Cells and cell membranes Flashcards
resolution of a light microscope
200nm
resolution of a TEM
0.1 nm
resolution of a SEM
0.1nm
magnificent of a light microscope
x1,500
magnification of a TEM
x500,000
magnification of s SEM
x100,000
magnification
the degree to which the size of an image is larger than the object itself
resolution
the degree to which it is possible to distinguish between two objects that are very close together
explain the need for staining for use in light microscopy and electron microscopy
a lot of biological material inside the cell isn’t coloured, so it might be difficult to distinguish between different features.
coloured stains are used to stain specimens for use with the light microscope.
chemicals which bind to other chemicals in or on the specimen allow the specimen to be seen
some chemicals bind to specific structures e.g. acetic orcein staying dna red
electron micrographs start off B&W with the colour being added by a specialised computer program afterwards.
linear magnificent of an image
image size= actually size x magnification
nucleus
largest organelle
houses all the cell’s genetic material in the form of DNA, which contains the instructions for protein synthesise.
nucleolus
dense spherical structure inside nucleus
makes ribosomes and RNA which pass into the cytoplasm and are used in protein synthesis
nuclear envelope
surround the nucleus
double membrane with nuclear pores
SER and RER
continuous with the nuclear envelope. RER is studded with ribosomes, SER is not
transports proteins made by the attached ribosomes
SER involved in making lipids
golgi apparatus
stack of membrane bound flattened stacks
modifies proteins received from the rough ER and then packages them into vesicles so they can be transported
ribosomes
tiny some are in cytoplasm some are bound to RER
site of protein synthesis
mitochondria
spherical or sausage shaped double membrane
where ATP is made during aerobic respiration
lysosomes
spherical sacs single membrane
contain digestive enzymes that are used to break down materials by catabolism
chloroplasts
only in plant cells, two membranes contain thlakoids
site of photosynthesus
centrioles
small tubes of protein fibres- pair of them next to nucleus in animal cells
form the spindle which moves chromosomes during cell division
flagella and cillia
hair like extensions projecting from the surface of a cell
move by ATP e.g. wave mucus along trachea or make sperm swim
outline the interelationship between the organelles involved in the production and secretion of proteins
- the gene containing the instructions for the production of the hormones is copied on to a piece of mRNA
- mRNA leaves the nucleus through a nuclear pore
- mRNA attaches to a ribosome
- ribosome read the instruction to assemble the protein
molecules are ‘pinched off’ in vesicles and travel towards the golgi apparatus - vesicles fuse with the golgi apparatus
- gogli apparatus processes and packages the molecules for release
- the molecules are ‘pinched off’ in vesicles from the golgi app and move towards the cell surface membrane
- vesicles five with the cell membrane
- cell surface membrane opens to release molecules outside.
exoskeleton- made of ?
cytoplasm contains 2 types of protein fibres: microfilaments (small solid strands made of actin 7nm diameter) and microtubules (protein cylinders made of tubulin molecules, 25nm diameter).
functions of exosketelon
supporting organelles
strengthening the cell and maintaining cell shape
transporting materials within the cell )e.g spindle during mitosis)
compare and contrast, with the aid of diagrams and electron micrographs, the structure of prokaryotic cells and eukaryotic cells
prokary- no nucleus - they are bacteria and much smaller than eukaryotes they have: one membrane no membrane bound organelles cell made made of peptidoglycan circular dna dna not surrounded by membrane ATP production takes place in specialised infolded regions of the cell surface membrane some have flagella
compare and contrast, with the aid of diagrams and electron micrographs, the structure of plant cells and animal cells
plants cells have a cell wall- outside cSM made of cellulose which forms a sieve link network of strands which make the cell wall v strong
this is kept rigid by the pressure of the fluid inside the cell (vacuole) so supports the cell and therefore the entire plant
plants cells also contains a vacuole- that maintains cell stability by making the cell turgid as it increases the pressure inside the cell this in turn also helps support the plant.
