Transcript Complex macromolecules

Chapter 1
Cells and macromolecules
RNA
Protein
DNA
Prokaryotic cell
Eukaryotic cell
Other macromolecules
unrelated to MB course
Polysaccharides
lipids
Complex macromolecules
including these molecules
1.1 Cellular classification (Eubacteria, Archea,
Eukaryotes, Cellular differentiation)
1.2 Subcellular organelles (Nuclei,
mitochondria and chloroplasts, endoplasmic reticulum,
microbodies, organelle isolation)
1.3 Macromolecules (protein and nucleic acids,
polysaccarides, lipids, complex macromolecules)
1.4 Large macromolecular Assemblies
(protein complex, nucleoprotein, membranes,
noncovalent interactions)
1.1 Cellular classification
Classifying organisms according to cell types
Eukaryotic cell
Prokaryotic cell
Prokaryotes （原核生物）
(Simplest living cells)
Eukaryotes
（真核生物）
Eubacteria
Archaea
（真细菌）
（古细菌）
Structural
1-10 mm, no distinct
10-100 mm,
features
subcellular organelles, pili,
Organelles
flagella
rRNA molecules are different among these
kingdoms
Biochemistry
(rRNA based phylogeny, Fig. S2)
Ester linkage Ether linkage
Ester linkage
（酯键）(link) （醚键）
（酯键）
Energy production, metabolism
重点
Differentiatio
n (link)
Replication, transcription and
translation
Formation of spores
Embryonic cell
differentiation
Phylogenetic tree determined by rRNA sequence comparisons
(rRNA序列比较得到的系统发育树）
Fig. S2
重点
(鞭毛)
(类核)
(纤毛)
典型原核细胞示意图
Cell wall: to prevent cell lysis in
environments of low osmolarity
Plasma membrane: lipid bilayer and
embedded proteins for small molecule
exchange
Genetic materials: nucleiod (single and
circular chromosome), plasmid
Ribosmes: protein synthesis machinery
Pili: to allow the cell to attach to other cells
and surface
Flagella: cell movement
重点
典型真核细胞示意图
Cytoskeletal Fiber：
1. Controls the shape and
movement of the cell
2. Organizes some metabolic
functions
Cellular differentiation (细胞分化)
1. Definition: The daughter cells change their
patterns of gene expression to become
functionally different from the parent cell after
cell division.
2. The main molecular reason: change of the
genes being transcribed, but not that of the DNA
content.
3. Regulated by developmental control genes,
mutations in these genes result in abnormal body
plans.
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For example
•Spore formation among prokaryotes and lower
eukaryotes
•Embryonic cell differentiate into highly
specialized cells among higher eukaryotes.
Cell differentiation in yeast (酵母）
Mating: n + n  2n
Spore formation: 2n  n + n
Embryonic cell differentiation in Xenopus (爪蟾属)：from a single
cell to an adult
tadpole
Differentiation is regulated by developmental control genes
Fig. S4
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1.2 Subcellular organelles
•Nuclei
•mitochondria and chloroplasts,
•endoplasmic reticulum,
•microbodies,
•organelle isolation
（核）
DNA replicationRNA transcription & processing
 Ribosome assembly
（线粒体）
Main function: cellular respiration/ATP production via oxidative phosphorylation
DNA replication, RNA transcription, protein synthesis
Nuclear-encoded Mitochonrial proteins: synthesis and transportation
（叶绿体）
A plant specific organelle
（类囊体）
（基粒）
Photosynthesis,
the light-dependent assimilation of
CO2 and H2O to form carbohydrates and O2
DNA replication, RNA transcription, protein synthesis
Nuclear-encoded chloroplast proteins: synthesis and transportation
(内质网)
Protein synthesis
drug oxidation and detoxificatin
（酯类代谢）
（药物的氧化和解毒）
Microbodies (lysosomes, peroxisomes and glycoxysomes)
（溶酶体，过氧化物酶体，醛氧化酶体）
Glyoxysomes are specialized plant peroxisomes which carry
out the reactions of glyoxylate cycle（乙醛酸循环）.
Organelle isolation: centrifugation (离心)
Differential (speed)
centrifugation:
Density gradient centrifugation
Rate zonal (velocity) centrifugation
Equilibrium centrifugation
Sedimentation coefficient (s)
Density gradients: to prevent convective mixing of the components after separation
and to ensure linear sedimentation rates of the components
Supporting materials: sucrose (蔗糖）, Ficoll, cesdium chloride
（氯化铯）
1.3 Macromolecules
Protein (Section B)
Nucleic acids (Section C)
Polysaccharides
MB course (X),
Lipids
Complex macromolecules
Biochemistry ()
Immunology ()
Polysaccharides are polymers of simple sugars covalently
linked by glycosidic bonds.
Lipids: individual lipids are not strictly macromolecules,
large lipid molecules are built up from small monomeric
units and involved in many macromolecule assembly
Triglycerides (甘油三酯)
Complex macromolecules (复合大分子）
Covalent or noncovalent associations of more than one major
classes of large biomolecules which greatly increases the
functionality or structural capabilities of the complex.
Nulceoprotein: nucleic acids + protein (Section A4)
Glycoprotein: carbohydrate + protein
Lipoprotein: Lipid + protein
生物大分子间相互作用的化学力
生物大分子的基本结构是靠共价键结合的，
但是生物学功能的执行是靠生物大分子之
间的相互作用来实现的。如：①蛋白质与
DNA的相互作用；②蛋白质与RNA的相互作
用；②蛋白质与蛋白质的相互作用。
生物大分子间相互作用的化学力
1 扩散作用 (Diffusion)
2 专一性相互作用
结构基序，离子键，氢键，范德华力
生物大分子内部相互作用的化学键
1、共价键 (Covalent bond)：成键原子间通过电子对共享形
成的。键
能一般在200KJ/mol以上。
磷酸二酯键、肽键、二硫键，－S－S－
2、弱键（非共价键 noncovalent bond）：小于20KJ/mol。
（1）氢键 (Hydrogen bond)
（2）盐键（离子键）静电作用力 (Ionic bond)
（3）范德华力（短程力）(Van der Waals force)
（4）疏水作用 (Hydrophobic interaction)
3、配位键一般在250KJ/mol以上
1.4
Large macromolecular Assemblies
Protein complexes
Nucleoprotein
Membranes
Noncovalent interactions
protein complexes
重点
(cilia and flagella)
Long polymers of tubulin
(microfilament)
actin and myosin, components of muscle fibers as well
keratin
Fig.1. Schematic diagram showing the (a)
cross-sectional and (b) surface pattern of
tubulin a and b subunits in a microtubule
Noncovalent interaction
Nulceoprotein (1)
重点
associations of nucleic acids and protein
Ribosome: ribosomal proteins ＋ rRNAs
Crystal structure of 50S rRNA
重点
Nulceoprotein (2)
•Chromatin (染色质): deoxyribonucleoprotein consisting
of DNA & histones to form a repeating unit called nucleosome
•Viruses: protein capsid + RNA or DNA
•Telomerase (端粒酶) : replicating the ends of eukaryotic
chromosomes. RNA acts as the replication template,
and protein catalyzes the reaction
•Ribonuclease P：tRNA maturation. Protein ＋ P RNA
重点
Noncovalent interactions
The force of macromolecule assembly
Charge-charge interactions (salt bridges): charged molecules
Charge-dipole, dipole-dipole: either or both of the
participants is a dipole .
Dispersion interactions: non-poplar molecule
van der Waals forces: noncovalent associations between
uncharged molecules.
*Hydrogen bonds (dipole-dipole): nucleic acids
*Hydrophobic interaction: proteins
(偶极)
(uncharged molecules)