Basic Concepts of Biotechnology PDF

BASIC CONCEPTS OF BIOTECHNOLOGY Dr. apt. LINA ELFITA, M.Si PRINCIPLES OF BIOLOGY All living organisms are composed of cells that contain a substance called DNA (deoxyribonucleic acid) in the chromosomes. The structure of DNA molecules contains informa...

BASIC CONCEPTS OF BIOTECHNOLOGY Dr. apt. LINA ELFITA, M.Si PRINCIPLES OF BIOLOGY All living organisms are composed of cells that contain a substance called DNA (deoxyribonucleic acid) in the chromosomes. The structure of DNA molecules contains information that is used by cells as a “recipe” for the organism; That is, the characteristics of any living thing essentially are determined by the information in DNA. The “words” for the DNA recipe, called genes, are derived from a 4-letter alphabet (A, C, G, T) and usually contain between 1,000 and 100,000 letters. The entire recipe, called the genome, may contain between 4 million (simple bacteria) and 3 billion (human) letters or more. Except for the sequence and number of letters in each recipe, DNA from any organism is chemically and physically the same. One of the great scientific discoveries of biotechnology is that DNA from any organism will function if it is transferred into any other organism! Combining DNA from different existing organisms (plants, animals, insects, bacteria, etc.) results in modified organisms with a combination of traits from the parents. The sharing of DNA information takes place naturally through sexual reproduction and has been exploited in plant and animal breeding programs for many years.  GENE q The basic unit of heredity passed from parent to child. q Genes are short pieces of DNA that carry specific genetic information. q Genes are made up of sequences of DNA and are arranged, one after another, at specific locations on chromosomes in the nucleus of cells. q They contain information for making specific proteins that lead to the expression of a particular physical characteristic or trait, such as hair color or eye color, or to a particular function in a cell. NUCLEOTIDA STRUCTURE What is a cell? Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body’s hereditary material and can make copies of themselves.  GENE Genes are made up of DNA. Each chromosome contains many genes The Human Genome Project estimated that humans have between 20,000 and 25,000 genes  CHROMOSOME DNA and histone proteins are packaged into structures called chromosomes.  CHROMOSOME In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females Chromosome 9  CENTRAL DOGMA OF MOLECULAR BIOLOGY The central dogma illustrates the flow of genetic information in cells, the DNA replication, and coding for the RNA through the transcription process and further RNA codes for the proteins by translation.  BASIS FOR COMPARISON PROKARYOTIC CELLS EUKARYOTIC CELLS Size 0.5-3um 2-100um Kind of Cell Single-cell Multicellular Cell Wall Cell wall present, comprise of peptidoglycan or Usually cell wall absent, if present (plant cells and mucopeptide (polysaccharide). fungus), comprises of cellulose (polysaccharide). Presence of Nucleus Well-defined nucleus is absent, rather 'nucleoid' is A well-defined nucleus is present enclosed within present which is an open region containing DNA. nuclear memebrane. Shape of DNA Circular, double-stranded DNA. Linear, double-stranded DNA. Mitochondria Absent Present Ribosome 70S 80S Golgi Apparatus Absent Present Endoplasmic Reticulum Absent Present Mode of Reproduction Asexual Most commonly sexual Cell Divison Binary Fission, Mitosis (conjugation, transformation, transduction) Lysosomes and Peroxisomes Absent Present Chloroplast (Absent) scattered in the cytoplasm. Present in plants, algae. Transcription and Translation Occurs together. Transcription occurs in nucleus and translation in cytosol. Organelles Organelles are not membrane bound, if present any. Organelles are membrane bound and are specific in function. Replication Single origin of replication. Multiple origins of replication. Number of Chromosomes Only one (not true called as a plasmid). More than one. Examples Archaea, Bacteria. Plants and Animals. DNA TRANSCRIPTION Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). DNA safely and stably stores genetic material in the nuclei of cells as a reference, or template. Meanwhile, mRNA is comparable to a copy from a reference book because it carries the same information as DNA but is not used for long-term storage and can freely exit the nucleus. Although the mRNA contains the same information, it is not an identical copy of the DNA segment, because its sequence is complementary to the DNA template.  Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors. Transcription factors can bind to specific DNA sequences called enhancer and promoter sequences in order to recruit RNA polymerase to an appropriate transcription site. Together, the transcription factors and RNA polymerase form a complex called the transcription initiation complex. This complex initiates transcription, and the RNA polymerase begins mRNA synthesis by matching complementary bases to the original DNA strand. The mRNA molecule is elongated and, once the strand is completely synthesized, transcription is terminated. The newly formed mRNA copies of the gene then serve as blueprints for protein synthesis during the process of translation. OVERVIEW OF TRANSCRIPTION  TARGETING TRANSCRIPTION  TARGETING TRANSLATION  TRANSCRIPTION FACTOR Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes. One distinct feature of transcription factors is that they have DNA-binding domains that give them the ability to bind to specific sequences of DNA called enhancer or promoter sequences. Some transcription factors bind to a DNA promoter sequence near the transcription start site and help form the transcription initiation complex. Other transcription factors bind to regulatory sequences, such as enhancer sequences, and can either stimulate or repress transcription of the related gene.  Transcription factor glossary gene expression – the process by which information from a gene is used in the synthesis of a functional gene product such as a protein transcription – the process of making messenger RNA (mRNA) from a DNAtemplate by RNA polymerase transcription factor – a protein that binds to DNA and regulates gene expression by promoting or suppressing transcription transcriptional regulation – controlling the rate of gene transcription for example by helping or hindering RNA polymerase binding to DNA upregulation, activation, or promotion – increase the rate of gene transcription downregulation, repression, or suppression – decrease the rate of gene transcription coactivator – a protein that works with transcription factors to increase the rate of gene transcription corepressor – a protein that works with transcription factors to decrease the rate of gene transcription response element – a specific sequence of DNA that a transcription factor binds to  STRUCTURE OF EUKARYOTE GENE o Exons. Exons code for amino acids and collectively determine the amino acid sequence of the protein product. It is these portions of the gene that are represented in final mature mRNA molecule. o Introns. Introns are portions of the gene that do not code for amino acids, and are removed (spliced) from the mRNA molecule before translation.  TRANSLATION Translation is the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis. The genetic code describes the relationship between the sequence of base pairs in a gene and the corresponding amino acid sequence that it encodes. In the cell cytoplasm, the ribosome reads the sequence of the mRNA in groups of three bases to assemble the protein.  REGULATION OF GENE EXPRESSION Gene regulation is the process of controlling which genes in a cell’s DNA are expressed (used to make a functional product such as a protein). Different cells in a multicellular organism may express very different sets of genes, even though they contain the same DNA. The set of genes expressed in a cell determines the set of proteins and functional RNAs it contains, giving it its unique properties. In eukaryotes like humans, gene expression involves many steps, and gene regulation can occur at any of these steps. However, many genes are regulated primarily at the level of transcription.  GENE CONTROL REGIONS o Start site. A start site for transcription. o A promoter. A region a few hundred nucleotides 'upstream' of the gene (toward the 5' end). It is not transcribed into mRNA, but plays a role in controlling the transcription of the gene. Transcription factors bind to specific nucleotide sequences in the promoter region and assist in the binding of RNA polymerases. o Enhancers. Some transcription factors (called activators) bind to regions called 'enhancers' that increase the rate of transcription. These sites may be thousands of nucleotides from the coding sequences or within an intron. Some enhancers are conditional and only work in the presence of other factors as well as transcription factors. o Silencers. Some transcription factors (called repressors) bind to regions called 'silencers' that depress the rate of transcription.