AS - Cells and microscopy Flashcards
Light Microscopes, Resolution Magnification Advantages Disadvantages
M = x1500
R = 200nm
+ Can view living organisms, Easy, cheap, small
- Limited resolution
Transmission Electron Microscope Resolution Magnification Advantages Disadvantages
M = x100 000
R = 0.1nm
+ Higher resolution and magnification than LM
- Specimen cannot be alive, black and white images
Scanning Electron Microscope Resolution Magnification Advantages Disadvantages
M = x500 000
R = 0.1nm
+ High magnification, can make 3D images
- Cannot be alive specimen, large, expensive
Confocal Microscope Resolution Magnification Advantages Disadvantages
M = x2000
R = higher than LM, lower than EM
+ Looking at living cells
Understanding relationships between cells
Highlighting individual components of cells
- large, expensive
Magnification Calculation
Image size = Magnification x Object size
(micrometres) = 1mm/1000
Leishman’s Stain
Blood dried firsr, fixed with methanol, flooded left for 2 minutes than diluted with water, left 5-7 minutes, washed
Wright’s stain
White Blood cell counts
What happens if blood smear is spread to thin/thick
too thin: small sample
too thick: individual cells cannot be seen
Blood Functions
- deliver oxygen/ nutrients to tissues
- removal of waste from tissues
- clotting
- distribution of heat to regulate core body temperature
What are Leucocytes
White Blood Cells
Granulocytes - contain granules
Agranulocytes - no granules
Neutrophils
Help body defend against fungal or bacterial infections
Multi lobed nucleus - allows flexibility
Engulf and breakdown bacteria
Thrombocytes (platelets)
2-3(micrometer) diameter, biconcave discs
produced in bone marrow + no nucleus
blood clotting
circulate in blood for 6-7 days
Erythrocytes
Deliver oxygen/ CO2
develop in bone marrow circulate i blood stream 100-120 days
Diameter = 6.2-8.2(micrometers)
2-2.5 (micrometers) thick
No nucleus, large SA/V ratio, biconcave flexible + squeeze through capillaries
Lymphocytes
B: produce immunoglobulins
T: Helper T - produce cytoxins coordinate immune response.
Cytotoxic T cells: bind to antigens and destroy them
Monocytes
Phagocytosis, remove dead cell debris
Nucleus
Control activites of cell, genetic material, manufacture rRNA
Mitochondria
1-10 (micrometers), produce ATP, energy carrier molecule, carry out later stages of aerobic respiration
Cell Wall
Control what enters and exits cell
Smooth Endoplasmic Reticulum
synthesise and store, transport lipids and carbohydrates
Rough Endoplasmic Reticulum
Large surface area for protein synthesis + transport
Ribosomes
Site of protein synthesis
Golgi
Assemble polypeptide to proteins, place into vesicles
Plant (only) organelles
Chloroplast: photosynthesis
Large Vacuole: Keeps cell turgid
Prokaryotic cells
Circular DNA, Plasmids, mesosome, pili, flagella
Cytoskeleton
Moves organelles through cytoplasm Microtubules: 23nm Intermediate filaments Microfilaments Maintain shape + structure of cell
Protein Synthesis
1) Genetic info copied to Mrna
2) Mrna enters from nucleus - Cytoplasm
3) Mrna attaches to ribosome
4) Ribosome translates code into polypeptide chain
5) Protein - Vesicle - transported to Golgi
6) Golgi packages protein
7) Secreted out of cell
Cell membranes exist…
around outside of ALL cells, surrounding organelles in Eukaryotic cells
Cell membranes functions
Control entry and exit of molecules in organelles
Provide an internal transport system
Isolate organelles to allow them to carry out specific chemical reactions
Phospholipid Bilayer
Disallows soluble molecules to cross membrane
Allows membrane flexibility
Allows membrane to be stable
Phospholipid structure
Phosphate - Glycogen - 2 fatty acid tails
Proteins
Intergral: within bilayer, sometimes intrinsic
Peripheral: edges of bilayer, extrensic proteins
Proteins functions
Structural support Carry soluble molecules across membrane Form channels for active transport Help cells adhere to each other Receptors for hormones, neurotransmitters
Cholesterol
Hydrophobic - water = :(
Provides strength
Regulates fluidity
Simple transport
Passive
High concentration –> Low concentration
DOWN concentration gradient
Factors affecting: Concentration gradient, molecule size, surface area, diffusion distance
Facilitated Diffusion
Passive
Channel/Carrier proteins
Bulk transport
Endocytosis: bulk movement of material into cell
Pinocytosis: Cells engulf liquid material
Phagocytosis: Cells engulf solid material
Active Transport
Uses carrier protein and ATP to change shape
