Unit 2: Cells & Cellular Transport Flashcards
What are the components of a Phospholipid and their attributes?
Phosphate head, polar and hydrophilic
Fatty Acid tails, no polar and hydrophobic
What do Phospholipids make up in the cell?
Plasma cell membrane (bilayer)
What does the cell membrane do? (2)
- separates living cell from aqueous envrionment
- controlls traffic in & out of the cell (some substances can cross over more easily than others)
How are cell membranes semi-permeable?
Only small, no polar molecules are able to pass without assistance (ex. water) and some molecules have protein channels to allow specific material to pass
What are the 6 structures embedded in the membrane?
carbohydrate, peripheral protein, integral protein, glycoprotein, cholesterol, glycolipid
Role of Cholesterol
- effects flexibility of the membrane
- & of unsaturated fatty acids is what determines the fluidity (more=more fluid)
Role of Carbohydrates
- cell-cell recognition
- identification
Why are proteins the best to make channels through the membrane?
Can have multiple properties that allows them to pass through the no polar, polar, hydrophilic, and hydrophobic regions of the phospholipids
How do amino acids connect to the membrane?
- within membrane: nonpolar, hydrophobic amino acids that anchors into the membrane
- outside of membrane: polar, hydrophilic amino acids extend into the extracellular fluid and into the cytosol
What is the name for the water channel?
aquaporin
What are the 6 functions of membrane proteins?
transporter, enzyme activity, cell surface receptor, identification marker, cell adhesion, cytoskeleton attachment
Role of Peripheral Proteins?
identification markers bound loosely on the membrane
Role of Integral Proteins?
penetrates the lipid bilayer as transmembrane proteins that transport proteins as channels or pumps
What is Diffusion?
- universe tends toward disorder (entropy)
- movement of particles from high to low concentration
What is Simple Diffusion?
- Movement from High to Low Concentration
- passive transport that doesn’t require energy
What is Facilitated Diffusion?
- Diffusion through protein channels, specific molecules need the assistance of a channel to pass)
- high to low concentration
What is Active Transport?
- protein pump
- requires energy/ATP
- can allow cells to move against the concentration gradient
What are the 2 methods to moving large molecules?
Endocytosis and Exocytosis
What is Phagocytosis?
the molecules are surrounded by membrane that creates a substance vacuole, which then fuses with a lysosome which contains digestive enzymes
- solid substances
What is Pinocytosis?
the molecules are surrounded by membrane that creates a substance vacuole, which then fuses with a lysosome which contains digestive enzymes
- liquid substances
What is Receptor-Mediated Endocytosis
similar to Phagocytosis, but is triggered by receptor proteins on the cell surface which capture a specific molecule
What is Osmosis?
Diffusion of water
Hypertonic
more solute, less water
Hypotonic
less solute, more water
Isotonic
equal solute, equal water
What are the names for animal cells for the 3 different osmolarities?
Hypo: lysed
Iso: normal
Hyper: shriveled
What are the names of the plant cells for the 3 different osmolarities?
Hypo: turgid
Iso: Flaccid
Hyper: Plasmolyzed
What is the solution to possible cell burst due to being in a hypotonic solution?
contractile vacuoles that pumps water out of the cell (ATP)
Why can plant cells be placed in hypotonic solutions and animal cells can’t?
Plant cells have a cell wall that protects them from bursting. Also, the bigger the vacuole is, the more it is pushing on the cell walls which improves rigidity
Solution for a cell being placed in a hypertonic solution?
Absorb more water to have a pump that takes out the solute out of the cell
What happens when a plant cell plasmolysizes?
the membrane pulls away from the cell way, causes the cell to shrink and crumple. This also results in wilting since there is less water and is less rigid
What state is the cell in when it is placed in a isotonic solution?
equilibrium
What is the flow of water when a cell is placed in a isotonic solution?
no net movement of water, flows across the membrane equally in both directions
What molecules can pass through the cell membrane directly?
fats and other lipids
What molecules can’t get through the membrane directly?
polar molecules, charged ions, large molecules
What is Water Potential?
Ψ, ability of water to do work, measured in bars
What is the Ψ of distilled water?
0
What does more solute do to water potential?
makes the Ψ more negative, less likely to do work, meaning a higher chance that it would receive water
Osmolarity Definition
- generic term for hypotonic, hypertonic, and isotonic
- concentration of a solution expressed as the total number of solute particles per liter
What are the 2 factors of water potential?
solute concentration and pressure
Why is pressure potential important in plants?
B/c plant cells are surrounded by a strong cell wall which is rigid. As water enters the cell, the volume increases and presses on the cell wall, increasing the pressure. This stops more water from entering the cell and also prevents bursting.
What is turgor pressure?
force from within the cell that pushes the plasma membrane against the cell wall created by water moving into the cell via osmosis
What is Cytology?
Study of cell structure
What is an amphipathic molecule?
Contains both hydrophobic and hydrophilic regions
What is a protist?
Unicellular eukaryotes
What are 5 features that prokaryotes and eukaryotes share?
Plasma membrane. Cytosol, chromosomes, ribosomes, cytoplasm
What are 2 factors that effect cell size?
Surface area - volume ratio
metabolic requirements
How does surface area to volume ratio effect cell size?
- smaller cells are more efficient compared to bigger cells b/c materials can cross through quicker and there is a higher surface area to volume ratio, meaning the cell can take in more nutrients to sustain a smaller amount
How does metabolic requirements effect cell size?
The cell has to be a certain size to fit all the components needed for it to function
What are the 2 cellular components involved in the genetic control of the cell?
Nucleus, houses the cell’s DNA
Ribosome, uses information from the DNA to synthesize proteins
What 3 organelles can gene information be found in?
DNA, mitochondria, chloroplasts
What is the function of mRNA?
It is synthesized in the nucleus and carries information out of the nucleus into the cytoplasm. It reaches the ribosomes and the ribosomes translate the information into a specific protein
What organelles does the Endomembrane system include?
Nuclear envelope, endoplasmic reticulum, Golgi, lysosomes, vesicles, vacuoles
What is the function difference between bound and free ribosomes?
Free Ribosomes: produces proteins that function primarily within the cytosol
Bound Ribosomes: produces proteins made for insertion into the membrane
How does the Smooth ER detoxify substances?
Adds hydroxyl groups to the toxic substances to make them water-soluble and able to e flushed from the body
What are the Cis and Trans faces of the Golgi Apparatus?
Cis Face: vesicles add materials to this part of the Golgi
Trans Face: vesicles pinch off from the trans face
What are the 2 organelles require to work together to aid cell motility?
Cytoskeleton and motor proteins
What are the 3 main types of fibers that make up the cytoskeleton?
Microtubules, intermediate filaments, micro filaments
How does the percentage of unsaturated fats in the plasma membrane effect the fluidity?
The higher percentage of unsaturated fats present in the membrane means it is more fluid. This is because of the various kinks in the fatty acid tails that prevent the phospholipids from solidifying due to them not being able to get close enough
What molecules can pass through the membrane without assistance?
Nonpolar, hydrophobic molecules and lipids
What molecules are able to pass slowly through the membrane?
Some polar molecules like water
What is Tonicity?
ability of a surrounding solution to cause a cell to gain or lose water
What is Osmoregulation?
control of solute concentrations and water balance
How does the Cell Wall prevent further water intake when a plant cell is placed in a hypotonic solution?
The pressure from the central vacuole pressing on the cell wall creates turgor pressure which prevents any more water from getting into the cell
