2.1.1 Basic Components of Living Systems Flashcards
Cell theory states that:
- both plant and animal tissue composed of cells
- cells are the basic unit of all life
- cells only develop from existing cells
Compound light microscope
Mag = 2000X
Res = 200nm
Objective and eyepiece lenses
Dead/alive specimens
Inexpensive
Can’t see ultrastructure of cell
Why is staining used?
To observe specific organelles
To differentiate between different types of cell
To distinguish between diff tissues
Positive staining
e.g. methylene blue
+ve charged stain attracted to -ve components
Negative staining
e.g. nigrosin
Contrast between anything and water
Units of measurement
mm ➗ 1000 = micrometer
micrometer ➗ 1000 = nanometer
definition of MAGNIFICATION
How many times larger the image is than the actual size of the object viewed
Calculating magnification
Mag=image➗actual
I
A M
definition of RESOLUTION
The ability to distinguish individual objects as separate entities
TEM
Mag = 500,000X Res = 0.5 nm
Beam of electrons
Travel through specimen
Create a b&w 2D image
Ultrastructure can be seen
SEM
Mag = 100,000X Res = 3-10 nm
Beam of electrons
Across surface of specimen
Reflected atoms collected
3D images of surface
Laser scanning confocal microscope
Res = higher than light
Single spot of focused light across specimen (point illumination)
Causes fluorescence from components labelled w dye
2D image
Light vs Electron
Light =
inexpensive,portable,simple prep, natural colour,X2000 mag,living and dead,200nm res
Electron =
expensive,large,complex sample prep,b&w images,X500,000 mag,dead specimens only,0.5/3-10nm res
Light mag/res
Mag X2000
Res 200nm
TEM mag/res
Mag X500,000
Res 0.5nm
SEM mag/res
Mag X100,000
Res 3-10mm
Nucleus
DNA Synthesis of proteins Nuclear envelope=double membrane Nuclear pores Chromatin coils into chromasomes
Nucleolus
In nucleus
Produces ribosomes
Mitochondria
Sire of final stages of cellular respiration
Energy stored in bonds
Production of ATP
Double membrane
Vesicles
Sacs for storage and transport
Transport materials inside the cell
Centrioles
Made of microtubules, two form centrosome
Flagella and cilia
Endoplasmic reticulum
Network of membranes with flattened sacs / cisternae
Rough ER
Ribosomes on surface
Synthesis and transport of proteins
Smooth ER
Lipid and carbohydrate synthesis
Storage
Ribosomes
Made of RNA
Made in nucleolus
Site of protein synthesis
Golgi apparatus
Cisternae
No ribosomes
Modify proteins
Packages proteins into vesicles
Protein production
i) synthesised on ribosomes on ER
ii) pass into cisternae, packaged into transport vesicles
iii) move to golgi via cytoskeleton
iv) vesicle fuses w cis face of golgi, proteins enter. Proteins modified then leave on trans face
v) secretory vesicles carry to surface membrane = exocytosis
Cellulose cell wall
Plants Carbohydrate Freely permeable Shape Defence mechanism
Vacuoles
Plants Contain cell sap Maintain turgor Membrane=tonoplast Selectively permeable
Chloroplasts
Plants Photosynthesis Green Double membrane Fluid=stroma Internal membranes=thylakoids Several thylakoids=granum Grana joined to membrane called lamellae
Lysosomes
Specialised vesicles
Hydrolytic enzymes
Break down waste material
Immune system
Cytoskeleton
i) microfilaments
Actin, contractile, cell movement/contraction
ii) microtubules
Globular tubulin, proteins, shape, tracts for movement
iii) intermediate fibres
Strength, shape
Prokaryotes
No nucleus Circular DNA Non-membrane-bound organelles Peptidoglycan cell wall 70s smaller ribosomes Reproduce: binery fission Unicellular
Eukaryotes
Nucleus Linear DNA Membrane-bound organelles Chitin cell wall (fungi) Cellulose cell wall (plants) 80s larger ribosomes Reproduce: asexual/sexual Uni/multicellular
