cells Flashcards
eukaryotic cell is…
cell with membrane bound organelles
can become specialised by process of differentiation
cell surface membrane
phospholipid bilayer
controls entry and exit of substances, sometimes requires active transport or membrane proteins
nucleus
double membrane
contains chromosomes
mitochondria
double membrane
fold called cristae (large SA)
site of aerobic respiration
chloroplasts
plants only
double membrane
site of photosynthesis
geranium (stack) individually called thylakoids
geranium connected by lamella
stroma (fluid)
Golgi apparatus/body
modifies proteins
role in ‘packaging’ and secretion of proteins
made of flattened sacs called cisternae
circles pf diagrams are Golgi vesicles which take proteins and get them ready for export
lysosomes
small membranous vesicles
breaks down ‘unwanted’ cells/organelles
contain lysozymes (enzymes that kill pathogens)
ribosomes
round shaped organelles that synthesise protein
some attach to surface of rough ER
rough endoplasmic reticulum
large no. of ribosomes attached to surface
synthesise and ‘make changes’ to proteins
smooth endoplasmic reticulum
no. of ribosomes on surface
lipid synthesis
toxin modification
glycogenesis
cell wall
plants only
determines strength, shape and support
composed of cellulose
controls tutor pressure
vacuole
membranous sacs
store water, nutrients and waste products
prokaryotic cells
no membrane bound organelles
smaller than eukaryotes
smaller ribosomes
DNA is not encoded in nucleus
DNA= singular circular molecule, not associated with proteins
may have plasmids, capsule and flagella
basic structure of a virus is…
genetic material can be DNA or RNA
capsid coats material, protects it
attachment proteins- attach to receptors on host cells and allow the virus to enter and inject genetic material
magnification is…
how large an image is compared to real life
resolution is…
the minimum distance where two objects are distinguishable as two objects
features of an optical microscope
light focused through condenser lens, then through specimen where certain wavelengths are filtered
light passes through objective sense, then to eye piece sense to provide visible images
max mag= x1500
max res= 200um
can view live specimens and observe processes
features of transmission electron microscope
electrons pass through specimen, denser parts absorb more electrons so appear darker ]max mag= x500000 max res= 0.1nm
cannot view live specimens or processes as interior is a vacuum so specimen has to be sliced very thinly
requires extensive staining process that can lead to artefacts
features of scanning electron microscope
produces 3D image
electrons ‘bounce off’ specimen and are detected at multiple detectors
max mag= x100000
mag res= 20nm
how is actual size measured
using eye piece graticule, calibrated using a micrometer
1. line up graticule with micrometer
2. count no. of graticule division that correspond with a set measurement on stage micrometer
3. calc. distance in um of one division on eye piece graticule
ultracentrifugation is…
used to separate cell components or to get s cell-free liquid