- Regulate internal environment
- They respond to the environment
- Able to reproduce
- They evolve and change over time
- Communicant with each other.
- They metabolize energy and transfer it as ATP.
- Contain genetic Information.
Schwann and Schleiden:
- The cell is the basic unit of life.
- Cells come from pre-existing cells.
Cells only arise from pre-existing cells. The cells that extend from the spinal cord to the muscles(down to the toe) of an animal like a giraffe is over
a meter long. (in all mammals)
All cells are made of the same typeof molecule and the membranes of all cells are made of the same lipids.
And the proteins and the DNA are composed of the samechemistry.
Limitation on cell size:
1- Rate of diffusion. The longer the distance, the longer the diffusion takes. As distance increases, it takes
longer for substances to diffuse.
so cell has to be small enough to keep up with the diffusion of oxygen to support their demand.
2- As surface area increases, the volume stays the same.
3- Thelarger the cell gets, the more substrates it needs.
By making an organism made of a lot of small cells ratherthan one big cell, you eliminate the surface
area:volume problem. Prokaryotes Eukaryotes
Don’t have a nucleus. Have a nucleoid Have a Membrane-enveloped nucleus
No organelles. Internal membranes to segregate functions. Have
No cytoskeleton. Some show that they may have a Use Cytoskeleton
Single circularChromosome with no protein Genetic information as DNA on chromosomes that
are covered in protein
Binary fission Meiosis, Mitosis, Cytokinesis
Organelles of Eukaryotic Cells
Eukaryotic ribosomes are larger than prokaryotes but they both have the same function.
Micro tubules,micro filaments, and intermediate filaments are important in cell movement. They're unique to
Eukaryotic cells. And they contribute in the size of the eukaryotic cells.
Prokaryotes lack this ^^. Another evident:
This animal carries out photosynthesis.
Where do these chloroplasts come from?
- Sea slugs are brown and become green when they start to feed on algae. So they steal the chloroplasts
from the algae. In a process called "Kleproplasty".
Chloroplasts become incorporatedin the intestine cells of the sea slug. And they start to carry out
photosynthesis and it doesn’t need to eat and can rely onphotosynthesis for energy 1-The chloroplasts are passed on from a generation to the next in the theory. But with the seaslug, every
generation needs to do the same thing to get the chloroplasts.
2- In the theory, it was an event that happened once, but for sea slug it happens all the time. Only certain things can pass through the membranes. And membranes organize things in the cell.
Within the mitochondria, the enzymes are efficiently organized for an efficient ATP synthesis.
Regulates what goes into and out of the cell.
Receptors respond to the outside environment.
Membranes are important in cell to cell contact. Recognize other cells.
When cells join together, it happens in the membrane. Have membranes that are high in lipids.
Although they all have the samestructure of membrane, we have different cells that differ as the
membrane presence is different. The membranes are held together by non-covalent linkages.. Into that lipid layer are proteins embeddedin
them. They're responsible of the specific role of the membrane. Only 10 Nano meters thick.
Took two cell lines, one of human and one of mouse. They labeled proteinsin cell membranes.
They fused the cells together, if the proteins aren't freelymoving in the proteins it should be evenly disputed
in halves. but they weren't, which tells us that the proteinis mobile in the membrane. The membrane molecules recover the area that was damaged by the laser. (Shows that they’re mobile).
If you plot the intensity of the fluorescent as a function oftime, you can see how mobile a protein is in a
1925, they estimated the cell size and the amount of lipidthey got and they said that the lipid is twice the size
of the cell so the membrane is madeof lipid.
Phosphoglycerides made of non-polar heads. (Serine.. Choline, ethanolamine,inositol)
Fatty acids: Hydrocarbon Chains.
The polar heads face water, the non-polar turn away from water.
In Spenhgolipids, there’s only one fatty acid (An important component of the animal cell). Hydrophobic chains face away of water
Hydrophilic chains face water
^^ this gives you the basic structure of the membrane. Glycolipids:
- Very similar to phospholipidin structure.
-They have a carbohydrate group rather than R group and phosphate.
-Glycolipids basedon sphigosine in animal cells.
-Two abundant glycolipids in plants cells
ABO blood groups are based on glycolipids.
- Functions as antigens to recognize other cells
In eukaryotic cells, chloroplasts and mitochondria lack sterols because they’re originated from bacteria which
are prokaryotes and prokaryotes don’t have sterols.
- Four ring is the defining characteristic of this group.
- Polar Hydroxyl group in one end and on the other is a hydrocarbon tail.
^^ This is the structure of sterols
The sterols are imbedded in the fatty acids chains.
No sterols in the walls of prokaryotic cells.
Within eukaryotic cells, each have unique characteristics sterols. << Check slide for names The composition of the two leaflets is different, lipids within a leaflet can move freely, but rarely
moves from one leaflet to another.
One half faces the cytoplasm and other one faces the external environment of the cell.
It's hard because the polar head would have to go downto the hydrophobic part and travel to the
Glycolipids would be more on the upper half because they're used for recognition (red blood
function) Cell membranesstiff when skin gets cold. Because it’s stiff, the sensors stop working.
At low temperature, the fatty acids become close together so it becomesless fluid. and opposite for
If it's not fluid enough, the membrane can't function properly.
The length of the fatty acid chains and their degree affect membrane fluidity.
Longer chain pack better so they have low fluidity
Shorter chains pack not as well so they have high fluidity
Highly saturated fatty acids don’t pack togetherso well so they have lower fluidity and vice versa.
The more fluid the membrane, the more double bonds present.
16-18 carbons forideal degree fluidity.
Phospho cholinelow fluidity
Phospo E .. High fluidity
(see picture on slide for summary)
Sterols have stiff frame work, much rigid.. at low temperature, they break the membrane to increase
fluidity..... (Buffering effect)
At high temperatures they decrease fluidity Rainbow trout adjust the ratioof phosphor-chlorine to phospho-E to compensate the change of the
When temp goes down, It lowers Phospho-choline and increases the other to adjust temperature
and vice versa.
More double bonds in the animals that live in cold temperatures.
^^ you need low PC to PE ration Unsaturated fatty acidsfrom the mud shrimp benefits the bird and add the fatty acids to the flight muscles
membrane and letting the fatty acids enter the membrane qui