IQ2 - Cell Function Flashcards
What are autotrophs?
Autotrophs produce their own food by using inorganic molecules
What is cellular respiration?
Cellular respiration is the process where glucose and oxygen are converted into carbon dioxide, water and energy (ATP) for cellular functions
What are heterotrophs?
Heterotrophs consume other organisms for energy and also carry out cellular respiration to break down food for energy
What raw materials do cells require?
Cells need water, carbon dioxide, lipids, proteins and carbohydrates to function properly
Why do cells need to remove waste?
Waste products can be toxic in high concentrations, damaging cells and interfering with cellular reactions
How do cells remove waste?
Cells may use diffusion for waste removal or more advanced methods like exocytosis
How do you test for glucose?
Benedict’s test
How do you test for starch?
Iodine test
How do you test for lipids?
Brown paper test
How do you test for protein?
Biuret test
How do you test for chloride ions?
Silver nitrate test
Define enzymes
Globular proteins made of long amino acid chains, catalyse biochemical reactions in cells
Define metabolism
Refers to the total of all biochemical reactions that occur within a living organism
What are catabolic reactions?
They break down substrates into simpler products
What are anabolic reactions?
They build larger molecules from smaller ones, requiring energy input
How do enzymes catalyse reactions?
Lower the activation energy needed for a reaction by binding to substrates at their active site
What is the lock and key model of enzyme action?
The substrate fits perfectly into the enzyme’s active site, like a key fitting into a lock
What is the induced fit model of enzyme action?
The enzyme’s active site molds around the substrate, improving the fit and facilitating the reaction
What factors affect enzyme acitvity?
Temperature, pH, concentration of enzyme and substrate and presence of cofactors or inhibitors
How does temperature affects enzyme activity?
Higher temperatures increase enzyme activity up to a point around 40 degrees, where they denature
What is the optimal temperature for human enzymes?
Human enzymes work optimally between 36-38 degrees
How does pH affect enzyme activity?
Each enzyme has an optimal pH, enzymes can be denatured by extreme pH values
How do enzyme and substrate concentrations affect enzyme activity?
Higher enzyme concentration speeds up reactions, high substrate concentration will eventually reach a saturation point, where the reaction rate stops increasing
What are cofactors and coenzymes?
Cofactors: non-protein molecules (e.g. metal ion, vitamins) that assist in catalysing biochemical reactions
Coenzymes: organic molecules that assist in enzyme catalysis
What is enzyme inhibition?
Inhibitors block the enzyme’s active site, preventing substrate binding, can be reversible or irreversible
What is diffusion?
The net movement of particles from an area of high concentration to low concentration
What substances diffuse across the cell membrane?
Small molecules e.g. oxygen, carbon dioxide and glucose
How does diffusion occur in cells?
Diffusion occurs due to the random movement of molecules, moving down the concentration gradient
What limits diffusion in large organisms?
Diffusion becomes less effective over longer distances and is insufficient in large organisms, which require specialised transport systems
How do multicellular organisms adapt to promote diffusion?
For example, the small intestine has villi to increase surface area, aiding faster diffusion of nutrients into the bloodstream
What is osmosis?
The spontaneous net movement of water molecules from an area of low solute concentration to high solute concentration across a semipermeable membrane
How does osmosis affect cells?
Water moves into or out of a cell depending on whether the external solute concentration is higher or lower than inside a cell
What is active transport?
The movement against the concentration gradient (from low to high) requiring ATP
What is bulk transport?
Bulk transport moves large molecules or groups of molecules into or out of the cell via vesicles
What is exocytosis?
Exocytosis is the process where a vesicle containing substances fuses with the cell membrane to release its contents outside the cell
What is endocytosis?
The process where substances are engulfed by the cell membrane and brough into the cell within a vesicle
How does diffusion impact cell function?
Diffusion provides cells with oxygen and glucose and removes waste like carbon dioxide
What happens if a cell gets too large?
As a cell increases in size, diffusion becomes less efficient, the cell may divide to maintain efficient nutrient and waste exchange
Why do larger organisms need specialised transport systems?
Larger organisms have more complex structures and require systems (e.g. circulatory) to transport oxygen and nutrients efficiently
What is tonicity?
Tonicity is the environment into which a cell is placed, determining whether it will lose or gain water
What is an example of a hypotonic cell, and what is it?
Definition: the inside concentration is higher than outside
Example: a cell placed in fresh water
What is an example of a hypertonic cell, and what is it?
Definition: inside concentration is lower than the outside concentration
Example: cell placed in salt water
What is an isotonic cell?
When a cell is placed in a solution with the same concentration as the cell’s cytoplasm
What happens when an animal cell is placed into a hypotonic solution?
It will swell and burst
What happens when a plant cell is placed into a hypotonic solution?
It will gain water and expand to become turgid
What happens when an animal cell is placed into a hypertonic solution?
It will shrink in a process called crenation
What is the surface area to volume ratio?
Measures how much surface area is available for diffusion relative to the cell’s volume
How does cell size affect diffusion efficiency?
Smaller cells have higher SA:V ratio, allowing faster diffusion
Large cells have lower ratios, slowing diffusion
Who do cells needs a high surface area to volume ratio?
A higher ratio allows for more efficient exchange of materials with the environment
How does a cell’s surface area affect its function?
The larger the surface area, the more material can diffuse across the cell membrane at once
What is the role of ATP in active transport?
Provides energy for proteins to move substances against their concentration gradient
What is the role of protein pumps in active transport?
Transport substances against their concentration using energy from ATP
What are the two types of bulk transport?
Endocytosis and exocytosis
How do cells manage osmotic pressure?
By controlling water intake and excretion via processes like osmosis and active transport
What is the difference between regular diffusion and facilitated diffusion?
Facilitated diffusion requires membrane proteins to transport molecules across a membrane
