topic one - cell structure - miss whitehouse Flashcards
state three things to do when drawing microscopes?
label lines
draw in pencil
informative title
define ‘magnification’
how much an image has been enlarged by compared to it’s original object
define ‘resolution’
the degree to which you can distinguish two close objects as being separate
formula for magnification?
image/actual
what’s light microscope?
used to look at whole cells or tissues, focus a beam of lights onto the specimen
ads - cheap and easy to use
LSCM?
how to get from nm (nanometres) to um(micrometres)?
divide by 1000
how to get from um(micrometres) to mm?
how to get from nm (nanometres) to um(micrometres)?
divide by 1000
divide by 1000
what is the average animal cell size?
10-50um (micrometres)
what is the average plant cell size?
10-100um (micrometres)
what is the average bacterial cell size?
1um (micrometres)
what are the two different types of microscopes?
transmission electron microscope (TEM)
scanning electron microscope (SEM)
define ‘TEM microscopes’ and explain how it works?
an electron microscope uses a focused beam
of electrons is used instead of light to
“see through” the specimen
the electrons pass through a very thinly
cut specimen and produce 2D images
define ‘SEM microscopes’ and what it does?
the beam of electrons is directed onto the specimen through a vacuum, the electrons bounce off the surface of the specimen and are sensed by a detector. these microscope produce 3D images
define ‘LSCM’ and explain how it works?
laser scanning confocal microscope
an laser beam is focused onto the specimen the specimen being scanned is tagged with fluorescent dye
when the laser hits the dyes they emit fluorescent light, which is sensed by a detector and produces a clear image
draw and label a light microscope?
diagram/check with the one in biology workbook
what is the magnification and resolution of ‘TEM’
what is the magnification and resolution of ‘LM’
magnification - up to *500,000
resolution - between 0.05-1nm
magnification - 1500
resolution - 200nm
define ‘a light microscope’
use lenses to focus rays of light to
produce a clear image. specimens must be sliced thinly so light can pass through them
what is the magnification and resolution of ‘TEM’?
magnification - up to *500,000
resolution - between 0.05-1nm
what is the magnification and resolution of ‘SEM’?
magnification - up to *100,000
resolution - 5-50nm
which microscope had the higher magnification, ‘TEM’ or ‘SEM’?
transmission electron microscope
which microscope ‘TEM’ or ‘SEM’ has the strongest resolution?
transmission electron microscope
Q: a nucleus measures 100mm, with a magnification of x1000 and what is the actual size a nucleus?
A: 100000/10000= 10um
practice some magnification questions using the OLC?
magnification
define ‘graticules’
graticules are measuring devices used in microscopy
what are the two types of graticules called?
eyepiece graticules
stage micrometres
what is an eyepiece graticules and how does they work?
a smaller ruler etched onto the microscope ‘s eyepiece,
there are no units and it represents different lengths at different magnifications
when you increase the magnification the image becomes larger but the actual size of the specimen hasn’t changed - the eyepiece scale must be marked for each objective lenses
what is an stage micrometre and how does it work?
a special microscope slide etched with a ruler exactly 1mm long, with 100 divisions
it is used to calibrate the eyepiece
practice calculations using the online curriculum
OLC
define ‘staining’
any process that helps to reveal or distinguish different features
stains may be coloured or fluorescent dyes
state the four different types of staining?
acetic orcein stains DNA dark red
gentian violet stains bacteria cell wall
methylene blue stains nuclei in animal cells
haematoxylin and eosin stains are use together in pathology
define ‘sectioning’
after staining, specimens are in embedded in wax, thin sections can be cut without distorting the structure of the specimens
define ‘artefacts’
structures that result from the specimen preparation process that are not representation of the tissues original structure
what’s the benefit of staining cells/tissues?
some stains bind to specific cell structures, staining each structure can be easily identified within a single preparation
name 6 features of prokaryotes?
no nucleus
only one membrane (cell surface)
no membrane-bond organelles (ribosomes)
cell wall is made of peptidoglycan
smaller ribosomes than eukaryotic
DNA is in a single loop called circular chromosomes
DNA is naked - not associated with proteins
smaller loops of DNA called plasmids
respiration occurs infolded parts of the membrane
some species have flagella for movement
name two features of eukaryotes?
has a nucleus
membrane-bond organelles (mitochondria)
draw the three different types of flagella and name them?
check with book and the names are:
monopolar
bipolar
peritrichous
draw a prokaryotic cell and label it?
check with biology book
what is the function of a cell wall in a bacterial cell?
physical barrier which protects against mechanical damage
what is the function of a capsule in a bacterial cell?
protects bacterium from WBC and helps groups of bacteria stick together
what is the function of a plasma membrane in a bacterial cell?
acts as a partially permeable layer to control entry/exit of substances
what is the function of a pilus in a bacterial cell?
helps cells stick to one another or to surface
what is the function of a flagellum in a bacterial cell?
aids movement through fluids by rotation
what is the function of cytoplasm?
jelly- like material containing all organisms
use organelle sheet in biology book to revise chloroplast’s functions?
check biology sheet in book
use organelle sheet in biology book to revise the cell wall’s functions?
check biology sheet in book
use organelle sheet in biology book to revise cilia and undulipodia (flagella) functions?
check biology sheet in book
use organelle sheet in biology book to revise a centrioles functions?
check biology sheet in book
use organelle sheet in biology book to revise lysosomes functions?
check biology sheet in book
use organelle sheet in biology book to revise vesicles and vacuoles functions?
check biology sheet in book
use organelle sheet in biology book to revise a nucleus’s functions?
check biology sheet in book
use organelle sheet in biology book to revise a ribosome’s functions?
check biology sheet in book
use organelle sheet in biology book to revise a cell surface membrane’s functions?
check biology sheet in book
use organelle sheet in biology book to revise an endoplasmic reticulum functions?
check biology sheet in book
use organelle sheet in biology book to revise a Golgi body functions?
check biology sheet in book
use organelle sheet in biology book to revise a mitochondria’s functions?
check biology sheet in book
how big is chloroplast?
4-10um
how big is lysosome?
0.5um
how big is a centriole?
0.2um
how big is a nucleus?
10um
how big is a ribosome?
0.02um
how big is a mitochondria?
2-5um
how big is a nuclear pore?
0.1um
what organelles does the protein production pass through?
nucleus ribosomes RER vesicles Golgi apparatus plasma membrane
define ‘the protein production’
where the cells make proteins
cells are capable of producing many different proteins e.g. hormones, antibodies & enzymes
some of these proteins are used inside the cell where they are produced
what are the two main stages of protein synthesis & describe what happens in those stages?
transcription -
an mRNA (a molecule that carries genetic info to make proteins) molecule is produced from DNA inside the nucleus
translation -
the code on the mRNA molecule is used to control the production of a polypeptide chain by a ribosome
state the three things that happen during protein production?
the protein is made (synthesised) inside the RER & once it has been made on a vesicle it’s pinched off the RER containing the protein
the vesicles will transport the protein to the Golgi apparatus
the Golgi apparatus may modify/process the protein (e.g. adding carbohydrate groups forms glycoprotein)
what is the folded membrane in a golgi/RER called?
cistermae
define ‘division of labour’
the specialised function of cell organelles which come together to ensure the cell is capable for surviving as well as performing it’s role in the body
describe the 10 step process of the ‘protein production)
DNA in nucleoplasm has gene for production of hormone on
a chromosome
mRNA copy of DNA is made in the nucleus (transcription)
mRNA leaves nucleus via nuclear pore
mRNA attaches to ribosome on RER
ribosome assembles protein using code from mRNA
(translation)
vesicle containing protein molecules are pinched off RER
vesicle travels to and fuses with Golgi apparatus
golgi apparatus modifies/processes and packages protein
packaged protein molecules are pinched off in vesicles
from Golgi body and move towards plasma membrane
vesicle fuses with plasma membrane and releases protein
this is called exocytosis
define ‘cytoskeleton’ and it’s function?
network of proteins filaments running through the cytoplasm
provides an internal framework to support the cell (mechanical strength) & to help maintain the cells stage
keeps the cells organelles in place, moves organelles & other materials around within the cell ( chromosomes during cell division)
name three things that are part of the structure of cytoskeleton?
microtubules: tubular cylinders made from tubulin (18-
30nm)
microfilaments: very thin (7nm diameter) rod-like protein strands made from action
intermediate filament: made from a variety of different proteins
