Cell Organelles, Fluid Mosaic Model & Membrane Transport Flashcards
membrane-enclosed sacs that contain DIGESTIVE enzymes which catalyze hydrolysis reactions and break down macromolecules
lysosomes
Whats a carrier protein
a protein that selectively interacts with specific molecules or ions so it can cross the membrane
ex. sodium and potassium pump
Describe the structure of a phospholipid
hydrophilic head (polar) and hydrophobic tails (non-polar)
- the polar heads love water & dissolve
- the non-polar tails hide from water
what is chlorophyll
the photosynthetic pigment found in thylakoids which absorb light energy and use it to convert carbon dioxide and water into energy-rich molecules through redox reactions
what is passive transport
transport/movement which requires NO energy (ATP) to move substances across cell membranes
~ (goes from high concentration to low concentration without any energy)
How does the cell membrane move?
- a membrane is held together by weak hydrophobic interactions between the carbon-hydrogen chains
- most membrane lipids and some proteins drift LATERALLY (side to side)
- molecules rarely flip transversely (flip flop) across the membrane as hydrophilic parts would have to cross the membrane hydrophobic core
a double membrane structure comprised of two phospholipid bilayers that surrounds the nucleus
nuclear envelope
What is plasmolysis?
when a plant in a hypertonic environment goes through water loss, leading the plant to shrivel and its cell membrane to pull away from the cell wall
membrane-bound sacs that contain OXIDATIVE enzymes which break down additional fatty acids and hydrogen peroxide
peroxisomes
What molecules/ions are transported by each transport?
Passive Transport: glucose, amino acids, ions (Na, Ca, etc.)
Primary Active Transport: metal ions (Na, Mg, Ca, etc.)
Secondary Active Transport: sodium ions (ex. sodium-glucose, sodium-amino acid, etc.)
what is active transport
transport from lower concentration to higher concentration which REQUIRES energy (ATP) to move molecules against a concentration gradient
~ particles bind to transport proteins that use ATP to pump them across the membrane (the loss of a phosphate group from ATP to form ADP produces a lot of energy which the cell uses)
Whats the function of the cell membrane
- controls what enters and exits the cell to maintain a balance called homeostasis
- provides protection and support for the cell
- is selectively permeable (allows some molecules in and keeps others out)
What is exocytosis
used to export, or remove large molecules from the cell
~ first, the material is surrounded at the golgi complex making a vesicle
~ next, the vesicle moves to the cell membrane and is expelled
~ ex. pancreas cells make insulin which is dumped into the blood stream
captures light energy from the Sun and stores it in the form of high-energy organic molecules like glucose
chloroplasts
what is the cytoskeleton
the internal network of protein fibers found throughout the cytoplasm which provide structure, shape, support and mobility; also anchors some organelles in place
What happens if the cell membrane is too fluid?
the bilayer permits too many molecules to diffuse across
What is isotonic?
- solutions of equal solute concentration on both sides of the membrane
- no net movement as an equilibrium is reached (ISOS = equal)
What is endocytosis?
used to move large molecules INTO the cell (endo - to enter)
~ material comes to the outside of the cell membrane, the membrane surrounds the material, and then pinches off inside the cell forming a vesicle; this vesicle travels to its final destination
What’s an enzymatic protein
a protein that catalyzes specific reactions (eg. ATP metabolism)
What are the two types of proteins present in cell membranes
1) Integral proteins: span through the bilayer
2) Peripheral proteins: attached to the outer surface
Both of these proteins act to transport molecules
What is diffusion
movement of particles from an area of high concentration to low concentration
~ they reach a dynamic equilibrium
Why is fluidity so important?
to maintain the transport of molecules into and out of the cell
a non-membrane bound structure located within the nucleus that contains RNA, proteins, and chromatin
nucleolus
breaks down high-energy organic molecules and converts stored energy into usable energy; stores released energy for later cell use as well
mitochondria
what are cilia and flagella
appendages that form on the outside of some eukaryotic cells
flagella - one or two longer appendages (like tails; their whip-like movement propels cells)
cilia - shorter appendages (wave-like motion enables the organism to move)
What is tonicity?
the capability of a solution to alter the water content of cells
~ there are 3 outcomes, depending on the solute content of the solution
~ water will diffuse across the membrane in response to establish equilibrium
How does temperature affect fluidity of the cell membrane?
- increasing temperature increases the fluidity of the membrane
- decreasing temperature causes the bilayer to solidify into a gel as the phospholipids pack closer together (solidification causes enzyme deactivation)
