BIO 104 > Untitled Deck > Flashcards

Untitled Deck Flashcards

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1
Q

What is the function of the plasma membrane?

A

Regulates exchanges between a cell and its environment

The plasma membrane is crucial for maintaining homeostasis within the cell.

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2
Q

Define exocytosis.

A

Large molecules are secreted when a vesicle fuses with the plasma membrane

This process is essential for releasing substances like hormones and neurotransmitters.

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3
Q

Define endocytosis.

A

Large molecules are taken in when the plasma membrane pinches inward, forming a vesicle

This process allows cells to intake nutrients and other large molecules.

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4
Q

What is active transport?

A

Moves small molecules using energy and a transport protein

Active transport is essential for maintaining concentration gradients across membranes.

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5
Q

What is passive transport?

A

Moves small molecules without requiring energy, may involve transport proteins

Passive transport includes processes like diffusion and osmosis.

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6
Q

What are the key components of cellular membranes?

A
  • Lipids
  • Proteins
  • Carbohydrates

These components contribute to the fluid mosaic model of membrane structure.

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7
Q

What does selective permeability refer to?

A

Allows some substances to cross more easily than others

This property is vital for regulating the internal environment of the cell.

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8
Q

What is the Fluid Mosaic Model?

A

The membrane is composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates

This model describes the dynamic nature of cell membranes.

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9
Q

What are phospholipids?

A

Amphipathic molecules with hydrophilic heads and hydrophobic tails

They are the most abundant lipids in membranes, forming bilayers.

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10
Q

What is the role of cholesterol in membranes?

A
  • Reduces fluidity at moderate temperatures
  • Prevents solidification at low temperatures

Cholesterol acts as a fluidity buffer, maintaining membrane integrity.

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11
Q

What are the two major types of membrane proteins?

A
  • Integral proteins
  • Peripheral proteins

Integral proteins span the membrane, while peripheral proteins are loosely attached to its surface.

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12
Q

What is the function of transport proteins?

A

Help specific ions and polar molecules move through cell membranes

They are crucial for maintaining selective permeability.

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13
Q

What is facilitated diffusion?

A

Transport of substances across a membrane via specific carrier proteins

An example is glucose entering cells through GLUT transporters.

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14
Q

What is the significance of membrane carbohydrates?

A

Essential for cell-cell recognition

They help in the sorting of cells into tissues and organs.

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15
Q

What is the process of exocytosis?

A

Vesicles fuse with the plasma membrane to release substances

This process is important for secretion of proteins and neurotransmitters.

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16
Q

What is osmosis?

A

Diffusion of water across a selectively permeable membrane

This process is vital for maintaining cell turgor pressure.

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17
Q

What happens during dynamic equilibrium?

A

Molecules continue to move across a membrane at equal rates in both directions

This results in no net movement of solutes.

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18
Q

What are aquaporins?

A

Channel proteins that facilitate the passage of water molecules through the membrane

They allow rapid movement of water, essential for cell function.

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19
Q

What is the role of glycoproteins?

A

Serve as identification tags recognized by other cells

They play a crucial role in cell-cell recognition and signaling.

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20
Q

True or false: Hydrophobic substances have an affinity for water.

A

FALSE

Hydrophobic substances are nonpolar and do not interact well with water.

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21
Q

What is the asymmetrical arrangement of membranes?

A

Differences in lipid composition and protein orientation on the inside and outside faces

This arrangement is established during membrane synthesis.

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22
Q

What is the effect of temperature on membrane fluidity?

A
  • Decreases as temperature drops
  • Increases as temperature rises

Membrane fluidity is crucial for proper function and permeability.

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23
Q

What is the sodium-potassium pump?

A

An example of active transport maintaining ion gradients in cells

It moves sodium out of the cell and potassium into the cell against their concentration gradients.

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24
Q

What is passive transport?

A

Diffusion of a substance across a membrane with no energy investment

Driven by the concentration gradient.

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25
Define **diffusion**.
Movement of molecules from an area of higher concentration to an area of lower concentration ## Footnote Occurs down the concentration gradient.
26
What occurs at **dynamic equilibrium**?
Molecules continue to move across a membrane at equal rates in both directions ## Footnote Results in no net movement.
27
In **diffusion of one solute**, how do molecules move?
Through membrane pores from high to low concentration ## Footnote Equilibrium is reached when concentrations are equal on both sides.
28
In **diffusion of two solutes**, how do solutes behave?
Each solute diffuses independently down its own concentration gradient ## Footnote Equilibrium is reached when both solutes are equally concentrated on both sides.
29
What is the **simple rule of diffusion**?
Substances diffuse from areas of higher concentration to areas of lower concentration ## Footnote Without needing energy.
30
What is **osmosis**?
Water diffuses across a selectively permeable membrane from higher free water concentration to lower free water concentration ## Footnote Until solute concentrations are more equal.
31
Define **tonicity**.
Ability of a surrounding solution to cause a cell to gain or lose water ## Footnote Depends on solute concentration and membrane permeability.
32
What happens in an **isotonic solution**?
No net movement of water; cell volume remains stable ## Footnote Ideal for animal cells.
33
What occurs in a **hypotonic solution**?
Water enters the cell, causing it to swell and potentially lyse ## Footnote Risk of bursting.
34
What happens in a **hypertonic solution**?
Water leaves the cell, causing it to shrivel and potentially die ## Footnote Cells lose water.
35
In plant cells, what is the effect of a **hypotonic environment**?
Cells become turgid (firm) due to water uptake ## Footnote Balanced by turgor pressure.
36
What occurs in plant cells in an **isotonic solution**?
Cells become flaccid (limp) and may wilt ## Footnote Water balance is disrupted.
37
What is **plasmolysis** in plant cells?
Plasma membrane pulls away from the cell wall due to water loss ## Footnote Leads to wilting and potential plant death.
38
How does **Paramecium caudatum** manage water balance?
Uses a contractile vacuole to pump out excess water in hypotonic environments ## Footnote Adaptation for osmoregulation.
39
What is **facilitated diffusion**?
Polar molecules and ions diffuse passively across the membrane with the help of transport proteins ## Footnote Does not require energy.
40
What are the two types of **transport proteins**?
* Channel proteins * Carrier proteins ## Footnote Each serves a specific function in facilitated diffusion.
41
What do **aquaporins** do?
Facilitate massive water diffusion (osmosis) in cells ## Footnote Important for cellular water movement.
42
What is the function of **gated channels**?
Open or close in response to specific stimuli ## Footnote Crucial in the nervous system.
43
What is the role of **carrier proteins** in facilitated diffusion?
Alternate between two shapes to move solutes across the membrane ## Footnote Solutes move from higher to lower concentration.
44
What is **active transport**?
Uses energy to move solutes against their gradients ## Footnote Typically involves carrier proteins.
45
What is the **sodium-potassium pump**?
Exchanges sodium ions (Na+) out of the cell and potassium ions (K+) into the cell ## Footnote A key example of active transport.
46
What provides the energy for **active transport**?
ATP hydrolysis ## Footnote Transfers a phosphate group to the transport protein.
47
What is the **electrochemical gradient**?
The combined effect of a chemical force and an electrical force on ion diffusion ## Footnote Drives the movement of ions across a membrane.
48
What is **cotransport**?
Coupled transport by a membrane protein ## Footnote Couples the downhill diffusion of one solute to the uphill transport of another.
49
What is **exocytosis**?
Process by which cells secrete molecules by the fusion of vesicles with the plasma membrane ## Footnote Involves transport vesicles from the Golgi apparatus.
50
Define **phagocytosis**.
Cell engulfs a particle by extending pseudopodia around it ## Footnote Forms a food vacuole.
51
What is **pinocytosis**?
Cell gulps droplets of extracellular fluid into tiny vesicles ## Footnote Nonspecific process.
52
What is **receptor-mediated endocytosis**?
Specialized type of pinocytosis for acquiring bulk quantities of specific substances ## Footnote Involves receptor proteins binding specific solutes.
53
What is the role of **membrane proteins**?
Function in transport, enzymatic activity, signal transduction, and cell-cell recognition ## Footnote Integral to cellular communication and function.
54
What is **diffusion**?
The spontaneous movement of a substance down its concentration gradient ## Footnote Diffusion occurs without energy investment.
55
Define **osmosis**.
The diffusion of water across a membrane ## Footnote Osmosis is a specific type of diffusion.
56
In a **hypertonic solution**, water diffuses _______ of a cell.
out ## Footnote This results in cell shrinkage.
57
In a **hypotonic solution**, water diffuses _______ a cell.
into ## Footnote This can lead to cell swelling or bursting.
58
What occurs in an **isotonic solution**?
No net osmosis ## Footnote The concentrations of solutes are equal inside and outside the cell.
59
What is **facilitated diffusion**?
Transport proteins speed the movement of water or solutes down their concentration gradient ## Footnote This process does not require energy.
60
What do **ion channels** do?
Facilitate the diffusion of ions ## Footnote Ion channels are specific to certain ions.
61
What are **carrier proteins**?
Proteins that change shape to translocate bound solutes across the membrane ## Footnote They assist in facilitated diffusion.
62
Define **active transport**.
Uses energy to move solutes against their gradients ## Footnote This process requires ATP.
63
What is the **electrochemical gradient**?
The combination of a concentration gradient and an electrical gradient ## Footnote It influences ion movement across membranes.
64
What is **cotransport**?
When a membrane protein enables the downhill diffusion of one solute to drive the uphill transport of another ## Footnote This process is also known as secondary active transport.
65
What are the two types of **bulk transport** across the plasma membrane?
* Exocytosis * Endocytosis ## Footnote These processes involve vesicles.
66
In **exocytosis**, what happens to transport vesicles?
They fuse with the plasma membrane and release their contents ## Footnote This is how cells secrete substances.
67
What occurs during **endocytosis**?
Molecules enter cells within vesicles that pinch inward from the plasma membrane ## Footnote This process allows cells to take in large molecules.
68
Name the **three types of endocytosis**.
* Phagocytosis * Pinocytosis * Receptor-mediated endocytosis ## Footnote Each type has a specific mechanism for intake.
69
What is **bioluminescence**?
The conversion of energy stored in organic molecules into light by organisms ## Footnote Example: Click beetle larvae attract termites.
70
State the **First Law of Thermodynamics**.
Energy can be transferred and transformed but cannot be created or destroyed ## Footnote This is also known as the principle of conservation of energy.
71
What does the **Second Law of Thermodynamics** state?
Every energy transfer or transformation increases the entropy of the universe ## Footnote This law explains the direction of energy transformations.
72
Define **metabolism**.
The totality of an organism's chemical reactions ## Footnote It involves the transformation of matter and energy.
73
What does a **negative free-energy change (ΔG)** indicate?
The reaction occurs spontaneously ## Footnote This means the system can perform work.
74
What role does **ATP** play in cellular work?
Powers cellular work by coupling exergonic reactions to endergonic reactions ## Footnote ATP is the primary energy currency of the cell.
75
What is the function of **enzymes**?
Accelerate metabolic reactions by lowering activation energy barriers ## Footnote Enzymes are crucial for regulating metabolic pathways.
76
What is **denaturation**?
The process where a protein loses its native shape due to environmental changes ## Footnote This leads to loss of function.
77
What is **chemical equilibrium**?
The point at which forward and reverse reactions offset one another exactly ## Footnote At equilibrium, concentrations of reactants and products stabilize.
78
What is the **free-energy change (ΔG)** equation?
ΔG = ΔH - TΔS ## Footnote ΔH is the change in enthalpy, ΔS is the change in entropy, and T is the absolute temperature.
79
What is the significance of **spontaneous processes**?
They increase entropy and occur without an input of energy ## Footnote Example: Water flowing downhill.
80
What is the role of **ATP hydrolysis**?
Releases energy that can be used for cellular processes ## Footnote This reaction converts ATP to ADP and inorganic phosphate.
81
What types of work do cells perform?
* Chemical work * Transport work * Mechanical work ## Footnote These types of work are essential for cellular functions.
82
What is **energy coupling**?
Using an exergonic process to drive an endergonic one ## Footnote This is a key feature in cellular energy management.
83
What does **catabolism** involve?
Breaking down molecules and releasing energy ## Footnote Catabolic pathways are energy-releasing.
84
What does **anabolism** involve?
Building up molecules and consuming energy ## Footnote Anabolic pathways require energy input.
85
What type of reactions are **exergonic reactions**?
Reactions that release energy and occur spontaneously ## Footnote They have products with less free energy than reactants.
86
In the synthesis of **glutamine**, what are the two main steps involved?
* Glutamic acid + ATP → Phosphorylated intermediate + ADP * Phosphorylated intermediate + NH₃ → Glutamine + ADP + Pi ## Footnote The overall reaction has a net ΔG of -3.9 kcal/mol, indicating spontaneity.
87
What is the role of **ATP hydrolysis** in transport work?
Changes the shape of transport proteins, enabling solute transport across membranes ## Footnote This process is crucial for cellular transport mechanisms.
88
How is **ATP regenerated**?
By adding a phosphate group to ADP ## Footnote The energy for this process comes from exergonic breakdown reactions (catabolism).
89
True or false: The regeneration of ATP from ADP and inorganic phosphate is an **endergonic process**.
TRUE ## Footnote This process requires energy input from catabolic pathways.
90
What is the **activation energy (EA)**?
The initial energy required to start a reaction ## Footnote It is necessary for reactant molecules to reach the unstable transition state.
91
What do **enzymes** do in metabolic reactions?
Speed up reactions by lowering activation energy ## Footnote They act as catalysts and are not consumed in the process.
92
What is the **induced fit model** in enzyme activity?
Describes how the enzyme changes shape to fit the substrate snugly ## Footnote This enhances catalysis and substrate binding.
93
What are **substrate inhibitors**?
* Competitive inhibitors: Compete with substrates for the active site * Noncompetitive inhibitors: Bind elsewhere, altering enzyme function ## Footnote Examples include toxins, poisons, and antibiotics.
94
What is **feedback inhibition**?
A regulatory mechanism where the end product of a metabolic pathway inhibits an enzyme involved early in the pathway ## Footnote This prevents overproduction of the product.
95
What factors affect **enzyme activity**?
* Substrate concentration * Enzyme concentration * Temperature * pH ## Footnote Each enzyme has optimal conditions for maximum efficiency.
96
What is the significance of **enzyme localization** within the cell?
Helps organize metabolic pathways and increases metabolic efficiency ## Footnote Enzymes may be grouped into complexes or contained within organelles.
97
What is the **ATP cycle**?
The process of ATP being consumed and regenerated in the cell ## Footnote It couples energy-yielding processes to energy-consuming ones.
98
What is the **role of cofactors** in enzyme activity?
Essential for enzyme activity, can be inorganic ions or organic molecules (coenzymes) ## Footnote Vitamins often act as coenzymes.
99
What is **cooperativity** in allosteric regulation?
Binding of one substrate molecule stimulates binding or activity at other active sites ## Footnote This enhances the enzyme's overall activity.
100
What is the **first law of thermodynamics**?
Energy cannot be created or destroyed, only transferred or transformed ## Footnote This principle underlies energy changes in reactions.
101
What is **bioluminescence**?
The process where organisms convert chemical energy into light energy ## Footnote An example is the click beetle, which uses bioluminescence during its larval stages.
BIO 104
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