNA

1. 분자생물학 기초 - Translation

http://www.youtube.com/watch?v=5bLEDd-PSTQ&feature=related


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Storing Information

2-13

Producing a protein from DNA information involves both transcription and trans-lation– A codon is the 3 base sequence

that determines what amino acid is used

– Template strand is the comple-mentary DNA strand that is used to generate the mRNA

– Nontemplate strand is not used in RNA transcription


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Protein Structure

Proteins are chain-like polymers of small sub-units, amino acids– DNA has 4 different nucleotides– Proteins have 20 different amino acids with:• An amino group• A hydroxyl group• A hydrogen atom• A specific side chain

http://en.wikipedia.org/wiki/File:AminoAcidball.svg


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Polypeptides• Amino acids are joined together via peptide bonds• Chains of amino acids are called polypeptides• Proteins are composed of 1 or more polypeptides• Polypeptides have polarity as does DNA

– Free amino group at one end is the amino- or N-terminus– Free hydroxyl group at the other end is the carboxyl- or C-terminus


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Types of Protein Structure

• Linear order of amino acids is a protein’s primary structure

• Interaction of the amino acids’ amino and carboxyl groups gives

rise to the secondary structure of a protein

– Secondary structure is the result of amino acid and carboxyl

group hydrogen bonding among near neighbors

– Common types of secondary structure:

· -a helix

· -b sheet


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Helical Secondary Structure

• In a-helix secondary structure polypeptide, backbone groups form H bond with each other

• Dashed lines in figure indicate hydrogen bonds between nearby amino acids


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Sheet Secondary Structure

• The b-sheet pattern of 2° structure also occurs when polypeptide backbone groups form H bonds

• In the sheet configuration, extended polypeptide chains are packed side by side

• This side-by-side packing creates a sheet appearance


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Tertiary Structure

• Total three-dimensional shape of a polypeptide is its tertiary structure

• A prominent aspect of this structure is interac-tion of the amino acid side chains

• The globular form of a polypeptide is a roughly spherical structure


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Protein Domains• Compact structural regions of a

protein are referred to as domains • Immunoglobulins provide an ex-

ample of 4 globular domains• Domains may contain common

structural-functional motifs – Zinc finger– Hydrophobic pocket

• Quaternary structure is the inter-action of 2 or more polypeptides

Immunoglobulin


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Protein Function

Proteins:

– Provide the structure that helps give cells in-

tegrity and shape

– Serve as hormones carrying signals from one cell

to another

– Bind and carry substances

– Control the activities of genes

– Serve as enzymes that catalyze hundreds of

chemical reactions


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One-gene / One-polypeptide

• Over time many experiments have built on Gar-

rod’s initial work

• Many enzymes contain more than one polypep-

tide chain and each polypeptide is usually en-

coded in one gene

• These observations have lead to the one gene

one polypeptide hypothesis:

Most genes contain the information for making

one polypeptide


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2. 생물의 다양성

• 온도에 따른 미생물의 분류 - 저온성 미생물 (psychrophiles): 20℃ 이하에서 생장 - 중온성 미생물 (mesophiles): 20 ~30 ℃ ℃ 에서 생장 - 호열성 미생물 (thermophiles): 50 ℃ 이상에서 생장

• 생장 대상에서 산소를 요구하는 여부에 따른 분류 - 호기성 (aerobic): 생장과 대사에 산소 요구 - 협기성 (anaerobic): 산소에 의해 생장이 억제 - 통협기성 (faculative): 호기성과 혐기성 조건에서 모두 자랄 수 있게 대사 경로를 바꿀 수 있음 .

• 모양에 따른 세포들의 분류 - 구균 (coccus): 구형과 타원형 모양 - 간균 (rod) 또는 bacillus: 원통형 모양 - spirillum: 나선형 모양


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• 진핵 세포 (eucaryotic cell) - 복잡한 내부 구조를 가지며 핵 안에 하나 이상의 염색체가 존재함 . - 핵막이 있으며 미토콘드리아 , 소포체 , 골지체와 같은 다양하게 분화된 세포 소기관을 갖고 있음 .

• 원핵세포 (procaryotic cell) - 단일 염색체 (chromosome) 의 단순한 구조로 되어 있고 핵막이 없으며 미토콘드리아나 소포체 같은 세포 소기관이 없음 .


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• 바이러스 - 매우 작으며 세포의 절대 기생체임 . - 200~330nm 수준으로 유전물질로서 DNA 와 RNA 를 가짐 . - 핵물질은 capsid 라는 단백질 껍질로 덮여 있음 . - 어떤 바이러스는 lipoprotein 으로 된 외피를 가지고 있으나 없는 바이러스도 있음 .


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• 바이러스 - Bacteriophage: 박테리아를 감염시키는 바이러스 . • Lytic cycle - 박테리오파지의 핵산은 숙주세포 안에서 복제되어 더 많은 파지를 만들어내고 바이러스 증식의 어떤 단계에서 숙주세포는 용해되거나 터져서 파지입자를 방출하고 이 파지는 다른 숙주세포를 감염시킴 . • Lysogenic cycle - 파지 DNA 가 숙주 DNA 에 꺼이 들어가서 숙주세포와 함께 증식 .


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• 원핵세포 (procaryote) - 반지름 : 0.5 – 3 µm - 구형을 구균 (coccus), 막대기 모양을 간균 (bacillus), 그리고 나선형 모양을 나선균 (spirillium) - 원핵세포는 double time 이 빠르고 탄수화물 , 탄화수소 , 단백질 및 CO2 를 포함한 다양한 물질을 탄소원으로 이 용함 .


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• 진정박테리아 (eubacteria) - 그람 염색법 : 세포벽의 구조의 차이로 인한 염색법 - 그람 음성 세포 : E. Coli 가 전형적인 예로 얇은 펩티도 글리칸 (peptidoglycan) 층에 의해 지지되는 외막을 가 지고 있음 . - 그람 양성 세포 : Bacillus subtillis 가 대표적인 예임 . 외박이 없지만 여러 층의 펩티도클리칸 층으로 된 두껍 고 단단한 세포벽을 지니고 있음 . 세포질 막만 지니기 때문에 음성 세포에 비해 단백질 분비가 용이해서 단백질이 원하는 산물일 때 이러한 분 비력은 기술적인 장점이 됨 .


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• 진핵세포 (eucaryote)


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• 세포주기


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2. 생물의 다양성– 항체


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2. 생물의 다양성– 단당류와 다당류

• 탄수화물 - 세포의 구조 물질과 저장물질로 중요한 역할 . - 동물과 식물에서 화학적 신호 현상을 조절하는 역할 . - 단당류는 가장 작은 탄수화물로 3 – 9 개의 탄소원자를 함유함 . - 알데하이드형과 케톤형


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2. 생물의 다양성– 단당류와 다당류

• 탄수화물 - D-ribose 와 deoxiribose - 5 개의 탄소원자를 갖는 환형 구조의 당분자 . - DNA 와 RNA 의 필수적인 구성 성분 .


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2. 생물의 다양성– 지질 , 지방 스테로이드

• 지질 (Lipid) - 물에 녹지 않는 소수성을 띤 생체물질 . - 벤젠 , 클로로포름 , 에테르와 같은 비극성 용매에 녹음 . - 세포막과 같은 비수성 생체계에 존재함 . - 생체의 연료 저장 역할을 담당 .


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2. 생물의 다양성– 핵산 , RNA, DNA

• 뉴클레오타이드

Drug delivery & Tissue engineering Lab Chapter 1. An Overview of Biological Basics.

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