Cell Structure and Function Exam 1
Terms in this set (54)
The cell is a unit of _____________, has a plasma ______ that serves as a barrier and ___________ complex, and is capable of _________ with _______________. EX:
replication with modification
Examples: DNA replication, gene transcription, mRNA translation- protein synthesis
1. highly complex and organized
2. info. to build cells ___________
3. reproduce by ___________
4. acquire and utilize __________ for ___________
5. ____________ actions
6. Number of mechanical activities
7. respond to outside ________
8. able to ____________
3. cell division
4. energy for metabolism
Diff. between eukaryotic and prokaryotic cells?
eukaryotic have membrane bound organelles and chromosomes are linear
prokaryotic don't have membrane bound organelles and are circular
Are viruses cells? Are they alive?
although they can replicate, they need assistance from host cells, can't do it alone, NO not alive
How big is a eukaryotic cell?
bigger than a prokaryotic cell
What are cells made of? (macromolecules + Subunits_
1. proteins----> amino acids
2. nucleic acids----> DNA and RNA nucleotides
3. Carbohydrates-----> sugars
Subunits are held together by _______ bonds to create macromolecules. Macromolecules are held together by _______ bonds to create ____________ assemblies. Ex. of macromolecule and assembly
EX. macromolecule-globular proteins and RNA
macromolecular assembly- ribosome
The plasma membrane _________ the cell and defines ___________. This barrier separates the _______________ from the ________________ env. What is its function?
Function: concentrate nutrients gathered/ retain products made
maintain ion concentration gradients
sensors of ext. signals and surface are for protein
Composition of plasma membrane? held together by? Importance/
lipids and proteins
IMPORTANCE: allows fluidity of movement
Phospholipid bilayer consists of a _______ head " ". and ____________ tails "".
polar - hydrophilic
Function of ER?
protein synthesis and calcium store
Function of Golgi?
Function of mitochondria?
List non-membrane bound complexes and function.
1. ribosomes- protein trans (freely float in cytoplasm)
2. nucleolus- concentration of materials
What's the most abundant membrane lipid?
What does unsaturated and saturated mean?
phospholipids have two fatty acid tails that are hydrophobic, when there is a double bond present it creates a kink affecting the fluidity of the membrane = unsaturated
when there are no double bonds present this is called saturated
What does amphipathic mean?
both hydrophilic and hydrophobic
Difference between lipid bilayer and liposome?
lipid bilayer has fatty acid tails facing inside and polar heads outside in a linear fashion
liposome is a circular arrangement accustomed to self assembly
Cell membranes are _________ and __________ meaning that the inner layer differs from the outer layer.
non-uniform and asymmetrical
3 classes of membrane lipids?
What is the main phospholipid in animal cells and their makeup?
composed of a:
1. 3 carbon glycerol backbone
2. 2 fatty acid tails
3. phosphate group
4. head group
4 Diff. Head groups and charge?
1. PE- phosphatidylethanolamine--- neutral
2. PC- phosphatidylcholine----- neutral
3. PS- phosphatidylserine ----- (-)
4. PI- phosphatidylinositol ----- (-)
Makeup of a sphingolipid?
fatty acid + sphingosine+ head group (sphingomyelin
) or sugar group (glycolipid with no phosphate group)
Makeup of cholesterol? How it differs?
rigid ring structure with short nonpolar tails
DIFFERS: can change packing and fluidity of membrane
3 Classes of Lipids? SO WHAT?
diff. lipids have diff. properties
Importance of lipids:
1. determine the _________ state
2. influence action of _____________ proteins
3. provide precursors for ___________ reactions that regulate
EXAMPLE: PC is ____________ and PE is ______________
This effects the _____________ and ___________ curvature
When certain lipids are mixed, patches can be made
patchy and not homogeneous
Diff proteins and lipids sequester together into ____________. What does this help do?
helps proteins to cluster together to favor certain protein-protein interaction
The fluid mosaic model shows us that membranes are?
dynamic, fluid structures
Membrane fluidity is affected by what?
1. saturated vs unsaturated fatty acid tails-- kinks cause them to not pack as tightly
2. cholesterol- causes stiffness
Membrane fluidity is regulated by?
membrane components and temp.
Protein components of membrane?
1. intergral(transmembrane) proteins- can cross bilayer and inserted into the bilayer
2. peripheral proteins- attach to one side of bilayer by noncovalent interactions
Types of amino acids embedded in bilayer?
hydrophobic amino acids
Mov. across membranes: What goes through and what doesnt?
hydrophobic molecules (sterioid hormones and gases pass)
don't- charged ions
Not all membranes are __________ permeable.
How do cells transport specific water soluble molecules?
Diff in transport?
1. passive- protein helps molecule move across bilayer without added energy from high to low concentration "down the gradient"
2. active- requires energy, against the gradient, from low to high
What is coupled transport?
active transport coupled with passive
Passive transport can occur through: (2)
How do ion channels work?
open and close due to ligand binding and voltage
3 types of transporter mediated mov.?
Passive transport is a ___________ carrier protein because transport is moved ________ concentration gradient, transport is ________, transporter undergoes __________ confromation change, and transporter is _________>
uniport, down, specific, reversible, saturable
Types of active transport?
1. cotransporter- use E with asst. with 1 molecules gradient to move another molecule against its gradient
2. pumps- use ATP E source
EX: of pumps?
ATPase- uses Energy of ATP hydrolysis to move both Na+ and K+ against their gradient
Distribution of ions across membrane:
which are higher inside and outside the cell?
What is equilibrium potential?
the electrical potential diff. that balances ionic concentration gradient, no net movement of ions across membrane
Cells that are specialized in taking advantage
of this charge separation are called? 3 types include?
Membrane channels recognize and open only for select ions. Each channel allows for one or a few types to pass due to ________. Open and close in response to some signal that involves change in shape of protein.
1. closed and activatable --
3. closes and non-activatable----
Action potentials convey info. over ________________. Fequencey and pattern of APS constitute the _________ code used to transfer info.
action potential rising and fallin phase:
rising: inward Na+ current
falling: outward K+ current
Info flow in neuronal cells (5 steps)
1. Chemical signal from cell 1:
2. chemical signal transformed to electrical signal
3. Electrical signal propagated along cell 2 membrane
4. electrical signal transformed to chemical signal
5. Release of chemical signal from cell 2 to cell 3
Specialized sites of cell-cell contact
CHEMICAL SIGNAL CONVERTED
TO ELECTRICAL SIGNAL
Neurotransmitter stored in membrane enclosed vesicles and released by exocytosis
Neurotransmitter binds to ligand-gated ion channel
Binding causes conformation change of channel protein
Channel opens: ions flows through channel
Membrane potential changes