1. cells and microscopy

cell theory

where all living organisms are composed of one (unicellular) or more (multicellular) cells

cell

basic structural and physiological unit of all living organisms and is the smallest unit capable of surviving independently, they are the site of metabolic process and contain genetic information

field of view

circular area visible down a microscope

magnification

number of times large an object appears

resolution

ability to distinguish two distinct objects separately and see detail

eyepiece graticule

scale inserted to eyepiece which is calibrated with a state micrometer and then used to measure cells

stage micrometer

a slide with typically 1 mm ruler on it

light microscope

a cheap low magnification microscope with limited resolution that requires little training and maintains natural colours (1500x, 200nm)

transmission electron microscope

an electron microscope which produces a 2D black and white image at high resolution and magnification (500,000x, 0.1nm) expensive and requires training

scanning electron microcsope

an electron microscope which passes a beam of electrons back and forth over a sample to produce a black and white 3D image, expensive and requires training, low resolution and magnification (100,000x, 0.1nm typiclay 5-20µm tho)

confocal laser scanning microscope

light is scanned through an object and reflected or emitted light is detected, produces a 2D image or 3D image by stacking and requires less training than electron microscopes, lower magnification and low resolution (2000x, 200nm)

transmission electron microscope preparation

complex preparation where tissue is fixed, dehydrated embedded in resin then very thin sections cut and stained using heavy metal salts finally placed on a copper grip in a vacuum

scanning electron microscope preparation

variable ease of preparation, where samples surface is coated in gold atoms to scatter electrons

confocal laser scanning microscope preparation

variable ease of preparation where samples may be combined with fluorescent markers

methylene blue

stain which is able to be added to living cells without been fixed

fixing

process to attach stain to tissue using alcohol which makes proteins and nucleic acids insoluble and kills the cells

differential stain

a stain which stains different structures different colours to help identify them

magnification calculation

image size (mm) ÷ actual size (nm or µm)

1, 3, 2, 6, 5, 4

1. place the stage micrometer on microscope and focus onto it with 4x lens
2. workout length of 1 eye peice graticule division with the stage micrometer
3. rotate eyepiece graticule to align with stage micrometer
4. measure object with eyepiece graticule and calculate its length
5. remove stage micrometer and place object under
6. repeat with the each lens

calculate eye peice graticule length

stage micrometer measurement (µm) ÷ divisions on eyepiece graticule

1, 6, 2, 8, 5, 4, 7, 3, 9, 10

1. wear latex free gloves
2. a spreader at 45˚ is pushed along to spread blood by capillary action forming a smear
3. dilute with distilled water and leave for 5-7mins
4. fix with methanol
5. air dry slide
6. place a drop of blood on end of slide
7. flood with leishman’s stain for 2 mins
8. label slide
9. wash slide to remove excess stain till it appears pale pink
10. blot gently with filter paper and apply a coverslip

latex free gloves worn

prevent contamination, protect from pathogens, reduce allergies and skin reactions

leishman’s stain

a stain which contains methylene blue and eosin

stains different compounds different colours

methylene blue stains nucleic acids blue-purple

eosin stains cytoplasmic proteins pink-red

erythrocyte/red blood cell

biconcave discs (squeeze and SA) no nucleus or mitochondria, lifespan of 120 days, carry oxygen and some CO2

thrombocyte/platelet

biconcave discs of cytoplasm fragments form megakaryocytes (giant cells) life span of 6-7 days. contribute to blood clotting and clot formation

neutrophil

most numerous leucocyte, multilobed nucleus (squeeze) granular cytoplasm containing lysosomes, engulf bacteria in phagocytosis, non specific

lymphocyte

smallest leukocyte, B and T versions, large darkly stained nucleus and clear cytoplasm with no granules, B produce immunoglobulins, helper T produce chemicals coordinating immune response and cytotoxic T destroy specific cells

monocyte

largest leucocyte, large kidney bean nucleus, clear cytoplasm, few granules, darl stained nucleus, carry out phagocytosis

granulocytes

type of leucocytes with granules that is neutrophils

agranulocytes

type of leucocytes with little granules that is monocytes and lymphocytes

precautions when sampling own blood

swap wound with ethanol before and after and cover with dressing, don’t work with others blood, dispose of all materials in bleach, wash hands

haemocytometer

chamber used to count cells, contains a 1mm by 1mm grid, count in 0.2mm square, 0.1mm depth, repeat 5 times

calculate cells in haemocytometer

1÷volume x number of cells x dilution factor

north west rule

count cells touching top and left but not right or bottom middle line

3, 1, 5, 2, 6, 4

1. apply a cover slip
2. count cells in one small central square
3. stir yeast cells in suspension and dilute using trypan blue to identify usable cells
4. calculate mean
5. introduce a sample under coverslip with a small pipette by capillary action
6. count in 4 other small squares

dacies fluid

used to dilute erythrocyte as it is isotonic preventing cells bursting or clumping

trypan blue

used to dilute yeast or mammalian cells as it is taken up by dead cells

flow cytometer

electronic counting apparatus to count and sort blood cells. By attaching fluorochromes to antigens which emit fluorescent light when a laser is shone

compartmentalisation

internal structures of cells are divided by membranes

organelles

intracellular structures with a specific function

eukaryotic cells

plant and animal cells with a nucleus

prokaryotic cells

bacteria cells with no nucleus

nucleus

largest organelle sounded by double envelope (nuclear envelope) with pores, contains chromatin( DNA coiled around histones), controls activities of the cells by mRNA

nucleolus

dark patch in nucleus which produces rRNA and assembles ribosomes

mitochondrion

spherical or sausage shaped, double membrane, inner is highly folded, site of aerobic respiration

chloroplast

double membrane, contains stack of membrane bound compartments called thylakoids, site of photosynthesis, only in plants

golgi body

stack of membrane bound flattened sacs, receives proteins vesicles from RER and modifies them, the repackaged to vesicles

vesicle

membrane bound sac moved within cells by cytoskeleton, transports materials around cells

ribosome

tiny organelle bound to RER or free in cytoplasm, made of 2 subunits of rRNA and proteins, site of protein synthesis

rough endoplasmic reticulum RER

series of flattened membrane bound compartments called cisternae, continuous membrane with nuclear envelope, ribosomes on surface, packages proteins from ribosomes into vesicles

smooth endoplasmic reticulum SER

series of flattened membrane bound compartments with no ribosomes, carry out lipid synthesis, metabolism and membrane formation

lysosome

spherical membrane bound vesicle produced by golgi body, contains hydrolytic enzymes, same function as vacuole, enzymes break down waste

cytoskeleton

network of protein fibres, including microfilaments (actin), microtubules (tubulin), intermediate filaments (fibrous proteins), support cells and organelles, motor proteins use ATP to move organelles/molecules

pair of centrioles

cylinder of 9 triplets of microtubules, 2 are arranged at right angles to form centrosome, organise spindle fibres in nuclear division

cillia

hair like extensions, 9+2 arrangement of microtubules, not really in plant cells, use ATP to beat and move fluids

eukaryotic flagellum

few long hair like extensions, 9+2 arrangement of microtubules, not really in plant cells, use ATP to beat and whole cell

cell wall

made of cellulose, located outside plasma membrane, gives shape and support, stops bursting, only in plants

plasmodesmata

strands of cytoplasm that pass through channels in cell wall between adjacent cells, only in plants

large permanent vacuole

fluid filled organelle, filled with water and solutes, pushes cytoplasm against cell wall making it turgid, only in plants

tonoplast

membrane around vacuole which is selectively permeable

circular DNA

genetic material of prokaryotic cell, naked and located in cytoplasm

plasmid

small circular DNA in some prokaryotes, carry additional genes for a slective advantage

pili of fimbriae

specific attachment of prokaryotes to other cells

mesosome

infolded regions of cell surface of prokaryotes

capsule

polysaccharide outside layer, attachment to surfaces, resists desiccation (drying up), protection against been engulfed, prokaryotic cells

flagellum

long hair like extensions for movement

7, 1, 2, 4, 6, 5, 8, 3, 9

order production of proteins:


1. messenger RNA leaves by nuclear pore
2. messenger RNA assembles to ribosome attached to RER
3. vesicle fuses with plasma membrane
4. ribosome reads mRNA and synthesis protein which is transported through RER and packaged into transport vesicle
5. golgi apparatus modifies proteins and repackages them into secretory vesicle
6. proteins transported in vesicles along cytoskeleton by motor proteins from RER to golgi apparatus
7. a gene is transcribed into mRNA in nucleus
8. vesicles carrying modified proteins are transported along cytoskeleton by motor proteins to cell surface
9. membrane opens and modified proteins released