Section A - Cells and macromolecules 单虫无核原生动物 原生动物 植 物植 物 真 菌真 菌 动 物动 物

Contents Contents A1 Cellular classification Eubacteria, Archea, Eukaryotes, Cellular differentiation EubacteriaArcheaEukaryotesCellular differentiation A2 Subcellular organelles Nuclei, Mitochondria and chloroplasts, Endoplasmic reticulum, Microbodies, Organelle isolation NucleiMitochondria and chloroplastsEndoplasmic reticulum MicrobodiesOrganelle isolation A3 Macromoleculares Protein and nucleic acids, Polysaccharides, Lipids, Complex Macromolecules Protein and nucleic acidsPolysaccharidesLipidsComplex Macromolecules A4 Large macromolecular assemble Protein complex, Nucleoprotein, Membranes, Noncovalent interactionsProtein complexNucleoproteinMembranesNoncovalent interactions

A1 Cellular classification Eubacteria A1 Cellular classification -- Eubacteria The Eubacteria are one of two subdivisions( 亚门 ) of the prokaryotes.The Eubacteria are one of two subdivisions( 亚门 ) of the prokaryotes. Escherichia.coli is the best studied eubacterium.Escherichia.coli is the best studied eubacterium. Prokaryotes are the simplest living cells.Prokaryotes are the simplest living cells. Most prokaryotes are unicellular( 单细胞 ), some, however, are multicellular( 多细胞 ). forms in which certain cells carry out specialized functions.Most prokaryotes are unicellular( 单细胞 ), some, however, are multicellular( 多细胞 ). forms in which certain cells carry out specialized functions.

STRUCTURE Flagella ： Cell movement. Pili ： To allow the cell to attach to other cells and surface. Capsule ： A well organized layer, it can be the cause of various diseases. Cell wall ： To prevent cell lysis in environments of low osmolarity. Plasma membrane: Lipid bilayer and embedded proteins for small molecule exchange. Nucleiod ： Single and circular chromosome. Ribosmes ： protein synthesis machinery

A1 Cellular classification— Archea The Archaea, or Archaebacteris, from the second subdivision of the prokaryotes and tend to inhabit extreme environments. Structurally, they are similar to eubacteria. But their rRNA are similar to eukaryotes (18s rRNA). ( 进化的 )ancestorIt appears that the archaea and the eukaryotes share a common evolutionary ( 进化的 ) ancestor which diverged from the ancestor of the Eubacteria.

A1 Cellular classification— Eukaryotes Eukaryotes are classified taxonomically ( 分类学 ) into four kingdoms comprising animals, plants, fungi, and protists. Cancerous HeLa cells (It can be indefinitely cultured as long as conditions are favorable )

Animal cells Plant cells Cytoskeletal Fiber ： 1. 1.Controls the shape and movement of the cell 2. 2.Organizes some metabolic functions

A1 Cellular classification— Differentiation Cell divides: the daughter cells may be idential in every way. In all but a few exceptional case, the DNA content remains the same, but the genes which are transcriptional have changed. Differentiation is regulated by developmental control genes. In some cases, a highly unequal cell division occurs in mammalian oocytes, resulting in one larger daughter cell than another.

1. 1.Definition: The daughter cells change their patterns of gene expression to become functionally different from the parent cell after cell division The main molecular reason: change of the genes being transcribed, but not that of the DNA content Regulated by developmental control genes, mutations in these genes result in abnormal body plans. Cellular differentiation

For example 1. 1.Spore formation among prokaryotes and lower eukaryotes Embryonic cell differentiate into highly specialized cells among higher eukaryotes. Fig

Cell differentiation in yeast ( 酵母） Mating: n + n  2n Spore formation: 2n  n + n back

Embryonic cell differentiation in Xenopus ( 爪蟾属 ) ： from a single cell to an adult tadpole Differentiation is regulated by developmental control genes

In the center of the diagram are three of the early steps in the development of a mammal. On the top and bottom are some of the fully-differentiated cell types that will eventually form in the adult.

Prokaryotes （原核生物） (Simplest living cells)Eukaryotes （真核生物） Eubacteria （真细菌） Archaea （古细菌） Structural features 1-10  m, no distinct subcellular organelles, pili, flagella  m, Organelles Biochemistry rRNA molecules are different among these kingdoms (rRNA based phylogeny) Ester linkage （酯键） Ether linkage （醚键） Ester linkage （酯键） Energy production, metabolism Replication, transcription and translation DifferentiationFormation of sporesEmbryonic cell differentiation

Phylogenetic tree determined by rRNA sequence comparisons (rRNA 序列比较得到的系统发育树）

A2 Subcellular organelles— Nuclei （细胞核） Bounded by a nuclear membrane having pores connecting it with the endoplasmic reticulum. Contains one or more paired, linear chromosomes composed of deoxyribonucleic acid (DNA) associated with histone proteins. Contain nucleolus.

The cell nucleus is a remarkable organelle because it functions to: 1) Store genes on chromosomes. 2) Organize genes into chromosomes to allow cell division. 3) Transport regulatory factors & gene products via nuclear pores.

Nuclear Envelope Structure-two unit membranes with a fluid-filled space. Two membranes were separated by 10 to 50nm. -nuclear pores present. -outer membrane may be continuous with the endoplasmic reticulum. Function -selectively permeable to control movement in or out. -contains nuclear contents. Average approximately 3000 nuclear pores per cell.

A2 Subcellular organelles— Mitochondria and chloroplasts Mitochondria are the site of cellular respiration where nutrients are oxidized to CO2 and water, and ATP is generated. Photosynthesis takes place in the chloroplasts. Mitochondrion Chloroplast Lighter energy Glucose ATP Chemical energy

A2 Subcellular organelles— Endoplasmic reticulum The endoplasmic reticulum (ER) is repsonible for the production of the protein and lipid components of most of the cell's organelles.

A2 Subcellular organelles— Microbodies A microbody is a cytoplasmic organelle of a more or less globular shape that comprises degradative enzymes bound within a single membrane. Types include lysosomes, peroxisomes, glyoxisomes, glycosomes and Woronin bodies.

A2 Subcellular organelles— Organelle isolation Density gradient centrifugation Rate zonal (velocity) centrifugation Equilibrium centrifugation Differential (speed) centrifugation:

A3 Macromoleculares— Protein and nucleic acids Proteins are polymers of amino acids, and nucleic acids DNA and RNA are polymers of nucleotides.

A3 Macromoleculares— Polysaccharides Polysaccharides are polymers of simple sugars covalently linked by glycosidic bonds

A3 Macromoleculares— Lipids Lipids:Lipids: individual lipids are not strictly macromolecules, large lipid molecules are built up from small monomeric units and involved in many macromolecule assembly.

Phospholipids( 磷脂 ) Cholesterol （胆固醇） Glycolipids （糖脂）

A3 Macromoleculares— Complex macromolecules NucleoproteinsNucleoproteins GlycoproteinsGlycoproteins ProteoglycansProteoglycans Lipid-linked proteinsLipid-linked proteins LipoproteinsLipoproteins GlycolipidsGlycolipids Histone, Chromatin, Telomerase, RNP (RNA/protein complex), and Protamines

Complex macromolecules Covalent or noncovalent associations of more than one major classes of large biomolecules which greatly increases the functionality or structural capabilities of the complex.

A4 Large macromolecular assemble— Protein complexes Cilia and flagella are also composed of microtubules complexed with dynein and nexin. Protein complex microbulemicrofilament intermediate fibre

A4 Large macromolecular assemble— Nucleoprotein Nucleoproteins comprise both nucleic acid and protein. 1.Ribosome: ribosomal proteins ＋ rRNAs 2.Caryotin: deoxyribonucleoprotein consisting of DNA & histones to form a repeating unit called nucleosome 3.Viruses: protein capsid + RNA or DNA 4.Telomerase: replicating the ends of eukaryotic chromosomes. RNA acts as the replication template, and protein catalyzes the reaction 5.Ribonuclease P: tRNA maturation. Protein ＋ P RNA

A4 Large macromolecular assemble— Membranes 1. 1.Membrane Lipid ( Glycolipid, Phospholipid)Membrane Lipid ( Glycolipid, Phospholipid) 2. Membrane proteins ( Integral protein, Transmembrane protein, Peripheral protein, Glycoprotein)

A4 Large macromolecular assemble— Noncovalent interactions Van Der Waals Force; Dispersion forces; Hydrogen Bonds; Ionic bonds ; Hydrophobic interactionsVan Der Waals Force; Dispersion forces; Hydrogen Bonds; Ionic bonds ; Hydrophobic interactions

Charge-charge interactions (salt bridges): charged moleculesCharge-charge interactions (salt bridges): charged molecules Charge-dipole, dipole-dipole: either or both of the participants is a dipole.Charge-dipole, dipole-dipole: either or both of the participants is a dipole. Dispersion interactions: non-poplar moleculeDispersion interactions: non-poplar molecule van der Waals forces: noncovalent associations between uncharged molecules.van der Waals forces: noncovalent associations between uncharged molecules. Hydrogen bonds (dipole-dipole): nucleic acidsHydrogen bonds (dipole-dipole): nucleic acids Hydrophobic interaction: proteinsHydrophobic interaction: proteins

Multiple choice questions 1 ． The glycosylation of secreted proteins takes place in the. A mitochondria. B peroxisomes. C endoplasmic reticulum. D nucleus. 2 ． Which of the following is an example of a nucleoprotein? A keratin. B chromatin. C histone. D proteoglycan.

3 ． Which of the following is not a polysaccharide? A chitin. B amylopectin. C glycosaminoglycan. D glycerol. 4. Transmembrane proteins. A join two lipid bilayers together. B have intra- and extracellular domains. C are contained completely within the membrane. D are easily removed from the membrane.

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