Cells Lectures 1-5 Flashcards
10 Angstrom
1nm
1,000nm
1micrometer
1,000,000micrometer
1m
How many ribosomes make one meter
20,000,000
Robert Hooke
Philosopher, astronomer and architect, Hook elasticity law
Micrographia - small things (insects), property of air, small stars and the moon
Looked at cork
Beginning of cells
Called cell because of the monk cell
Antony Van Leeuwenhoek
Discovered bacteria, free living and parasitic microscopic protists, sperm cells and muscle fibres
What is Scheleiden and Schwann’s cell theory say?
Cell is the unit of structure, physiology and organisation in living things
Cell retain a dual existence as a distinct entity and a building block in construction of organisms
Cells form by free cell formation, similar to the formation of crystals (WRONG) - all cells only arise from pre-existing cells
What are the common features of a cell?
Cells gather material from environment and duplicate
Information is stored and inherited by DNA
Information is partially transcribed into an immediate form (RNA)
RNA serves for translation
Proteins put genetic info into action
All cells are enclosed by plasma membrane where material must pass
What are the basic unit of life?
All cells come from pre-existing cells by division
Cells contain DNA which is passed from cell to cell during division
All cells are the same in chemical composition
All energy flow of life occurs in the cell
How many cells does the human body contain?
10^14
Describe the phases of the mitotic cycle
M phase - chromosome inheritance and cell division
S phase - DNA replication
G2 phase - cell growth
G1 phase
How many cells are in the brain?
10^11
Organisation of a bacterium
Pili, flagellum, cell wall, plasma membrane, nucleiod, ribosomes, cytoplasm
Organisation of eukaryotic cells
Plasma membrane, Golgi, peroxisome, nuclear membrane, ER, lysosome, mitochondrium
What is monera?
Bacteria and archae
Organisation of pungi
mitochondria, cell wall, endomembrane system, nucleus
What is the major difference between prokaryotes and eukaryotes
Prokaryote don’t have compartments
Describe the central dogma
Francis Crick
3 molecules can interact to pass on detailed information(DNA –> RNA –> protein)
Describe RNA
It can form a riboenzyme, it has enzymatic activity, can fold and form molecules that catalyse chemical reactions
Translate mRNA into proteins
Large and small subunit
Enzymatic activity of ribosomes depend on RNA part of the ribosomes
How do ribonucleotides spontaneously polymerise?
On clay surfaces
How can replicase be made
Ribozyme replicates an un-folded RNA strand of another replicase molecule
At high temp, both strands separate, one folds into a new replicase and one serves as a template
What is needed to make a cell?
A bi-layer
What is needed for a bi layer
Amphiphatic molecule, likes water at one end but not at the other,
Spontaneous assembly into lipids
Some minerals catalyse the formation of fatty acids from hydrogen and CO
Describe Micelles
Polar fatty acids self organise into micelles
How are vesicles formed?
Spontaneously formed from micelles, formation requires an acidic pH, larger than micelles and can grow by fusion with more micelles
Describe lipid bilayer
Flexible molecules, flipping lipids can transport molecules over the membrane
Which molecules accumulate within the vesicle?
Ribonucleotides, ribozymes and other molecules
Describe a protocell
Vesicle has ribozyme and template strand, bigger so unstable and therefore can pop into two,
Overall production of a protocell
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 form better replicase and uptake of new RNA could incorporate new ribozymes - protocol grow and divide faster
Protocells compete for resources and faster growing protocells are more competitive
What is optical resolution limit?
minimum distance that allows recognition of object details, depends on wave length of light.beam
smaller wavelength = better resolution
Describe light microscopy
Visible light, glass lenses focus light, resolution limit 200nm, cells alive
Describe electron microscopy
High resolution but material is always dead and fixed, electron beam
Principle of fluorescent microscopy
Fluorescnce is the emission of light by a substance that has absorbed light
Emission at a higher wavelength than excitation
Sends electrons into a high energetic stages and then falls back
GFP emits green light after excitation with
Blue light
What is GFP used for?
Reporter to analyse proteins in the living cell
Fusion proteins allow us to visualise sub cellular structures
Describe FRAP
Fusion protein is in the nucleus and cytoplasm, bleaching the nuclear population of fusion protein, fluorscence in the nucleus recovers because the cytoplasmic fusion protein enters the nucleus
Reveals differences in membrane fluidity and protein motility - bleached area closes due to diffusion of integral membrane, unbleached don’t close due to reduced membrane fluidity
Describe FLIP
Photobleach the cytoplasmic population, fluorescence in the nucleus decreases as the fusion protein moves into the cytoplasm, visualise the nuclear population of fusion protein by photo-activation with a laser
Describe photoactivation
400bm laser light induces a chemical reaction, about 100-fold increase in fluorescence after photo-activation, photoactivatable red fluorescent proteins available
