Structure and Function of cells Flashcards
Approx size of a cell
0.1-100 micrometers
Why cant cells be too. small?
They must fit DNA and must also fit cellular components to sustain life and reproduce
Why cant they be too big?
Needs to exchange w outside environment, the cell needs depend on. the volume
What does the exchange capacity of.a cell depend on?
SURFACE AREA
Briefly explain surface to volume ratio and square cube law
The more volume a cell has, the more nutrients it requires to get (through surface area) however, volume and surface area do not increase at the same time therefore the nutrients needs cannot be met
What are the parts of the cell theory
- a cell is the basic structural and functional unit of living organisms
- cells come from pre existing cells
- cell characteristics are passed from parent to off spring
- cells have a plasma membrane
- proteins are produces by ribosomes
What is a cell?
Membrane bound structure contained genetic material ,cytoplasm and various organelles
Name the 3 functions of a cell
1) Can store and transmit info
2) has a plasma membrane
3) can harness energy from the environment
Explain how the cell membrane is a fluid mosaic
It contains different components and it is not uniform.
the membrane contains phospholipids, steroids like cholesterol, proteins and lipid rafts to aggregate)
Why and how is the cell asymmetrical
IT is asymmetrical because the two layers (outer and inner) are different because they have different functions/jobs)
Why is the phospholipid bilayer amphipathic
it has hydrophilic heads to intereact with the water outside the cells and hydrophobic tails on the inside layer
Explain the movements of phospholipids
They can move laterally but usually do not “flip flop” because the hydrophilic heads to not want to interact with the hydrophobic tails.
What are the 2 types of proteins within the membrane
- Integral membrane proteins
- Peripheral membrane proteins
How does cholesterol help in the membrane?
Interacts with the phospholipid bilayer and maintains the fluidity of the membrane by preventing the tails to cflump/aggregate when its too cold and to prevent them from moving alot then temp is high.
Explain the integral membrane proteins
they can cross the membrane because they have both va hydrophilic region and a hydrophobic region
Explain the peripheral membrane proteins
DO NOT cross plasma membrane because the do not have a hydrophobic region. It binds to the polar heads of the lipids and also to the hydrophilic regions of intergtral proteins
What can these two protein types do?
Transport energy have enzymatic activity signal transducdtion cell-cell recognition intracellular joining attachement to tje cytoskeleton and extracellular matrix
Explain how the membrane is a selective barrier?
It regulates what goes in and what comes out (ions, macromolecules, water)
It requires various means of transport to get across the membrane
What are the two types of membrane transport
Passive and Active Transport
Explain Passive transport
It includes diffusion and facilitated diffusion
- normal high to low concentration
- no outside energy is needed
- facilitated by channel proteins and carrier proteins
What is the difference between simple diffusion and facilitated diffusion
Simple diffusion: straight across membrane, no help needed from proteins
Facilitated diffusion: either by channel mediated or carrier mediated proteins that get the outer molecules inside the cell
What is osmosis
a process by which molecules of a solvent WATER tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane.
what are the three types of solutions and explain them
Hypotonic: it is lysed therefore has less solute and more water
Isotonic: at equlibrium
Hypertonic: it is shrivelled and has more solute and less water
Why do hydrophobic molecules go straight through the membrane with no aid?
Because the membrane itself is also hydrophobic