Nutrient Uptake Mechanisms

Study Notes

Primary Active Transport

Moves molecules against their concentration gradient, meaning from a region of lower concentration to a region of higher concentration.
Requires energy, often in the form of ATP, to move substances uphill.
Uses transmembrane proteins to pump molecules across the membrane.

Secondary Active Transport

Uses the energy stored in the electrochemical gradient of another molecule to move a substance against its concentration gradient.
Relies on the movement of a substance down its concentration gradient to provide energy for the uphill movement of another substance.
Primary function is to transport molecules against their concentration gradient.

Factors Affecting Nutrient Uptake

Concentration Gradient: The difference in concentration of a nutrient between the outside and inside of a cell.
Membrane Permeability: The ease with which a nutrient can cross the cell membrane
Temperature: A higher temperature generally increases the rate of diffusion.
Surface Area: A larger surface area provides more space for nutrient uptake.
Carrier Protein Availability: Limited availability of carrier proteins can restrict uptake rates.

Passive Transport vs. Active Transport

Passive transport: Does not require energy, as molecules move down their concentration gradient from a region of high concentration to a region of low concentration.
Active transport: Requires energy to move molecules against their concentration gradient, from a region of low concentration to a region of higher concentration.

Membranes in Nutrient Uptake

Act as selective barriers, controlling the passage of molecules into and out of the cell.
Possess transport proteins that facilitate the movement of specific nutrients across the membrane.

Facilitated Diffusion

A type of passive transport that uses transport proteins to facilitate the movement of molecules across the membrane
Still relies on the concentration gradient, but the transport protein speeds up the process.
Doesn't require energy expenditure by the cell.

Active vs. Passive Transport Rates

Active transport: Can achieve higher uptake rates, as it can accumulate nutrients against their concentration gradient
Passive transport: Rates are limited by the concentration gradient and may be slower, especially when concentrations are low.

Simple Diffusion

Small, non-polar molecules are most likely to pass through the cell membrane via simple diffusion.
Examples of these molecules include oxygen, carbon dioxide, and some lipids.

Description

This quiz explores the mechanisms of nutrient uptake, covering both active and passive transport. You'll learn about the definitions, types, and functions of each mechanism, along with factors influencing nutrient movement. Test your understanding of these essential biological processes.