Chapter 5 Flashcards
3 Major components of cell membrane
- Lipids
- Proteins
- Carbohydrates
Lipids function in cell membrane
- Allows some smaller molecules to diffuse freely while blocking the diffusion of the polar substances
- Phospholipid bi-layer
- Hyprophilic (water loving) head on the outside with hydrophonic (water-fearing) tail on the inside
Proteins function in cell membrane
- The transmembrane proteins let in large molecules and/or polar molecules
- A large part of the facilitated diffusion
- Some are permenantly open and are used to transport ions and water across the cell
- Aquaporins, ion channels (transport ions)
- gated channels and ligands don’t stay open all the time
- pores or gates
Aquaporins
- Proteins
- Channels that transport water
Carbohydrate function in the cell membrane
- not very well understood and plays a role in cell communication
- like cat whiskers: sensors, signals for the cell
What is the relationship between structure/composition and function in a cell membrane
The function of a cell membrane is to control what goes in and out of the cell. The cell maintains homeostasis by regulating levels of things like CO2, sugar, oxygen, and water. The cell membrane is selectively permeable (it can control the movement of some sustances, but not the movements of all things. The build of the cell membrane lets some small molecules like oxygen to slip between the gaps in the phospholipids. The cell membrane is sometimes described as an ocean of phospholipids with protein ships floating within it. Transport proteins let in large, ions, and polar molecules in.
How is equilibrium established as a result of diffusion and what happens to the movements of molecules when equilibrium is reached
Diffusion is when molecules move from high to low concentration. Diffusion acheives equilibrium because the molecules will continue to mobve from high to low concentration and eventually balance out and achieve equilibrium. The molecules will still move after equilibrium is reached in both directions but = numbers of each particles will move in opposite directions so concentration is kept
Diffusion: def, location, energy use, examples, limitations and abilities
Def: the tendency for particles of any kind to spread out evenly in an available space moving from where they are more concentrated to regions where they are less concentrated. High to low
Location: cell membrane/ phospholipid layer
Energy use: No
Examples at cellular level: ?
Examples at classroom level: Spraying perfume in the front of the classroom will eventaully make it to the back
Abilities: small,nonpolar molecules
Limitations: ions, polar, and large molecules
Osmosis:def, location, energy use, examples, limitations and abilities
Def: the diffusion of water across the cell membrane/a semi-permeable membrane
Location: water/cell membrane/aquaporins
Energy use?: no
cellular examples: water moves into the cell because there isnt enough water in the cell
Classroom examples: when markets spray water onto vegetables because they have have higher salt ans will fill with water
Limitations:only water
Abilities: transports water across cell membrane
The diffusion of water towards the higher concentration of solute
Facilitated diffusion: Def, relate to concentration gradient, relate to integral protein, location energy use, examples at cellular level, limitations and abilities
Def: A molecule that diffuses across a cell membrane with the help of transport proteins because they can’t move across the cell membrane freely bc of their size or charge
Concentration gradient: facilitated diffusion moves the molecule with the concentration gradient. High to low
-facilitated diffusion uses a integral protein to move the molecule across the cell membrane
Location: cell membrane/transport protein
Energy use: no
Example at cellular level: transporting glucose
Limitations: only large, polar, charged molecules
Abilities: transporting polar (hydrophylic), substances, large, ions/charged particles
How do ion channels assist the diffusion of ions across the cell membrane: Def, relate to concentration gradient, relate to integral protein, location energy use, examples at cellular level, limitations and abilities
Ion channels: a type of transport protein that transports ions
With concentration gradient: Yes, high to low, passive transport
Def: the use of an integral protein to transport ions across a cell membrane
Location: cell membrane/ion channel
Examples at cellular level: sodium potassium pump
Limitations: ions only
Abilities: can transport ions across the cell membrane
Passive transport
EX: diffusion, facilitated diffusion, osmosis
Def: Going from high to low concentration
Energy: no, happens naturally
Active transport
EX: endosytosis, active transport
Def: going from low to high concentration
Energy: yes, swimming up stream, goes upstream
Sodium potassium transport pump
Moves sodium (NA+) ions out of the cell and potassium ions into the cell -Against concentration gradient, ATP
Endocytosis: Def, dif between movement of liquids and solids, where, energy use, ex at cellular level, limitations and abilities
Def: the bulk transport of substances into the cell
Liquids: pinocytosis- small or liquid
Solids: phagocytosis- solids or larger particles
location: cell membrane or cell
Requires energy: yes
Ex at cellular level: bringing in large food particle
Limitations: none, has to be able to make vesicles
Abilities: ability to transport large amounts of food/liquid/substances into the cell
* utilizes vesicles to move substances into the cell
Exocytosis: def, location, organelles, energy use, examples at cellular level, limitations, abilities
Def: The bulk transport of substances out of the cell
Location: the cell/cell membrane
Organelles: vesicles for transport
Energy use: yes
Ex at cellular level: releasing a lot of waste
limitations: none, has to be able to make vesicles
Abilities: release a lot of substances at once
Hypertonic
-solution has higher solvent concentration so the water leaves the cell
-the cell becomes shriveled up
-crenated
-Plamolysis
Water will always move to higher concentration of solute
Isotonic
- equilibrium, solution has equal solute/solvent concentration
- Cell’s volume stays constant
- same amount of water going in and out of the cell
Hypotonic
Extracellular (outside solution) has lower solute (salt) concentration so it invades the cell to get to the higher concentration
- Cell fills up with water
- Turgid/turgor pressure
Plasmolysis
The shrinking of the cell as a result of water loss
- hypertonic.
- Water is
Turgor pressure
Pressure that builds in a plant cell as a result of osmosis
-hypotonic
Cytolysis
The bursting of an animal cell membrane in a hypotonic environment
- lysed
- hypotonic
How does a unicellular paracium get rid of excess water using a contractile vacuole and explain what type of solution would cause the vacuole to contract the most. Is energy used? Why don’t multicellular eukaryotes need this organelle
- A unicellular paracium gets rid of it’s excess water using a contratile vacuole with active transport
- A hypotonic solution would cause the vacuole to contract the most because a hypotonic solution has a higher water concentration so it would move into the cell were there is a lower water concentration
- Energy is used
- multicellular eukaryotes don’t have this or need this organelle because they have other methods to expel water. They have aquaporins or protein channels specifically to pump water
Explain how molecules move across a membrane and give examples of real world situations where movement would occur
Molecules move across a cell membrane going from high to low concentration using diffusion, facilitated diffusion, or osmosis. Small, non polar, or uncharged things are able to cross a cell membrane freely using diffusion. Large, polar, or charged molecules can cross the cell membrane with the help of a trans-membranw protein. Molecules can go from low concentration to high concentration using active transport, exocytosis, or endocytosis all of which require ATP energy. Examples where movement would occur os if there is a lot of glucose or something large outside of the cell and not much glucose inside the cell and use a transport protein to eventually reach equilibrium. Oxygen would move across the cell membrane if there were a higher concentration outside the cell. The oxygen would slip in between the phospholipid bi-layer gaps
