Exam 2 Cell Bio Flashcards
The plasma membrane is involved in many vital functions including:
cell communication
import and export of molecules
cell growth and motility
A cell membrane is composed of what:
a lipid bilayer in which proteins are embedded
The properties of fats depend on what?
the length and saturation of the fatty acid chains they carry
Effects of Fatty Acid Composition on Membrane Fluidity (number of carbon atoms and heat)
More fluid with fewer carbon atoms (more heat required with more carbons)
Effects of Fatty Acid Composition on Membrane Fluidity (number of double bonds and heat)
More fluid with more saturated double bonds (more heat required for no double bonds)
Cholesterol
a type of sterol (lipid) found in lipid bilayers that stiffens cell membranes
Has a polar head, ring structure head and nonpolar tail)
Four types of membrane protein functions:
- Transporters and channels
- Anchors
- Receptors
- Enzymes
Types of integral membrane proteins
- Transmembrane
- Monolayer associated
- Lipid linked
Types of peripheral proteins
Protein attached proteins
Why are a-helices proteins the most common to cross the bilayer?
They easily form hydrophilic interiors and hydrophobic exteriors that reside in the hydrophobic portions of a membrane
What types of channels are formed with porins?
B-barrels made with B-sheets
Two common detergents
SDS and Triton X-100
What are three protein filaments found in cytoskeletons?
- Actin filaments
- Microtubules
- Intermediate filaments
Actin filaments
AKA Microfilaments - flexible structures and linear networks found in the cortex and other locations in a cell
Microtubules
Hollow cylinder proteins of tubulin that are straight and long conjoined at a centromere
Assists in meiosis and mitosis to separate cells
Intermediate filaments
Provides strength to cells and tissues
Rates at which different molecules can pass through a membrane through simple diffusion?
Quickly (Small, nonpolar)
Semi-quick (small, uncharged polar)
Slow (larger, uncharged polar)
Impossible (ions)
Passive transport examples
Channel mediated and transporter mediated (from high to low concentration)
Active transport example
pump (low to high concentration)
An electrochemical gradient has two components: it is the sum of a force of the ___ ____ of the solute and a force from the ___ ___.
concentration gradient ; membrane potential
What happens if there are unequal concentrations of an ion across a membrane?
The ion will move from an area of high to low concentration until the charges are balanced. Otherwise, energy is required to go from low to high
aquaporin
Water channels for fast diffusion
Example of a passive transporter
Glucose comes in through a glucose transporter, binds at binding site and releases into cell
Randomly opens and closes with movement from high to low concentration
