First Unit 3 SAC?

[Snorlax]

Ok thanks guys!!! How about the mosaic model? I have a dot point on my Osmosis potato SAC revision sheet that says we should know the mosaic noedel of the cell membrane including the functions of all its components? what would I say?

Do you simply have to state the cell membrane is made up a phopholipid bilayar; where the heads (phosphate) are hydropllic and face outwards and the tails are hydrophobic which means they repel with water hence face inwards. There are also protein channels embedded in the membrane that assist large non-soluble substances to pass the membrane. What about the glycolipid? what do they do?

Glycolipids are lipids with an attached carbohydrate. They are involved in cell recognition.

[Yacoubb]

Those glycolipids embedded within the phospholipid bilayer are involved in cell reception and detection of self from non-self.

[Bad Student]

Those glycolipids embedded within the phospholipid bilayer are involved in cell reception and detection of self from non-self.

Are glycolipids antigens?

[Jayward]

antigens can be anything. proteoglycans usually though. glycolipids can also act as antigens on the rare occasion.

[Bad Student]

antigens can be anything. proteoglycans usually though. glycolipids can also act as antigens on the rare occasion.

Are proteoglycans the same as glycoproteins? They're like the same word but swapped around.

[Scooby]

Are proteoglycans the same as glycoproteins? They're like the same word but swapped around.

Not really. It has to do with the ratio of carbohydrate to protein in the molecule. Glycoproteins contain a higher proportion of protein than carbohydrate; proteoglycans contain a higher proportion of carbohydrate than protein

[Bad Student]

Not really. It has to do with the ratio of carbohydrate to protein in the molecule. Glycoproteins contain a higher proportion of protein than carbohydrate; proteoglycans contain a higher proportion of carbohydrate than protein

How about peptidoglycan and proteoglycan? Are these similar in any way?

Also, are proteoglycans part of the vce course? This is the first time I've heard of them.

[ealam2]

If free water molecules can pass through the membrane freely, why do aquaporins exist?

Also, why do the skin of our fingers become wrinkled when they've been wet for a long period of time?

[psyxwar]

If free water molecules can pass through the membrane freely, why do aquaporins exist?

Also, why do the skin of our fingers become wrinkled when they've been wet for a long period of time?

Speed. Aquaporins facilitate the transport of massive amounts of water molecules quickly, whereas if they were to diffuse through the bilayer it would be much slower due to the dipole nature of water.

[pi]

How about peptidoglycan and proteoglycan? Are these similar in any way?

Also, are proteoglycans part of the vce course? This is the first time I've heard of them.

Peptidoglycan is completely different. It's found in bacterial cell walls, and becomes very relevant when looking at Gram staining and certain drug interactions (which may or may not be me confusing bio stuff with med stuff).

It's good to have an idea of it.

Speed. Aquaporins facilitate the transport of massive amounts of water molecules quickly, whereas if they were to diffuse through the bilayer it would be much slower due to the dipole nature of water.

Aquaporins are pretty much only found in the kidneys. And not just speed, but also volume.

If free water molecules can pass through the membrane freely, why do aquaporins exist?

The theory is that it remains from evolutionary processes.

Read more -> http://www.nature.com/news/2011/110628/full/news.2011.388.html

[ealam2]

Thank you psyxwar and pi! That article was really interesting!

[siddhartharora]

Got my First Unit 3 SAC on this Friday. Just reading the chapter from the textbook and the summary notes as well. Our SAC is a

'Written report of a practical activity on the movement of substances across membranes'. Task overview says 'You will be required to observe and describe the movement of substances across a differentially permeable mebrane and to observe the effects of concentration gradients in living cells. You will undertake an experiment using a real cell membrane (potato) and observe the movement of water across the membrane."

Just a few general questions; if I were to study the structure and function of the cell membrane (glycoproteins, glycolipids, cholestrol, hydrophillic/phobic ends, 2 types of proteins present), the way molecules move through the membrane (osmosis, diffussion, etc.), isotonic and hypotonic and hypertonic environments, would that basically suffice the needs for this outcome? Am I missing anything else?

Cheers

[ealam2]

Got my First Unit 3 SAC on this Friday. Just reading the chapter from the textbook and the summary notes as well. Our SAC is a

'Written report of a practical activity on the movement of substances across membranes'. Task overview says 'You will be required to observe and describe the movement of substances across a differentially permeable mebrane and to observe the effects of concentration gradients in living cells. You will undertake an experiment using a real cell membrane (potato) and observe the movement of water across the membrane."

Just a few general questions; if I were to study the structure and function of the cell membrane (glycoproteins, glycolipids, cholestrol, hydrophillic/phobic ends, 2 types of proteins present), the way molecules move through the membrane (osmosis, diffussion, etc.), isotonic and hypotonic and hypertonic environments, would that basically suffice the needs for this outcome? Am I missing anything else?

Cheers

I suggest practicing questions on experimental designs such as hypothesis, aim and different types of variables. Also, maybe the characteristics of water molecules may help- such as polarity.

All the best!

[Snorlax]

Got my First Unit 3 SAC on this Friday. Just reading the chapter from the textbook and the summary notes as well. Our SAC is a

'Written report of a practical activity on the movement of substances across membranes'. Task overview says 'You will be required to observe and describe the movement of substances across a differentially permeable mebrane and to observe the effects of concentration gradients in living cells. You will undertake an experiment using a real cell membrane (potato) and observe the movement of water across the membrane."

Just a few general questions; if I were to study the structure and function of the cell membrane (glycoproteins, glycolipids, cholestrol, hydrophillic/phobic ends, 2 types of proteins present), the way molecules move through the membrane (osmosis, diffussion, etc.), isotonic and hypotonic and hypertonic environments, would that basically suffice the needs for this outcome? Am I missing anything else?

Cheers

For a 'just in case', you should think of the importance and relevance of osmosis/diffusion for an wider example/application in the discussion or perhaps it may come up as a question.

[forchina]

Hey another question guys
When cells are placed in hypertonic or hypotonic environments other there will be movement of both solute and water down its concentration gradients. So if they were both moving until the cell and its environment are isotonic which would do more affect to make it isotonic? (Sorry im not really sure how to word my question so i hppe you understand)

In the beetroot prac would there be both movement of the pigment and water? If it is place in a hypertonic environment only water would move out of the beetroot but if its in a hypotonic would pigment move out of it and water from outside move into beetroot?

Sorry if my questions are confusing ill try to reword it if they are.