cells and macromolecules section a proteindna. a1 cellular classification a2 subcellular organelles...

Cells and macromolecules

Section A

Protein DNA

A1 Cellular classification

A2 Subcellular organelles

A3 Macromolecules

A4 Large macromolecular Assemblies

A1-1 Eubacteria

A1-2 Archaea

A1-3 Eukaryotes

A1-4 Cellular differentiation

A1 Cellular classification

Prokaryotes原核细胞

Eukaryotes真核细胞

Eubacteria 真细菌

Archaea 古细菌

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 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.

A1-1 Eubacteria

A1-2 Archaea

• The second subdivision of the prokaryotes

• Structurally, they are similar to eubacteria

• The display some unusual biochemical

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

Controls the shape and movement

of the cellOrganizes some metabolic

functions

Genetic system

A1-3 Eukaryotes

Prokaryotes EukaryotesEubacteria 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 Ester linkageEnergy production, metabolism

Replication, transcription and translation

Differentiation 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）

A1-4 Cellular differentiation

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.

Definition: The daughter cells change their patterns of gene

expression to become functionally different from the parent cell

after cell division.

A1-4 Cellular differentiation

•Spore formation

among prokaryotes

and lower

eukaryotes

tadpole

Embryonic cell differentiate into highly specialized cells

among higher eukaryotes.

A1-4 Cellular differentiation

A2-1 Nuclei

A2-2 Mitochondria and chloroplasts

A2-3 Endoplasmic reticulum

A2-4 Microbodies

A2-5 Organelle isolation

A2 Subcellular organelles

Nuclei: The membrance-bound nucleus contains the bulk of the

cellular DNA in multiple chromosomes.

A2-1 Nuclei

DNA replication

RNA transcription & processing

Ribosome assembly

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 Mitochondria

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

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.

A2-3 Endoplasmic reticulum

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.

A2-4 Microbodies

A2-5 Organelle isolation

Differential centrifugation

Rate zonal centrifugation

Equilibrium 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.

Polysaccharides are polymers of simple sugars covalently linked by glycosidic bonds.

A3-1 Macromolecules

Lipidsindividual lipids are not strictly

macromolecules, large lipid

molecules are built up from

small monomeric units and

involved in many

macromolecule assembly

A3-1 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

NucleoproteinsAssociations of nucleic acid and protein telomerase / ribonuclease P

GlycoproteinsContain both protein and carbohydraty componentsThey are important components of cell membranes and mediate cell-cell recognition.

Proteoglycans / MucoproteinsLarge complexes of protein and mucopolysaccharideFound in bacterial cell walls and in the extracellular space in connective tissue

A3-2 Complex macromolecules

Lipid-linked proteinsHave 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.

Lipoproteins The lipids and proteins are linked noncovalentlyLipid transport

GlycolipidsCovalently linked lipid and carbohydrate include cerebrosides and gangliosides. Abundant in the membrans of brain and nerve cells

A3-2 Complex macromolecules

A4-1 Protein complexes

A4-2 Nucleoprotein

A4-3 Membranes

A4-4 Noncovalent interactions

A4 Large macromolecular Assemblies

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.

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

A4-2 Nulceoprotein

A4-3 Membranes

peripheral transmembrane protein integral transmembrane protein transmembrane protein

Charge –chargeCharge –charge interactions operate between ionizable groups of opposite charge at physiological pH.

Charge –dipole/ dipole -dipoleCharge –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 interactionTransient dipoles arising from the motion of their electrons.

A4-4 Noncovalent interactions

(偶极 )

(uncharged molecules)

A4-4 Noncovalent interactions

Van der waals forcesNoncovalent associations between electrically neutral molecules.

Hydrogen bondsForm between a covalently bonded hydrogen atom on a donor group and a pair of nonbonding electrons on an acceptor group.

A4-4 Noncovalent interactions