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.
All eukaryotic cells contain what two types of cytoskeletal fibers?
microtubules and microfilaments
microtubules
largest cytoskeletal element, formed by tubulins protiens
Function in cellular movement, intercellular movement, help move chromosomes
microfilaments
smallest cytoskeletal element, formed by actins protiens
(def) are thin protein fibers 5 to 7 nm in diameter that consist of two strands of globular actin subunits wound around each other in a long helical spiral.
Function in cell movement
microtubules radiate outward from a membraneless organelle called?
centersome
Intermediate filaments
A cytoskeletal filament about 10 nm in diameter that provides mechanical strength to cells in tissues.
Stabilize cell shape
B/c lack of cell wall in animal cells, what determines its shape?
cytoskeleton
What helps strengthen and maintain the shape of an animal cell’s nucleus?
Lamin intermediate filaments
How do Motor proteins move molecules and organelles around in cells?
by pulling on microtubules or microfilaments,
pseudopodia
A temporary cytoplasmic extension of a cell. Used up by single-celled amoebas
Within cells, interactions between microfilaments and myosin are involved in the actively flowing motion of cytoplasm called?
cytoplasmic streaming, which can transport nutrients, proteins, and organelles in both animal and plant cells.
cilia
Motile structure, extending from a cell surface, that moves a cell through fluid or fluid over a cell.
shorter than flagella and occur in greater numbers
9+2 complex
A bundle of microtubules extends from the base to the tip of a flagellum or cilium. In the bundle, a circle of nine double microtubules surrounds a central pair of single microtubules, forming the 9+2 complex
Did the three types of flagella evolve independently?
Yes, the three types of flagella are analogous, not homologous, structures, and they must have evolved independently.
What three structures give plants distinctive characteristics?
Chloroplasts, a large and highly specialized central vacuole, and cell walls
Where does photosynthesis take place?
chloroplasts
plastids
A family of plant organelles that includes chloroplasts, amyloplasts, and chromoplasts.
Amyloplasts
Colorless plastid that stores starch in plants.
Chromoplasts
Plastid containing red and yellow pigments.
Do all plastids contain DNA genomes?
Yes
outer boundary membrane
A smooth membrane that surrounds a chloroplast, enclosing the stroma.
inner boundary membrane
Membrane lying just inside the outer boundary membrane of a chloroplast, enclosing the stroma.
thylakoids
A flattened, closed sac within the stroma of a chloroplast.
grana
stacks of thylakoids
chlorophyll
The primary molecule absorbing light, a green pigment that is present in all chloroplasts.
Central vacuoles
A large, water-filled organelle in plant cells that maintains the turgor of the cell and controls movement of molecules between the cytosol and sap.
tonoplast
The membrane that surrounds the central vacuole in a plant cell.
roles of cell wall
provide support to individual cells, contain the pressure produced in the central vacuole, and protect cells against invading bacteria and fungi.
primary cell wall
initial cell wall, soft and flexible
secondary cell wall
A layer added to the cell wall of plants that is more rigid and may become many times thicker than the primary cell wall.
middle lamella
Layer of gel-like polysaccharides that holds together walls of adjacent plant cells.
plasmodesmata
A minute channel that perforates a cell wall and contains extensions of the cytoplasm that directly connect adjacent plant cells.
Proteins and nucleic acids are transported through some plasmodesmata.
cell adhesion molecules
A membrane protein that mediates the selective binding of cells together.
glycoproteins embedded in the plasma membrane
cell junctions
Junction that seals the spaces between cells and provides direct communication between cells.
extracellular matrix (ECM)
A molecular system that supports and protects cells and provides mechanical linkages. Glycoproteins are main component
ie. muscles and bone
Anchoring junctions
Cell junction that forms belts that run entirely around cells, “welding” adjacent cells together
desmosomes
Anchoring junction for which microfilaments anchor the junction in the underlying cytoplasm.
adherens junctions
Animal cell junction in which intermediate filaments are the anchoring cytoskeletal component.
Tight junctions
Region of tight connection between membranes of adjacent cells.
seal the spaces between cells in the cell layers
Gap junctions
Junction that opens direct channels allowing ions and small molecules to pass directly from one cell to another.
In vertebrates, gap junctions occur between cells within almost all body tissues, but not between cells of different tissues.
What are the three types of cell junctions?
Anchoring, Tight, and Gap
collagen
Fibrous glycoprotein—very rich in carbohydrates—embedded in a network of proteoglycans.
Good tensile strength and elasticity
Proteoglycans
Glycoproteins that consist of small proteins noncovalently attached to long polysaccharide molecules.
fibronectins
A class of glycoproteins that aids in the attachment of cells to the extracellular matrix and helps hold the cells in position.
bind to receptor proteins called integrins
A prokaryote converts food energy into the chemical energy of ATP on/in its
plasma membrane
Why do membraneless organelles often contain intrinsically disordered proteins (IDPs)?
The flexibility of IDPs helps maintain the fluidity of membraneless organelles.
Which technique allows scientists to see the smallest details of cells?
electron microscopy
Which organelles produce food?
Chloroplasts and Plastids
Where does aerobic respiration take place inside mitochondria?
Matrix
