Chapter 4a Flashcards
Cells are known as
the functional units of the body
What’s the study of cells?
cytology
Microscopy is what?
the use of a microscop to view small-scale structures
What’s the light microscope?
produces a two dimensional image
-passes light through a specimen
The electron microscope does what?
- uses a beam of electrons to “illuminate” the speciment
Which has a higher magnification LM or EM?
electron microscope, also has better ability to see details
What the main difference between a TEM and SEM?
TEM produces two dimensional structure, SEM generates a three dimensional study
Whats does the plasma membrane do?
it forms outer limiting barrier, separates internal contents of cell from external environment
What small structures does the plasma membrane have?
cilia, flagellum, microvilli
Whats holds the nucleus and what does the nucleus contain?
nuclear envelope, contains genetic material
What the cytoplasm?
cellular contents between plasma membrane and the nucleus
What does the cytoplasm include?
cytosol, organelles and inclusions
Organelles are what?
organized structures within cells, all have unique shape and function
Membrane- bound organelles are enclosed by what and whats the function of this?
a membrane that separates the contents from the cytosol
What’s missing form non-membrane-bound organelles?
no enclosed within a membrane
What is the non-membrane-bound organelles usually composed of?
proteins
Inclusions are what?
large diverse group of molecules
Are inclusions considered an organelle and are they membrane-bound
not an organelle, not considered organelles
Where is the cholesterol in a cell?
scattered withing the phospholipid bilayer
What does cholesterol do within the membrane?
strengthens the membrane and stabilized the membrane against temperature extremes
Plasma membranes are solid or liquid?
liquid
What equal parts is it composed of?
lipid and protein by weight
What does the plasma membrane regulate?
movements of most substances in and out of the cell
Is the plasma membrane polar or non polar?
nonpolar
Because the plasma membrane is nonpolar what substances are able to penetrate it?
small and non polar substances without assistance
What types of lipids does the plasma membrane contain?
phospholipds, cholestrol and glycolipds
Most membranes are made up of what type of lipid?
phospholipid
Phospholipds have a polar and and hydrophobic parts..what are they?
polar head, two hydrophobic tails
What type of sheet does the phospholipds in the plasma membrane form?
parallel sheets of molecules
Does the head or tail of the phospholipd form the internal area membrane?
the tails
What is the structure of the phospholipds called?
phospholipid bilayer
What does the phospholipid ensure?
that the cytosol and fluid surrounding the cells remain seperate
What is the surrounding fluid termed?
interstitial fluid
Glycolipids are lipids attached to what type of group?
carbohydrate
Glycolipids are located on the what region of the phospholipid?
only on the outer
What do glycolipids help form on the cell’s surface? and define term…
glycocalyx- the coating of sugar
What protein composes half of the plasma membrane by weight?
the membrane proteins
How do membrane proteins move around the cell?
they float and move about fluid bilayer
How do the membrane proteins get their functions?
by resident proteins
Membrane proteins are classified as what?
integral or peripheral membranes
What’s the major difference between integral and peripheral proteins?
integral is embedded withing and extend across lipid bilayer
- Peripheral proteins are not embedded in lipid bilayer and attach loosely to surfaces of the membrane
Membrane proteins are categorized how?
functionally
What are the 4 different types of membrane proteins?
transport proteins, cells surface receptors, identity markers, enzymes
Transport proteins do what
regulate movement of substances across membrane
• e.g., channels, carriers, and pumps
Cell surface receptors do what?
bind ligand molecules released from a specific cell
• bind receptors on another cell
• e.g., neurotransmitters and hormones
Identity markers do what?
- communicate to other cells
* e.g., immune system cells distinguishing healthy cells from foreign cells
Enzymes do what?
• catalyze chemical reactions
What is a very important function of plasma membrane?
Regulating movement of materials into and out of a cell
What is the process the plasma membrane uses to regulate movement?
membrane transport
Membrane transport can be categorized as what?
passive or active transport
Describe passive transport as related to energy and concentration gradient?
– Do not require energy
– Depend on substances moving down concentration gradient
• move from where there is more of a substance to where there is less
What are the two types of passive processes?
diffusion
• osmosis
Describe active transport as related to energy and the concentration gradient…
Require energy
– E.g., movement of a substance up its concentration gradient
Wehn a membrane bound vesicle is released is it active or passive and what is this called?
active…termed vesicular transport
Diffusion describes what?
Moves from area of greater concentration to area of lesser
concentration
What types of concentration does diffusion move from and to?
Molecules and ions in constant motion due to kinetic energy
Molecules and ions in constant motion due to
kinetic energy
If unopposed, diffusing will continue until the substance reaches what? and describe this…
molecules evenly distributed throughout a given area
What type of conditions affect rate of diffusion?
Environmental conditions
What are the two environmental conditions that affect diffusion ?
“Steepness” of concentration gradient, Temperature
“Steepness” of concentration gradient is the mesure of the difference in what?
concentration between two areas
Temperature reflects what?
kinetic energy and random movement
Simple diffusion is what?
Molecules passing between phospholipid molecules
What solutes does simple diffusion include
– Solutes small and nonpolar
The solutes in simple diffusion cannot be regulated by what?
– Include respiratory gases (O2 and CO2), some fatty acids, ethanol, urea
– Cannot be regulated by plasma membrane
The movement of simple diffusion is dependents on what?
on concentration gradient alone
Simple diffusion will continue to move as long as what?
as long as gradient exists
Facilitated diffusion is what?
Transport process for small charged or polar solutes
Facilitated diffusion requires substances from what?
Require assistance from plasma membrane proteins
What are the two types of facilitated diffusion?
channel-mediated diffusion
• carrier-mediated diffusion
A maximum rate of transport in facilitated diffusion is determined by what?
by number of channels and carriers
• higher rate with greater number of transport proteins
Channel- mediated diffusion is what?
Movement of small ions through water-filled protein channels
The Channel- mediated channels are specific for what
Channels specific for one ion type
The Channel- mediated leak channels are what?
• continuously open
The Channel- mediated gated channels are what?
usually closed
• open in response to stimulus
Na+ leak channels can be two ways what are they?
leak channels and chemically gated Na+ channels
Na+ leak channels allow what?
allow Na+ to pass through continuously
Na + chemically gated channels allow what?
allow Na+ to move through in response to a particular chemical
Carrier mediated diffusion is what?
Small, polar molecules assisted across membrane by carrier protein
What substances does Carrier mediated diffusion transport?
Transport substances such as glucose
In Carrier mediated diffusion binding of a substance causes what?
binding of substance causing change in carrier protein shape
– Releases substances on other side of membrane
Carrier-mediated diffusion moves substances up or down gradient?
Move substances down their gradient
Osmosis definition:
Passive movement of water through selectively permeable membrane
The selectively permeable membrane in osmosis allows for what to pass and prevents what from passing?
membrane allowing passage of water
• membrane preventing passage of most solutes
Why does osmosis occur?
Occurs in response to differences in water concentration
• different concentrations on either side of a membrane
The two types of solutes that have to do with selectively permeable membranes are what?
permeable solutes, non permeable solutes
Permeable solutes can do what and what are some examples?
pass through bilayer
• small and nonpolar solutes
• e.g., oxygen, carbon dioxide
Nonpermeable are what from passing through bilayer and what are the three types of nonpermeable solutes?
prevented from passing through bilayer
• charged, polar, or large solutes
• e.g., ions, glucose, proteins
The net movement of water by osmosis is dependent on what and does it move up or down it’s gradient?
Dependent on concentration gradient between cytosol and solution
– Moves down its gradient
Net movement of water by osmosis moves until what occurs?
Moves until equilibrium is reached
What is equilibrium with osmosis?
Equal concentration of water inside and outside cell
Net movement of water by osmosis moves toward what type of solution?
Moves toward solution with lower water concentration
In osmotic pressure steeper gradient causes what two things?
Steeper gradient, more water moved by osmosis
– Steeper gradient, greater osmotic pressure
What is tonicity?
ability of a solution to change the volume or pressure of the cell by osmosis
An isotonic solution is has what relative concentration which causes what type of movement of water?
Both cytosol and solution with same relative concentration of solutes
– No net movement of water
An hypotonic solution is has what relative concentration which causes what type of movement of water?
- Solution with a lower concentration of solutes than cytosol
- Water moving down concentration gradient
• from outside the cell to inside
What can happen with hypotonic solutions with a cell?
lysis (rupture)
Hemolysis
• hemolysis, term for ruptured red blood cells
Hypertonic solution is what type of concentration and where does water move?
Solution with a higher concentration of solutes than cytosol
– Water moves down concentration gradient
What does hypertonic solutions cause within a cell?
Moves from inside the cell to outside
– Decreased volume and pressure of cell
– May cause cell to shrink
What is the shrinking of a cell called?
crenation
