biology

• what are Prokaryotic cells


  • Simple cells lacking a distinct nucleus
  • They have no membrane-bound organelles
  • DNA is typically a single, circular molecule found in the nucleoid region
  • They are usually smaller and less complex than eukaryotic cells
  • Found in bacteria and archaea
• Prokaryotic cell structure


  • Cell membrane
  • Cytoplasm
  • Ribosomes
  • Cell wall in some cases
• what are Eukaryotic cells


  • Complex cells containing a distinct nucleus enclosed by a nuclear membrane
  • They possess membrane-bound organelles, such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and chloroplasts (in plant cells)
  • DNA is organised into multiple linear chromosomes located within the nucleus
  • Generally larger and more structurally and functionally complex than prokaryotic cells
  • Found in plants, animals, fungi, and protists
• Eukaryotic cell structure


  • Cell membrane
  • Cytoplasm
  • Organelles
  • Cytoskeleton
• function of the Cell membrane


  Controls the passage of substances in and out of the cell, maintaining cell integrity (structure)
• Cytoplasm


  The gel-like substance that fills the cell, containing enzymes and nutrients necessary for cellular processes
• Nucleoid


  Region where the genetic material (DNA) is located; it lacks a nuclear membrane
• Ribosomes


  Sites (area) of protein synthesis, where RNA (Ribonucleic Acid) molecules are translated into proteins
• Cell wall


  Provides structural support and protection to the cell, found in bacteria but not archaea
• Flagella


  Tail-like appendages (something attached) that facilitate movement in some prokaryotic cells
• Pili or fimbriae


  Hair-like appendages (something attached) that help bacteria stick to surfaces or transfer DNA during conjugation
• Capsule


  A protective layer outside the cell wall in some bacteria, aiding in protection and attachment to surfaces
• Plasmids


  Small, circular DNA molecules that can replicate independently and may carry genes for antibiotic resistance or other traits
• Gas vesicles


  Structures that regulate flotation in some aquatic bacteria, allowing them to move up or down in the water column
• Endospores


  Highly resistant structures formed by some bacteria under harsh conditions, allowing them to survive adverse environments
• Cell membrane


  Controls the movement of substances in and out of the cell, maintaining cell integrity
• Nucleus


  Contains the cell's genetic material (DNA), regulating gene expression and providing instructions for protein synthesis
• Cytoplasm


  The gel-like substance that fills the cell, containing organelles and serving as the site for many cellular processes
• Endoplasmic reticulum (ER)


  A network of membranes involved in protein and lipid synthesis, with rough ER attached with ribosomes and smooth ER involved in lipid metabolism and detoxification
• Golgi apparatus


  Modifies, sorts, and packages proteins and lipids for transport to their final destinations inside or outside the cell
• Mitochondria


  Powerhouses of the cell, generating energy (ATP) through cellular respiration
• Lysosomes


  Digestive organelles containing enzymes that break down waste materials and cellular debris
• Vacuoles


  These organelles, found in plant cells, are involved in regulating osmotic balance, maintaining cell turgor pressure, and storing water, nutrients, and waste materials.
• Chloroplasts (in plant cells)


  Site (area) of photosynthesis, converting light energy into chemical energy (glucose) in the presence of chlorophyll
• Ribosomes


  Sites of protein synthesis, where mRNA (transports messages around the cell) molecules are translated into proteins
• Cytoskeleton


  A network of protein filaments (microtubules, microfilaments, and intermediate filaments) that provide structural support, maintain cell shape, and facilitate cell movement and intracellular transport
• Cell wall (in plant cells and some other organisms)


  Rigid structure outside the cell membrane that provides support and protection
• function of a Light microscope


  • Uses visible light to illuminate specimens
  • Magnifies objects up to around 1000 times their actual size
  • Utilises a system of lenses to magnify and focus the image
  • Can observe living cells and tissues
  • Generally less expensive and easier to use than electron microscopes
  • Limited resolution compared to electron microscopes, typically around 200 nanometers
  • Commonly used in biology, medicine, and materials science for routine laboratory work and educational purposes
• Fluorescence microscope


  • Uses a specific type of light source to excite fluorescent molecules within a specimen
  • Specimens are labelled with fluorescent dyes or proteins that emit light of a different colour when excited by the light source
  • Filters are used to select the wavelengths of light that excite the fluorophores and to filter out unwanted background light
  • Allows for the visualisation of specific structures or molecules within cells or tissues
  • Can provide high contrast images with minimal background noise
  • Used extensively in cell biology, molecular biology, immunology, and neuroscience for studying the localization and dynamics of molecules within cells, as well as for diagnostic purposes
  • Enables researchers to perform various techniques such as fluorescence microscopy, confocal microscopy, and super-resolution microscopy
• 
  

  Electron microscope

  An electron microscope is a powerful tool that uses a beam of electrons instead of light to magnify tiny objects, allowing scientists to see details at the atomic level.
• function and strucutre of a Cell membrane


  • Barrier: Separates inside and outside of the cell
  • Selectively permeable: Controls what enters and exits
  • Transport: Moves molecules in and out
  • Signalling: Allows communication
  • Adhesion: Helps cells stick together
  • Compartmentalization: Divides cells into parts
  • Gradient Formation: Establishes differences
  • Energy Production: Generates ATP
  • Recognition: Identifies self and others
• function of a Nucleus


  • Genetic Control: Holds DNA, which guides the cell's activities
  • RNA Production: Makes RNA from DNA, important for building proteins
  • Ribosome Assembly: Builds ribosomes, which make proteins
  • DNA Copying: Ensures DNA is copied accurately during cell division
  • Molecule Transport: Controls what goes in and out of the nucleus
  • Cell Communication: Participates in cell signalling
  • DNA Organization: Helps organise DNA for proper function
  • DNA Repair: Fixes DNA damage to keep the cell healthy
• Function of Ribosomes

  • Protein Making: Ribosomes build proteins by following instructions from the cell's genetic material
  • Cell Growth and Repair: They create proteins needed for the cell to grow, repair itself, and function properly
  • Secretion: Ribosomes on the rough endoplasmic reticulum (RER) make proteins for export or for use in cell membranes
  • Free Ribosomes: Those floating in the cell make proteins used internally
• Function of Golgi bodies

  • Protein Modification: Modifies proteins received from the endoplasmic reticulum
  • Glycosylation: Adds carbohydrate chains to proteins, forming glycoproteins
  • Lipid Processing: Processes and packages of lipids synthesised by the endoplasmic reticulum
  • Vesicle Formation: Forms vesicles for transporting molecules within the cell or for excretion
  • Excretion: Plays a key role in the secretion of proteins and lipids from the cell
• Lysosomes


  • Digestion: Breaks down waste and cellular debris
  • Recycling: Recycles biomolecules for reuse
  • Cellular Maintenance: Removes damaged organelles
  • Defence: Destroys pathogens
  • Apoptosis: Facilitates programmed cell death
• Mitochondria


  1. ATP Production: Mitochondria produce ATP, the cell's energy source, through aerobic respiration, extracting energy from nutrients like glucose.
  2. Cellular Respiration: They break down nutrients to produce ATP, providing essential energy for cellular activities.
  3. Calcium Regulation: Mitochondria help regulate calcium levels, vital for processes like muscle contraction and signaling.
  4. Heat Production: Mitochondria can generate heat through uncoupling, aiding thermoregulation in certain animals.
• Golgi bodies


  • Protein Modification: Modifies proteins received from the endoplasmic reticulum
  • Glycosylation: Adds carbohydrate chains to proteins, forming glycoproteins
  • Lipid Processing: Processes and packages of lipids synthesised by the endoplasmic reticulum
  • Vesicle Formation: Forms vesicles for transporting molecules within the cell or for excretion
  • Excretion: Plays a key role in the secretion of proteins and lipids from the cell
• The Golgi apparatus acts as a processing and distribution centre within the cell, ensuring molecules are properly modified, sorted, and transported
• Lysosomes


  • Digestion: Breaks down waste and cellular debris
  • Recycling: Recycles biomolecules for reuse
  • Cellular Maintenance: Removes damaged organelles
  • Defence: Destroys pathogens
  • Apoptosis: Facilitates programmed cell death
• Mitochondria


  1. ATP Production: Mitochondria produce ATP, the cell's energy source, through aerobic respiration, extracting energy from nutrients like glucose.
  2. Cellular Respiration: They break down nutrients to produce ATP, providing essential energy for cellular activities.
  3. Calcium Regulation: Mitochondria help regulate calcium levels, vital for processes like muscle contraction and signaling.
  4. Heat Production: Mitochondria can generate heat through uncoupling, aiding thermoregulation in certain animals.