Membrane
What factors affect membrane fluidity?
- Temperature
-Fatty Acid composition
- Cholesterol
Most cells cannot harness heat to perform work because
heat does not involve a transfer of energy.
cells do not have much heat; they are relatively cool.
temperature is usually uniform throughout a cell.
heat can never be used to do work.
temperature is usually uniform throughout a cell.
Which type of membrane transport uses ATP? Why does the other one not use ATP?
Active! Passive transport goes down the gradient which does not require energy!
What role do ribosomes play in carrying out genetic instructions?
Ribosomes in the cytoplasm translate the genetic message, carried from the DNA in the nucleus by mRNA, into a polypeptide chain.
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.
exergonic; spontaneous
exergonic; endergonic
free energy; entropy
work; energy
exergonic; endergonic
A cell is placed in a solution containing 10% glucose, while the inside of the cell contains 2% glucose. The cell membrane is permeable to water but NOT to glucose.
After several minutes, which of the following will most likely occur?
A. Glucose will move into the cell because its concentration is higher outside the cell.
B. Water will move out of the cell, causing the cell to shrink.
C. Water will move into the cell, causing the cell to swell.
D. Neither water nor glucose will move because the membrane is selectively permeable.
Water will move out of the cell, causing the cell to shrink.
Metabolism is...
the controlled capacity to acquire and use energy
What are the proteins used in passive transport, and how do they differ?
Channel: a channel opens and the molecule can flow down the membrane.
Carrier: the molecule causes a shape change which then causes the protein to open and release the molecule out of the membrane. (ruler example in class)
Describe the molecular composition of nucleoli and explain their function.
Nucleoli consist of DNA and the ribosomal RNA (rRNA) made according to its genes in the DNA, as well as proteins imported from the cytoplasm. Together, the rRNA and proteins are assembled into large and small ribosomal subunits. (These are exported through nuclear pores to the cytoplasm, where they will participate in polypeptide synthesis.)
What is the name of the side of the protein towards the ECM? What is the name of the side of the protein towards the cytoplasm? Explain the importance.
ECM: N terminus
Cytoplasm: C terminus
This allows for signaling inside and outside of the cell!
A cell needs to take in glucose from its surroundings. Glucose is too large and polar to pass directly through the hydrophobic interior of the phospholipid bilayer. The cell has a protein channel that allows glucose to cross the membrane without using ATP.
Which explanation BEST describes how the cell membrane works together to allow glucose into the cell?
A. The phospholipid bilayer actively pumps glucose through the membrane, while cholesterol provides the ATP needed for transport.
B. The phospholipid bilayer provides the selectively permeable barrier, membrane proteins provide a pathway for glucose, and glucose moves through the protein by facilitated diffusion because it is moving down its concentration gradient.
C. Cholesterol transports glucose across the membrane, while the phospholipids provide energy for the transport protein.
D. The carbohydrate chains on membrane proteins pull glucose through the membrane using ATP.
The phospholipid bilayer provides the selectively permeable barrier, membrane proteins provide a pathway for glucose, and glucose moves through the protein by facilitated diffusion because it is moving down its concentration gradient.
What are two ways in which energy is released?
Heat and CO2
What is osmosis?
The movement of water in response to its gradient. It flows from high H2O concentration to low H2O concentration.
Describe how transport vesicles integrate the endomembrane system.
Transport vesicles move membranes and the substances they enclose between other components of the endomembrane system.
What is a coupled reaction?
An exergonic reaction driving an endergonic reaction to occur
If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?
Additional product will be formed.
The reaction will change from endergonic to exergonic.
The free energy of the system will change.
Nothing; the reaction will stay at equilibrium.
Nothing; the reaction will stay at equilibrium.
What is Gibbs Free energy equation? Define what each part means?
ΔG=ΔH-TΔS
ΔG- Free energy
ΔH- enthalpy (how much heat is released (-ΔH) or absorbed (+ΔH))
T- absolute temp in K
S- entropy (disorder)
List the 3 types on endocytosis and explain what they do.
Phagocytosis: "cell eating" brings in large particles or whole cells and surrounds it with the membrane.
Pinocytosis: "cell drinking"Brings in extracellular fluid and dissolved substances. Forms small vesicles from the membrane.
Receptor mediated endocytosis: Brings in specific molecules that bind to receptors on the cell membrane. The receptor recognizes the molecule, and the membrane folds inward to form a vesicle.
Describe two characteristics shared by chloroplasts and mitochondria. Consider both function and membrane structure.
Both organelles are involved in energy transformation, mitochondria in cellular respiration and chloroplasts in photosynthesis. They both have multiple membranes that separate their interiors into compartments. In both organelles, the innermost membranes—cristae, or infoldings of the inner membrane, in mitochondria, and the thylakoid membranes in chloroplasts—have large surface areas with embedded enzymes that carry out their main functions.
Explain the difference between cells that are hypertonic, isotonic, and hypotonic. What do red blood cells prefer? Explain Turgid, Plasmolyzed, and flaccid for a plant cell. What does the plant cell prefer?
Hypertonic: high solute (shriveled)
Isotonic: normal levels of each (preferred)
Hypotonic: too much water (swollen/burst)
Turgid: lots of water in cell. (preferred, firm and full)
Plasmolyzed: water moves out of cell (shriveled/dead)
Flaccid: movement is equal (limp)
Name every part of a cell membrane and give their functions.
phopholipid: creates the cell bilayer and the hydrophobic core
cholesterol: maintains membrane fluidity
glycolipid:cell recognition and cell to cell communication
ECM: helps hold cells together to form tissues
Microfilaments of Cytoskeleton: allows cells to have different shapes so they can move
integral protein: can contact the hydrophobic core
peripheral protein: does not pass through bilayer, connects membrane to cytoskeleton and helps with cell signaling
transmembrane protein: completely crosses both sides of the bilayer
vesicle: membrane bound organelle that carries cargo
True or False: Metabolism is the creation of energy to be used to do work
False, rule one of thermodynamics states energy cannot be CREATED or destroyed
Is the Na+/K+ pump an example of active or passive transport? Why or why not?
It is an example of active transport. The pump is moving each solute against its gradient. 3 Na+ out and 2 K+ in. This requires ATP to move AGAINST the gradient.
Cyanide binds to at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the
mitochondria.
ribosomes.
peroxisomes.
lysosomes.
The mitochondria
What are the 3 main domains of life?
Domain Bacteria
Domain Archea
Domain Eukarya