Cells Biology PDF

Exploring Cells Group 3 BS CHEM - 3B  Today, you will... Undertstand the fundamental concepts of cell, including the definition and importance of cells. Understand how cells differentiate and specialize to form tissues and organs. Analyze how cells communicate through signaling path...

Exploring Cells Group 3 BS CHEM - 3B  Today, you will... Undertstand the fundamental concepts of cell, including the definition and importance of cells. Understand how cells differentiate and specialize to form tissues and organs. Analyze how cells communicate through signaling pathways and the role of receptors and second messengers.  Let’s start! Introduction Cells are the fundamental units of life, essential for the survival, growth, and reproduction of all organisms, from simple bacteria to complex multicellular forms. They carry out crucial processes such as metabolism, energy production, and genetic regulation, and work together to maintain homeostasis and adapt to environmental changes. Cells are categorized into prokaryotic cells, which lack a nucleus, and eukaryotic cells, which have a defined nucleus and specialized organelles, reflecting the diversity and complexity of life.  A cell is the smallest unit of a living What is a cell? thing. It is the basic building block of all living organisms.  Importance of Cells Basic unit of life unicellular organisms: made of single cell that performs all life functions multicellular organisms: made of different cells that specialize to perform various functions. Genetic Information: DNA Metabolism: Chemical reactions that occur within a cell to maintain life Reproduction: Asexual: mitosis, binary fission, budding Sexual: meiosis Response to stimuli Adaptation Discovering the Cell  Discovering the Cell Robert Hooke English scientist “Micrographia” Observation of cork Coined the term ‘cell’ in 1665.  Discovering the Cell Antonie van Leeuwenhoek Dutch microbiologist “Father of Microbiology”. First person to observe living cells in detail. “animalcules”(little animals), which now we recognize as single-celled organisms like bacteria, protozoa.  Cell Theory Matthias Schleiden Theodor Schwann, Rudolf Virchow 1. All living organisms are composed of one or more cells. 2.The cell is the basic unit of structure and function in living things. 3.All cells arise from pre-existing cells.  Types of Cells Prokaryotic cell vs. Eukaryotic cell  Prokaryotic Cell Unicellular Organisms -Single cell performs all life functions Characteristics: No nucleus; DNA is in a circular form. Lack of membrane-bound organelles. Smaller and simpler structure compared to eukaryotic cells Function: survival, growth, and reproduction Reproduction: Asexual process Binary fission Budding Adaptation: Highly adaptable Size: Generally microscopic  Eukaryotic Cell Multicellular Organisms -Made up of more than one cell, often organized Characteristics: into tissues, organs, and systems. Contain nucleus; DNA is organized into chromosomes Have various membrane-bound organelles. Function: survival, growth, and reproduction Reproduction: Asexual : Mitosis Sexual: Meiosis Adaptation: More complex Size: from microscopic to large organisms  Structure of Prokaryotic Cell Cell Wall: A rigid structure outside the cell membrane, composed primarily of peptidoglycan in bacteria. Cytoplasm: A jelly-like fluid that fills the interior of the cell, containing water, salts, and various organic molecules. Nucleoid: A region in the cytoplasm where the cell’s circular DNA is located; not surrounded by a membrane. Ribosomes: Small structures made of ribosomal RNA and proteins found throughout the cytoplasm.  Structure of Prokaryotic Cell Plasmids: Small, circular, double-stranded DNA molecules found in addition to the nucleoid DNA. Flagellum: Long, whip-like appendages that can be single or multiple Plasma membrane: also known as the cell membrane, is a thin, flexible barrier that surrounds the cell. Capsule: thick, gelatinous outer layer that surrounds the cell wall in some bacteria.  Structure of Eukaryotic Cell Lysosomes: contains enzymes for digestion of cellular waste and macromolecules. Ribosomes: are small, non-membrane-bound structures found in all cells, composed of RNA and proteins Nucleus: a membrane-bound organelle that contains the cell's genetic material (DNA). Smooth Endoplasmic Reticulum: lacks ribosomes; synthesizes lipids and detoxifies substances.  Structure of Eukaryotic Cell Rough Endoplasmic Reticulum: studded with ribosomes; synthesizes proteins. Transport Vesicles: are small, membrane-bound sacs that shuttle molecules, like proteins and lipids. Cristernae: are flattened, membrane-bound sacs found in the Golgi apparatus and the endoplasmic reticulum.  Feature Plant Cell Animal Cell Absent; only a flexible cell Cell Wall Present; made of cellulose membrane Present; site of Absent; do not perform Chloroplasts photosynthesis photosynthesis Large, central vacuole for Central Vacuole Small or absent storage and support Regular, rectangular shape Irregular, more flexible Shape due to the cell wall shape  Feature Plant Cell Animal Cell Present; help in cell Centrioles Usually absent in plant cells division (mitosis) Energy Storage Starch Glycogen Present; involved in Lysosomes Rare or absent digestion and waste removal Surrounded by a cell wall and Only a plasma membrane, Plasma Membrane plasma membrane no cell wall The Plasma Membrane Determine its structure and functions. Plasma Structural Components of the Membrane Plasma Membrane also known as the cell membrane, is a semipermeable Phospolipid Bilayer: barrier that surrounds the cytoplasm of the cell. The plasma membrane is primarily made up of two layers of phospholipids. The bilayer forms the basic structure of the membrane, creating a barrier.  Structural Components of the Plasma Membrane Plasma Protein: Membrane Embedded within the phospholipid bilayer also known as the cell are proteins that can either span the entire membrane, is a semipermeable membrane (integral proteins) and be barrier that surrounds the attached to the surface (peripheral proteins) cytoplasm of the cell. Proteins perform a variety of roles: 1. Transport proteins 2.Receptor proteins 3.Enzymatic proteins Plasma Structural Components of the Membrane Plasma Membrane also known as the cell membrane, is a semipermeable barrier that surrounds the Cholesterol: cytoplasm of the cell. Cholesterol molecules are scattered within the phospholipid bilayer. Plasma Structural Components of the Membrane Plasma Membrane also known as the cell membrane, is a semipermeable Carbohydrates: barrier that surrounds the cytoplasm of the cell. Carbohydrates are attached to proteins (glycoproteins) or lipids (glycolipids) on the outer surface of the membrane. The Nucleus The nucleus is the control center of a eukaryotic cell. It contains most of the cell’s genetic material (DNA) and regulates activities like growth, metabolism, and reproduction. Structural Components of the Nucleus: Nuclear Envelope: A double membrane that surrounds the nucleus. Nuclear Pores: Small openings in the nuclear enevelope. Nucleoplasm: The gel-like substance inside the nucleus. Chromatin: DNA combined with proteins (mainly histones). Nucleolus: A dense region inside the nucleus. Ribosomes: Are not directly located in the nucleus, but they are produced in a specific part of the nucleus called nucleolus.  Energy Production Energy production in cells is a crucial process that involves converting nutrients into usable energy, which is essential for maintaining cellular functions and sustaining life. Functions of Energy Production: Cellular Work, Metabolism, Growth and Repair. Examples of Energy Production Processes: Cellular Respiration, Fermentation, Photosynthesis  Protein Synthesis Protein synthesis involves two main phases: Protein synthesis is process in which polypeptide chains are formed from Transcription: coded combinations of single amino DNA is converted into acids inside the cell. messenger RNA (mRNA) by RNA polymerases in the nucleus. The synthesis of new polypeptides requires a coded sequence, enzymes, Translation: and messenger, ribosomal, and transfer mRNA is used by ribonucleic acids (RNAs). ribosomes to synthesize proteins. Certain parts of the cell are essential for protein synthesis RIBOSOMES Responsible for synthesizing proteins by translating the genetic code transcribed in mRNA into an amino acid sequence. Ribosomes use cellular accessory proteins, soluble transfer RNAs, and metabolic energy to accomplish the initiation, elongation, and termination of peptide synthesis. ROUGH ENDOPLASMIC RETICULUM The site for synthesis of proteins that are destined to be exported from the cell. The ER also has mechanisms for maintaining the quality of the proteins synthesized, especially those destined for transport. Certain parts of the cell are essential for protein synthesis GOLGI APPARATUS The Golgi apparatus, or Golgi complex, functions as a factory in which proteins received from the ER are further processed and sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion. In addition, as noted earlier, glycolipids and sphingomyelin are synthesized within the Golgi. Cell Division Mitosis and Meiosis: Phases and Significance Mitosis Meiosis Mitosis, a process of cell duplication, or Meiosis, is the process in eukaryotic, reproduction, during which one cell gives sexually reproducing animals that rise to two genetically identical daughter reduces the number of chromosomes in a cells. Strictly applied, the term mitosis is cell before reproduction. Many organisms used to describe the duplication and package these cells into gametes, such as distribution of chromosomes, the egg and sperm. structures that carry the genetic information. Cell Division (Mitosis) Prophase The replicated pairs of chromosomes condense and compact themselves. The pairs of chromosomes that have been replicated are called sister chromatids, and they remain joined at a central point called the centromere. A large structure called the mitotic spindle also forms from long proteins called microtubules on each side, or pole, of the cell. Metaphase The nuclear envelope that encloses the nucleus breaks down, and the nucleus is no longer separated from the cytoplasm. Protein formations called kinetochores form around the centromere. Cell Division (Mitosis) Anaphase The sister chromatids are separated simultaneously at their centromeres. The separated chromosomes are then pulled by the spindle to opposite poles of the cell. Anaphase ensures that each daughter cell receives an identical set of chromosomes. Telophase Telophase, a nuclear membrane forms around each set of chromosomes to separate the nuclear DNA from the cytoplasm. The chromosomes begin to uncoil, which makes them diffuse and less compact. Along with telophase, the cell undergoes a separate process called cytokinesis that divides the cytoplasm of the parental cell into two daughter cells. Cell Division (Meiosis I) Prophase I The complex of DNA and protein known as chromatin condenses to form chromosomes. The pairs of replicated chromosomes are known as sister chromatids. Metaphase I The pairs of homologous chromosome form tetrads. Within the tetrad, any pair of chromatid arms can overlap and fuse in a process called crossing-over or recombination. Cell Division (Meiosis I) Anaphase I The spindle fibers contract and pull the homologous pairs, each with two chromatids, away from each other and toward each pole of the cell. Telophase I The chromosomes are enclosed in nuclei. The cell now undergoes a process called cytokinesis that divides the cytoplasm of the original cell into two daughter cells. Cell Division (Meiosis II) Prophase II Metaphase II The chromosomes condense, The centromeres of the and a new set of spindle paired chromatids align fibers forms. The along the equatorial plate in chromosomes begin moving both cells. toward the equator of the cell Anaphase II Telophase II The chromosomes separate at The chromosomes are the centromeres. The spindle enclosed in nuclear fibers pull the separated membranes. Cytokinesis chromosomes toward each follows, dividing the pole of the cell. cytoplasm of the two cells.  What is a Cell Communication? The study of cell communication focuses on how a cell gives and receives messages with its environment and with itself. Indeed, cells do not live in isolation. Their survival depends on receiving and processing information from the outside environment, whether that information pertains to the availability of nutrients, changes in temperature, or variations in light levels. Two Types of Cell Communication: Intercellular Intracellular Communication Communication the communication the communication between cells within a cell Catergories AUTOCRINE SIGNALING of Chemical a cell targets itself Signaling PARACRINE SIGNALING a cell signals a nearby cell Autocrine Signaling Paracrine Signaling Endocrine Signaling ENDOCRINE SIGNALING Direct Signaling a cell targets a distant cell through the bloodstream DIRECT SIGNALING a cell targets a neighboring cell through a gap junction Examples: GAP JUNCTIONS a type of cell junction in which adjacent cells are connected through connection channels. it allow direct cell-cell transfer of ions, small molecules, and electrical impulses. NEUROTRANSMITTERS are chemical messengers that carry, boost, and balance signals between nerve cells and target cells throughout the body. HORMONES a chemical that is made by specialist cells, usually within an endocrine gland, and it is released into the bloodstream to send a message to another part of the body.  Specialized Cells What are specialized cells? a cell that has a unique structure that allows it to carry out a specific job in the body. Examples of Specialized Cells: neurons muscle cells epithelial cells others: red blood cells, white blood cells, reproductive cells, and many more  Specialized Cells Neurons the basic working unit of the brain. it is a specialized cell designed to transmit information to other nerve cells, muscle, or gland cells. Muscle Cells are found in bundles which make up our muscles. these cells are able to contract (get shorter) and relax (return to original length). Epithelial Cells are a type of cell that covers the inside and outside of the surfaces of your body. it covers the skin, body cavities, and blood vessels. they perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.  Summary Importance of Understanding Cell Biology: Cells are the primary building blocks of life, and it is essential to understand their structure, metabolism, and division to comprehend life processes. Aside from that, it provides explanation of inheritance patterns, shows evolutionary processes, and gives insight into how cells differentiate and organize into tissues What are cells? and organs that helps us understand A cell is the smallest unit of a living development and growth. To conclude, thing. An organism may be made of one studying cells offers a way to learn about cell or many cells. growth, reproduction, and all other functions that living things perform.