biology cell structure Flashcards
what are the two main advantage of a electron microscope over a light microscope
- electron beams have a shorter wavelength and there for a high reslutitution
-electrons are charged and can be focused using electromagnets
what are the two types of electron microscope
-scanning
-transmission
how dose a TEM work
give 3 limitations
an electron gun produces a beam of electrons focused onto a thin specimen by condenser electron magnets. the denser parts of the specimen absorb the electrons and appear darker
the resolving power of a TEM is 0.1 nanometres
higher energy beam required may damage specimen
there is a complex staining method
it has to be in a vacuum which means living specimens cant be observed
artefacts- may appear in the photomicrograph but are nt actually part of the cell
how dose a SEM work
give 3 limitations
SEM directs beams of electrons onto the surface of the specimen from above. the beam is passed back amd fourth across the portions of the specimen in a pattern. electrons are scattered by the specimen we can build up a 3d image by computer anylsis of the patterns of electrons.
has a resolving power of 20nm so lower than the TEM
has all the same limtations of a TEM appart from the specimen dosnt need to be thin as a result of it not needing to penitrate the specimen
what is the nucleus function and what are the parts of it called
the nucleus contains the organisms hereditary material and controls the centre of control of the cell
- nuclear envelope a double membrane out side of the nucleus
-nuclear pores allows the passage of large molecules out of the nucleus
chromosomes
what are the mitocondria
mitocondria are the sight in which areobic resperation takes place. they are responsible for the production of atp a energy carrier molecule. it also realses energy for the cell. they are high in cells with a high metabolic rate
- conatins matrix and has a folded structure
what are the structures of the mitoconria
it has a double outside membrane that controls materials entering and exiting the cell.
an inner membrane is folded to form a cristea which provides a large surface area for the attachment of enzymes
name a protein associated with DNA in the chromosones
histones
describe the structure of the nucleus
-contains a nuclear envelope which is a double membrane
-nuclear pours for exit of mRNA
-dense area which is called the nucleolus which produces ribosomes
what is the structure of DNA in the nucleus
DNA is linear and wrapped around hi stone
what are 3 factors both mitochondria and chloroplasts share
-Both have a double membrane
-both contain there own circular DNA
- both contain ribosomes for protein systehsis
what is the function of mitochondria
-ATP synthesis
-site of aerobic respiration
structure- folded internal membrane
what is the function of chloroplast
thyroidal membrane contains pigments to absorb light and stroma contains enzymes needed for photosynthesis
during certification what type of fluid do the organelles have to be put into
- buffered neutral pH
- iostonic same water potential prevent osmotic effect
- cold prevent enzyme activation and break down
what is homogenasation
blending cells- breaking open cell membrane and realseasing the orgnaelles
what type of material gose to the bottom of the center during certification
denser material (eg neucleus at the bottlom forms pellet first
what results from mitosis
two genetically identical daughter cells
what results from meiosis
4 daughter haploid cells
what are the name of the process in mitosis
PMAT
-prophase
-metaphase
-anaphase
-telophase
what happens in interphase
the cell grows in size and increases
prophase events
- chromosomes becomes very thick and visible
- centrioles move to the opposite ends of the cell and produce spindle fibres( centroles not in plant cells but spindle apparatus is)
- nucleolus disappear and nuclei envelope breaks down
meta phase
- centro mere
- chromosomes aline themself along the equator with the spindle fibres attache
anaphase
- the centro mere divide into 2 and chromstids are pulled in opposite directions to the other ends of the cell
telophase
chromatids at opposite ends un coil and a new nuclear envelope forms
cystokenisis
cell membrane and cytoplasm divides
- and new cell membrane forms
name 3 factors that increase the risk of cancer
- exposure to ionzing radiation
mutation in the DNA base sequences
exposure to chemicals
how do tumors form
cell passes check point in cell cycle with damaged DNA which can lead to uncontrollable cell division
what are channel proteins
proteins tta allow movement of large polar molecules through facilitated diffusion and active transport
what is ATP useful for
- breaking down and regenerating
-soulable and small can move easily - relase the right amount of energy at once
what factors effects facilitated diffusion
-concentration gradient
- surface area (folding)
-higher temprature( more energy)
membernae thickness (shorter ddiffusion pathway
what happens during co transport
na+ is pumped out of the the cell into the capillaries therefore the concentration gradient gose down
glucose binds with the co transporter and a co transport proteins allows glucose to move against the concentration gradient into the cell
