Cell structure Flashcards
Nucleus structure and function
contains genetic material (chromosomes)
Site of RNA transcription
Double membrane- nuclear envelope
Nucleolus- site of rRNA synthesis
Nuclear pores allow transport of recently transcribed rna
Mitochondria structure and function
site of aerobic respiration to produce ATP
double membrane
folded inner membrane (cristae)-provides large surface area to increase respiration
Fluid called matrix contains enzymes, ribosomes, mitochondrial DNA (Plasmids(circular and no histones)), granules
Chloroplasts structure and function
Site of Photosynthesis
Double membrane
thylakoids= folded membranes embedded with pigment
lamellae join grana
stroma contains enzymes, DNA, Ribosomes, starch granules
Smooth and Rough ER
both have folded membranes called cisternae
Rough ER: have ribosomes on cisternae
site of protein synthesis
Smooth ER: no ribosomes,
synthesis and storage of lipids and carbohydrates
toxin modification
glycogenesis
golgi apparatus and vesicles structure and function
what is emulsification
add carbohydrates to proteins to form glycoproteins produce secretory enzymes secrete carbohydrates transport, modify and store lipids molecules labelled with destination
lipids into micelles
Cell wall in plants, fungi and bacteria
plants- provides tensile strength
made of cellulose
fungi- chitin
prokaryotes- murein
eukaryote v prokaryote definition
eukaryote- DNA in a nucleus and has membrane bound organelles
prokaryote DNA not in a nucleus and has no membrane bound organelles
Prokaryotic DNA v Eukaryotic DNA
Eu: associated with histones found in nucleus long, linear, double stranded contains introns
Pro: not associated with histones not found in nucleus- free in cytoplasm shorter, circular double stranded do not contain introns have plasmids for exchange of genetic material
How do optical microscopes work?
1) light is radiation source lenses focus ray of light and magnify the view of a specimen
2) certain wavelengths of light absorbed by different structures in the cell specimen
3) reflected light transmitted to the observer
preparation of an optical microscope specimen
- get thin section, squash
- stain
- add coverslip using mounted needle
advantages and limitations of optical microscope
colour
living specimen
cheap
only 2d
low resolution
low magnification
how do TEM work
how to prepate a sample
high energy beam of electrons through specimen
denser organelles appear darker as they absorbed more electrons
Add drop of water to (glass) slide;
- Obtain thin section (of plant tissue) and place on slide / float on drop of water;
- Stain with / add iodine in potassium iodide.
limitations and advantages of TEM:
high magnification and resolution (electrons have shorter wavelength than light)
but in vacuum so dead specamin 2d black and white extensive staining process may lead to artefacts extremely thin specimen
how do SEM work
high energy beam of electrons hit specimen and bounce off specimen and detected
advantages and limitations
3d image
high magnification and resolution
but requires a vacuum
no colour image
shows only the surface
