Cells Flashcards
What is the basic structural and functional unit of living organisms?
The cell
All eukaryotic cells are composed of what three parts?
- Plasma Membrane
- Cytoplasm
- Nucleus
The plasma membrane has what kind of permeability?
Selective
What does the cytoplasm contain?
all the cellular contents between the plasma membrane and the nucleus. Cytosol and organelles
What contains the DNA?
The nucleus
DNA in molecules is called?
Chromosomes
Each chromosomes consists of a single molecule of ____ and associated packaging _____
DNA
Proteins
Define the plasma membrane
A phospholipid bilayer with associated integral and peripheral proteins. (he stressed the proteins were associated)
What model describes the arrangement of molecules within the plasma membrane as “a sea of phospholipids with protein icebergs floating in it?”
Fluid Mosaic Model
Why is the plasma membrane fluid?
it provides for and allows cell movement, growth, division, and sealing itself if torn.
A rigid membrane would lack mobility and a completely fluid membrane would lack structure.
What do the membrane lipids (phospholipids) do?
Allow passage of many lipid-soluble substances and a barrier to passage of charged or polar substances.
Cholesterol in the bilayer does what?
Mediates membrane fluidity, makes the lipid bilayer less fluid at normal body temperatures/ Increases membrane fluidity at lower temperatures.
Forms hydrogen bonds with heads of phospholipids and glycolipids, and fills the space between fatty acid tails.
Cholesterol is weakly_______ having a small -OH group as the only polar part.
amphipathic
What are the three things does the phospholipid bilayer consist of?
Phospholipids
Cholesterol
Glycoproteins
What are glycoproteins?
membrane proteins with a carbohydrate group attached that protrude into the extracellular fluid.
What is the glycocalyx?
the entire “sugary coating” surrounding the membrane
Membrane proteins are classified as either?
integral proteins or peripheral proteins
Integral proteins vs transmembrane proteins
Integral go well into the bilayer
Transmembrane go all the way through
Peripheral proteins go all the way through the membrane or stay on one side?
Stay on one side
What kind of channels do transmembrane proteins form? And they are also?
Ion channels
Transporters (carriers)
What are the examples of the different membrane proteins?
Ion Channels Transporters Receptors Enzymes Linkers Cell-identity markers
Name the channel: Allows specific ions to move through a water-filled pore
Ion Channel
Name the channel: Carries specific substances across the membrane by changing shape
Carrier
Name the channel: Recognizes specific ligand and alters the cell function in some way
Receptor
Name the channel: Catalyzes reaction inside or outside of the cell
Enzyme
Name the channel: Anchors filaments inside and outside of the plasma membrane, providing structural stability and shape for the cell
Linker
Name the channel: Distinguishes your cells from anyone elses (MHC)
Cell-identity marker
What are the functions of the glycocalyx?
To protect cells from enzymatic action
For cell adhesion
For cell recognition
Changes in the glycocalyx occurs in cells that are transformed into what?
Cancer cells
What kind of molecules freely pass through the plasma membrane?
small, neutrally-charged, lipid soluble substances and water.
The lipid bilayer is
- permeable to ________ uncharged molecules like oxygen, CO2, and steroids
- is impermeable to ions and large uncharged ______ molecules such as glucose
- Slightly permeable to small uncharged ______ molecules like water and urea
- nonpolar
- polar
- polar
Molecules can passively diffuse the plasma membrane if they are?
- lipid soluble
- small enough to pass through the membrane
- Assisted by carrier molecules
Examples of molecules that can passively diffuse the plasma membrane?
- O2
- CO2
- Fats
- Alcohol
What are membrane gradients?
differences of attributes of a membrane compared to the other side.
What are the three gradients talked about?
- concentration
- electrical
- electrochemical
Oxygen molecules and sodium ions are more concentrated in the ______
Carbon dioxide and potassium ions are more concentrated in the ________
Extracellular fluid
Cytosol