cells Flashcards
eukaryotic cells: what is the nucleus
the spherical nucleus contains hereditary material & regulates cell activities
eukaryotic cells: what is the nuclear envelope
double membrane
associated w/ er
surrounds nucleus that controls movement of genetic material
eukaryotic cells: what are nuclear pores
allows passage of large molecules (around 3000 pores)
eukaryotic cells: what is the nucleoplasm
granular jelly like matieral that suspends nucleus bound structures e.g chromatin
eukaryotic cells: what are chromosomes
protein bound, linear dna
what are bound in chromosomes
histones
what are histones
proteins
eukaryotic cells: what is the nucleolus
makes ribosomal rna & assembles the ribosomes
may be more than one
eukaryotic cells: what is mitochondria
produces atp through aerobic respiration
how is atp produced in the mitochondria
krebs cycle and oxidative phosphorylation
eukaryotic cells: what type of membrane does mitochondria have, and name them
double membrane
inner and outer
eukaryotic cells: what does the outer membrane do in mitochondria
controls entry and exit of material
eukaryotic cells: what does the inner membrane do in mitochondria
it folds to form cristae
eukaryotic cells: what does the cristae do in mitochondria
increases surface are for enzymes and proteins
eukaryotic cells: what is the matrix in mitochondria
remainder of mitochondrian
containing proteins, ribosomes, lipids and dna
eukaryotic cells: what are chloroplasts
disc shaped organelles that carry out photosynthesis
eukaryotic cells: what is the envelope in chloroplasts
selectively permeable double membrane
eukaryotic cells: what is a thylakoid in chloroplasts
contains chlorophyll
where does the first stage of photosynthesis occur
in the thylakoid
eukaryotic cells: what is the grana in chloroplasts
stacks of thylakoids
eukaryotic cells: what is the stroma in chloroplasts
fluid filled matrix
where does the second stage of photosynthesis take place
in the stroma
what is the cell membrane made out of
phospholipid bilayer
eukaryotic cells: what is the structure of endoplasmic reticulum
flattened sacs called cisternae
eukaryotic cells: what is the rough er
rough due to ribosomes on it
large sa for ribosomal synthesis
proteins and glycoproteins synthesised and packaged into vesicles
eukaryotic cells: what is the smooth er
lacks ribosomes
synthesis storage & transport of lipids and carbohydrates
eukaryotic cells: what is the golgi apparatus
stack of flattened membrane sacs (cisternae) w/ vesicles
modifies proteins & lipids produced by er
eukaryotic cells: what are vesicles
small fluid filled sacs that transport substances around the cell
what does the golgi apparatus do
labels added to sort & transport glycoproteins to correct destination
produces lysosomes
modified proteins transported in vesicles
pinched off from ends of cisternae
there’s endocytosis and exocytosis
eukaryotic cells: what are lysosomes
formed when golgi vesicles contain lysozymes that hydrolyse cell walls of bacteria
what do lysomsomes do
contain hydrolytic enzymes to break down pathogens
eukaryotic cells: what are ribosomes
80s
carry out protein synthesis
eukaryotic cells: what are cell walls made up of
cellulose
eukaryotic cells: what are cell walls
rigid walls w/ microfibrils provide strength and support
stops cell from bursting
turgidity
eukaryotic cells: what is the middle lamella in cell walls
boundary between adjacent cells & cements them together
eukaryotic cells: what are algaes cell wall made of
cellulose and/or glycoproteins
eukaryotic cells: what are fungi’s cell wall made of
polysaccharide chitin & glycoproteins
eukaryotic cells: what are vacuoles
cell sap stores sugars, amino acids, wastes and pigments
maintains turgidity to herbaceous plants
food store
attraction for pollination
what type of organelles does eukaryotic cells have
membrane bound organelles
what is the definition of eukaryotic
true nucleus
what is the definition of prokaryotic
before nucleus
notes on prokaryotic cells
unicellular
less than 2 micrometres (smaller)
3.5 billion years ago
only 1 chromosome
what features are always present in prokaryotic cells
plasma membrane
circular dna
cytoplasm
ribosome
cell wall
what ribosomes do prokaryotic cells have
70s (smaller)
prokaryotic cells: what is the cell wall made of
peptidoglycan (murein)
prokaryotic cells: what type of grams are found at the cell wall
gram positive & negative at structure of cell wall
prokaryotic cells: what is a capsule
waxy mucus layer, protective
prokaryotic cells: what is the flagellum
for movement
prokaryotic cells: what is cillia/pili
small hair like structures that can attach to other cells
prokaryotic cells: what is a plasmid
small loop of dna
prokaryotic cells: what is a nucleoid
where circular dna is
is fungi prokaryotic or eukaryotic
eukaryotic
what is magnification
how many times bigger the image is when compared to the actual object
what is resolution
the minimum distance apart that two objects can be distinguished as separate items in an image
what does resolving power depend on
wavelength or form of radiation used
what is the definition of cell fractionation
cells are broken up & organelles separated out
what are the 3 things required of the solution for cell fractionation
must be cold
have same water potential as tissue
be buffered
why does the solution need to be cold for cell fractionation
to reduce enzyme activity that might break down the organelles
why does the cell need to have the same water potential for cell fractionation
to prevent organelles bursting or shrinking due to osmotic gain/ loss of water
why does the cell need to be buffered for cell fractionation
so that ph doesn’t fluctuate
changes in ph can alter the structure of organelles or affect the enzyme function
what are the 2 stages of cell fractionation
homogenation
ultracentrifugation
cell fractionation process
cells undergo homogenation in homogeniser
resultant homogenate filtered to remove complete cells & large debris
centrifugation spins homogenate in centrifuge
heaviest organelles (nuclei) are forced to the bottom where pellet/ sediment formed
fluid at the top (supernatant) is transferred & centrifuged at faster speed, next heaviest forms at bottom
process repeated until all organelles are sedimented and separated out
adavantages of the electron microscope
high resolving power
focused using magnets as they are charged
electrons can be deflected or absorbed by molecules in the air t/f a near vacuum has to be created
why does electron microscopes have higher resolution
shorter wavelength
what are the 2 types of electron microscopes
transmission electron microscope (tem)
scanning electron microscope (sem)
how does tem work
beam of electrons passes through a thin section of specimen
focused through magnets within vacuums
areas that absorb electrons appear darker on electron micrograph that is produced
what resolving power does tem have and why can’t it always be achieved
0.1nm h/e can’t always reach due to difficulties preparing specimen or high energy electrons may destroy specimen
4 limitations of tem
vacuum means living organisms can’t be observed –> no air
staining still doesn’t produce coloured images
specimen needs to be extremely thin
image may contain artefacts
why does tem need thin specimens
the specimen is in the middle t/f electrons need to pass through
how does sem work
directs beam of electrons back & forth across specimen
electrons are scattered depending on contours of specimen t/f causing 3d image
what resolving power does sem have
20nm, lower than tem, better than light microscope
what are the limitations of sem
expensive
require skills
same limitations as tem apart from thin specimen
what magnification does sem and tem have
tem - 500000
sem -100000
what is the eyepiece called on a light microscope that can measure sizes
graticule
what is the microscope calibration method
align stage micrometer w/ graticule
work out how many stage units is 10 graticules
convert stage units into micrometre –> this is equal to 10 graticules
divide stage units by 10 to find out 1 graticule unit