Intro to Biotechnology

👩‍🔬Intro to Biotechnology Unit 2 – Cellular and Molecular Biology Basics

Cellular and molecular biology form the foundation of biotechnology, exploring the intricate workings of cells and their components. This unit covers essential concepts like cell structure, DNA replication, protein synthesis, and cellular energy production, providing a crucial understanding of life's building blocks. From gene regulation to cutting-edge lab techniques, this unit delves into the practical applications of cellular and molecular biology. It examines how these principles drive advancements in fields like genetic engineering, personalized medicine, and synthetic biology, showcasing the real-world impact of biotechnology.

Key Concepts and Terminology

  • Cells are the basic unit of life, performing essential functions to maintain an organism's survival
  • Prokaryotic cells lack a nucleus and other membrane-bound organelles, while eukaryotic cells contain a nucleus and specialized organelles
  • DNA (deoxyribonucleic acid) stores genetic information, while RNA (ribonucleic acid) plays a role in gene expression and protein synthesis
  • Proteins are essential macromolecules that perform various functions within cells, including structural support, enzymatic reactions, and cell signaling
    • Amino acids serve as the building blocks of proteins, linked together through peptide bonds
  • Cellular respiration is the process by which cells break down glucose to produce ATP (adenosine triphosphate), the primary energy currency of the cell
  • Cell division allows for growth, repair, and reproduction in organisms
    • Mitosis results in two genetically identical daughter cells, while meiosis produces four genetically diverse haploid cells (gametes)
  • Gene expression is the process by which genetic information is used to synthesize functional gene products, such as proteins

Cell Structure and Function

  • The plasma membrane is a selectively permeable barrier that regulates the movement of substances in and out of the cell
    • Composed of a phospholipid bilayer with embedded proteins, the plasma membrane maintains cellular homeostasis
  • The nucleus contains the cell's genetic material (DNA) and is the site of DNA replication and transcription
    • The nuclear envelope, consisting of a double membrane with nuclear pores, separates the nucleus from the cytoplasm
  • Ribosomes are the sites of protein synthesis, translating mRNA (messenger RNA) into polypeptide chains
    • Ribosomes can be found freely in the cytoplasm or attached to the rough endoplasmic reticulum (ER)
  • The endoplasmic reticulum is a network of membranous channels involved in protein and lipid synthesis, as well as transport within the cell
    • Smooth ER lacks ribosomes and plays a role in lipid synthesis and detoxification, while rough ER is studded with ribosomes and participates in protein synthesis and modification
  • Mitochondria are the powerhouses of the cell, generating ATP through the process of cellular respiration
    • Mitochondria contain their own DNA and ribosomes, suggesting an endosymbiotic origin
  • The Golgi apparatus is responsible for modifying, packaging, and sorting proteins and lipids for transport to their final destinations
  • Lysosomes are membrane-bound organelles containing digestive enzymes that break down cellular waste, foreign particles, and damaged organelles

DNA, RNA, and Protein Synthesis

  • DNA is a double-stranded helix composed of nucleotides, each containing a sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases (adenine, thymine, guanine, or cytosine)
    • Complementary base pairing (A-T and G-C) and hydrogen bonds stabilize the DNA double helix
  • DNA replication is the process by which a cell duplicates its genetic material before cell division
    • DNA replication is semiconservative, meaning each new DNA molecule consists of one original strand and one newly synthesized strand
  • Transcription is the process of creating an RNA copy of a gene, which occurs in the nucleus
    • RNA polymerase catalyzes the synthesis of RNA from a DNA template, producing mRNA, tRNA (transfer RNA), or rRNA (ribosomal RNA)
  • Translation is the process of synthesizing a protein from an mRNA template, which occurs at the ribosomes
    • tRNAs carry specific amino acids to the ribosome, where they are linked together based on the codons in the mRNA
  • The genetic code is the set of rules that determines which amino acid corresponds to each three-base codon in mRNA
    • The genetic code is nearly universal across all living organisms, with a few exceptions (mitochondrial DNA)

Cell Division and Reproduction

  • The cell cycle is the series of events that take place in a cell, leading to its division and duplication
    • The cell cycle consists of interphase (G1, S, and G2 phases) and the mitotic phase (mitosis and cytokinesis)
  • During interphase, the cell grows, performs its normal functions, and prepares for cell division
    • The S phase is when DNA replication occurs, doubling the cell's genetic material
  • Mitosis is the process of nuclear division, resulting in two genetically identical daughter nuclei
    • Mitosis consists of four stages: prophase, metaphase, anaphase, and telophase
  • Cytokinesis is the division of the cytoplasm, which occurs after mitosis and results in two separate daughter cells
    • In animal cells, cytokinesis involves the formation of a cleavage furrow, while in plant cells, a cell plate forms between the daughter cells
  • Meiosis is a specialized form of cell division that produces four haploid gametes, each with half the genetic material of the parent cell
    • Meiosis involves two rounds of cell division (meiosis I and II) and includes crossing over, which increases genetic diversity
  • Errors in cell division can lead to genetic disorders or cancer
    • For example, Down syndrome is caused by an extra copy of chromosome 21 (trisomy 21), which occurs due to nondisjunction during meiosis

Cellular Energy and Metabolism

  • Metabolism refers to the sum of all chemical reactions that occur within a cell, including catabolic (breaking down molecules) and anabolic (building up molecules) processes
  • ATP is the primary energy currency of the cell, used to power various cellular processes
    • ATP consists of an adenosine molecule bonded to three phosphate groups, and energy is released when these bonds are broken
  • Cellular respiration is the process by which cells break down glucose to produce ATP
    • Cellular respiration occurs in three stages: glycolysis, the Krebs cycle, and the electron transport chain
  • Glycolysis is the first stage of cellular respiration, taking place in the cytoplasm and breaking down glucose into two pyruvate molecules
    • Glycolysis produces a net gain of 2 ATP and 2 NADH (reduced nicotinamide adenine dinucleotide) molecules
  • The Krebs cycle, also known as the citric acid cycle, occurs in the mitochondrial matrix and generates high-energy molecules (NADH and FADH2) from the oxidation of acetyl-CoA
  • The electron transport chain is the final stage of cellular respiration, located in the inner mitochondrial membrane
    • The electron transport chain uses the high-energy molecules from the Krebs cycle to create a proton gradient, which drives the synthesis of ATP through chemiosmosis
  • Fermentation is an anaerobic process that allows cells to generate ATP in the absence of oxygen
    • Lactic acid fermentation occurs in animal cells and some bacteria, while alcoholic fermentation occurs in yeast and some plant cells

Gene Regulation and Expression

  • Gene regulation is the process by which cells control the expression of their genes, determining which genes are transcribed and translated into proteins
  • Prokaryotic gene regulation often involves operons, which are clusters of genes under the control of a single promoter
    • The lac operon in E. coli is a well-studied example of gene regulation, where the presence of lactose induces the expression of genes necessary for its metabolism
  • Eukaryotic gene regulation is more complex, involving transcriptional, post-transcriptional, and post-translational modifications
    • Transcriptional regulation involves the binding of transcription factors to regulatory sequences (enhancers and silencers) to control the initiation of transcription
  • Epigenetic modifications, such as DNA methylation and histone modifications, can alter gene expression without changing the underlying DNA sequence
    • These modifications can be inherited across cell divisions and even generations, contributing to cellular differentiation and development
  • Alternative splicing is a post-transcriptional modification that allows a single gene to produce multiple protein isoforms
    • Alternative splicing involves the selective inclusion or exclusion of exons during the processing of pre-mRNA
  • Post-translational modifications, such as phosphorylation, glycosylation, and ubiquitination, can alter the function, stability, or localization of proteins
    • These modifications allow for rapid changes in protein activity in response to cellular signals or environmental stimuli

Lab Techniques and Applications

  • Polymerase Chain Reaction (PCR) is a technique used to amplify specific DNA sequences, generating millions of copies from a small initial sample
    • PCR involves three main steps: denaturation, annealing, and extension, which are repeated for multiple cycles
  • Gel electrophoresis is a method used to separate DNA, RNA, or proteins based on their size and charge
    • Agarose gel electrophoresis is commonly used for DNA and RNA, while polyacrylamide gel electrophoresis (PAGE) is used for proteins
  • DNA sequencing determines the precise order of nucleotides in a DNA molecule
    • Sanger sequencing, also known as the chain termination method, was the first widely used sequencing technique
    • Next-generation sequencing (NGS) technologies, such as Illumina and Nanopore sequencing, have revolutionized the field by enabling high-throughput and cost-effective sequencing
  • CRISPR-Cas9 is a powerful gene-editing tool derived from the bacterial adaptive immune system
    • CRISPR-Cas9 allows for precise editing of DNA sequences, with applications in basic research, agriculture, and medicine
  • Recombinant DNA technology involves the insertion of foreign DNA into a host organism, enabling the production of desired proteins or the study of gene function
    • Plasmids and viral vectors are commonly used to introduce recombinant DNA into host cells
  • Bioinformatics is the application of computational tools to analyze and interpret biological data
    • Bioinformatics plays a crucial role in managing and analyzing the vast amounts of data generated by modern biotechnology techniques, such as genome sequencing and proteomics

Biotech Connections and Real-World Examples

  • The Human Genome Project, completed in 2003, aimed to sequence the entire human genome, providing valuable insights into human biology and disease
    • The project has led to the identification of genes associated with various genetic disorders and the development of targeted therapies
  • Genetically modified organisms (GMOs) are organisms whose genetic material has been altered using genetic engineering techniques
    • GMO crops, such as Bt corn and herbicide-resistant soybeans, have been developed to improve yield, nutritional content, and pest resistance
  • Biopharmaceuticals are drugs produced using living organisms, such as bacteria, yeast, or mammalian cells
    • Examples include insulin for diabetes treatment, erythropoietin for anemia, and monoclonal antibodies for cancer therapy
  • Personalized medicine aims to tailor medical treatments to an individual's genetic profile, lifestyle, and environment
    • Pharmacogenomics studies how a person's genetic makeup influences their response to drugs, enabling the development of targeted therapies with fewer side effects
  • Forensic DNA analysis uses DNA profiling techniques to identify individuals based on their unique genetic fingerprint
    • DNA evidence has revolutionized criminal investigations and has been used to exonerate wrongfully convicted individuals
  • Synthetic biology is an emerging field that combines principles from biology, engineering, and computer science to design and construct novel biological systems
    • Applications of synthetic biology include the production of biofuels, the development of biosensors, and the creation of artificial organs
  • Stem cell research explores the potential of using stem cells, which have the ability to differentiate into various cell types, for regenerative medicine and disease modeling
    • Induced pluripotent stem cells (iPSCs) are adult cells that have been reprogrammed to a pluripotent state, offering a promising alternative to embryonic stem cells


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© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.