Cells and macromolecules Section A Cells and macromolecules Protein DNA

A1 Cellular classification A2 Subcellular organelles A3 Macromolecules A4 Large macromolecular Assemblies

A1 Cellular classification A1-1 Eubacteria A1-2 Archaea A1-3 Eukaryotes A1-4 Cellular differentiation

Prokaryotes 原核细胞 Eukaryotes 真核细胞 Eubacteria 真细菌 Archaea 古细菌

A1-1 Eubacteria The Eubacteria are one of two subdivisions of the prokaryotes.

A1-1 Eubacteria 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 surfaces Flagella: whose rotating motion allows the cell to swim

A1-1 Eubacteria Escherichia. coli Mycoplasma genitalium E.coli has a genome size of 4600 kb, which is sufficient genetic information for about 3000 proteins. Mycoplasma genitalium It has only 580 kb of DNA and encodes just 470 proteins.

A1-2 Archaea The second subdivision of the prokaryotes Structurally, they are similar to eubacteria The display some unusual biochemical

A1-3 Eukaryotes Eukaryotes are defined by their possession of membrane-enclosed organelles with specialized metabolic function. Eukaryotic cells tend to be larger than prokaryotes. Eukaryotes are classified taxonomically into four kingdoms: animals, plants, fungi and protists.

A1-3 Eukaryotes Organelles Cytoskeleton Genetic system Controls the shape and movement of the cell Organizes some metabolic functions Genetic system

1-10 mm, no distinct subcellular organelles, pili, flagella 10-100 mm, Prokaryotes Eukaryotes Eubacteria Archaea Structural features 1-10 mm, no distinct subcellular organelles, pili, flagella 10-100 mm, Organelles Biochemistry rRNA molecules are different among these kingdoms Ester linkage Ether linkage Energy production, metabolism Replication, transcription and translation Differentiation Formation of spores Embryonic cell differentiation

Phylogenetic tree determined by rRNA sequence comparisons

A1-4 Cellular differentiation 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.

A1-4 Cellular differentiation Spore formation among prokaryotes and lower eukaryotes

A1-4 Cellular differentiation Embryonic cell differentiate into highly specialized cells among higher eukaryotes. tadpole

A2 Subcellular organelles A2-1 Nuclei A2-2 Mitochondria and chloroplasts A2-3 Endoplasmic reticulum A2-4 Microbodies A2-5 Organelle isolation

RNA transcription & processing A2-1 Nuclei Nuclei: The membrance-bound nucleus contains the bulk of the cellular DNA in multiple chromosomes. DNA replication RNA transcription & processing Ribosome assembly

A2-2 Mitochondria Oxidation of nutrients to genetate energy in the form of adenosine 5’-triphosphate(ATP). Main function: cellular respiration/ATP production via oxidative phosphorylation

A2-2 Chloroplasts The chloroplasts of plants are the site of photosynthesis, the light-dependent assimilation of CO2 and water to form carbohydrates and oxygen.

A2-3 Endoplasmic reticulum The endoplasmic reticulum is an extensive membrane system within the cytoplasm and is continuous with the nuclear envelope. Two forms are visible in most cells. Smooth endoplasmic reticulum Rough endoplasmic reticulum

A2-3 Endoplasmic reticulum The rough endoplasmic reticulum is so-called because of the presence of many ribosomes. These ribosomes specifically synthesize proteins intended for secretion by the cell or those destined for the plasma membrane or certain organelles.

A2-3 Endoplasmic reticulum The Smooth endoplasmic reticulum carries many membrane-bound enzymes, including those involved in the biosynthesis of certain lipids and the oxidation and detoxificatin of foreign compounds such as drugs.

A2-4 Microbodies Lysosomes: Contain a variety of digestive enzymes capable of degrading proteins, nucleic acids, lipids and carbohydrates. Peroxisomes: Confine highly reactive free radicals and hydrogen peroxide. Glyoxysomes: Carry out the reactions of the glyoxylate cycle.

A2-5 Organelle isolation Equilibrium centrifugation Rate zonal centrifugation Differential centrifugation To call the parameter which characterizes the movement of the particle at the centrifugal force place.

A3 Macromolecules A3-1 Macromolecules A3-2 Complex macromolecules

A3-1 Macromolecules Proteins Proteins are polymers of amino acids linked together by peptide bonds.

A3-1 Macromolecules Nucleic acids Nucleic acids are polymers of nucleotides.

A3-1 Macromolecules Polysaccharides are polymers of simple sugars covalently linked by glycosidic bonds.

A3-1 Macromolecules Lipids individual lipids are not strictly macromolecules, large lipid molecules are built up from small monomeric units and involved in many macromolecule assembly

A3-2 Complex macromolecules Many macromolecules contain covalent or noncovalent associations of more than one of the major classes of large biomolecules, which can greatly increase the functionality or structural capabilities of the complex.

A3-2 Complex macromolecules Nucleoproteins Associations of nucleic acid and protein telomerase / ribonuclease P Glycoproteins Contain both protein and carbohydraty components They are important components of cell membranes and mediate cell-cell recognition. Proteoglycans / Mucoproteins Large complexes of protein and mucopolysaccharide Found in bacterial cell walls and in the extracellular space in connective tissue

A3-2 Complex macromolecules Lipid-linked proteins Have a covalently attached lipid componemt. This groups serve to anchor the proteins in membranes through hydrophobic interactions with the membrance lipids and also promote protein-protein association. Glycolipids Covalently linked lipid and carbohydrate include cerebrosides and gangliosides. Abundant in the membrans of brain and nerve cells Lipoproteins The lipids and proteins are linked noncovalently Lipid transport

A4 Large macromolecular Assemblies A4-1 Protein complexes A4-2 Nucleoprotein A4-3 Membranes A4-4 Noncovalent interactions

A4-1 Protein complexes The eukaryotic cytoskeleton consists of various protein complexes: Microtubules Microfilaments Intermediate filaments

A4-2 Nulceoprotein Nucleoproteins comprise both nucleic acid and protein. Ribosomes are the large cytoplasmic ribonucleoprotein.

A4-2 Nulceoprotein Chromatin: deoxyribonucleoprotein consisting of DNA and histones to form a repeating unit called nucleosome Viruses:protein capsid + RNA or DNA Telomerase: replicating the ends of eukaryotic chromosomes. RNA acts as the replication template, and protein catalyzes the reaction

A4-3 Membranes peripheral transmembrane protein integral transmembrane protein transmembrane protein

A4-4 Noncovalent interactions Charge –charge Charge –charge interactions operate between ionizable groups of opposite charge at physiological pH. Charge –dipole/ dipole -dipole Charge –dipole form when either or both of the participants is a dipole due to the asymmetric distribution of charge in the molecule. Dispersion force/ hydrophobic interaction Transient dipoles arising from the motion of their electrons.

A4-4 Noncovalent interactions (偶极) (uncharged molecules)

A4-4 Noncovalent interactions Van der waals forces Noncovalent associations between electrically neutral molecules. Hydrogen bonds Form between a covalently bonded hydrogen atom on a donor group and a pair of nonbonding electrons on an acceptor group.