Cells Flashcards
5 kingdom classifications of life?
Plantae Fungi Animalia Protista Prokaryotae
Classification mainly based on morphology
3 domain classifications of life?
Bacteria
Archaea
Eukaryota
What are eukaryotic cells and what are prokaryote?
Eukaryote: Plants Animals Fungi Protoctisa
Prokaryote:
Bacteria and Archaea (both are monera)
Organisation of a bacterium?
Pilli Cell wall Plasma membrane Cytoplasm Nucleoid (DNA) (so no nucleus) Ribosomes Flagellum
Organisation of a eukaryotic cells?
Plasma membrane Golgi apparatus Peoxisome Mitochondrium Lysosome Enoplasmic reticulum Nuclear membrane Nucleus
Only cell that doesn’t have cell wall?
Animals
What extra do plants have?
Vacuole
Cell wall
Chloroplast
What extra do fungi have?
Cell wall
What is larger pro or eukaryote?
Eukaryote by far, also more complicated so theory that they developed after prokaryotes
A catalytic RNA molecule is called a?
Riboenzyme
Evidence RNA earlier than proteins?
RNA makes protein
RNA fundamental part of ribosome, whereas protein have just been added
How were the building blocks or RNA generated?
Random early earth conditions (eg lightening)
What could ribonucleotides bind together to form?
Replicase ribozymes which could make new replicases after polymerising on a clay surface
So can duplicate, due to temperature changes
How was a the lipid bi-layer in a cell made?
In Geysers, minerals catalyse the formation of fatty acids from hydrogen and carbon monoxide
Which have one end which hydrophilic (outside) and one is hydrophobic (inside) in a droplet known as micelles
Vesicle formation triggered by acidic pH or clay surfaces
What then occurs within the vesicle to from a protocell?
Flipping of fatty acids could bring in molecules, so they accumulate within the vesicle
The RNA replicase uses ribonucleotides to make a copy of another RNA replicase
Micelles fuse with the vesicle and enlarge it until it becomes unstable and divides
Random mistakes could lead to better replicases which could make protocol grow and divide faster
Protocell competes for resources driving evolution
What is the optical resolution limit and what does it rely on?
Minumum distance that allows recognition of object details
The optical resolution depends on the wave length of the light/beam used (smaller wave length = better resolution)
Features of light microscope?
Visible light ( wave length 390-700nm)
Glass lenses focus light
Resolution limit is 200 nm
Advantage is cells alive
Features of electron microscopy?
Electron beam ( wave length 0.0025 nm)
Electromagnetic lenses focus beam
Resolution limit 0.05 nm
Advantage is high resolution
Difference between scanning electron microscopy (SEM) and Transmission electron microscopy (TEM)?
SEM:
Electron beam scans over surface of sample
Can produce 3d images
Image shown on monitor
TEM:
Electron pass through THIN sample
Samples specially prepared
2D image shown on fluorescent screen
What is freeze fracture electron microscopy?
Freeze cell in resin, cut in half and analysis
What is averaging in microscopy?
Averaging many images together allowing reconstruction of the ultra-structure
What is fluorescence?
The emission of light by a substance that has absorbed light
The emission will be at a higher wavelength than excitation (the initial light), energy is lost before light is emitted
Allows visualisation of single molecules
What is GFP?
A reporter to analyse proteins in the living cell
It fuses to the DNA which will make the protein - which are normally still functional
These proteins are transcribed
They are exposed to blue light and will appear green
Different colours discovered so can observe interactions between different proteins
Also quantitive information as brightness represents how many there are
Advanced use of fluorescent proteins
FRAP (fluorescent recovery after photobleaching):
High energy sent in, which photobleaches the gfp molecules so can’t reflect light, if molecules are moving they will move into it and it will light up again, if not then nothing is moving
FLIP Fluorescent loss in photobleaching:
Used to see if one protein moves to another, so photo bleach, and then see if this photo bleach area appears in the place we think it will move
Photoactivation (photo-activatble GFP):
400nmlaser light induces a chemical reaction
About 100 fold increase in fluorescence after photo-activation
So allows you to identify the proteins you want to, as they will give lots of light off as their gfp has been activated