cell structure Flashcards
how do light microscopes work and what is the resolution and magnification?
light microscopes shine light through the specimen
low resolution of 0.2micrometres
low magnification of x1500
how do transmission electron microscopes work and what is the resolution and magnification?
uses electromagnets to focus a beam of electrons which is transmitted through a specimen. denser parts absorb more electrons so appear darker
high resolution of 0.0002micrometres or 0.2nm
magnification of x1000000
how do scanning electron microscopes work and what is the resolution and magnification?
they scan a beam of electrons across the specimen which knocks off electrons which are gathered in a cathode ray tube to form an image
the images are of the surface of the specimen and can be 3D
resolution of 0.002micrometres or 2nm
magnification of x500000
what is a laser scanning confocal microscope?
uses laser beams to scan a specimen which is tagged with a flourescent dye
light is focused through a pinhole onto a detector which is hooked up to a computer and creates an image which can be 3D
can be used to look at objects at different depths
what is the difference between magnification and resolution?
magnification is how much bigger thr image is than the specimen
resolution is how detailed the image is- how well the microscope distinguishes between two points that are very close together
why do you stain a specimen in light microscopy?
to add contrast to be able to identify different cellular comoponents
what does methylene blue stain?
DNA
what does eosin stain?
cytoplasm
what is the equation for magnification?
image size/object size
what does the nucleus do?
controls cells activites and contains instructions to make proteins
what does the nucleolus do?
makes ribosomes
what does the nuclear envelope do?
cotains pores which allow substances to move between the nucleus and the cytoplasm
what does the rough endoplasmic reticulum do?
folds and processes proteins made in its ribosomes
what does the smooth endoplasmic reticulum do?
synthesises and processes lipids
what does the golgi aparatus do?
processes and packages lipids and proteins - makes lysosomes
what do ribosomes do?
synthesise proteins
what do lysosomes do?
contain hydrolytic enzymes that are used to digest invading cells or digest worn out components of the cell
what do mitochondria do?
they are the site of aerobic rspiration
what does the plasma membrane do?
regulates movement of substances into and out of cell
what do the chloroplasts do?
site of photosynthesis
what does the cell wall do?
rigid structure of cellulose to support plant cells
what do cilia do?
move substances across surface
what do flagella do?
move cell around
what do centrioles do?
involved in the separation of chromosomes during cell diviison
what is the importance of the cytoskeleton?
give mechanical support to cells
aids transport within cells
enables the cell to move (cilia and flagella)
what is the cytoskeleton?
network of protein threads called microtubules and microfilaments
describe the function of organelles in the synthesis of proteins
proteins are made at the ribosomes
new proteins are folded and processed at the RER
these proteins are then transported to the golgi aparatus in vesiciles to undergo further processing and
golgi packages proteins into vesicles to be transported around the cell
what are the similarities and differences between eukaryotic and prokaryotic cells in terms of size DNA nucelus cell wall organelles flagella ribosomes
prokaryotic cells are smaller than eukaryotic 2micrometres vs 10-100micrometres
circular DNA for prokaryotic and linear DNA for eukaryotic
no nucleus in prokaryotic and a nucleus in eukaryotic
cell wall of peptidoglycan in prokaryotic, no cell wall in eukaryotic
few organelles and no membrane bound in prokaryotic
lots of organelles in eukaryotic
flagella made of flagellin arranged in helixes in prokaryotic and flagella of microtubules in 9+2 formation in eukaryotic
70S ribosomes in prokaryotic and 80S ribosomes in eukaryotic
