Chapter 4-Textbook Flashcards
What energy sources do cells use for their activities?
chemical molecules or light
what is microscopy?
technique for producing visible images of objects that are too small to be seen by the human eye
what is resolution?
is the minimum distance two points in the specimen can be separated and still be seen as two points
can electron microscopy be used in living specimens?
nope
What is fluorescence microscopy?
visualizes specific molecules of interest by labeling them with fluorescent dyes
can fluorescence microscopy be used on living tissue?
Yes
What is super-resolution microscopy?
enable molecules to be localized with higher resolution than had previously been thought possible by light microscopy.
Is cytosol polar/nonpolar
The cytosol is a polar environment, so the molecules dissolved in that aqueous solution are hydrophilic.
What are aggregates/what causes them?
These molecules are crowded together so closely that the attractions between them can cause solid clumps of molecules to form—“aggregates”—
What type of interactions are membrane-less organelles held together by?
hydrogen bonds and van der Waals forces
Why does the liquid of the membrane-less organelles form separate compartments with the cell?
because the molecules that make up the membrane-less organelle are more attracted to each other than they are to the water molecules surrounding the membrane-less organelle. As a result, they tend to remain within the organelle, even as they move around relative to one another. This phenomenon is referred to as phase separation.
Scaffolding protiens
has many binding surfaces at which it is attracted to other proteins.
What is the role of stress granules?
• Stress granules concentrate messenger RNA molecules to keep them from the ribosomes that would otherwise translate the genetic information in them, in the process of protein synthesis. Sequestering messenger RNA molecules saves the cell the energy it would otherwise use in protein synthesis, so it can instead use that energy to cope with the stress it is experiencing.
Is rate of flux of molecules into and out of membrane-less organelles faster than those of membrane bound organelles?
Yes
disadvantage of membrane-less organelles?
incompatible with processes that require the long-term retention of certain molecules and exclusion of others.
three shapes most common among prokaryotes
spherical, rodlike, and spiral.
Where is genetic material of prokaryotes located?
nucleoid, singular circular, highly coiled
where do most cellular functions occur?
plasma membrane or cytosol
What shape is bacterial flagellum?
helically
Do prokaryotes or eukaryotes perform a wider range of chemical reactions
prokaryotes
nucleoli
A eukaryotic nucleus contains one or more membraneless organelles called nucleoli
Are eukaryotic ribosomes relatively large?
• In general, eukaryotic ribosomes are larger than either bacterial or archaeal ribosomes; they contain four types of rRNA molecules and more than 80 proteins.
Do the ER Sheets and Tubes move?
ER sheets and tubes constantly extend and contract so that over a period of minutes, it moves through almost every part of the cell’s volume, outside of the nucleus. In doing so, the ER frequently comes in contact with other membrane-bound organelles,
How many cisternae are in a stack typically?
4-8, but varies with metabolic activity
How many lysosomes does a typical human cell have?
100s
Do plant and fungal cells have lysosomes?
nope
Where are lysosomes formed from?
budding from Golgi complex
Where are the hydrolytic enzymes synthesized for lysosmes?
Rough ER—the modified in lumen of ER
Cellular respiration
is the process by which energy-rich molecules such as sugars, fats, and other fuels are broken down to water and carbon dioxide by mitochondrial reactions, with the release of energy.
mitochondrial matrix
inner most compartment of mitochondria
How many lipid bilayer membranes do mitochondria have?
2
How do microtubules change their lengths?
addition or removal of tubulin dimers, with dimers adding or detaching more rapidly at the + end than at the − end.
