T1 Cell structure Flashcards
chromatic aberration
production of images with light split into different colours, prevented since 1800s via combination of 2 images.
optical microscopes
where light focussed through a series of lenses magnifies objects up to 100 times.
magnification
number of times larger an object appears compared to actual size.
magnification lens equation
objective lens power * eyepiece lens power
resolution
ability to distinguish between close together but separate objects
dissecting microscope function
used for observation at low magnification
wet mount
temporary preparation in which specimen and a drop of fluid are trapped under a coverslip so thin tissue sections can be seen.
non-viable stains
for use on dead specimens
viable specimens
for use on alive specimens
iodine stain
tests for starch, turning blue-black
crystal violet stain
tests for gram/nucleus, turning purple
aniline sulfate stain
tests for lignin, turning yellow
methylene blue stain
nuclei turns blue
hematoxylin and eosin
H turns nucleus blue/violet
E turns proteins red/pink
difference between a compound microscope and dissecting microscope
compound produces a 2d image through a thin, transparent sample// dissecting produces a 3d image, looking at surface details.
compound has smaller distance between the lens and the specimen
example of mounting liquid
water, glycerol, stain
why must specimens be so thin?
so that light can pass through so that features can more easily be seen.
Also to reduce the number of layers of cells.
function of coverslip
to exclude air bubbles that obscure the view of the specimen/ to smooth out the specimen.
why is the lowest magnification always used first?
allows a larger area to be viewed so that specific areas can be more easily located. Also, makes focussing easier, protects slide from large movements.
stain function
enhancement of specific features of a sample
electron microscopes
use short wavelengths of electrons to produce high resolution images of small specimens
SEM
scanning electron microscope
electrons bounce off surface of object to produce detailed images of external appearance.
TEM
transmission electron microscope
TEM process
electrons pass through specimen and are scattered.
magnetic lenses focus the image onto a fluorescent screen/photographic plate.
ultramicrotome
cuts v thin wafers of specimens
SEM process
scans sample w a beam of primary electrons, knocking them from the sample’s surface.
secondary electrons are picked up by a collector, amplified and transmitted onto a viewing screen/photographic plate (3D image).
wavelength, lenses, specimen type, max res, max mag of light microscope
400-700nm glass lenses living/non-living specimens 200nm res 1300 * mag coloured surface image
wavelength, lenses, specimen type, max res, max mag of TEM microscope
0.005 nm
EM lenses
non-living specimen on copper grid in a vacuum
1nm res
250,000*mag
heavy metal stains used to produce monochrome image
wavelength, lenses, specimen type, max res, max mag of SEM microscope
0.005 EM lenses non-living specimen on metal disc in vacuum 10nm res 100,000 mag
graticule
part within the eyepiece, enabling you to measure the size of an object
usually 1mm divided into 100 equal widths, used in combination w a stage micrometer to work out size
haemocytometer
used to count no. of cells in a set area/volume using a grid
stage micrometer
a slide w a scale exactly 1mm long, divided into 100 divisions, allowing calibration of graticule.
linear magnification
calculated by taking a ratio of image height to the object’s actual height
linear mag ratio enlargement
greater than 1
linear mag ratio reduction
smaller than one
cell theory
all living cells are composed of cells/cell products
new cells are formed by divisions of pre-existing cells
cells contain genes needed to function, grow and develop.
all chemical reactions of life take place in cells
functions of life
Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition
virus structure
(non-living/cellular)
20-300nm w no cytoplasm/organelles/chromosomes. RNA/DNA found in a protein coating, depending on host cells for metabolism and reproduction.
prokaryotic cells
autotrophic/heterotrophic
single-celled
lack membrane-bound organelles
cell walls contain peptidoglycan
eukaryotic cells
contain linear chromosomes and membrane-bound organelles
types of eukaryotic cell
plant
animal
fungal
protoctist
plant eukarya
multicellular, autotrophic (photosynthetic) and has cellulose cell walls
animal eukarya
part of multicellular organism w specialised cells
no cell wall
heterotrophic
fungal eukarya
plant-like
chitin cell walls
heterotrophic
what is found in fungal cell walls?
chitin
what is found in plant cell walls?
cellulose
protoctist eukarya
single-celled/w cell colonies
autotrophic/photosynthetic/heterotrophic
what is found in prokaryotic cell walls?
peptidoglycan
cell size range
between2-100 micrometres
size difference between prokaryotes and eukaryotes
prokaryotes are up to 10* smaller than eukaryotes
amyloplasts
plastids specialised for storage, particularly of starch.
chloroplast
contains green pigment chlorophyll, dense stacks of membranes within a colourless fluid, enables photosynthesis
what ribosomes do chloroplasts contain?
10S
cell wall
semi-rigid, cellulose structure to support the cell and regulate pressure/volume.
middle lamella
first layer of cell wall formed during division, containing pectin and protein. It provides stability and allows formation of plasmodesmata.
plasmodesmata
channels allowing communication and transport between the cells.
cytoplasm
solution of enzymes and dissolved substances, the site of translation in the cell.
ribosome
structures manufacturing protein, lying free or coming off of the endoplasmic reticulum.
nucleus
controller of cells activities
endoplasmic reticulum
a continuous network of tubes and flattened sacs w the plasma and nuclear membrane.
rough ER
ER w ribosomes attached
mitochondrion
energy transformers from chemical energy into ATP
what sort of ribosomes do mitochondria contain?
10S
large central vacuole
aqueous solution of ions found to function in storage, waste disposal and growth.
where are 80S ribosomes found
in the cytoplasm
tonoplast
vacuole membrane
lysosome
sac bound by a single membrane from the Golgi apparatus, containing transport enzymes that break down food/foreign matter.
when specialise dare absent from plant cells.
tight junctions
join cells together in formation of tissues
nuclear pore
hole in the nuclear membrane allowing nucleus to communicate w the rest of the cell.
centrioles
structures associated with nuclear division, composed of microtubules.
absent in some plants/protoctists
mitochondrion
organelle bounded by a double membrane system, numbers depending on metabolic activity of the cell
smooth endoplasmic reticulum
ER without ribosomes.
site for lipid/carb metabolism and hormone synthesis.
ribosomes
small free structures in the cytoplasm with the ER.
animal cells have 80S ribosomes.
rough ER
site of protein synthesis, synthesising new membranes by adding proteins and phospholipids.
Golgi apparatus
series of flattened, disc-shaped sacs stacked and connected with ER. Stores, modifies and packages proteins, ‘tagging’ them to go to their correct destination.
cytoskeleton
complex structure of tubules and fibres, resisting tension and providing structural support to maintain cellular shape.
3 proteinaceous elements
microfilaments
intermediate filaments
microtubules
what features of an animal cell also count as cytoskeleton?
the flagella and cilia (are microtubules)
how is the cytoskeleton dynamic?
use of motor proteins which move along cytoskeletal tracks while hydrolysing ATP.
why is the cytoskeleton dynamic?
to alter the cell’s shape and move materials/ the cell itself.
what are the sub-units of microfilaments?
actin
structure of microfilaments
2 intertwined strands
function of microfilaments
shape maintenance
motility
contraction
cytokinesis
intermediate filaments sub-units
fibrous proteins
structure of intermediate filaments
fibres in thicker cables
functions of intermediate filaments
shape maintenance
anchors nucleus and organelles
microtubules sub-units
alpha and beta tubulin dimers
microtubules structure
hollow tubes
microtubules function
shape maintenance
motility
move chromosomes
how do microfilaments grow/shrink?
actin sub-units are added/taken away from either end
which side do vesicles enter the Golgi from?
cis
which side do transport vesicles leave the Golgi?
trans
function of enzymes in the ER
aid the synthesis of lipids, phospholipids, steroid hormones and lipids
stages of protein production for excretion?
polypeptide chains grow from bound ribosome
chain threaded through pore to ER and folded into correct 3D shape. carb attached to protein by enzyme while separated from ribosomes in cytosol. Leave ER in a vesicle bud then received by Golgi for storage, modification and transport to the plasma membrane for exocytosis
macromolecule
large organic polymers made up of many smaller repeating units. made up of high molecular weight
examples of macromolecules
proteins, nucleic acids, polysaccharides
why are transporting proteins synthesised by membrane-bound ribosomes?
so that they can easily be transported into the cisternal part of the ER
role of SER in production of secreting proteins
synthesises lipids and transports them into transport vesicles.
role of Golgi in production of secreting proteins
receives transport vesicles, modifies, stores and transports them for export out of the cell
cellular respiration
a set of metabolic reactions converting biochemical energy from food into ATP.
ATP
adenosine triphosphate
phosphorylated nucleotide which acts as the universal energy carrier
where’s ATP produced?
mitochondria and chloroplasts
how does ATP produce energy?
via hydrolysis
cell wall of prokaryote
provides shape and prevents rupture, anchoring flagella
composed of peptoglycan, lipolysaccharide and lipoprotein
cytoplasmic inclusions
aggregations of storage molecules
Fimbrae
hairs used to attach to surfaces/other cells
plasmid
provides genes for antibiotic resistance and can be transferred between cells
flagella
provides locomotion
how do prokaryotic plasma membranes differ from eukaryotic?
less rigid
what sort of ribosomes are found in prokaryotes?
70S
where’s circular chromosome found?
in the nucleoid region
polysaccharide capsule
contributes to virulence of pathogenic prokaryotes
bacterial shapes
rod, comma, sphere and spiral
process by which bacteria divide
binary fission
virus
infectious, v specialised intracellular parasite which are acellular and non-living.
Pathogens which replicate inside living cells of other organisms.
general structure of a virus
genetic material (RNA/DNA) encased in a capsid (protein coat) or envelope too w glycoprotein receptor spikes.
what happens when viral replication is complete?
how does this differ in plant/animal cells?
virons leave the cell to infect more cells
buds off animal cells and travels through plasmodesmata of plant cells.
