Principles of Biochemistry Volume 3 - A. Lehninger 1985
Selected Aspects of Human Biochemistry
Digestion, Nutrient Transport, and Intermediary Metabolism
Food undergoes enzymatic digestion to prepare it for subsequent absorption
Digestion, Nutrient Transport, and Metabolic Interrelationships
The liver processes and distributes nutrients
The liver possesses five distinct pathways of sugar metabolism
There are also five metabolic pathways for amino acids
Digestion, nutrient transport, and metabolic interrelationships
There are five pathways of lipid transformation
Each organ possesses specialized metabolic functions
Skeletal muscles use ATP to perform mechanical work as needed
Digestion, Nutrient Transport, and Metabolic Interrelationships
The cardiac muscle must work continuously and rhythmically
Digestion, nutrient transport, and metabolic interrelationships
The brain utilizes energy to transmit impulses
Digestion, nutrient transport, and metabolic interconnection
Adipose tissue is characterized by an active metabolism
Digestion, nutrient transport, and metabolic interrelationships
Kidneys use ATP to perform osmotic work
Blood has a very complex composition
Digestion, Nutrient Transport, and Intermediary Metabolism
Blood carries large volumes of oxygen
Digestion, nutrient transport, and metabolic interconnection
Hemoglobin as an oxygen carrier
Digestion, Nutrient Transport, and Metabolic Interrelationships
Erythrocytes also transport CO2
Diagnosis and treatment of diabetes mellitus rely on biochemical assay data
In diabetes, the level of ketone bodies increases
In diabetes, urea excretion increases
Severe diabetes is accompanied by acidosis
Hormones
Hormones function within a complexly overlapping hierarchical system
Some General Properties of Hormones
Hypothalamic and pituitary hormones are peptides
The adrenal medulla secretes amine-class hormones: adrenaline and noradrenaline
Epinephrine stimulates the formation of cyclic adenosine monophosphate
cAMP stimulates protein kinase activity
Epinephrine also inhibits glycogen synthesis
Phosphodiesterase inactivates cyclic adenosine monophosphate
The pancreas secretes a number of hormones that regulate metabolic processes
Insulin: A Hypoglycemic Hormone
Insulin secretion is regulated primarily by blood glucose concentrations
The secondary messenger of insulin action remains unknown
Insulin affects many metabolic processes
Glucagon is a hyperglycemic hormone of the pancreas
Somatostatin inhibits the secretion of insulin and glucagon
Somatotropin also influences the action of insulin
Adrenal cortex hormones are steroids
Thyroid hormones regulate the metabolic rate
The mechanism of action of estrogens on target cells is gradually becoming clearer
There are many other hormones present in the organism
Prostaglandins and thromboxanes influence the action of a number of hormones
Human Nutrition
A balanced diet must contain five essential components
The body derives energy through the oxidation of organic macronutrients
Selected aspects of human biochemistry
Human nutrition
Ethanol also serves as a source of energy
Some aspects of human biochemistry
Obesity results from the consumption of excessively calorie-dense foods
Selected Aspects of Human Biochemistry
Human Nutrition
Proteins are essential as sources of amino acids
Certain plant proteins in food can be mutually complementary
Starvation and Kwashiorkor: Global Public Health Challenges
Deficiency of certain vitamins can be life-threatening
Thiamine deficiency remains a nutritional concern
Dietary intake of nicotinamide and tryptophan is interrelated
Many food products contain little ascorbic acid
Riboflavin deficiency is a phenomenon as common as ascorbic acid deficiency
Folic acid deficiency is the most common occurrence
Deficiencies of pyridoxine, biotin, and pantothenic acid in humans are extremely rare
Dietary vitamin B12 deficiency is extremely rare
Some Aspects of Human Biochemistry
Vitamin A deficiency leads to numerous consequences
Selected Aspects of Human Biochemistry
Vitamin D deficiency leads to rickets and osteomalacia
Vitamin E or K deficiency in humans is extremely rare.
Human nutrition must include a wide range of chemical elements
Some aspects of human biochemistry
Human nutrition
Calcium and phosphorus are essential for the development of bones and teeth
Selected Aspects of Human Biochemistry
Human Nutrition
Mild magnesium deficiency is a relatively common phenomenon
Iron and copper are essential for the synthesis of heme proteins
Selected aspects of human biochemistry
Human nutrition
Goiter is a result of iodine deficiency
Selected Aspects of Human Biochemistry
Human Nutrition
Dental caries is an important nutrition-related problem
Zinc and Certain Other Trace Elements as Essential Dietary Components
A balanced diet must be multicomponent
Certain aspects of human biochemistry
Human nutrition
Special food labels serve the interests of consumers
Molecular Mechanisms of Genetic Information Transfer
DNA: Structure of Chromosomes and Genes
DNA and RNA perform different functions
DNA and RNA nucleotide units contain specific bases and pentoses
Molecular mechanisms of genetic information transmission
DNA: structure of chromosomes and genes
Consecutive nucleotides are linked by phosphodiester bonds
DNA stores genetic information
Molecular Mechanisms of Genetic Information Transmission
DNA: Structure of Chromosomes and Genes
DNA from different species has a distinct nucleotide composition
Molecular Mechanisms of Genetic Information Transfer
Watson and Crick postulated the double helix model of DNA
Molecular mechanisms of genetic information transfer
DNA: structure of chromosomes and genes
The nucleotide sequence of DNA serves as a template
Molecular Mechanisms of Genetic Information Transmission
DNA: Structure of Chromosomes and Genes
DNA double helices can undergo denaturation, i.e., unwind
Molecular Mechanisms of Genetic Information Transfer
DNA strands from two different species can form DNA-DNA hybrids
Native DNA molecules are extremely fragile
Viral DNA molecules are relatively small in size
Chromosomes of prokaryotic cells are single, very long DNA molecules
Molecular mechanisms of genetic information transfer
DNA: structure of chromosomes and genes
Molecular Mechanisms of Genetic Information Transmission
DNA: Structure of Chromosomes and Genes
Some bacteria contain DNA in the form of plasmids
Molecular mechanisms of genetic information transfer
DNA: Structure of chromosomes and genes
Eukaryotic cells contain significantly more DNA than prokaryotes
Molecular Mechanisms of Genetic Information Transmission
DNA: Structure of Chromosomes and Genes
Eukaryotic chromosomes consist of chromatin fibers
Histones are small basic proteins
DNA-histone complexes form bead-like nucleosomes
Eukaryotic cells also contain cytoplasmic DNA
Molecular Mechanisms of Genetic Information Transfer
Genes are regions of DNA that encode polypeptide chains and RNA
A large number of genes are concentrated in a single chromosome
Molecular mechanisms of genetic information transfer
DNA: structure of chromosomes and genes
Bacterial DNA is protected by restriction-modification systems
DNA: Structure of chromosomes and genes
Eukaryotic DNAs contain highly repetitive base sequences
Molecular Mechanisms of Genetic Information Transfer
DNA: Structure of Chromosomes and Genes
Some eukaryotic genes are present in multiple copies
Molecular Mechanisms of Genetic Information Transmission
Eukaryotic DNA contains a large number of palindromes
Molecular mechanisms of genetic information transfer
DNA: Structure of chromosomes and genes
Many eukaryotic genes contain intervening untranslated sequences (introns)
Molecular Mechanisms of Genetic Information Transfer
DNA: Structure of Chromosomes and Genes
The nucleotide sequences of several DNAs have already been deciphered
DNA Replication and Transcription
DNA replicates in a semi-conservative manner
Molecular mechanisms of genetic information transfer
DNA replication and transcription
Circular DNA replicates bidirectionally
Eukaryotic DNAs have multiple origins of replication
Molecular Mechanisms of Genetic Information Transfer
DNA Replication and Transcription
Sometimes DNA is replicated via a “rolling circle” mechanism
Bacterial extracts contain DNA polymerase
DNA polymerase action requires a pre-existing DNA template
Molecular mechanisms of genetic information transfer
DNA replication and transcription
DNA replication requires numerous enzymes and protein factors
Molecular Mechanisms of Genetic Information Transfer
DNA Replication and Transcription
E. coli cells contain three DNA polymerases
Simultaneous replication of both DNA strands poses challenges
Discovery of Okazaki Fragments
An RNA primer is required for the synthesis of Okazaki fragments
Okazaki fragments are joined together by DNA ligase
Replication requires the physical separation of the strands of the parental double-stranded DNA
DNA polymerases can detect and correct errors
Molecular Mechanisms of Genetic Information Transmission
Replication in eukaryotic cells is particularly complex
Molecular mechanisms of genetic information transfer
DNA replication and transcription
Genes are transcribed to form RNA
Molecular Mechanisms of Genetic Information Transfer
DNA Replication and Transcription
Messenger RNAs encode polypeptide chains
Molecular Mechanisms of Genetic Information Transmission
Messenger RNA is synthesized by means of DNA-dependent RNA polymerase
Molecular mechanisms of genetic information transfer
DNA replication and transcription
Eukaryotic cell nuclei contain three RNA polymerases
DNA-dependent RNA polymerase can be selectively inhibited
RNA transcripts undergo further processing
Molecular Mechanisms of Genetic Information Transmission
DNA Replication and Transcription
Heterogeneous nuclear RNAs serve as precursors to eukaryotic messenger RNAs
Molecular mechanisms of genetic information transfer
DNA replication and transcription
Introns must be removed from mRNA precursors
Small nuclear RNAs help remove introns from RNA
Molecular Mechanisms of Genetic Information Transfer
DNA Replication and Transcription
In RNA-containing viruses, DNA is transcribed using reverse transcriptase
Molecular mechanisms of genetic information transfer
DNA replication and transcription
Some viral RNAs are replicated using an RNA-dependent RNA polymerase
Molecular Mechanisms of Genetic Information Transfer
DNA Replication and Transcription
Protein Synthesis and Its Regulation
Early discoveries laid the foundation for research into protein biosynthesis
Protein synthesis proceeds in five main stages
tRNA is required for amino acid activation
Aminoacyl-tRNA synthetases attach the corresponding amino acid to tRNA
Polypeptide chain synthesis begins at the N-terminus
Molecular mechanisms of genetic information transfer
Protein synthesis and its regulation
The initiating amino acid in prokaryotes is N-formylmethionine, and in eukaryotes, methionine
Molecular Mechanisms of Genetic Information Transfer
Protein Synthesis and Its Regulation
Ribosomes are molecular machinery designed for the synthesis of polypeptide chains
Molecular mechanisms of genetic information transfer
Protein synthesis and its regulation
Eukaryotic cytoplasmic ribosomes are larger in size and have a more complex structure
Molecular Mechanisms of Genetic Information Transmission
Protein Synthesis and Its Regulation
Polypeptide chain initiation occurs in several stages
Molecular Mechanisms of Genetic Information Transfer
Polypeptide chain elongation is a repeating process
A special signal is required for the termination of polypeptide synthesis
Energy is required to ensure the accuracy of protein synthesis
Polyribosomes enable rapid translation of a single template
Molecular mechanisms of genetic information transfer
Protein synthesis and its regulation
Polypeptide chains undergo folding and processing
Molecular Mechanisms of Genetic Information Transfer
Protein Synthesis and Its Regulation
Newly synthesized proteins are directed to their cellular destinations
Molecular mechanisms of genetic information transfer
Protein synthesis and its regulation
Protein synthesis is inhibited by various antibiotics
Molecular mechanisms of genetic information transmission
The genetic code has been deciphered
The genetic code possesses a number of interesting features
Molecular Mechanisms of Genetic Information Transfer
Protein Synthesis and Its Regulation
The "wobble" hypothesis allows a number of tRNAs to recognize multiple codons
Molecular mechanisms of genetic information transfer
Protein synthesis and its regulation
Viral DNAs sometimes contain genes within other genes or overlapping genes
Protein synthesis is regulated
Molecular Mechanisms of Genetic Information Transfer
Protein Synthesis and Its Regulation
Bacteria contain constitutive and inducible enzymes
Enzyme repression also occurs in prokaryotes
Molecular mechanisms of genetic information transfer
Protein synthesis and its regulation
Molecular Mechanisms of Genetic Information Transfer
Protein Synthesis and Its Regulation
Repressor molecules were isolated
Molecular Mechanisms of Genetic Information Transmission
Operons also contain a promoter region
Molecular Mechanisms of Genetic Information Transfer
More About Genes: Repair, Mutation, Recombination, and Cloning
Damage is constantly occurring in DNA
Regions damaged by ultraviolet radiation can be excised and repaired
More on Genes: Repair, Mutation, Recombination, and Cloning
Spontaneous deamination of cytosine to uracil can be repaired
More About Genes: Repair, Mutation, Recombination, and Cloning
Damage caused by environmental chemical agents can also be repaired
More on Genes: Repair, Mutation, Recombination, and Cloning
A change in a single base pair causes a point mutation
Nucleotide insertions and deletions cause frameshift mutations
More About Genes: Repair, Mutation, Recombination, and Cloning
Mutations are random, rare events in the lives of individuals
More on Genes: Repair, Mutation, Recombination, and Cloning
Genes frequently undergo recombination
More About Genes: Repair, Mutation, Recombination, and Cloning
Chromosome regions frequently undergo rearrangement
More on Genes: Repair, Mutation, Recombination, and Cloning
Antibody Diversity Results from Translocation and Recombination
Molecular Mechanisms of Genetic Information Transmission
More About Genes: Repair, Mutation, Recombination, and Cloning
Genes from different organisms can be artificially combined
Molecular Mechanisms of Genetic Information Transfer
More on Genes: Repair, Mutation, Recombination, and Cloning
Plasmids and phage lambda serve as vectors for introducing foreign genes into bacteria
Gene Isolation and cDNA Synthesis
Construction of a Gene-Bearing Vector
Integration of "loaded" plasmids into the E. coli chromosome
cDNA cloning can be used to search for corresponding natural genes
Expression of cloned genes is enhanced using a promoter
Recombinant DNAs and gene cloning have opened up new directions in genetic research
The study of recombinant DNA is of great practical importance
Interferon gene cloning has been successfully achieved
Unit designations, prefixes, constants, and conversion factors