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Cell Exam Unit 1 Review - Ch. 1/25/6/7
AP Review- Benskin
Define the following terms or concepts
(6) The Cell | function | structure | location in the cell | other details |
|---|---|---|---|---|
nucleus | “library of the cell” contains most of the cell’s genes | (see below) | in front of rough e.r | |
nuclear envelope | encloses the nucleus and has pore that allow genes in and out (RNA) | Double membrane | nucleus | |
nuclear lamina | provides mechanical support | net like structure on the inside of the nucleus. constructed of proteins | nucleus | |
nuclear matrix | provides additional structural support | framework inside the nucleus | nucleus | |
nucleolus | RNA synthesis | looks like dark spot in the nucleus due to gene concentration | nucleus | this is the RNA that can come out of the pore in the nuclear envelope |
ribosomes | protein synthesis | cytoplasm; floating in cytosol (free). attached to the outside of e.r and nuclear envelope (bound) two sizes: 70s (in euks- mitochondria & chloroplast: in proks- cytoplasm) & 80s (cytoplasm or rough e.r). | free and bound ribosomes can switch positions based on cellular needs. found in eukaryotic and prokaryotic cells. | |
rough endoplasmic reticulum (e.r) | make proteins and glycoproteins | cisternae (sacks/folds) lumen - space inside the cisternae | behind nucleus | ‘rough’ because of ribosomes attached to surface. part of endomembrane system |
smooth endoplasmic reticulum (e.r) | *synthesis of lipids + detoxification of drugs/poison + can contain the drug/toxin | behind rough e.r | no ribosomes. part of endomembrane system | |
golgi apparatus | shipping, processing, modifying contents in vesicles from e.r. transport in and out of cell. | cisternae (flat sacks) | near e.r | **cisternal maturation model- actual cisternae progress from cis (enter) to trans (leave) side. part of endomembrane system |
lysosome | intracellular digestion and recycling (autophagy) | basically vesicles that contain enzymes that digest macromolecules | anywhere | part of endomembrane system |
vacuoles | storage. (very importantly - water in plant cells) hydrolysis | central vacuole in plants is surrounded by a membrane called a tonoplast | wherever i guess vacuoles can be in animals, large, central vacuole is for plant cells. | contractile vacuoles pump out extra water. part of endomembrane system |
mitochondria | make energy. proteins | double membrane. outer - smooth; inner- folded (cristae) | both in plant and animal cells | increase the surface area, increase the amount of ATP produced |
chloroplast | light to sugar energy | a plastid. double membrane. the inner membrane is connected to sacks, thylakoids, that absorb light. stack of thylakoids - grana fluid surrounding grana - stroma (contains DNA/ribosomes) | only found in plant cells | |
peroxisomes | oxidation. contains enzymes that break down molecules and produce hydrogen peroxide (H2O2) as a byproduct | metabolic component bound by a membrane. | breaks down small molecules unlike lysosomes, which are for macromolecules | |
cytoskeleton | framework that organizes structure and activities. mechanical support/shape, motility, motor proteins used to help the cell change shape, can act like a monorail and transport goods | |||
cytoskeleton: microtubules | crush resistant | hollow but fairly thick rods. composed of *tubulin | centrosomes -region where they form. | in all euks , not proks. centrioles - made of microtubules. duplicate when the cell duplicates & look like churros. cilia and flagella - microtubules that cause movement. *the 9 + 2 arrangement is found in them. |
cytoskeleton: microfilaments | bear tension, pull | composed of actin protein. solid small rods. twisted double chain of actin | aka actin filaments. main component of muscle | |
cytoskeleton: intermediate filaments | tension beares, reinforce cell shape | somewhere between the size of microtubules and microfilaments | more permanent structure than the other cytoskeleton types | |
cell wall | protects the cell, gives shapes and keep the cell watertight | in plant, composed of cellulose. held together by middle lamella (sticky substance) | outside | primary cell wall built when the cell is ‘young’ but eventually it will either harden or a secondary cell wall will be built |
intercellular junctions | plant junctions: a) plasmodesmata - pores that cytosol can pass through animal junctions: a) tight junctions- prevents leaking from b/t cells. not strong, waterproof b) desmosomes- rivets that hold the cell together, not waterproof, strong c) gap junctions- cytoplasmic channels for communication between cells (similar to plasmodesmata) | in between cells |
(6) Electron microscopes
scanning electron (SEM): scans surface of an object
transmissions electron (TEM): transmits electron through objects
(7) Cell membrane
The cell membrane is selectively permeable. Only specific molecules are allowed in. Hydrocarbons, carbon dioxide, oxygen all dissolve into cells without the aid of proteins. The cell membrane is made up of a phospholipid bilayer.
Fluid mosaic model: Model of the membrane created by Singer and Nicolson in 1972. Phospholipids and proteins can move around in the membrane. Proteins in the membrane are embedded throughout the membrane and not in an uniform layer.
Phospholipid: hydrophilic heads & hydrophobic tails.
* Amphipathic molecule: molecule with hydrophilic & hydrophobic regions
Lipids move laterally in the membrane
Glycoprotein: carbohydrate chain attached to a protein. Glycolipid: carbohydrate chain attached to phospholipids. These carbohydrates are essential for cell-cell recognition.
Cholesterol: Helps keep the membrane fluid at high and low temperatures.
Integral protein: penetrate hydrophobic core of lipid bilayer vs. peripheral protein: not embedded at all; “appendages’
Selective permeability
Water potential: solutes + pressure. In osmosis, the tendency for a system (a cell or solution) to take up water from pure water, through a differentially permeable membrane.
** Water will always move from a region of higher water potential to an area of lower water potential.
tonicity: ability of a solution to cause a cell to gain or lose water.
isotonic: no net movement of water. Volume of animal cells remain the same.
hypertonic solution: more non penetrating solutes on the outside of the cell. Cells will lose water.
hypotonic solution: less non penetrating solutes outside the cell. Cell will fill and maybe *lyse(burst).
Plant, fungi, protist cells:
turgid: full of water and happy
flaccid: limp
(in plants) plasmolysis: shrinking of membrane, pulls away from cell wall, cell dies.
Membrane Potential: Difference of voltage across the membrane.
Intercellular side has a negative charge in comparison to the positive charge of the extracellular side.
The sodium potassium pump establishes an electrochemical gradient which creates the membrane potential.
Cotransport: uses a protein pump to drive active transport of several solutes.
The proton is pushed out of the cell by a proton pump (active transport, low -> high)
The proton, now outside, wants to be let back into the cell due to diffusion.
The sucrose-proton cotransporter will let the proton in if it brings a sucrose molecule.
The sucrose needs to be forced through by active transport. It can't go in through diffusion/passive transport because that would go against the concentration gradient. However, the proton is in an area where diffusion is possible.
the proton diffuses through the pump. The diffusion of the proton releases energy.
This energy released activates the pump and brings sucrose into the cell (through active transport) simultaneously with the proton (undergoing diffusion). Cotransport achieved! 🎉
Passive transport | Active transport |
|---|---|
No energy investment. Goes with concentration gradient. | Needs energy. Goes against the concentration gradient. |
*Osmosis:Diffusion of water across a semipermeable membrane until the solutes on both sides are equal. Facilitated Diffusion: passive transport aided by proteins. Ex: Aquaporins. | Sodium Potassium pump: Exanches sodium for potassium. 3 sodium ions out, 2 sodium ions in. Causes the membrane potential. |
Bulk transport
Endocytosis: fusion of vesicles to ‘eat’
phagocytosis: eating. ex: endosymbiosis theory
pinocytosis: drinking
** Receptor mediated endocytosis: proteins collect what they need. Ligands bind to receptors, triggering endocytosis.
Exocytosis: fusion of vesicles with membrane in order to dump wastes.
(25) Origins of life
** Serial Endosymbiosis; Endosymbionts by Serial Endosymbiosis- Prokaryotes ate other prokaryotes but didn't digest them. Over time they formed a symbiotic relationship. These eaten prokaryotes became the mitochondria and chloroplasts.
Evidence: both the mitochondria and the chloroplast have their own looped DNA.
Protobionts: Polymers surrounded by a membrane-like structure (*liposome)
Two main characteristics of life: Accurate replication & simple metabolism.
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