C5 - How do we fuel our body? Flashcards
(67 cards)
What are the ways that ions and molecules can pass through the cell membrane?
Ions and molecules can pass through the cell membrane via:
- Passive transport
- Active transport
- Osmosis
- Facilitated diffusion
Passive transport does not require energy, while active transport requires energy.
What is osmosis?
Osmosis is the diffusion of water across a selectively permeable membrane, determined by the concentration gradient of solutes.
Water moves from a solution with high free water concentration to one with low free water concentration.
Define hypotonic, isotonic, and hypertonic solutions.
Definitions:
- Hypotonic: Less solutes and more water than the inside of the cell
- Isotonic: Same total concentration of solutes as intracellular fluid
- Hypertonic: More solutes and less water than the inside of the cell
These terms describe the relative concentrations of solutes in solutions.
What are ATP and ADP in terms of energy?
ATP (adenosine triphosphate) is the primary energy carrier in cells, while ADP (adenosine diphosphate) is formed when ATP releases energy.
The conversion between ATP and ADP is central to energy transfer in cellular processes.
List the main stages of glycolysis.
The main stages of glycolysis include:
- Energy investment phase
- Cleavage phase
- Energy payoff phase
The products of glycolysis include pyruvate, ATP, and NADH.
Describe the main stages of the citric acid cycle (Krebs cycle).
The main stages of the citric acid cycle include:
- Acetyl-CoA formation
- Citrate formation
- Isomerization
- Oxidative decarboxylation
- Regeneration of oxaloacetate
The products of the citric acid cycle include NADH, FADH2, ATP, and CO2.
What is oxidative phosphorylation?
Oxidative phosphorylation is the process by which ATP is produced via the electron transport chain and chemiosmosis.
This process occurs in the mitochondria and is a key stage of cellular respiration.
Why can some things pass through a cell membrane whereas others can’t?
Some substances can pass through a cell membrane due to its selectively permeable nature, which allows certain molecules to cross while preventing others.
This selectivity is influenced by factors such as size, polarity, and charge of the molecules.
How do ions and molecules pass through the cell membrane?
Ions and molecules pass through the cell membrane via:
- Passive transport (diffusion)
- Active transport (requiring energy)
- Facilitated diffusion (with the help of proteins)
The method of transport depends on the type of molecule and its concentration gradient.
Why does water move from one place to another within the body?
Water moves based on osmotic gradients, where it travels from areas of low solute concentration to areas of high solute concentration.
This movement is essential for maintaining homeostasis in body fluids.
What is the fluid mosaic model of cell membranes?
The fluid mosaic model describes the cell membrane as a dynamic structure with a flexible arrangement of phospholipids and proteins that can change shape and composition.
This model emphasizes the fluidity of the membrane and the diverse functions of membrane proteins.
What does it mean that the cell membrane is selectively permeable?
Being selectively permeable means that the cell membrane allows certain substances to pass while restricting others.
This property is crucial for maintaining the internal environment of the cell.
Define diffusion.
Diffusion is the passive movement of solute molecules from a region of high concentration to a region of low concentration.
This process does not require energy and is influenced by concentration gradients.
What is facilitated diffusion?
Facilitated diffusion is a passive transport process that uses membrane proteins to help molecules cross the cell membrane.
It does not require energy and is critical for transporting larger or polar molecules.
What is the sodium-potassium pump?
The sodium-potassium pump is an example of active transport that moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients.
This pump is essential for maintaining cellular homeostasis and membrane potential.
What happens to water movement in a hypertonic solution?
In a hypertonic solution, water moves out of the cell, leading to cell shrinkage.
This occurs because the concentration of solutes outside the cell is higher than inside, creating a concentration gradient.
What happens to water movement in a hypotonic solution?
In a hypotonic solution, water moves into the cell, which can lead to cell swelling or bursting.
This occurs because the concentration of solutes inside the cell is higher than outside, creating a concentration gradient.
Define diffusion
Movement of solute molecules passively from high concentration to low concentration
There is net movement of molecules down their concentration gradient.
What is facilitated diffusion?
A passive process that uses carrier/channel proteins to help molecules cross the cell membrane
It moves down the concentration gradient, similar to simple diffusion.
Is facilitated diffusion an active process?
No, it is a passive process.
Give an example of a substance that crosses the membrane via facilitated diffusion.
Glucose
What is the process by which water crosses the cell membrane?
Osmosis
What are the channels used by water to cross the cell membrane?
Aquaporins
When is active transport required?
When a solute moves up its concentration gradient
This means moving from low to high solute concentration.
