* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download What is a cell?
Survey
Document related concepts
Gel electrophoresis of nucleic acids wikipedia , lookup
Molecular cloning wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Cell membrane wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Transformation (genetics) wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Endomembrane system wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Transcript
Thermodynamics of life Does life contradict the 2-nd law of thermodynamics? No!! Energy conservation: - when a rock falls potential energy becomes kinetic energy E = K + V = const. > 0 - when it hits the ground, E = 0 ! - due to friction, E went to heat, Q -> E = Q - friction transforms mechanical energy into heat = random motion of atoms in the rock+ground - 1-st law of thermodynamics: ΔU = Q + W (the change in the energy of the system is equal to the inflow of heat plus the work done on it). Can you use the heat from the rock+ground to make the rock jump back up? No!! Not because of energy conservation. But because Q is a lower quality of energy. To convert it to mechanical energy, E, you will always get less than Q, E < Q -> Mechanical energy = high quality • Q is in the Brownian motion of atoms – larger if T grows. The randomness is measured by S (entropy). • How much useful energy is in the system, F (free energy) F = U – TS • An open system at fixed T will change only to lower its F. If F minimal = system in equilibrium • A process will take place if it lowers U (rocks tend to fall) or increases S (disorder tends to increase) • A closed system will change only to increase its entropy, S (2nd law of thermodynamics) • A drop of ink in water will always mix up. Never will the ink come back together to form back the drop. • Then how can a mixture of H, C, O, N, P combine to make an E. coli? • Earth is not a closed system!! • Light from the Sun (high quality energy) illuminates the Earth. To keep T = const, the energy will have to be irradiated by the Earth back to the cosmos (low quality energy) • There is “flow of order” into the Earth. • Plants take in high quality energy from the sun to build complex molecules from simple ones. They also give out heat. • Plants capture order from the Sun. • Animals do that indirectly. Cells How do cells organize their many processes? a) Bilayer membranes self-assemble -> separate compartments b) Active transport -> motors move on tracks to deliver synthesized materials c) Biochemical processes are specific -> enzymes only act on the target molecule What is in a cell? The different length scales: a) 5 E. coli, b) 2 yeast, c) red blood cell, d) white blood cell, e) sperm, f) skin, g) muscle, h) neuron (light microscopy, 103x) a) molecules, b) E. coli, c) HIV (virus), d) phage (electron microscopy, 105x) a) Carbon atom, b) Glucose (a sugar), c) ATP (nucleotide), d) clorophyl, e) transfer RNA, f) antibody, g) ribosome, h) polio virus, i) myosine (motor), j) DNA, k) actin (cell skeleton), l) 10 enzymes for glycolysis: glucose -> ATP, m) a large enzyme Cell anatomy Nucleus – DNA, nuclear membrane Cytoplasm – cell skeleton, organelles (mitochondria, ribosomes, …) Envelope – membrane, cell wall Yeast cells (electron microscope) Prokaryotes – simplest cells – no nucleus, only ribosomes, cell wall - bacteria, archaea E. coli - Cw – cell wall, N – nucleoid (DNA), R - ribosomes Eukaryotes - larger (> 10 µm), many organelles - mitochondria – transform processed food into ATP - endoplasmic reticulum – produces membranes and exports stuff out of the cell - Golgi apparatus – processes stuff coming from the endoplasmic reticulum DNA is packed in chromosomes - 1 m human DNA in 46 chromosomes (23 pairs) What are the molecules in the cell? Small molecules - basically only C, H, N, O, Ca, K, P and S. Other atoms in very small amounts. - water – 70% - HPO42- - phosphate - ring molecules – sugars (1 ring - glucose, ribose, 2 rings sucrose), DNA bases (1 ring – cytosine, thymine – pyrimidines; 2 rings – guanine, adenine – purines), RNA bases – like DNA but thymine -> uracil) DNA complementarity Watson Crick - base+sugar (ribose or deoxyribose) + i*phosphate -> nucleotide, e.g. adenosine monophosphate (AMP), ADP, ATP - ATP -> ADP – burning fuel - fatty acids – chain of carbons with COOH at the end, building blocks of phospholipids (membranes) - amino acids – 20, building blocks of proteins a) R – side group, b) polypeptide (histidine, cysteine, valine) Molecular composition of bacteria Medium-size molecules - phospholipids – 2 fatty acids (tails) + (glycerol + phosphate+head group) (head) - Head - hydrophilic, tail – hydrophobic -> in water form bilayer (membrane) phosphate glycerol DPPC (dipalmitoyl phosphtidycholine) Bilayer (membrane) - fats – 3 fatty acids + glycerol - triglycerides Large molecules - many are polymers - polynucleotides – ribose + nucleotides -> ribonucleic acid (RNA), deoxyribose -> deoxyribonucleic acid (DNA) - 2 strands of DNA with complementary bases form a helix – contains the genetic information Double stranded DNA Transfer RNA (tRNA) It binds amino acid phenylalanine, transports it to the ribosome, then releases it