Chapter 3: The Cell Flashcards
Theory of Endosymbiosis
The theory that eukaryotic cells emerged when chloroplasts and mitochondria took residence inside larger cells.
Modern Cell Theory
Theory that all cells arise from preexisting cells.
All cells have…
a plasma membrane, cytosol, and DNA of some sort.
Prokaryotic Cells
Simple cells with no nucleus or organelles, like bacteria.
These types of cells have a nucleic region (where the DNA is located) instead of an enclosed nucleus.
Eukaryotic cells
Have a nucleus bound by a double membrane, as well as organelles.
Surface Area to Volume
Surface area increases slower than volume (look at the formulas for surface area and volume for different shapes).
Thus, the surface area limits the amount of stuff that can enter and exit the cell.
Nucleolus
Located within the nucleus, and controls ribosome and rRNA synthesis.
Ribosomes
Can be bound (on the rough ER) or free floating within the cytoplasm, and takes part in protein synthesis.
Peroxisomes
Found in both plants and animals. and contain “catalase,” which converse peroxide (H2O2) into water. Can also detoxify alcohols in the liver.
Endomembrane System
Regulates protein traffic and metabolic functions. Includes the golgi apparatus, ER, vacuole, vesicles, lysosomes, nuclear envelope, lysosomes, and the plasma membrane.
Nucleus
Has a selectively permeable “nuclear envelope” with pores that separates the stuff inside the nucleus from the cytoplasm.
Endoplasmic Reticulum
Rough ER: protein synthesis, and covered in ribosomes.
Smooth ER: steroid hormone synthesis, stores Ca2+ ions, and detoxifies drugs and poison from the body.
Golgi Apparatus
The mail man of the endomembrane system. It packages and processes substances, which is then secreted to other parts of the cell for export.
Lysosomes
Sacs of hydrolytic enzymes that plays a major role in intercellular digestion. The enzymes also play a role in apoptosis, or cell suicide.
Mitochondria
Site of cellular respiration, and present in both plants and animals. Mitochondria have a double membrane and cristae, which contain their own DNA.
Vacuoles
Large vesicles used for storage.
Plants have a “central vacuole,” protists have a “contractile vacuole” to pump out excess water, and food vacuoles play a major part in phagocytosis.
Chloroplast
Only present in plants, and absorb light to synthesize sugar for the plant. Chloroplasts have a double membrane and thylakoids to function in photosynthesis.
Cytoskeleton Function
- Maintain cell shape.
- Protection.
- Anchors them to the plasma membrane.
- Involved in the flow of cytoplasm.
Composed of microfilaments and microtubules.
Microtubules
Make up the cilia, flagella, spindle fibers, etc. Often assists in structures that require movement.
Microfilaments
Help maintain the shape of the cell using actin filaments.
Cell Wall
Made of cellulose. Has primary cell wall, secondary cell wall, and the middle space called the middle lamella.
Plasma membrane
Selectively permeable membrane that regulates what enters and exits the cell.
Fluid Mosaic Model
Model that states the eukaryotic plasma has a phospholipid bilayer with proteins loosely attached to it. These proteins include integral and peripheral proteins, as well as cholesterol molecules.
Function of Protein in the Plasma Membrane
- Transport
- Enzymatic activity
- Cell-cell signaling
- Cell-cell attachments
- Signal transduction
- Attachment to the cytoskeleton and extracellular matrix.
Passive Transport
Movement of molecules down a concentration gradient from high to low until an equilibrium is reached, and thus does not require any energy. Examples include diffusion and osmosis.
Simple Diffusion
Does not require any protein channels, and just naturally occurs.
Facilitated Diffusion
Requires the use of hydrophilic protein channels to transport larger, polar materials such as K+, Cl-, Ca2+.
Concurrent Exchange
Flow of adjacent fluids in opposite directions that maximize the rate of simple diffusion. Example: fish gills.
Diffusion
The random movement of molecules from high to low concentration.
Osmosis
Diffusion through a semi-permeable membrane.
Hypotonic Solution
The concentration of solute in the beaker is less than the concentration of the solute in the cell which causes the cell to burst (in animals). In plants, the cell wall prevents the cell from bursting, so it simply becomes turgid.
Hypertonic
The concentration of solute in the beaker is greater than the concentration of the solute in the cell, which causes the cell to shrink (plasmolysis).
Aquaporins
Water channel proteins, which facilitates the diffusion of water molecules through a cell membrane.
Active Transport
Movement of molecules against a gradient, which requires energy. Examples include pumps and carriers.
Sodium-Potassium Pump
An example of active transport. Pumps Na+ and K+ across the nerve cell membrane to return back to resting state.
Electron Transport Chain
An example of active transport. Consists of proteins that pump protons across the crust membrane
Contractile Vacuole
An example of active transport. The freshwater Protista ejects excess water that has already been diffused because the cell lives in a hypotonic environment.
Pinocytosis
“Cell drinking.” Involves the uptake of large, dissolved particles through vesicles.
Phagocytosis
“Cell eating.” Uptake of large particles using vacuoles.
Receptor Mediated Endocytosis
Enables a cell to take up large amounts of a specific substance. Occurs when extracellular substances (ligand) bind to receptors on the cell membrane and cause the membrane to turn inwards, which then pinches off and becomes a “coated vesicle” in the cell.
Bulk Flow
Overall movement of fluid in one direction in an organism.
Cell Communication: Cell Contact
Examples include gap junctions in animal cells and plasmodesmata in plant cells. Gap junctions and plasmodesmata allow the passage of material from the cytoplasm of one cell to the cytoplasm of another cell.
Cell Communication: Paracrine Signaling
Release of local signals, such as growth factors, from one cell to many more
Cell Communication: Long Distance Signaling
A characteristic of the endocrine system where hormones are released in once place and are circulated to far away organs and locations through blood flow.
Cell Membrane Receptors
Span the entire length of the membrane, so it touches both the cytoplasm and the extracellular fluid. Hydrophilic (polar) receptor molecules cannot pass through the membrane with diffusion, so they bind to a part of the cell membrane receptor, which changes its shape, and the signal is carried through.
Then, once in the cell, the signal is carried by a cAMP.
Ion Channel Receptors
Involves a receptor that opens and shuts a gate that allows an influx of ions, such as Na+, K+, Cl-, Ca2+.
G-Protein Coupled Receptors
Span the entire cell membrane. When the signaling molecule binds to the extracellular area of the receptor, it changes the cytoplasmic side.
Receptor Tyrosine Kinases
Individual units aggregate and activate the tyrosine region.
Three steps of Cell Signaling
Reception: Binding of the ligand to the cell membrane receptors.
Transduction: conversion of the signal to a response.
Response: transduction brings out a response in the cytoplasm or nucleus.
Signal Transduction Pathway
- Can cause a cascade affect.
- Evolves from a common ancestor.
- Comes from a signal and a transduction.
- Can be highly specific.
