bio 205 questions pt.2

• A cell is the fundamental structural and functional unit of life, comprising cytoplasm enclosed by a membrane.
• Many cells contain organelles, each with a specific function.
• The term "CELL" comes from the Latin word "CELLULAR," meaning small room.
• Seen under a microscope, cells can replicate, synthesize proteins, and move and are grouped into prokaryotic and eukaryotic types.
• Eukaryotic cells have a nucleus, unlike prokaryotic cells, which have a nucleoid region but are "denucleoid".
• Prokaryotes are single-celled organisms like Bacteria, while eukaryotes can be single-celled, such as Amoeba, or multicellular like algae, plants, animals, and fungi.
• Eukaryotic cells have organelles, including mitochondria (powerhouses for energy), chloroplasts (for sugar production via photosynthesis), and ribosomes (for protein synthesis).
• Robert Hooke discovered cells in 1665 and named them based on their resemblance to cellular envelopes like skin.

Prokaryotic Cells

• Includes Bacteria and Archaea, belonging to two of the three domains of life.
• The first life forms on Earth are characterized by vital biological processes such as cell signaling.
• Simpler and smaller than eukaryotic cells, lacking a nucleus and membrane-bound organelles.
• Prokaryotic cell DNA consists of a single circular chromosome in direct contact with the cytoplasm.
• The nucleoid is the term for the nuclear region in the cytoplasm.
• The prokaryotic cell mainly has three regions:
• A cell envelope encloses the cell, typically made of a plasma membrane covered by a cell wall or capsule.
• Cell walls are common in prokaryotes, with exceptions like Mycoplasma (in bacteria) and Thermoplasma (in Archaea).
• The cell envelope provides rigidity and separates the cell's interior from its environment, serving as a protective barrier.
• Typical bacteria have a cell wall made of peptidoglycan, providing extra protection against external forces and osmotic pressure.
• The cytoplasmic region contains genomic DNA, ribosomes, and other inclusions, with genetic material freely present in the cytoplasm.
• Some prokaryotes have flagella and pili on the outside for movement and cellular communication, made of protein.

Eukaryotic Cell

• Plants, animals, fungi, slime molds, protozoa, and algae are examples of eukaryotic cells.
• Eukaryotic cells are roughly 15 times wider than typical prokaryotes.
• Compartmentalization is the main feature differentiating eukaryotes from prokaryotes, with membrane-bound organelles performing specific activities.
• The most important organelle is the cell nucleus, which houses the cell's DNA.

Cell Organelles and Function

• Cell Wall:
• Plant cells are surrounded by a non-living rigid cell wall.
• It is a plant product, thicker than a plasma membrane.
• Responsible for plant shape and growth rate and it acts as an energy, fiber, and food source.
• It is layered, with three portions: intercellular substance or middle layer, primary cell wall, and secondary wall.
• The middle layer cements primary walls.
• Composed of a pectic compound, mostly calcium pectate.
• The primary wall is made of cell, and the secondary walls may be composed of cellulose or other secondary substances.
• Plasma Membrane:
• Known as the cell or cytoplasmic membrane
• Is a selectively permeable membrane composed of a lipid bilayer and proteins.
• It is present in plant and animal cells and facilitates permeability and material transfer in and out of the cell.
• It provides shape and protects the cell's contents in animal cells.
• Cytoplasm:
• Found in both plant and animal cells.
• It is a jelly-like substance between the cell membrane and the nucleus, mainly made of water, and organic and inorganic compounds.
• It is essential as it suspends cell organelles and contains enzymes for metabolic activities and chemical reactions.
• Nucleus:
• A double-membrane organelle in eukaryotic cells and also the largest.
• Functions as the control center for cell activities and DNA storage.
• Structurally round, with a porous membrane separating it from the cytoplasm.
• Contains spherical nucleoli and chromosomes.
• Chromosomes carry genes, the hereditary units for trait inheritance.
• The nucleus monitors cell activities like metabolism and growth using DNA information.
• Nucleoli synthesize protein and RNA.
• Endoplasmic Reticulum (ER):
• A fluid-filled network of membranous canals that transport material throughout the cell.
• Rough endoplasmic reticulum (RER) has cisternae, tubules, and vesicles for protein production.
• Smooth endoplasmic reticulum (SER) stores lipids and steroids and detoxifies the cell.
• Mitochondria:
• Known as the cell's powerhouse for producing energy-rich molecules.
• The mitochondrial genome is inherited maternally.
• Sausage-shaped with a double membrane, it has an inner matrix folded into cristae and an outer boundary with the cytoplasm.
• Varies in size and shape and is the primary site for aerobic respiration, ATP production, and molecule transformation.
• Plastids:
• Large organelles with membranes, composed of pigments.
• Chloroplasts are double-membrane organelles in the mesophyll of leaves.
• They store chlorophyll and carotenoids and trap light energy for photosynthesis with an inner membrane enclosing the stroma.
• Chromoplasts have fat-soluble carotenoid pigments, like xanthophylls, which provide colors like yellow and orange to plants.
• Leucoplasts are colorless and store nutrients, such as amyloplasts storing carbohydrates in potatoes, aleuroplasts storing protein, and elaioplasts storing oil and fat.

History and Trends in Cell Biology

• Cell biology, or cytology, studies cell structure, function, and behavior as the fundamental unit of life.
• It examines physiological properties, metabolic pathways, life cycles, the interaction of cells, and genetic material.
• Cells are basic building blocks from single-celled microorganisms to complex multicellular organisms like humans.
• Cells are grouped into eukaryotes (with a nucleus) and prokaryotes (with a nucleoid region).
• Cell biology is vital for life function at the basic level and is used in medicine, biotechnology, and environmental sciences.
• Overlaps with molecular biology, genetics, and biochemistry.
• Researchers use microscopy, cell culture, and molecular analysis to explore cells and their implications for health and disease.
• Major branches of cell biology include:
• Cytotaxonomy: the study of cell taxonomy.
• Cytopathology: the study of pathological conditions of cells.
• Cytecology: study of the ecology of cells in health and disease.
• An understanding of how cell walls behave enables the development of vaccines, medicine, and plants with higher quality.

Key Aspects of Cell Biology

• Cell Structure: study of components including the nucleus, mitochondria, ribosomes, and cell membrane.
• Cell Function: understanding of processes such as energy production, protein synthesis, and communication.
• Cell Division: exploration of mechanisms of mitosis and meiosis essential for growth, development, and reproduction.
• Cell Interaction: study of how cells communicate with each other and their environment.
• Specialization of Cell: examination of cell type variations, such as muscle, nerve, and immune cells.
• Cell biology provides a foundation for advances in research, including cancer research, regenerative medicine, and development of targeted therapies.
• Molecular Biology: focuses on molecular medicine within cells, including DNA, RNA, and protein synthesis.
• Biochemistry: studies chemical processes and substances within cells, including metabolic pathways and enzyme activity.
• Cytogenetics: studies the structure and function of chromosomes within the cell.
• Cell Signaling: investigates how cells communicate and respond, crucial for understanding hormone action and immune responses.
• Developmental Biology: studies how cells differentiate, explaining how a zygote develops into diverse cell types.
• Structural Biology: explores the architecture of cellular components to understand the relationship between structure and function.
• Immunology: examines the roles of immune cells in defending against pathogens.
• Microbiology: studies microorganisms and their structure
• Stem Cell Biology: investigates stem cell properties and applications, relevant for regenerative medicine and intervention.
• System Biology: uses computational and experimental approaches to study interactions between cellular components.
• Pathology: studies alterations in cells and tissues leading to diseases, relevant for cancer and infectious disease research.
• Cell Physiology: examines the physical and chemical function of cells, including ion transport and electrical activities.
• These sub-fields contribute to the application of cell biology in medicine, biotechnology and environmental science.

Importance of Cell Biology

• Understanding the Basics of Life: cells are the basic structural and functional unit of life and studying their behavior explains organismal growth, reproduction, and homeostasis.
• Advancement in Medicine:
• Disease mechanisms: facilitates the understanding of diseases like cancer, diabetes, and neurodegenerative disorders at the cellular level.
• Drug Development: identify drug targets and test the efficacy and safety of new drugs.
• Regenerative Medicine: researches stem cells and cellular therapy for revolutionary tissue and organ replacement approaches.
• Biotechnology and Genetic Engineering: bio-cell biology facilitates the production of vaccines, monoclonal antibodies, and biologics.
• Agricultural Improvement: enhances the understanding of plant cells to improve crop yield, resistance to pests, and tolerance to environmental stressors.
• Environmental Conservation: using microbial cells in bioremediation to clean up pollutants and manage waste.
• Education and Research: provides the foundation for biological and biomedical sciences, fostering innovation and discovery.
• Interdisciplinary Impact: enhances the understanding of biological systems.
• Public Health and Epidemic Study: compacting infectious diseases, education is pivotal in designing vaccine.

Introduction to Developmental Biology and Cell Biology

• Sexual reproduction makes zygotes by uniting two gametes.
• The cell cycle has two steps, these are growth and M-phase.

Mitosis

• Cells originate from other cells through cell division, according to Schleiden and Schwann in 1838.
• Virchow in 1858: cells are the smallest functional and structural unit that maintains life's continuity and organisms come into existence from preexisting cells ("Omni Cellular e Cellular").
• Growing cells duplicate their DNA and give genetic information to daughter cells .
• There are two phases in the cell cycle for prokaryotic and eukaryotic cells.
• Cell division and separation of daughter cells.
• Interphase: cell growth.

Cell Cycle

• The genome of a prokaryotic cell, such as bacteria, is a single circular DNA molecule, or naked DNA.
• The division of cytoplasm, or cytokinesis immediately follows the completion of DNA replication, this is referred to as binary fission.
• No visible cell division occurs like we have for eukaryotes, the daughter DNA strands are linked at the plasma membrane.
• Escherichia coli has a whole cell cycle which can take up to 20 min under good conditions.
• Cell cycle in eukaryotes occurs in distinct stages or phases:
• Growth & Gap-phase (G-phase) with G1 and G2 phases.
• Synthesis phase or S-phase.
• M-Phase (mitosis or meiosis), or division phase.

Molecular Basis of Cell Interactions

• Cell to cell interaction is crucial for multicellular species because such an interaction allows cells to coordinate organ activities and maintain homeostasis.
• Interactions happen by contact or chemical signals, which play roles in development, tissue repair and immunity :
• Tight junctions prevent leakage by sealing cells, which applies in epithelial layers.
• Gap junctions: Allow direct communication between connecting neighbouring cells, such as those in cardiac and smooth muscle.
• Adhesions junctions: support connections cells by adhesion, providing structure.
• Cell-ECM (extra cellular matrix) interactions.
• Cell Interaction Roles:
• Development and cell differentiation: formation of the embryo and its organs is regulated
• Immune response: communication between immune cells (antigen presentation / activation) is enabled
• Tissue maintenance & repair: during the healing of a wound, cell proliferation and migration is coordinated
• Cancer: tumour growth, metastasis, and immune invasion can be caused by altered cell-cell interaction

Cell ECM

• Refers to reciprocal communication between cells surrounding the ECM.
• The extracellular matrix is a network of protein, glycoprotein and polysaccharide which provides structural support to regulate cellular behavior.
• Functions:
• Mediated integrins, which link ECM to the cytoskeleton
• Influences adhesion and signaling
• Tissues Architecture: Maintain the structural integrity of tissues
• Signaling molecules are essential components of cell communications and enable cells to respond to environmental changes.
• Classes of signaling molecules:
• Hormones: endocrine messenger hormones affect target cells, such as steroid hormones, peptide hormones and Amino-acid derived hormones.
• Cytokines: Small immune response inflammation & cell signaling proteins, such as interleukins and interferences.
• Neurotransmitters: chemical messengers that transmit signals, for example Acetylcholine, Dopamine, Serotonin, Glutamate, Gamma Amino Butyric Acid [GABA].
• Growth Factors: proteins that stimulate cell growth proliferation & differentiation. Examples are Epidermal growth factors [EGF], Vascular Endothelial growth factor [VEGF] and Platelet-derived growth factor [PDGF}.
• Lipid-derived molecules: Examples are Prostaglandins, Leukotrienes and Phosphatidylinositol derivatives
• Gaseous Molecule: Examples are Nitric oxide (NO), Carbon Monoxide (CO) & Hydrogen Sulphide (H2S)
• Ions: Examples are calcium ions used in muscle contraction & neurotransmitter release
• Pheromones: Chemicals used to influence the behaviour or physiology of others (same species).

Mitosis and Cell Division

• The G1 period is a phase of systemic growth and production of molecules.
• Energy and raw materials like sugar, oil and starch are synthesized and damaged DNA is also repaired.
• Synthesis of DNA occurs, DNA helixes are replicated into two daughter DNA particles, in coordination with protein.
• DNA is ultimately divided such that each daughter cell receives an identical copy.
• S, G2, and N-phases last about 7, 3, and 1 hour, respectively, with variable overall time.
• A simple cell cycle can divide every 90-120 minutes in standard conditions, liver cells only divide once a year.
• In Eukaryotes, there are two division configurations, these are Mitosis and Meiosis.
• Mitosis: the mechanism which uses cell division to form new cells, is used in processes such as;
• Embryonic Development
• Cell and Asexual Reproduction
• Tumor formation or cancer
• M phase of eukaryotic cell: chromosomes, which were produced in S-phase, must align and separate at the poles.
• The cytoplasm splits: to send the correct number of molecules and organelles to daughter cells.
• First two stages, nuclear/cytoplasm division: [Mitosis and cytokinesis].
• Nuclear division [karyokinesis] and cytoplasmic division [cytokinesis] occur successively until cytokinesis reaches the end.
• There are multiple processes, 6 stages in cell division: First five belong to stages of cell division create mitosis.
• These stages are Prophase, Late Prophase ( aka early metaphase), followed by metaphase, anaphase, telophase, and finally Cytokinesis.

Ribosomes

• Important cytoplasmic organelles without membranes attach themselves to the Endoplasmic Reticulum.
• Many tiny particles make up cells, 2/3 RNA and 1/3 protein, it was defined as in prokaryotes 1940s, and in eukaryotes 1980s.
• The primary ribosomes function: protein synthesis is essential for survival

Golgi Apparatus

• Composed of stacked pouches called cisternae, it is a main organelle with a membrane which will be transporting, changing and packaging proteins and lipids to transport.
• It is found in plant and animal cells.

Micro Bodies

• They are a type of organelle found in plant and animal cells which are small, full of enzymes, and have membrane.

Cytoskeleton

• Proteinaceous structures run all over the cytoplasm structure and connect the nucleus and plasma membrane.
• Its filament structure, is available living tissue notable in eukaryotic cells.
• Its primary functions are providing the cell shape and, giving contraction during motion due to the dynamic function which they hold.

Cilia and Flagella

• Cilia are smaller strands outside cell walls which cook for cell movement or flow.
• Flagella, which is more big, will move that cells and in an eukaryotic cell the strands are structurally distinct from related prokaryote’s counterpart.
• The basic Cilia & Flagella composition: the inner ring called Axoneme contains nine pairs of peripheral ring protein.
• The cilia are the cell from which protein strands travel, which are generated by Centrosomes and Centrioles.

Centrosome and Centrioles

• The Centrosome is an organelle created from two perpendicular centriole structural units are known the composition.
• The centrioles are nine in quantity, which is a pattern that is equally made up, made of protein, of space fibers protein of interconnected tubules.

Vacuole

• Made for storage of round products which are sealed by membrane, they store nutrition for a cell survive and throw products out.
• Animal and plant cells possess many vacuole that are differentiated according to number size which is smaller larger.
• Prokaryotic cells types are created from plant fungi to animals, but the most cells type is their construction that define, with their specific structure defining the cells.
• Nucleus stores, for Eukaryotes in nuclear form [”Compartment], no membrane in cytoplasm.

Modern Cell Theory

• All species alive are made of cells.
• Cells are composition and foundation.
• Cells derive via splitting and pass-on heritage info, from cell to cell split.
• Cells have the same components while energy flows are the same.
• The first continuous cell line used to be in 1951 by Grey & his co-workers, derived from Locks who had.
• This cell line is Hela line.

Cell Cycle Phases

• The cell first stage is made of developing and dividing.
• Cell progress: Gap or Synthesis [S] gap2 and mitosis [M].
• Cell can turn cycle or cell cycle is performed (G) at this stage.
• Cell’s content and content in replicated.
• S-PHASE: Cell replicates chromosome each of 46 which were initially.
• New molecules produced for preparation of division, which happens in G2-PHASE.
• M-PHASE [Cytokinesis]: Cytokinesis occurs when resulting in generating 2 division of daughters happens.
• G0 phase: These cells enter job preparation division, and cells progress.

Cell Theory

• This idea was given in 1839 by Schwann and Schleiden remained as current.

Historical Overview of Cell Biology

• The study of cell biology developed the deeper understanding of life via breakthroughs in microscopic tools.
• First infection was noticed in microscopy in 1595 Janssen created and Hooke noticed [1665], and then, van Leeuwenhoek noted micro-organisms [Animalcules / Protozoa].
• Development of Cell Theory (1800's): Schleiden/Schwann hypothesized on cell composition in plants/animals.
• Virchow's Contribution: "Omnis cellula e cellula".
• Roelliker found sperm and egg cells in 1840, Fleming determined mitosic chromosomes, and Kolliker described Mitochondrion by 1879.
• Structures: Nucleus, key was seen by Brown, Chloroplast as discovered by von Kolliker and Golgi noticed in 1898.
• Purkinje described protoplasm.
• Watson & Crick: Connected DNA double Helix and genes to cell foundation & production of Protein/RNA
• Developed Electro microscopes allowed ribosomes and in high Lysosomes (1930s detail).
• Study genetic of Mitois.
• Pathways: Neurotransmitters and hormones + cell manipulation/genome rev.
• Cell therapy/regen.

System of Biology

• Genomics/Proteomic/Metabolomics combined the view of cell production.
• Analysis on Heterogeneous population and artificial definition
• Personalised Medicine support is for personalised and Genetic for fundamental.