Unit 4


Microscopes



Light 

  • Uses light as an energy source 

  • Mirrors direct the light to your eyes 

  • Lenses are used to enlarge and focus image 



Electron

  • Uses electricity as energy source 

  • Magnets direct flow of electrons for viewing 

  • Scanning 

    • e- reflect off the specimen for 3d viewing 

  • Transmission 

    • e- flow through providing an internal structure 



Structure of Cell membrane



Fluid mosaic model 



Fluid

Phospholipids: create flexible bilayers act as water barrier

Cholesterol: regulates the fluidity of the cell membrane 



Mosaic

Proteins: carry out various functions 

Transport proteins move substances from one side of the membrane to another.




Why are cells small in size 







Prokaryotic Cell



Cytoplasm: Gel-like fluid (cytosol) that contains chemicals (proteins) and cell structures (ribosomes) inner region of the cell contained by cell membrane


Bacterial chromosome: circular DNA that contains genetic information 

Nucleoiod: region of the cytoplasm where the bacterial chromosome is located 

Ribsomoes: Proton synthesis, creation of proteins for the cell 


Plasmid: extra small pieces of DNA that provide superpowers to cells

  • Antibiotic resistance: cant be fought off by antibodies & neither will its offsprings 

  • Motility: mobility by itself & spreads easily 

  • Production of a capsule: proteins itself & moves around & sticks to surfaces 

  • Fertility: ability to reproduce sexually, creation of new bacteria


Pathogenic: ability to cause infection or disease 

Cell membrane: made up of phospholipids, cholesterol proteins & carbohydrates, it creates the boundaries of the cell it acts as a barrier controlling what comes in & out 


Cell well: made up of a mixture of carbohydrates and proteins called peptidoglycan provies structure & shape 

Capsule: may or may not be present, attaches to surfaces to induce infections, strong enough to resist digestion by white blood cells 


Flagella: made up of protons, extending from the cell membrane, allow cells to move, moves by rotation. 

Fimbriae: made up of protons that extend from the cell membrane for attachment ot surfaces. 

Extracellular fluid: fluid on the outside of the cell

Eukaryotic Cells

Have compartmentalisation while prokaryotic don’t

The process of creating compartments closed off within the cell



Vacuole 


Large vesicles with specialised functions 

  1. Food vacuole 

    1. Part of phagocytosis brings in large substances 

  2. Central vacuole 

    1. Found in plants; usually the largest structure 

      1. Stores water to create ‘pressure’ that helps with structure & shape of the cell & plant

      2. Stores chemicals 

      3. Stores waste 

  3. Contractile vacuole 

    1. Found in freshwater protists; like the paramecium 

      1. Removes excess water from the cell



Water always moves to regions that have more solutes. 

Paramecium 

Water rushes in to fill up the vacuole when it reaches a certain point it opens a trap dopr and push it out to maintain a certain pressure



Endomembranal System 


Nucleus



Controls the function of the cell & stores genetic material 

Nucleolus: stains deeply create rRNA & tRNA

Chromatin: unwinded DNA wrapped around proteins 

Nucleoplasm: the cytoplasm of a nucleus

Inner nuclear membrane: inner wall 

Outer nuclear membrane: outer wall 

Nuclear pores: openings between the membranes 

Proton complex control the opening and closing of the pores 

Ribosomes: made up of proteins & rRNA on outer membrane 

Nuclear envelope: where the nucleus is held



Ribosomes


Proteins synthesis 

Made up of two parts; large subunit and small subunit 

Made with proteins & rRNA

Bound ribosomes: attached to the membrane 

Free ribosomes: located in the cytoplasm 


Bound ribosome creates proteins for:

  • Organisms they are attached to 

  • Other organelles 

  • Cell membrane 

  • Exporting out the cell 



Endoplasmic reticulum (ER)

Endo: in 

Plasmic: thick fluid 

Reticulum: network

Smooth ER

Tubular network of membrane

Liquid synthesis stores Ca^2+ detoxification of harmful chemicals 



Rough ER

Flattened sack-like membrane covered with in bound ribosomes for protein synthesis 


Functions 

  • Bound ribosomes release the polypeptide chain into the lumen of the RER

    • Lumen: space contained within a structure 

  • Polypeptide chain twists & folds into 2 or 3-degree structure % sugar chains are attached to create glycoprotein. 

    • Sugar chains act as tags for sorting & delivering. 

  • Glycoproteins are sorted into the ends of the RER for delivery when the transport vesicle is created by building 

    • Trans vesicle

    • Budding: a process that creates vesicles by pinching off segments from a membrane 

  • Newly created transport vehicle packages with protons is delivered to the next destination. 

    • Vesicles: membrane-bound structures that have a spherical appearance and store or transport substances 

    • Big ones are called vacuoles 


Golgi Apparatus 

Functions

  • Receives chemicals from other organelles 

  • Modifies the chemicals 

  • Sorts & packages the chemicals 

  • Ships the chemicals to their final destination 



Possible destination 

  • Other organelles 

  • Cell membrane

  • Export out of the cell 

  • They become new organelles 

    • Exp: Lysosome 



Digestive enzymes Lysosome Plasma membrane Digestion Food vacuole (a) Phagocytosis Peroxisome (b) Autophagy Lysosome Mitochondrion Vesicle Digestion



Lysosome



Specialised vesicle filled with hydrolytic enzymes 



Breaking down… using water 

  • Protons 

  • Carbohydrates 

  • Lipids 

  • Nucleic acid 



Major functions

  • Phagocytosis

    • A cell process that involves lysosomes which breaks down large structures 

  • Autophagy 

    • A cell process where the cell digests…

      • Old worn-out organelles 

      • Damages organelles 

      • Uneeded organelles 


End of endomembranal system 



Energy organelles 


Mitochondrion 

Generates energy in the form of ATP 

Found in all eukaryotic cell 





Chloroplast 

Harvest light to produce food by photosynthesis found in plants & algae 

Chlorophyll is the chemical that absorbs light to provide energy to the chloroplast 



Cytoskeleton 

Skeleton of the cell located in the cytosol 

Cytoplasm = cytosol + organelles 



Components 





Flagells & cilia 



Flagella

Few and very long

Sperm cell



Cilia 

Many & very short 

Inside the throat 



Flagells & cilia have the microtubles in a 9 (doubles) and 2 (singles) arrangement 





Extra Cellular Matrix 


Located on the outside of the cell made up of a network of proteins and carbohydrates found in the extracellular fluid & attached to the cell membrane 


Fibronectin: holds cell matric to the membrane. 


Functions 

  • Holds cells together, creating tissues using collagen 

  • Communication between cells 

  • Identification of self using immunoglobulins (glycoproteins) 

Cell junction

Attach cells together that are adjacent to each other. 


Functions:

  1. Tight junction

    1. Holds cells tightly, preventing any substance from passing between them 

    2. Important for the skin & intestine 

    3. Made up of intermediate filaments (fibrous)

  2. Desmosome (anchoring J.)

    1. Holds cells together in place but not tightly 

    2. Important for lung cells & cells in capillaries 

    3. Made up of intermediate filimates 


  1. Gap junction

    1. Membrane protein (globular) that connects two adjacent cells to create tunnels 

    2. which allows the cytoplasm of one cell to mix with the cytoplasm of another

    3. Such as cardiac muscle 



Cell Wall Plants 

  • Made up of cellulose (B Glu)

  • Provides the shape of a structure of a plant cell 

  • Resits pressure created by cells to become rigid 

  • All plants have a primary cell wall, but some woody plants will also have a secondary cell wall

  • Cell walls are always built on the outside of the cell membrane. 


Plasmodesmata 

  • Plant cell junctions create opening which connect the cytoplasm of adjacent cells 

  • Permit rapid movement & communication between plant cells 


Peroxisomes 

  • Specialised vesicles filled with hydrogen peroxide (H2O2)

  • Mainly found in plants (found only in our liver)

  • Oxidation of amino acids & fatty acids 

  • Detoxify poison 

*  not produced by Golgi apparatus 



Anatomy of a microscope



Handling

  • Hold with 2 hands 

  • Don’t slide the microscope 

  • Rotate the head if someone wants to see



Parts 

  • Eyepiece (ocular lens)

    • Magnifies specimen 10x 

  • Diopter adjustment 

    • Zooms in & out 

  • Head 

    • Tube w/ mirrors direct light to the eye 

  • Nose piece 

    • Changes objective lens 

  • Objective lens 

    • Scanning objective lens (4x)

    • Low-power objective lens (10x)

    • High-power objective lens  (40x)

    • Oil immersion lens (100x)

  • Arm 

    • Holds upper structure 

  • Course adjustment 

    • Moves stage up & down quickly 

  • Fine adjustment 

    • Moves stage slightly up & down 

  • Stage 

    • Where you place your specimen/ must be over the hole 

  • Stage clip 

    • Holds specimen in place 

  • Stage control 

    • Moves stage towards or away 

    • Moves stage left or right 

  • Condensor 

    • Controls how much light is coming in (pupil)

  • Brightness adjustment 

    • Dimmer switch 

  • Illumination 

    • Light source 

  • Light switch 

  • Base 

    • Supports the microscope, keeps it sturdy 


How to draw your specimen 

  • Use a pencil & unlined paper. 

  • Take up most of the paper 

  • Draw on the left side 

  • Boundary structures of the specimen is more important than the secondary 

  • Stipple method to show dark regions 

  • Draw clear, continuous lines, no sketches 

  • Draw part by part → look & draw 

  • Label parts you can identify; lines need to be drawn by a ruler 

  • Do not cross label lines; must touch what they point to 

  • No arrowheads 

  • Include descriptors 

  • Include magnification used 

  • Possible specimen descriptors 

    • Cross section 

    • Longitudinal section 

    • Dry mount 

    • Water mount 

    • Stained 

  • Include the type of magnification bottom right