Cell Transport and Cell Communication Flashcards
What is selective permeability?
allows some substances to cross the membrane more easily than others. This is fundamental to life! Why?
Why is a phospholipid considered to be amphipathic?
It has both a hydrophilic and hydrophobic region. Which region is hydrophilic?
How do the phospholipids arrange themselves in a cell membrane?
The heads face out and the tails face in. Why?
Why does fluid mosaic model describe the structure of the cell membrane?https://www.khanacademy.org/science/ap-biology/cell-structure-and-function/membrane-permeability/a/fluid-mosaic-model-cell-membranes-article
What is a mosaic? Protein molecules are bobbing (like corks) in a fluid layer of phospholipids. Proteins are not randomly arranged!
Why would some membranes stay fluid to a lower temperature than other membranes?
Phospholipids with unsaturated tails cannot pack together as closely as saturated tails. What determines if a tail is saturated?
Fish that live in extreme cold have membranes with a high proportion of unsaturated tails. Why?
Membranes will remain fluid. The kinks don’t allow the close packing.
How many different kinds of proteins are in a red blood cell?
50!
What is the difference between an integral protein and a peripheral protein?
Integral: penetrate the hydrophobic interior of the cell membrane. Peripheral proteins are loosely bound to the surface of the membrane.
Transport protein
channel for a solute. Glucose, for example.
Enzymatic activity
A protein built into the membrane that performs an enzymatic function.
Signal transduction
Protein with a binding site that fits a chemical messenger. Good example is insulin.
Cell-cell recognition
A glycoprotein that functions as an Identification tags on the cell surface.
Intercellular joining
Membrane proteins of adjacent cells that can hook together to make a junction. Ex, gap junction
Attachment to ECM
Stabilizes protein, coordinate cell activity, maintain cell shape
How are glycolipids different than glycoproteins?
carbohydrate attached to lipid-GL carbohydrate attached to protein-GP
Aquaporin
channel to move water molecules across the cell membrane
diffusion
movement of particles of any substance so they spread out in available space. Substances move from High concentration to low concentration . Another way to say this? moving down the concentration gradient.
Why is diffusion considered passive transport?
no energy!
What is osmosis?
diffusion of water across the cell membrane
What is tonicity?
the ability of a surrounding solution to cause a cell to gain or lose water
hypertonic
more solute than the cell
hypotonic
less solute than the cell
isotonic
same solute than the cell
What is the effect of a hypotonic solution on an animal cell?
the cell will burst or lyse. Why?
osmoregulation
control of solute concentrations and water balance
turgid
normal for a plant, firm, full central vacuole
flaccid
if environment is isotonic to a plant cell, plant will wilt.
plasmolysis
if environment is hypertonic to a plant cell. Plasma membrane pulls away from the cell wall.
facilitated diffusion
with gradient, use of a transport protein, no energy ex. aquaporins
ion channels
channel proteins that transport ions
What is an example of a disease that is due to malfunctioning cell transport?
cystic fibrosis. The CFTR channel is not the right shape. Cl- can’t move across and mucus builds up.
What is active transport?
What is the sodium-potassium pump?
Exchanges Na+ for K+. Needs ATP
What is the electrochemical gradient?
What is the proton pump? Why is it important to chapter 7?
Proton pump uses energy to move H+ across the membrane. A H+ gradient is established. (What happens to the pH?)
This gradient that is established in the innermembrane space (mitochondria) is part of ATP synthesis!
What is cotransport?
The use of a H+ gradient (see proton pump) to actively transport amino acids, sugars or other nutrients into a cell.
Good example? sucrose
What is exocytosis?
A type of bulk transport. Uses energy.
Removal of substances by using a vesicle.
Good example? insulin
What is endocytosis?
Example of bulk transport
Uses energy
Taking in materials by forming a vesicle.
Can be: phagocytosis, pinocytosis or receptor-mediated
What is familial hypercholesterolemia?
The receptors are either reduced in number (mild) or absent (severe) to remove LDL cholesterol.
Cholesterol builds up in blood, can cause atherosclerosis or build up of lipids on blood vessel walls. This can impede blood flow-can cause stroke/heart damage
What is a hormone?
What is paracrine signaling?
a Type of local.
What is synaptic signaling?
What are the three steps of the cell signaling pathway?
reception
transduction
response
What is a protein kinase?
An enzyme that transfers phosphate groups from ATP to a protein (activates it!)
2% of our genes code for protein kinases!
One key role? regulate cell division! We’ll talk more about this when we discuss cancer.
How can a growth factor (type of signaling molecule) activate a gene?
The last kinase enters the nucleus and activates a transcription factor.
Transcription is the production of mRNA from a gene (segment of DNA).
mRNA is read by ribosomes to make protein.
