Unit 2 Flashcards
What are the components of water potential?
Pressure potential and osmotic potential or solute potential.
What is water potential?
It is the voltage across a membrane. It measures the tendency of water to diffuse from one compartment to another.
How can you use water potential to predict the movement of water?
Water moves from an area of higher water potential to an area of lower water potential.
What’s the difference between passive transport and active transport?
Passive transport doesn’t use energy and more solutes along their concentration gradients. Its spontaneous and random.
Active transport requires energy in order to more solutes against their gradients.
What are the types of passive transport?
Diffusion and facilitated diffusion
What is diffusion and what kinds of molecules does it move?
- movement of molecules from high to low concentration
- Allows small nonpolar molecules to pass through the membrane freely.
- Water is polar but can pass because it is so small.
What is facilitated diffusion and what kinds of molecules does it move?
Allows polar, hydrophilic molecules to pass through the membrane through the use of transport proteins.
How are facilitated diffusion and diffusion similar?
Don’t require energy to move molecules. Move them down their concentration gradients. High to low concentration.
How are diffusion and facilitated diffusion different?
Diffusion allows small nonpolar molecules through without help. Facilitated diffusion uses proteins that only allow a specific protein through.
What are the types of proteins that aid in facilitated diffusion?
Carrier proteins and channel proteins
What do channel proteins do?
Provide corridors that allow a specific molecule or ion through.
What are aquaporins?
Channel proteins that aid in the diffusion of water
What do carrier proteins do?
Bind to molecules, change shape, and bring the molecule across. For specific molecules.
How do particles move in relation to their concentration gradients?
They move from areas of high concentration to areas of low concentration
What might happen to a cell if aquaporins are added to its cell membrane?
Would let in more water, quicker. Would reach dynamic equilibrium quicker.
What would happen to a cell if aquaporins are removed from the cell membrane?
Wouldn’t take in water as quickly. Would take longer to reach dynamic equilibrium.
What are the parts of a cell membrane?
- lipid bilayer (amphipathic phospholipids)
- proteins, aren’t randomly distributed, floating in the bilayer
- carbohydrates on the surface
- cholesterol in the bilayer
What is the structure of the lipid bilayer of the cell membrane?
Phospholipids that are held together by weak hydrophobic interactions.
Where are the proteins in the cell membrane? (Includes types of proteins)
Clustered in groups, determine the membrane’s function
- peripheral proteins, on the surface
- integral proteins, penetrate the hydrophobic core
- transmembrane proteins, Integral proteins that down the membrane
What are the functions of proteins on the cell membranes?
Cell to cell recognition, intercellular joining, transport, structure, enzymatic activity, signal transduction
What is the function of carbohydrates on the cell membrane?
Cell to cell recognition, bind with molecules
What is the function of the cholesterol in the lipid bilayer?
Is located within the bilayer.
- at high temps it restrains the movement of the lipids
- at low temps it maintains fluidity by preventing tight packing
How does temperature affect the fluidity of a cell membrane?
As temperature decreased membranes switch from a fluid to a solid state. Membranes with more unsaturated fats are less tightly packed and more fluid.
A cell membrane must be fluid to proper function.
What are the 3 types of tonicity and where does water move for each?
Isotonic - concentration inside is equal to outside the cell, no net water movement
Hypertonic - solute concentration is greater outside the cell, cell loses water
Hypotonic - solute concentration is greater inside the cell, cell gains water
What might happen to a cell placed in a hypotonic environment?
The cell will gain more water
- animal cells –> lyse (burst)
- plant cells –> become turgid/firm (ideal environment for plant cells)
What might happen to a cell placed in a hypertonic environment?
The cell will lose water
- animal cells –> shrivel
- plant cells –> plasmolysis (membrane pulls away from the cell wall, causes wilting)
What might happen to a cell placed in a isotonic environment?
No net water movement, dynamic equilibrium
- animal cells –> ideal environment
- plant cells –> flaccid, no water coming in and pushing cell contents against cell wall
What are the types of bulk transport?
Exocytosis and Endocytosis
What is bulk transport?
A type of transport that uses energy to move polysaccharides and proteins and other large molecules across the membrane through the use of vesicles.
What is exocytosis?
- releases molecules out of cell
- vesicles fuse with the membrane and release their contents
What is endocytosis?
The cell takes in macromolecules by forming vesicles from the plasma membrane
What are the three types of endocytosis and what do they do?
Phagocytosis - the cell engulfs a particle in a vacuole which fuses with a lysosome to digest
Receptor-mediated Endocytosis - binding of specific solutes to receptor triggered vesicles
Pinocytosis - cell forms a vesicles around a fluid and it’s solute
What is the endosymbiotic theory and what evidence supports it?
- free aerobic prokaryote engulfed an anaerobic cell through endocytosis. The engulfed cell did not get digested and instead the arrangement became mutually beneficial. Over time the engulfed cell lost functionality and became the mitochondria of the eukaryotic cell.
- They both create energy from stored material
- contain their own DNA in ribosomes
- Double membranes
Pathway of a protein produced by bound ribosomes on rough ER
Rough ER –> creates the protein
vesicles –> takes it to the golgi
golgi –> modifies the protein
vesicles –> takes them out or in the cell
Together they synthesize and isolate proteins for use within or outside the cell
What do all cells have in common?
- plasma membrane
- cytoplasm, jelly like region within the cell
- DNA, genetic material of the cell
- ribosomes, which synthesize proteins
What is the difference between plant and animal cells?
- plants have cell walls to provide structure, animal cells only have a cell membrane
- plant cells have chloroplasts
- animal cells have mitochondria
What is the difference between prokaryotic and eukaryotic cells?
- eukaryotic has a nucleus, prokaryotic has a nucleoid, DNA is stored in these two locations
- prokaryotic cells have membrane-bound organelles
What is the structure of the nucleus?
- DNA is organized into chromosomes
- nuclear envelope = inner and outer membrane
- ribosomes, nuclear pores located on the membrane
What is the function of the nucleus?
Contains the DNA in a eukaryotic cell, controls the cell’s activities
What is the structure of the endoplasmic reticultum (ER, smooth and rough)?
- smooth ER lacks ribosomes
- rough ER has a surface studded with ribosomes
- both are made up of cisternae, flattened vesicles
What is the function of the endoplasmic reticulum (ER, smooth and rough)?
smooth ER
- detoxify, create lipids, metabolize carbs
- stores calcium ions
rough ER
- ribosomes secrete glycoproteins (proteins bonded to carbs)
- distributes transport vesicles
What is the structure of the golgi apparatus?
flattened membranous sacs called cisternae
What is the function of the golgi apparatus?
modifies proteins created by the ER, sorts and packages them into transport vesicles
What is the structure of the vesicles and vacuoles?
Vesicles are secretory proteins surrounded by membranes
Vacuoles are large vesicles derived from the ER and golgi
What is the function of vesicles and vacuoles?
Vesicles transfer proteins around the cell
Vacuoles help move things out of the cell
What is the structure of lysosomes?
membranous sacs of hydrolytic enzymes
What is the function of lysosomes?
digests macromolecules
What is the structure of the mitochondria?
- double membrane
- free ribosomes
- circular DNA molecules
What is the function of the mitochondria?
Cellular respiration, uses oxygen to make ATP
What is the structure of a chloroplast?
- double membrane
- free ribosomes
- circular DNA molecules
What is the function of a chloroplast?
- sites for photosynthesis
- grow and reproduce independently in cells
What is the function of the ribosomes (free vs bound)?
Free ribosomes
- located in cytosol
- create proteins that stay in the cytosol
Bound ribosomes
- located on the outside of the ER
- create proteins that will be exported out of the cell or will become part of the plasma membrane
