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Factors Affecting Rates of Respiration. Temperature - For every 10 degree C rise in temperature between 0-35 C the rate of respiration increases 2X – 4X.
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Factors Affecting Rates of Respiration • Temperature- For every 10 degree C rise in temperature between 0-35 C the rate of respiration increases 2X – 4X. • Storage temperature for harvested plant parts is often critical because these parts continue to respire after harvest ( a catabolic process) which causes a build up of heat, and the breakdown of the product.
Factors Affecting Rates of Respiration • Most plants grow better when night time temperatures are 5 degrees C lower than day time temperatures. • This is because lower night time respiration reduces the use of carbohydrates and allows more carbohydrates to be stored or used for growth.
Factors Affecting Rates of Respiration • Oxygen concentration- Generally speaking, lower oxygen level results in the reduction of respiration. • Controlled atmosphere (CA) storage in which oxygen is decreased is useful in storage of fruits and vegetables because of lower respiration rates.
Factors Affecting Rates of Respiration • Soil conditions- Compacted and/or wet soil conditions result in low oxygen in the root zone and reduced root respiration. • Consequently, roots don’t function well in supplying mineral nutrients essential for the activity of respiratory enzymes which decreases overall respiration.
Factors Affecting Rates of Respiration • Light- Lower light intensities result in lower respiration rates. • Lower photosynthesis rates in low light supply fewer carbohydrates essential for respiration. • Plant growth- As a plant grows it depends on energy to be supplied by respiration. • The more growth that is occurring, the higher the respiration rate must be.
Summary of Respiration • Aerobic Respiration • Glycolysis • Transition Rx. • Kreb’s Cycle • Electron Transport Chain • Anaerobic Respiration • Pyruvate • Lactic Acid • Mixed Acids • Alcohol + CO2 • Recycle NADH • 2 ATP / Glucose
Amino Acids • Building blocks for polymers called proteins • Contain an amino group, –NH2, and a carboxylic acid, –COOH • Can form zwitterions: have both positively charged and negatively charged groups on same molecule • 20 required for humans
Peptide Bond • Connect amino acids from carboxylic acid to amino group • Produce amide linkage: -CONH- • Holds all proteins together • Indicate proteins by 3-letter abbreviation
Sequence of Amino Acids • Amino acids need to be in correct order for protein to function correctly • Similar to forming sentences out of words
Transaminaseenzymes (aminotransferases) Catalyze the reversible transfer of an amino group between two a-keto acids.
Example of aTransaminasereaction: Aspartate donates its amino group, becoming the a-keto acid oxaloacetate. • a-Ketoglutarate accepts the amino group, becoming the amino acid glutamate.
In another example, alanine becomes pyruvate as the amino group is transferred to a-ketoglutarate.
Essential amino acidsmust be consumed in the diet. Mammalian cells lack enzymes to synthesize their carbon skeletons (a-keto acids). These include: Isoleucine, leucine, & valine Lysine Threonine Tryptophan Phenylalanine (Tyr can be made from Phe.) Methionine (Cys can be made from Met.) Histidine (Essential for infants.)
Amino Acid Metabolism • Metabolism of the 20 common amino acids is considered from the origins and fates of their: (1) Nitrogen atoms (2) Carbon skeletons • For mammals: Essential amino acids must be obtained from dietNonessential amino acids - can be synthesized
The Nitrogen Cycle and Nitrogen Fixation • Nitrogen is needed for amino acids, nucleotides • Atmospheric N2 is the ultimate source of biological nitrogen • Nitrogen fixation: a few bacteria possess nitrogenase which can reduce N2 to ammonia • Nitrogen is recycled in nature through the nitrogen cycle
An enzyme present in Rhizobium bacteria that live in root nodules of leguminous plants • Some free-living soil and aquatic bacteria also possess nitrogenase • Nitrogenase reaction: • N2 + 8 H+ + 8 e- + 16 ATP • 2 NH3 + H2 + 16 ADP + 16 Pi Nitrogenase
Assimilation of Ammonia • Ammonia generated from N2 is assimilated into low molecular weight metabolites such as glutamate or glutamine • At pH 7 ammonium ion predominates (NH4+) • At enzyme reactive centers unprotonated NH3 is the nucleophilic reactive species
A. Ammonia Is Incorporated into Glutamate • Reductive amination ofa-ketoglutarate by glutamatedehydrogenase occurs in plants, animals and microorganisms
Glutamine Is a Nitrogen Carrier in Many Biosynthetic Reactions • A second important route in assimilation of ammonia is viaglutaminesynthetase
Glutamate synthase transfers a nitrogen to a-ketoglutarate Prokaryotes & plants
Alternate amino acid production in prokaryotes Especially used if [NH3] is low. Km of Gln synthetase lower than Km of Glu dehydrogenase.
The First Step in Amino Acid Degradation is the Removal of Nitrogen • Amino acids released from protein turnover can be resynthesized into proteins. • Excess amino acids are degraded into specific compounds that can be used in other metabolic pathways. • This process begins with the removal of the amino group, which can be converted to urea and excreted. • The -ketoids that remain are metabolized so that their carbon skeletons can enter glycolysis, gluconeogenesis, or the TCA cycle.
The Biosynthesis of Amino Acids • Amino acids are the building blocks of proteins and the nitrogen source of many other important molecules including nucleotides, neurotransmitters, and prosthetic groups such as porphyrins. • Ammonia is the source of all nitrogen for all of the amino acids. • The carbon backbones come from the glycolytic pathway, the pentose phosphate pathway, and/or the TCA cycle. • Amino acid biosynthesis is feedback regulated to ensure that all amino acids are maintained in sufficient amounts for protein synthesis and other processes.
Summary of Protein and Amino Acid Degradation • Proteins are degraded to amino acids. • Protein turnover is tightly regulated. • The first step in amino acid degradation is the removal of nitrogen. • Ammonium ion is converted into urea in most terrestrial vertebrates. • Carbon atoms of degraded amino acids emerge as major metabolic intermediates. • Inborn errors of metabolism can disrupt amino acid degradation.
Summary of Amino Acid Biosynthesis • Microorganisms use ATP and a powerful reductant to reduce atmospheric nitrogen to ammonia. • Amino acids are made from intermediates of the TCA cycle and other major pathways. • Amino acid metabolism is regulated by feedback inhibition. • Amino acids are precursors of many molecules.
Overview of Nucleotide Biosynthesis • Nucleotides serve as active precursors of nucleic acids. • ATP is the universal currency of energy. • Nucleotide derivatives such as UDP-glucose participate in bioynthetic processes. • Nucleotides are essential components of signal transduction pathways.
Two Classes of Pathways for the Synthesis of Nucleotides. • In the salvage pathway, a base is attached • to a ribose, activated in the form of 5- • phosphoribosyl-1-pyrophosphate (PRPP). • In de novo synthesis, the base itself is • synthesized from simpler starting materials, • including amino acids. • ATP hydrolysis is necessary for de novo • synthesis.
Summary of Nucleotide Biosynthesis • In de novo synthesis, the pyrimidine ring is assembled from bicarbonate, aspartate, and glutamine. • Purine bases can be synthesized de novo or recycled by salvage pathways. • Deoxyribonucleotides are synthesized by the reduction of ribonucleotides. • Key steps in nucleotide biosynthesis are feeback regulated. • NAD+, FAD, and Coenzyme A are formed from ATP. • Disruptions in nucleotide metabolism can cause pathological conditions.
Structure of Proteins • Four organizational levels • Primary structure: amino acid sequence • Secondary structure: arrangement of chains around an axis • Pleated sheet • Alpha helix: right-handed helix
Tertiary Structure • Spatial relationships of amino acids relatively far apart in protein chain • Globular proteins: compact spherical shape
Quaternary Structure • Structure when two or more amino acid sequences are brought together • Hemoglobin has four units arranged in a specific pattern
Intermolecular Forces in Proteins • Hydrogen bonding • Ionic bonds • Disulfide linkages • Dispersion forces
Protein metabolism Transamination: use the essential AA to synthesize the others!
Protein metabolism Another route: Intestinal bacteria -> ammonia (toxic) -> liver uses it to make amino acids
Protein metabolism Amino acids: C, H, O plus amine group with N
Protein metabolism Amino acids are broken down into: a) ammonia -> urea b) pyruvate or molecules that are part of the krebs cycle -> respired for energy, or converted to fats or glucose
Proteins are degraded into amino acids. • Protein turnover is tightly regulated. • First step in protein degradation is the removal of the nitrogen • Ammonium ion is converted to urea in most mammals. • Carbon atoms are converted to other major metabolic intermediates. • Inborn errors in metabolism
Amino acids used for synthesizing proteins are obtained by degrading other proteins • Proteins destined for degradation are labeled with ubiquitin. • Polyubiquinated proteins are degraded by proteosomes. • Amino acids are also a source of nitrogen for other biomolecules.
Excess amino acids cannot be stored. • Surplus amino acids are used for fuel. • Carbon skeleton is converted to • Acetyl–CoA • Acetoacetyl–CoA • Pyruvate • Citric acid cycle intermediate • The amino group nitrogen is converted to urea and excreted. • Glucose, fatty acids and ketone bodies can be formed from amino acids.
1. Protein Degradation • proteins are a vital source of amino acids. • Discarded cellular proteins are another source of amino acids.
What Is Biotechnology? • Using scientific methods with organisms to produce new products or new forms of organisms • Any technique that uses living organisms or substances from those organisms to make or modify a product, to improve plants or animals, or to develop microorganisms for specific uses
What Is Biotechnology? • GMO- genetically modified organisms. • GEO- genetically enhanced organisms. • With both, the natural genetic material of the organism has been altered. • Roots in bread making, wine brewing, cheese and yogurt fermentation, and classical plant and animal breeding