Molecular Cell Biology e-book

Department of Molecular Biology Prof. Ho Sung Kang

1. Molecular Cell Biology (7th ed) Lodish et al. (2012)/(5th and 6th ed) 2. Molecular Biology of the Cell (6th ed) Alberts et al. (2014)/(4th and 5th ed)

Cell Biology 1. The cell and subcellular organelles 2. Protein structure and function 3. Membrane structure and transport 4. Nerve cells 5. Protein sorting and vesicular trafficking Molecular Physiology 1. Cell signaling 2. Integrating cells into tissues: cell adhesion, junction and extracellular matrix 3. Cytoskeleton 4. Cell cycle and death 5. Cancer

MCB e-book 한글판 에 대한 소개 Molecular Cell Biology (MCB, Lodish et al.. 7th ed)은 세포생물학 분야에서 좋은 책으로 정평이 나 있으며, 대학교재로 가장 많이 사용되는 책 중 하나입니다. 그러나, MCB는 전공 때문에 어려운데다 영어로 되어 있으니 한국 학생들이 무척 힘들어 합니다. 그리고, MCB 내용이 많다 보니 학부 학생들이 이해하기에 다소 어렵게 쓰여진 부분도 있습니다. 뿐만 아니라, paper book이다 보니 학 생 들 에 게 필 요 한 새 로 운 세 포 생 물 학 적 정 보 를 소 개 하 지 못 하 고 있 습 니 다 . 이러한 문제를 해결하기 위하여 한글판 e-book을 만들었습니다.

한글판 e-book은 MCB 내용을 기본 틀로 하여,

1) 학생들이 공부하는데 도움이 되도록 한글본과 영어 원본을 같이 첨부하였습니다. 2) MCB 내용 중 어려운 부분을 정리 하여 학생들의 이해력을 높이고자 하였습니다 (well-organized). 3) 학부학생들도 반드시 알아야 할 새로운 세포생물학적 정보를 포함시키고, MCB 책에서 발견된 잘못된 부분은 바로 잡았습니다. 4) 또한 공부하는데 도움이 되는 인터넷 사이트를 첨가하는 등 e-book의 장점을 최대한 활용하였습니다.

한글판 e-book은 크게 2 part로 나누어 집니다. part I 세포소기관의 기능 및 상호작용 (e1-e9), part II 세포사이의 communication (e10-20)을 다룹니다. 한글판 e-book은 "세포생물학" 카페에 탑재되어 있습니다. 세포생물학: http://cafe.daum.net/mcb3361 카페는 전국 모든 학생들(학부생, 대학원생)에게 open합니다. ① 아이디는 "학번 이름" (20160222 홍길동)으로 하고, 카페 가입 신청 시 가입 질문에 "학과(혹은 전공)"를 기입하기 바랍니다. 카페 가입하기: 왼쪽 메뉴창에 카페 가입하기를 클릭하여 가입을 진행하기 바랍니다. ② 혹시 학생이 아닌 분 중에서 관심이 있는 분은 카페 "비공개댓글" 게시판에 가입의사를 남기면 가입할 수 있도록 조치를 취할 것입니다.

Lodish • Berk • Kaiser • Krieger • scott • Bretscher • Ploegh • Matsudaira

MOLECULAR CELL BIOLOGY SEVENTH EDITION

CHAPTER 1 Molecules, Cells, and Evolution

Copyright © 2013 by W. H. Freeman and Company

1

細胞 (cell): 生命 현상의 構造的, 機能的 基本單位

Cells Organisms contain organs, organs are composed of tissues, tissues consist of cells, and cells are formed from molecules. (Figure 1-1, 6th ed)

Figure 1.12 Eukaryotic cells have a complex internal structure with many membrane-limited organelles.

Figure 1.11 Prokaryotic cells are have a relatively simple structure.

Prokaryotic and eukaryotic cells The biological universe consists of two types of cells—prokaryotic (Figure 1-11) and eukaryotic (Figure 1-12).

Procaryotes Eucaryotes

Subcellular organelle

- +

DNA circular DNA in cytosol long linear DNA with intron in nucleus

Protein synthesis mRNA and protein synthesis in cytosol RNA synthesis and processing in nucleus proteins synthesis in cytosol

Cytoskeleton no cytoskeleton cytoskeleton

Ribosome 50S+30S 60S+40S

Figure 4.22 Prokaryotic and eukaryotic ribosome components.

Figure 1.9 The information coded in DNA is converted into the amino acid sequences of proteins by a multistep process.

Figure 1.14 The three types of cytoskeletal filaments have characteristic distributions within mammalian cells.

Differences between prokaryotic and eukaryotic cells 1. Prokaryotic cells such as bacteria consist of a single closed compartment that is surrounded by the plasma membrane, lack a defined nucleus, and have a relatively simple internal organization. Eukaryotic cells, unlike prokaryotic cells, contain a defined membrane-bound nucleus and extensive internal membranes that enclose the organelles. 2. In most prokaryotic cells, most or all of the genetic information resides in a single circular DNA molecules about a millimeter in length; this molecule lies, folded back on itself many times, in the central region of the micrometer-sized cell. In contrast, DNA in the nuclei of eukaryotic cells is distributed among multiple long linear structures called chromosomes. 3. In eukaryotic cells, the initial RNA product is processed into a smaller messenger RNA (mRNA) molecule, which moves to the cytoplasm. Here the ribosome, an enormously complex molecular machine composed of both RNA and protein, carries out the second process, called translation. (Figure 1-9) 4. The cytoplasm of eukaryotic cells contains an array of fibrous proteins collectively called the cytoskeleton. (Figure 1-14) 5. The lengths of the rRNA molecules, the quantity of proteins in each subunit, and consequently the sizes of the subunits differ in bacterial and eukaryotic cells. The assembled ribosome is 70S in bacteria and 80S in vertebrates. (Figure 4-22)

I. Procaryotes (원핵세포): eubacteria와 archaebacteria

Two kinds of prokaryotes: true bacteria and archaea In recent years, detailed analysis of the DNA sequences from a variety of prokaryotic organisms has revealed two distinct kingdoms: the eubacteria, often simply called “bacteria,” and the archaea. Although all organisms in the eubacterial and archaean lineages are prokaryotes, archaea are more similar to eukaryotes than to eubacteria (“true” bacteria) in some respects. (Figure 1-3, 6th ed)

II. Eucaryotes (진핵세포) 細胞內小器官 (subcellular organelle): 세포내 특수기능을 담당하는 膜성 구조물

Figure 1.12 Eukaryotic cells have a complex internal structure with many membrane-limited organelles.

Eucaryotes A single membrane (the plasma membrane) surrounds the cell and the cell interior contains many membrane-limited compartments, or organelles. Unlike prokaryotic cells, most eukaryotic cells (the human red blood cell is an exception) also contain extensive internal membranes that enclose specific subcellular compartments, the organelles, and separate them from the rest of the cytoplasm, the region of the cell lying outside the nucleus. Each type of organelle contains a collection of specific proteins, including enzymes that catalyze requisite chemical reactions. (Figure 1-12)

Figure 9.32 Schematic overview of a “typical” animal cell (top) and plant cell (bottom) and their major substructures.

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Intracellular structures The cell is in a dynamic flux. In the light microscope, a live cell exhibits myriad movements ranging from the translocation of chromosomes and vesicles to the changes in shape associated with cell crawling and swimming. Investigation of intracellular structures begins with micrographs of fixed, sectioned cells in which all cell movements are frozen. Such static pictures of the cell reveal the organization of the cytoplasm into compartments and the stereotypic location of each type of organelle within the cell. In this section, we describe the basic structures and functions of the major organelles in animal and plant cells. Plant and fungal cells contain most of the organelles found in an animal cell but lack lysosomes. Instead, they contain a large central vacuole that subserves many of the functions of a lysosome. A plant cell also contains chloroplasts, and its membrane is strengthened by a rigid cell wall. Those organelles bounded by a single membrane are covered first, followed by the three types that have a double membrane— the nucleus, mitochondrion, and chloroplast.

Organelles Structure Function Nucleus (핵) 이중막(핵막), 핵공 유전정보(DNA) Mitochondria (미토콘드리아) 이중막 DNA, ATP 생성, endosymbiosis Chloroplast (엽록체) 이중막 DNA, 광합성, endosymbiosis Endoplasmic reticulum (소포체) Rough ER (조면소포체) 리보솜 부착 막성/분비성 단백질 합성 Smooth ER (활면 소포체) 탄수화물, 지질, 스테로이드 합성 저장 Golgi complex (골지체) 조면소포체에서 합성된 단백질의 변형 및 분비 Endosome endocytosis Vesicle (소낭) secretory/transport vesicle Lysosome (리소좀) 세포내 물질 및 소기관 분해, autophagy Peroxisome catalase long/branched fatty acids의 catabolism Vacuole 식물 H2O, 노폐물/영양물질, tugor pressure, acidic pH Cell membrane (세포막) lipid bilayer barrier & selective permeability Cell wall 식물, cellulose Cytoplasm (세포질) Cytoskeleton (세포내골격) actin filament, microtubule, intermediate filament Centrosome Ribosome (리보좀) 단백질 합성기구

Organelles 1. Nucleus : Double membrane surrounding the chromosomes and the nucleolus. 2. Mitochondria : Surrounded by a double membrane with a series of folds called cristae. Functions in energy production

through metabolism. 3. Chloroplasts (plastids) : Surrounded by a double membrane, containing stacked thylakoid membranes. Responsible

for photosynthesis, the trapping of light energy for the synthesis of sugars.

4. Rough endoplasmic reticulum (RER) : A network of interconnected membranes forming channels within the cell. Covered with ribosomes (causing the "rough" appearance) which are in the process of synthesizing proteins for secretion or localization in membranes.

5. Smooth endoplasmic reticulum (SER) : A network of interconnected membranes forming channels within the cell. A site for synthesis and metabolism of lipids. Also contains enzymes for detoxifying chemicals including drugs and pesticides.

6. Golgi apparatus : A series of stacked membranes. Vesicles (small membrane surrounded bags) carry materials from the RER to the Golgi apparatus. Vesicles move between the stacks while the proteins are "processed" to a mature form. Vesicles then carry newly formed membrane and secreted proteins to their final destinations including secretion or membrane localization.

7. Lysosymes : A membrane bound organelle that is responsible for degrading proteins and membranes in the cell, and also helps degrade materials ingested by the cell.

8. Peroxisomes : Produce and degrade hydrogen peroxide, a toxic compound that can be produced during metabolism. 9. Vacuoles : Membrane surrounded "bags" that contain water and storage materials in plants.

10.Plasma Membrane : A lipid/protein/carbohydrate complex, providing a barrier and containing transport and signaling

systems. 11.Cell wall : Plants have a rigid cell wall in addition to their cell membranes.

12.Centrosome : In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center

(MTOC) of the animal cell as well as a regulator of cell-cycle progression. 13.Ribosomes : Protein and RNA complex responsible for protein synthesis.

Figure 12-1 Molecular Biology of the Cell (© Garland Science 2008)

Figure 12-8 Molecular Biology of the Cell (© Garland Science 2008)

Nucleus

Nucleus The defining characteristic of eukaryotic cells is segregation of the cellular DNA within a defined nucleus, which is bounded by a double membrane. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression—the nucleus is, therefore, the control center of the cell. (Figure 12-1, 12-8 Molecular Biology of the Cell)

Figure 6.1 Overview of the structure of genes and chromosomes.

The structure of genes and chromosomes DNA of higher eukaryotes consists of unique and repeated sequence. Only ~1.5 percent of human DNA encodes proteins and functional RNAs and the regulatory sequences that control their expression; the remainder is merely spacer DNA between genes and introns within genes. Much of the DNA, ~45 percent in humans, is derived from mobile DNA elements, genetic symbiotes that have contributed to the evolution of contemporary genomes. Each chromosome consists of a single, long molecule of DNA up to ~280 Mb in humans, organized into increasing levels of condensation by the histone and nonhistone proteins with which it is intricately complexed. Much smaller DNA molecules are localized in mitochondria and chloroplasts.

Figure 1.9 The information coded in DNA is converted into the amino acid sequences of proteins by a multistep process.

Figure 4.1 Overview of four basic molecular genetic processes.

We discuss the basic process summarized in Figure 4-1: transcription of DNA into RNA precursors, processing of these precursors to make functional RNA molecules, translation of mRNAs into proteins, and the replication of DNA. During transcription of a protein-coding gene by RNA polymerase (1), the four-base DNA code specifying the amino acid sequence of a protein is copied, or transcribed, into a precursor messenger RNA (pre-mRNA) by the polymerization of ribonucleoside triphosphate monomers (rNTPs). Removal of noncoding sequences and other modifications to the pre-mRNA (2), collectively known as RNA processing, produce a functional mRNA, which is transported to the cytoplasm. During translation (3), the four-base code of the mRNA is decoded into the 20-amino acid language of proteins. Ribosomes, the macromolecular machines that translate the mRNA code, are composed of two subunits assembled in the nucleolus from ribosomal RNAs (rRNAs) and multple proteins (left). After transport to the cytoplasm, ribosomal subunits associate with an mRNA and carry out protein synthesis with the help of transfer RNAs (tRNAs) and various translation factors. During DNA replication (4), which occurs only in cells preparing to divide, deoxyribonucleoside triphosphate monomers (dNTPs) are polymerized to yield two identical copies of each chromosomal DNA molecule. Each daughter cell receives one of the identical copies.

Basic molecular genetic processes Cells use two processes in series to convert the coded information in DNA into proteins (Figure 1-9). In the first, called transcription, the coding region of a gene is copied into a single-stranded ribonucleic acid (RNA) whose sequence is the same as one of the two in the double-stranded DNA. A large enzyme, RNA polymerase, catalyzes the linkage of nucleotides into an RNA chain using DNA as a template. In eukaryotic cells, the initial RNA product is processed into a smaller messenger RNA (mRNA) molecule, which moves out of the nucleus to the cytoplasm. Here the ribosome, an enormously complex molecular machine composed of both RNA and protein, carries out the second process, called translation. During translation, the ribosome assembles and links together amino acids in the precise order dictated by the mRNA sequence according to the nearly universal genetic code.

Figure 12-20 Molecular Biology of the Cell (© Garland Science 2008)

Nucleus disassembly When a nucleus disassembles during mitosis, the nuclear lamina depolymerizes. The disassembly is at least partly a consequence of direct phosphorylation of the nuclear lamins by the cyclin-dependent kinase activated at the onset of mitosis (discussed in Chapter 17). At the same time, proteins of the inner nuclear membrane are phosphorylated, and the nuclear pore complexes disassemble and disperse in the cytosol. Nuclear envelope membrane proteins—no longer tethered to the pore complexes, lamina, or chromatin—diffuse throughout the ER membrane. Together, these events break down the barriers that normally separate the nucleus and cytosol, and these nuclear proteins that are not bound to membranes or chromosomes intermix completely with the cytosol of the dividing cell (Figure 12-21). (http://www.ncbi.nlm.nih.gov/books/NBK26932/#A2172)

Figure 12-5 Molecular Biology of the Cell (© Garland Science 2008)

ER, Golgi, lysosome, vesicle and endosome: exocytosis and endocytosis

3

Figure 12-1 Molecular Biology of the Cell (© Garland Science 2008)

Figure 9.33ab Examples of organelles viewed by transmission electron microscopy of thin sections.

Experimental Figure 14.15 Electron micrograph of the Golgi complex in an exocrine pancreatic cell reveals secretory and retrograde transport vesicles.

Endoplasmic reticulum and Golgi complex The outer nuclear membrane is continuous with the rough endoplasmic reticulum, a factory for assembling proteins. Golgi vesicles process and modify proteins, mitochondria generate energy, lysosomes digest cell materials to recycle them, peroxisomes process molecules using oxygen, and secretory vesicles carry cell materials to the surface to release them. Each organelle membrane and each space in the interior of an organelle has a unique set of proteins that enable it to carry out its specific functions. (Figure 12-1 Molecular Biology of the Cell) Proteins to be secreted from the cell and most membrane proteins, in contrast, are made on ribosomes associated with the endoplasmic reticulum (ER). This organelle produces, processes, and ships out both proteins and lipids. Most protein chains produced on the ER move to the Golgi complex, where they are further modified before being forwarded to their final destinations. (Figure 12-5 Molecular Biology of the Cell, Experimental Figure 14-15)

Ribosome

Figure 4.17 The three roles of RNA in protein synthesis

Ribosome Messsenger RNA (mRNA) is translated into protein by the joint action of transfer RNA (tRNA) and the ribosome, which is composed of numerous proteins and three (bacterial) or four (eukaryotic) ribosomal RNA (rRNA) molecules. Note the base pairing between tRNA anticodons and complementary codons in the mRNA. Formation of a peptide bond between the amino-group N on the incoming amino acid-tRNA and the carboxyl-terminal C on the growing protein chain is catalyzed by one of the rRNAs.

Figure 13-36 Molecular Biology of the Cell (© Garland Science 2008)

Figure 13-42 Molecular Biology of the Cell (© Garland Science 2008)

Lysosome

Lysosome A lysosome is a membrane-bound cell organelle found in most animal cells (they are absent in red blood cells). Structurally and chemically, they are spherical vesicles containing hydrolytic enzymes capable of breaking down virtually all kinds of biomolecules, including proteins, nucleic acids, carbohydrates, lipids, and cellular debris. Lysosomes are cellular organelles that contain acid hydrolase enzymes that break down waste materials and cellular debris. They can be described as the stomach of the cell. Lysosomes digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. The membrane around a lysosome allows the digestive enzymes to work at the pH they require. Lysosomes fuse with autophagic vacuoles (phagosomes) and dispense their enzymes into the autophagic vacuoles, digesting their contents. They are frequently nicknamed "suicide bags" or "suicide sacs" by cell biologists due to their autolysis. (Figure 13-42 Molecular Biology of the Cell)

Molecular Biology of the Cell (3rd ed)

Cell wall, plastid and vacuole in plants and fungi Cells of plants and fungi have cell wall, plastid and vacuole. Plants and fungi contains a vacuole that also has a low-pH interior and stores certain salts and nutrients. The rigid cell wall, composed of cellulose and other polymers, that surrounds plant cells contributes to their strength and rigidity. (Molecular Biology of the Cell)

Figure 12-21 Molecular Biology of the Cell (© Garland Science 2008)

4

Figure 9.33cd Examples of organelles viewed by transmission electron microscopy of thin sections.

Mitochondria and chloroplasts In animal and plant cells, most ATP is produced by large multiprotein “molecular machines” located in the organelles termed mitochondria. Plants carry out photoshynthesis in chloroplasts, organelles that contain molecular machines for synthesizing ATP from ADP and phosphate, similar to those found in mitochondria. Both mitochondria and chloroplasts contain small genomes that encode a few of the essential organelle proteins; the sequences of these DNAs reveal their bacterial origins (Figure 12-21 Molecular Biology of the Cell, Figure 9-33cd).

The major function of mitochondria is ATP production

Figure 1.5 Adenosine triphosphate (ATP) is the most common molecule used by cells to capture and transfer energy.

Figure 12.8 Summary of aerobic oxidation of glucose and fatty acids.

Figure 2.31 Hydrolysis of adenosine triphosphate (ATP).

The major function of mitochondria is ATP production: "powerhouse of the cell" (Philip Siekevitz, 1957) 1. In eukaryotic cells, aerobic oxidation is carried out by mitochondria (stages II-IV). In effect, mitochondria are ATP-generating factories, taking full advantage of this plentiful oxygen (Figure 12-8). 2. An important and universally conserved small molecule is adenosine triphosphate (ATP), which stores readily available chemical energy in two of its chemical bonds. When one of these energy-rich bonds in ATP is broken, forming ADP (adenosine diphosphate), the released energy can be harnessed to power an energy-requiring process such as muscle contraction or protein biosynthesis. The useful energy in an ATP molecule is contained in phosphoanhydride bonds, which are covalent bonds formed from the condensation of two molecules of phosphate by the loss of water. In these reactions, Pi stands for inorganic phosphate (PO4

3-) and PPi for inorganic pyrophosphate, two phosphate groups linked by a phosphodiester bond. As the top two reactions show, the removal of a phosphate or a pyrophosphate group from ATP leaves adenosine diphosphate (ADP) or adenosine monophosphate (AMP), respectively (Figure 1-5, 2-31).

Mitochondria produce reactive oxygen species (ROS)

O2- (superoxide)

H2O2 (hydrogen peroxide)

OH.

(hydroxyl radical)

superoxide dismurtase (SOD)

H2O

Fenton reaction (Cu, Fe)

catalase

Figure 12.8 Summary of aerobic oxidation of glucose and fatty acids.

Int J Biochem Cell Biol. (2007) 39(1):44-84

Mitochondria produce reactive oxygen species (ROS) 1. About 1-2 percent of the oxygen metabolized by aerobic organisms, rather than being

converted to water, is partially reduced to the superoxide anion radical (O2∙-, where the “dot”

represents an unpaired electron). Superoxide and other highly reactive oxygen-containing molecules, both radicals (e.g., O2

∙-) and non-radicals (hydrogen peroxide, H2O2) are called reactive oxygen species (ROS). ROS are of great interest because they can react with and thus damage many key biological molecules, including lipids (particularly unsaturated fatty acids and their derivatives), proteins, and DNA, and thus severely interfere with their normal functions. At moderate to high levels, ROS contribute to what is often called cellular oxidative stress and can be highly toxic. Although there are several mechanisms for generating ROS in cells, the major source in eukaryotic cells is electron transport in the mitochondria (or in chloroplasts as described below). Electrons passing through the mitochondrial electron transport chain can have sufficient energy to reduce molecular oxygen (O2) to form superoxide anions. Mitochondria have evolved several defense mechanisms that help protect against O2

∙- toxicity, including the use of enzymes that inactive superoxide, first by converting it to H2O2 (Mn-containing superoxide dismutase, SOD) and then to H2O (catalase). Hydrogen peroxide itself is a ROS that can diffuse readily across membranes and react with molecules throughout the cell. It can also be converted by certain metals such as Fe2+ into the even more dangerous hydroxyl radical (OH∙) (Figure 12-8).

2. The dose-dependent effect of relationship between level of oxidative stress and the tumour promotion process, process of mutagenesis and the process of apoptosis/necrosis. ROS-induced DNA damage involves single- or double-stranded DNA breaks, purine, pyrimidine, or deoxyribose modifications, and DNA cross-links. DNA damage, mutations, and altered gene expression are thus all key players in the process of carcinogenesis. The involvement of oxidants appears to be the common denominator to all these events. The role of oxidative stress at various stages of carcinogenic process and the process of apoptosis are outlined in the Fig. 3 (Int J Biochem Cell Biol. (2007) 39(1):44-84).

Mitochondria play an important role(s) in apoptosis

Figure 21.33 Evolutionary conservation of apoptosis pathways

Figure 21.30 Ultrastructural features of cell death by apoptosis.

Mitochondria play an important role(s) in apoptosis 1. The demise of cells by programmed cell death is marked by a well-defined sequence of morphological changes, collectively referred to as apoptosis, a Greek word that means “dropping off” or “falling off,” as leaves from a tree. Dying cells shrink, condense, and then fragment, releasing small membrane-bound apoptotic bodies, which generally are then engulfed by other cells. In dying cells, nuclei condense and the DNA is fragmented (Figure 21-30). 2. Mitochondria play a central role in many other metabolic tasks, such as apoptosis-programmed cell death, Calcium signaling (including calcium-evoked apoptosis). ① Apoptotic proteins that target mitochondria affect them in different ways. They may cause

mitochondrial swelling through the formation of membrane pores, or they may increase the permeability of the mitochondrial membrane and cause apoptotic effectors to leak out. Cytochrome c is released from mitochondria due to formation of a channel, the mitochondrial apoptosis-induced channel (MAC), in the outer mitochondrial membrane, and serves a regulatory function as it precedes morphological change associated with apoptosis. Once cytochrome c is released it binds with Apoptotic protease activating factor-1 (Apaf-1) and ATP, which then bind to pro-caspase-9 to create a protein complex known as an apoptosome. The apoptosome cleaves the pro-caspase to its active form ofcaspase-9, which in turn activates the effector caspase-3 (Figure 21-33, Wikipedia)

② The concentrations of free calcium in the cell can regulate an array of reactions and is important for signal transduction in the cell. Mitochondria can transiently store calcium, a contributing process for the cell's homeostasis of calcium. Ca2+ signaling in the mitochondria passes a certain threshold, it stimulates the intrinsic pathway of apoptosis in part by collapsing the mitochondrial membrane potential required for metabolism (Wikipedia).

Mitochondria: a bacteria-like life inside eucaryotic cells

Figure 12.6 Internal structure of a mitochondrion.

Molecular Cell Biology (5th ed)

Figure 12.25 Endosymbiont hypothesis for the evolutionary origin of mitochondria and chloroplasts.

Molecular Biology of the Cell (5th ed)

Endosymbiosis

Figure 1.1 All living organisms descended from a common ancestral cell.

Endosymbiosis (내공생설) These commonalities between mitochondria, chloroplasts, and bacteria undoubtedly have an evolutionary origin. In bacteria both photosynthesis and oxidative phosphorylation occur on the plasma membrane. Analysis of the sequences and transcription of mitochondrial and chloroplast DNAs has given rise to the popular hypothesis that these organelles arose early in the evolution of eukaryotic cells by endocytosis of bacteria capable of oxidative phosphorylation or photosynthesis, respectively (Figure 12-6, Figure 10-37 5th ed). According to this endosymbiont hypothesis, the inner mitochondrial membrane would be derived from the bacterial plasma membrane with the globular F1 domain still on its cytosolic face pointing toward the matrix space of the mitochondrion. Similarly, the globular F1 domain would be on the cytosolic face of the thylakoid membrane facing the stromal space of the chloroplast (Figure 12-25, Figure 1-1).

The origin of the cell: molecular evolution

RNA in evolution (2010) John Wiley & Sons, Ltd. Vol 1

46억년전 - 40억년전 - 36억년전 - 30억년전 - 20억년전 - 10억년전 (지구생성) (유기물질합성) (원시세포출현) (광합성박테리아) ( 진핵세포) (다세포생물체)

O2 발생 → endosymbiosis

화학진화/분자진화

Figure 6-98 Molecular Biology of the Cell (© Garland Science 2008)

생물진화

화학진화 1) 1938년 소련의 과학자 Oparin 2) 1958년 Urey와 Miller (원시지구모형실험) - 생명체가 없는 상태에서 생명분자 생성 가능

in the absence of O2

Purves et al., Life 7th ed (2004)

Which is the first molecule for life? RNA : Genetic information and enzymatic activity

Figure 2.16 Common structure of nucleotides.

RNA enzyme (Ribozyme)

Figure 8.8 Two transesterification reactions that result in splicing of exons in pre-mRNA.

Figure 8.41 Splicing mechanisms in group I and group II self-splicing introns and spliceosome-catalyzed splicing of pre-mRNA.

Figure 6-110 Molecular Biology of the Cell (© Garland Science 2008)

1. RNA world RNA: not versatile than protein enzyme more labile than DNA genetic information - DNA enzyme - proteins

2. RNP world 1) 단백질 합성기구 확립 2) DNA 합성 3. DNA World - DNA-RNA-protein system 확립 - Roles of RNA in DNA world 1) mRNA, tRNA, rRNA/protein synthesis 2_ RNA enzyme

Molecular evolution

Molecular fossil for RNA and RNP world

1) RNA enzyme (ribozyme): self-splicing group I and group II introns 2) Coenzymes: nucleotides or compounds that could be derived from nucleotides

3) Histidine An unusual biosynthetic pathway that begins with phosphoribosyl pyrophosphate and ATP The functional imidazole moiety may be evolved from a purine base within an RNA enzyme.

UN Figure 2.2

4) Peptidyl transferase

Table 6-5 Molecular Biology of the Cell (© Garland Science 2008)