Cell membranes Flashcards
What are glucose and many other water soluble molecules too big for?
To diffuse across the membrane by themselves
What must the molecules be helped across by?
Carrier proteins
What does each substance have?
It’s own specific carrier protein
What does a molecules of glucose fit onto and result in?
The outside end of a glucose carrier protein, causing the protein to change shape, allowing the glucose molecule to diffuse through it into the cytoplasm of the cell
What doesn’t the cell need to provide for facilitated diffusion?
Energy
What do mineral ions like sodium (Na+) and potassium (K+) have and so..?
Electrical charges on them, so need help to cross the membrane
What do specific channel proteins in the membrane do?
Allow the mineral ions like sodium and potassium to diffuse through
When a cell needs to move substances across the membrane from a region of low concentration to a region of higher concentration what must it provide (What is this called as well)?
Energy (Active transport or active uptake)
What does the substance fit into?
A specific carrier protein
What provides the energy to change the shape of the protein?
Molecules of ATP
What happens as the protein changes shape?
The protein actively transports the substance across the membrane
What are the special carrier proteins also sometimes called and why?
Pumps, because they’re moving substances against a concentration gradient
