Cell theory Flashcards
What are three statements of cell theory?
Living organisms are made of one or more cells.
Cells are the smallest units of life.
All cells are from cells.
What are two main types of organisms (considering the number of cells)?
Unicellular and multicellular.
Are viruses alive?
No, they are not made of cells.
What are 7 functions of living things?
Nutrition
Growth
Reproduction
Response - reaction to stimulus
Excretion - expelling of waste
Metabolism - all chemical reactions in the body
Homeostasis - attempt to keep the conditions inside the body unchanged.
What is differentiation?
The process in which cells become different and specialise for particular function.
All cells in our body are more or less the same.
What are emergent properties?
All properties that emerge from the interactions of all their component parts.
What is the main idea of emergent properties?
The whole is greater than the sum of its parts.
Explain why is surface area/volume ratio as it is.
The bigger/smaller the cell the smaller/bigger the surface area/volume ratio.
Cells need large surface areas for the exchange of materials.
A lot of small cells have bigger surface area than large cells of a comparable V
Cell area is small because they can exchange material better.
What are STEM cells?
Cells that have not yet differentiated.
They can become any other types of cells.
Where can we find STEM cells?
In embryos
We can obtain them from ambrical cord or placente.
What is the difference between prokaryotic and eukaryotic cells? Give examples.
Prokaryotic do not have a nucleus or internal membrance bound - organelles (cyanobacteria and bacteria).
Eukaryotic do have a nucleus (everything else).
Give to features of prokaryotic cells.
Smaller than eukaryotic, and the structure is surrounded by a membrane.
P
Cell membrane
Controls what will enter or leave the cell.
P
Cell wall
Protects the cell.
P
Slime capsule
Additional protection of a cell (only sometimes present)
P
Flangella
Responsible for the moving of the cell.
P
Pili
Attaching to the surface.
P
Cytoplasm
Space inside of a cell, various chemical reactions occur there.
P
Ribosomes
Not organelles since do not have a membrane
Produce proteins
Size is 70S.
P
Nucleoid
Region of a cytoplasm that controls the whole cell, contains genetic material (DNA)
P
Plasmid
Small additonal pieces of genetic material that can be usefull.
How do prokaryotic cells decide?
Binary fussion.
How are eukaryotic cells organised?
They have internal structures with their own membranes.
What is an organelle?
The body inside the euk. cell surrounded by its own memb.
Each organelle has a specific function.
What are the advantages of compartmentalization?
One process will not be interrupted by another.
Each compartment is constructed for a particular function (pH, temperature…)
Which euk. organelles have double membrane?
Nucleus
Mitochondrion
Chloroplast
E
Cell nucleus
surrounded by a double-layered membrane with nuclear pores.
Contains genetic material which controls the cell.
E
Nucleolus
Small area inside a cell nucleus with different density.
E
Endoplasmic reticulum
A system of membranes which looks like a labyrinth.
Production and transport of substances.
sER and rER
smooth endoplasmic reticulum - without ribosomes
produce and transport some fats for cell use
rough endoplasmic reticulum - with ribosomes
produce and transports proteins that go outside of the cell
E
Free ribosomes
Protein production
The structure of ribosomes in rER and free ribosomes is the same size the 80S
Produce proteins for the cell - enzymes for destruction of something.
E
Vesicles
Small bubbles in a cell that might contain various substances.
E
Lysosomes
Vesicles which contain digestive enzymes - it can attack and destroy unwanted materials.
E
Golgy apparatus (golgy body)
No ribosomes
Proteins synthesized on rERs are refound here
Processed proteins are packed into vesicles ade secreted (that is why they are so many vesicles next to it)
How to distinguish ER and golgy apparatus?
Golgy apparatus has typical shape and ER is more wide spread.
E
Mitochondrion
ATP production
double membrane
E
Chloroplast
Double membrane
Contains chlorophyll
Photosynthesis - only in plants, algae…
E
Central vacuole
A big vesicle
Largest organelle in a plant cell
Stores water and other juices
The membrane that surrounds it is under pressure from within and exerts a force on the cytoplasm, cell is firm.
What are plasma membranes composed of?
A phospholipid bilayer
What is the relationship between phosolipids and water?
Hydrophilic head
Hydrophobic tail
What is the model of a membrane called?
Fluid - mosaic model
Why is the membrane stable?
Hydrophobic tails
Hydrophilic heads
It is barely stable.
Why is the memb. fluid?
Components can move position a little bit, they are notrigid.
Why is the memb. a barrier?
Only the smallest molecules can pass
Why is memb. a mosaic?
Because phospholipid bilayer is embedded with protein
What is the memb. composed of?
Phospholipids
Cholesterol
Proteins
Cholesterol
Found in animal cell membranes and functions to improve stability and reduce fluidity.
What are three types of proteins in the memb.?
Integral (transmembrane)
Peripheral
Gylcoprotein
Integral proteins
Penetrate the mebrane, partially at least
Take it out, you disrupt the membrane
Pheripheral
On the inner/outer surface of the membrane
Glycoprotein
prot+sugar on the outer surface of the membrane
Integral protein
What are mem. prot. responsible for?
The majority of functions of the cell membrane
5 functions of the membrane proteins
They can be channels through which substances can travel
They can be pumps which are able to pump substances actively in or out
They can be glycoproteins which sense the presence of some substances in the environment
they can be enzymes which speed up chemical reactions
They can be electron carriers which are able to carry electrons
What is diffusion?
Spontaneous movement of particles from higher to lower concentrations
What is gradient?
Difference in concentration
What does down the gradient mean?
From higher to lower concentration
What five factors impact the speed
temperature higher T - faster diffusion
Surface area - larger surface area - faster diffusion
Concentration gradient - higher gradient - faster diffusion
size of particles - smaller particles - faster diffusion
Diffusion medium -
s slowest
l faster
g fastest
What is simple diffusion
Small molecules (O2, CO2) across a cell membrane directly
What is facilitated diffusion
Big molecules (eg. glucose) across a cell membrane through channel proteins
What is the characteristics of channel proteins and why
They are specific, so they can control what goes in and what out.
What the cell cannot control?
The direction ofthe movement
Facilitated and simple diffusion graph
At first, facilitated is faster but as some point all channel proteins are taken
Solute
substance being dissolved
Solvent
suvstance present in greater amount (H2O)
solution
homogeneous mixture of solute and solvent
absolute conc.
diluted solution
concentrated solution
diluted solution
a little bit of solute
concentrated solution
a lot of solute
relative conc.
hypertonic solution
isotonic solution
hypotonic solution
hypertonic solution
higher solute conc.
isotonic solution
equal solute conc.
hypotonic solution
lowe solute conc.
semipermable membrane
partially permable memb. that allows some substances to pass, but not others
semipermable membrane ex.
cell membrane
osmosis
a spontaneous process in which traveling of H2O through semipermable memb. from less dense to more dense solution
two caracteristics of osmosis
movement of H2O
semipermable memb. is required
what happens to a red blood cell in a hypertonic solution
it shrivels because water goeas out
what happens to a red blood cell in a hypertonic solution
it shrivels because water goes out
what happens to a red blood cell in a hypotonic solution
it bursts because water travels inside of the cell
4 characteristics of passive transport
spontaneous
doesn’t require E
needs a conc. gradient
particles move down the conc. gradient
3 ex. of passive transport
simpe diffusion
facilitated diffusion
osmosis
What are four characteristics of active transport?
Not spontaneous
Requires energy from ATP
moves up the concentration gradient (from lower to higher conc.)
What are the three characteristics of protein pumps?
Active transport is possible because of protein pumps
they require ATP
they are specific - each pump transports only a particular substance in a particular direction.
Give and example of a protein pump
Na+ and K+ pump transports Na+ outside of the cell and K+ inside - axon action potential
When are endocytosis and exocytosis used
For transport of big molecules, or huge amounts of molecules through the memb. using vesicles
Are endo/exocytosis active or passive
neighter
Do endo/exocytosis require E?
Yes
How do exo/endocytosis move in the conc. gradient
They are not dependend of it
Which role does the memb. fluidity have in endo and exocytosis
It allows the meb. to change shape, break and reform
