Topic 2B- Cell Membranes Flashcards
What is the full definition of osmosis?
What direction does water move in?
What do solutes (like salt) do to water potential?
What is the water potential of distilled water?
What is the full definition of water potential?
What does it mean the more negative the water potential?
The movement of water from a relatively higher water potential to a lower water potential through a partially permeable membrane
Water moves in the direction of the most negative water potential
Lower the water potential of a solution
Distilled water has a water potential of zero
The potential (likelihood) of water molecules to diffuse out of or into a solution
The stronger the concentration of solutes in the solution.
What are and describe glycoproteins in cell membranes?
What does fluid mean?
What does mosaic mean?
What is the name of the pattern used by cell membranes?
What happens to lipid soluble substances when entering or leaving cell membranes and give some examples?
What happens to water soluble substances when entering or leaving cell membranes?
What are cell membranes therefore described as?
What two proteins allow the movement of larger/water soluble substances?
Glycoproteins (globular proteins) in cell membranes are proteins with a carbohydrate side chain. These are involved with recognition or binding to messengers/hormones (some are in fixed position, others can move sideways)
Molecules can move in relation to each other (phospholipids are always moving)
Pattern created by phospholipids and proteins
Fluid Mosaic Pattern
Lipid soluble (non polar) substances (eg gases like oxygen) can leave or enter
Water soluble substances cannot enter or leave cell membranes
Partially permeable
Carrier and channel proteins allow movement of larger/water soluble substances.
What are the six parts of a cell membrane diagram?
What are the two types of proteins described as in cell membranes layer?
What is a glycoprotein?
What type of process is facilitated diffusion?
What is facilitated diffusion?
How are the molecules moved across the plasma membrane?
What does facilitated diffusion allow (and give two examples)?
What do these carrier proteins have?
- Globular protein
- Glycolipid
- Channel protein
- Glycoprotein
- Phospholipid bilayer
- Carrier protein
Extrinsic and intrinsic proteins
Proteins that have carbohydrates attached
A passive process
The net movement of molecules down a concentration gradient
By carrier proteins or channel proteins
The movement of water soluble molecules (eg glucose and amino acids)
Molecule specificity.
What does isotonic mean?
What won’t cells do in an isotonic solution and why?
Why is this?
What will happen if a cell is placed in a solution that has a higher water potential?
What does hypotonic mean?
What might happen if a cell is placed in a solution that has a higher water potential?
What does hypertonic mean?
If two solutions have the same water potential
Won’t lose or gain any water because there’s no net movement of water molecules
Because there’s no difference in water potential between the cell and the surrounding solution
It will swell as water moves into it by osmosis
Solutions with a higher water potential compared with the inside of the cell
It will swell as water moves into it by osmosis
Solutions with a lower water potential than the inside of the cell.
What is adenosine?
What does ATP stand for?
What is the equation for the reaction for ATP?
What do the different parts of this equation mean?
What is the equation for what happens in the mitochondrion?
What is Fick’s law (in full)?
How is glucose absorbed in the body?
What happens to these walls and what does this form?
What are the five properties of these?
What is the mammalian ileum?
What happens in the mammalian ileum?
What how is glucose absorbed instead and what is the process called?
Nucleotide base
Adenosine Triphosphate
(energy) ATP <===> ADP + Pi
(Respiration, aerobic and anaerobic)
Pi stands for phosphate group
ADP + Pi —> ATP
Diffusion is proportional to:
(Concentration Gradient x Surface Area) -:- Thickness of Exchange Surface
Absorbed through the walls of the small intestine
The wall is folded to form villi
- Thin outer cell layer
- Able to move
- Good blood supply
- Mitochondrion in epithelial cells
- Plenty of membrane proteins
The final part of a mammal’s small intestine
The concentration of glucose is too low for glucose to diffuse out into the blood
From the lumen (middle) of the ileum by co-transport.
What are the seven parts of the process of active transport?
What is the explanation for the following steps of co-transport and absorption of glucose:
Step 1
Step 2
Step 3
- Molecules being transported bump into the carrier protein
- The molecules being transported then bind to receptors on the channels of the carrier protein
- Inside the cell, ATP binds to the protein causing it to split into ADP and a phosphate molecule (which remains attached to the protein for a short time). As a result, the protein molecule changes shape so that it is now open to the opposite side from before
- The molecules or ions are released to the other side of the membrane
- The phosphate molecule is now released from the protein
- And the protein now returns to its original shape ready to repeat the process
- ADP and Pi are recombined in respiration (mostly this process happens in mitochondria) and this means they are also available in case the process needs to be repeated
- Sodium ions are actively transported out of the epithelial cells in the ileum, into the blood, by the sodium-potassium pump. This creates a concentration gradient- there’s now a high concentration of sodium ions in the lumen of the ileum than inside the cell
- This causes sodium ions to diffuse from the lumen of the ileum into the epithelial cells, down their concentration gradient. They do this via the sodium-glucose co-transporter proteins.
The co-transporter carries glucose into the cell with sodium. As a result the concentration of glucose inside the cell increases
- Glucose diffuses out of the cell, into the blood, down its concentration gradient through a protein channel, by facilitated diffusion.
What does temperature do to cell membranes?
What two things does this then affect?
What happens to the phospholipids in the cell membrane in temperatures below 0 oC (full description)?
What happens to the channel and carrier proteins and what does this do?
What might form on the membrane and what two things does this then cause?
What happens to the phospholipids in the cell membrane in temperatures between 0 and 45 oC?
What two things happen to the phospholipids as the temperature increases?
It affects how much the phospholipids in the bilayer can move, which affects membrane structure and permeability
Affects membrane structure and permeability
The phospholipids don’t have much energy so they can’t move very much. They’re packed closely together and the membrane is rigid
They denature (lose structure and function), increasing the permeability of the membrane
Ice crystals may form and pierce the membrane, making it highly permeable when it thaws
The phospholipids can move around and aren’t packed as tightly together- the membrane is partially permeable
The phospholipids move more because they have more energy- this increases the permeability of the membrane.
What happens to the phospholipids in the cell membrane in temperatures above 45 oC?
What happens to water inside the cell and what does this cause to the membrane?
What two things happen to channel and carrier proteins in the membrane?
What does this then increase?
The phospholipid bilayer starts to melt (break down)and the membrane becomes more permeable
Water inside the cell expands, putting pressure on the membrane
They denature so they can’t control what enters or leaves the cell
This increases the permeability of the membrane.
