Cell Flashcards
how is the image magnified in a microscope
lenses refract the light in such way that the image of the specimen is magnified as it is projected into the eye or into the camera
what are the 3 important parameters in microscopy
magnification, resolution and contrast
what is magnification
is the ratio of an objects images size to real size
how much can light microscope magnify
1000 to 1500
what is resolution
is the measure of the clarity of the image and minimum distance 2 points can be separated & still be distinguished as 2 points
whats the maximum resolution the light microscope can give
0.2 micrometer or 200 nano meters
what is contrast
the difference in brightness between the light and dark areas of the image
what does electron microscope use
it uses a beam of electrons
is resolution inversely related to wavelength of light or electrons
yes
how much resolution can electron microscope give
0.002 nm
what is topography
the distribution of parts or features on the surface of or within an organ or organism
what does SEM stand for
what does Scanning electron microscope
does SEM show 3D
yes
why do we use SEM
to study the the derailed topography
how does SEM work
The electron beam scans the surface of the sample which is usually coated with a thin filament of gold. And these secondary electrons are detected by the device which translates the pattern into the Electronic signal in the video screen
why do we use TEM
to study the internal structure of the cell
what does TEM stand for
transmission electron microscope
how does TEM work
TEM, the specimen has been stained with atoms of heavy metals, which attach to certain cellular structures, thus enhancing the electron density of some parts of the cell more than others.instead of using glasses both sem and TEM use electromagnets as lenses to bend pathways electrons
what is the disadvantage of electron microscopes
method used to prepare the specimen kills the cell
why is cell fractionation used
takes the cells apart and separate major organelles and other sub cellular structure
are protists and fungi eukaryote
yes
what does protist mean
a diverse group unicellular eukaryotes
which domains consist of prokarytic cell
archea and bacteria
list eukaryotic cell domain
plant, animal, fungi and protoctist
what is plasma membrane
is the cell membranes
is cell membrane permeable,
Yes
what is cytosol
area of the cytoplasm that’s not held by organelles, (cytoplasm-organellles)
whats is protoplasm
include the cytoplasm, nucleus and other organelles & its divided into cytoplasm and nucleoplasm
what is cytoplasm
everything in the cell é membrane excluding the nucleus contains cytosol and organelles
do all cells have chromosomes
Yes
do all cells have ribosome
yes except virus
where is th dna found in eukarytic cells
Nucleus
where is the dna found in prokarytic cells
nucleoide
whats is the typical diameter of bacteria
1-5 micrometer
what is the typical eukarytic cell diameter
10-100 micrometer
why does smaller organisms have greater surface area to volume ration
area is promotional to linear dimension squared whereas volume is proportional to cubic dimentional cube
isn’t true that larger organism have bigger cells
no they have more cells in quantity t
what is the average diameter of nucleus
6 micrometer
what does nuclear envelope
it enclose the nucleus and separates from cytoplasm
what are the nuclear double membrane made of
phospholipid bilayer
Where is most of the genes in eukaryotic cell present
nucleus
Which other place rather then nucleus can genes of eukaryotic cell be present
Chloroplast and mitocondria
What is the average diameter of nucleus
5 micrometer
What is the largest organelle
Nucleus
What does nuclear envelope do
Encloses the nucleus separating the content form cytoplasm,
What is the nuclear double membrane made of
Lipid bilayer with associated proteins,
What is the diameters of pored between nuclear pores
100nm
Is nuclear pore selective
Yes very selective
How is the outer membrane of the nucleus continuous
They start forming Endoplasmic reticulum
What are the things that can enter and leave the nuclear pore
Proteins, rna and large complexes of macromolecules
What does nuclear lamina do
They maintain the shape of the nucleus by mechanically supporting the nuclear envelope.
In the nucleus the dna is organized into discrete unit called …
Chromosome
Chromosome ARe made of?
Chromatin fibre n
What happens to the chromosome when the cell divides
It condenses and is visible
Can nucleoli be seen under light microscope
No
What happens in the Nucleolus
Ribosomal rna or rRna is synthesized for the instruction of the dna
What happens to the proteins imported from the cytoplasm to the nucleuolus
Assembled with the rRNA into large and small subunits of ribosome
How does a ribosome form
The small and large subunits leave the nucleus through nuclear pore where they assemble into ribosome.
Can a nucleus have more than one nucleolus
Yes
Whta does the number of nucleolus depend on
Species and stage of reproductive cycle
How does nucleus direct protein synthesis
It makes mRNA from dna, and exits the nucleus via nuclear pore, where the ribosome translates the mRNA into protein
Are ribosomes organelle?
No
Why aren’t ribosome organelles
Do not have a membrane bound organelles
What are the 2 organelles that cells with high protein synthesis have
Prominent nucleoli and many ribosome
Where are free ribosomes and bound ribosome present
The free ones are found in the cytosol and the membrane bound are found in Endoplasmic reticulum or nuclear envelope.
Are bound and free ribosomes structurally identicle
Yes
What happens to the protein made in free ribosomes
They mainly remain in the cytosol
What happens or protein made in bound ribosome
Make protein destined for insertion into membrane for packaging within the organelles such as lysosome or for exportation from the cell
