transport across cell membranes

?
  • Created by: o_cook
  • Created on: 30-09-19 14:48
What is the plasma membrane?
Boundaries between cells and their environment
1 of 28
What is diffusion?
Particles that move down the concentration gradient -> passive
2 of 28
What factors effect rate of diffusion?
1.) Size of conc. gradient 2.) thickness of exchange surface 3.) size of molecules
3 of 28
What is facilitated diffusion?
Movement of particles down the conc. gradient where protein carriers are involved
4 of 28
Why is facilitated diffusion used?
large molecules can't diffuse across phospholipid bilayer -> still passive and is specific (certain molecules for corresponding carrier/ channel)
5 of 28
How do carrier proteins work?
1.) molecule attaches 2.)carrier changes shape 3.)releases molecule on the other side
6 of 28
How do channel proteins work?
1.) forms pores in membrane 2.) allow charged particles to move down conc. gradient
7 of 28
What is active transport?
particles move against the conc. gradient across a partially permeable membrane (e.g. intestines)
8 of 28
Sequence of active transport:
1.) molecule attaches to carrier protein 2.) ATP provides energy 3.) carrier changes shape and releases molecule on the other side (higher conc.)
9 of 28
What provides energy for active transport?
mitochondria provide ATP (energy)
10 of 28
What is osmosis?
Movement of across a partially permeable membrane from an area with a less negative water potential to an area of more negative water potential
11 of 28
What is water potential?
how freely water can move [measured in kiloPascals]
12 of 28
What is the water potential of pure water?
0 kPa
13 of 28
Water with dissolved solutes is ____ negative
more
14 of 28
What is a hypotonic solution?
lower conc. than the cell
15 of 28
What is an isotonic solution?
same conc. than the cell
16 of 28
What is a hypertonic solution?
higher conc. than cell
17 of 28
Sequence of co- transport:
1.) sodium out of epithelial cell, into blood by active transport 2.) maintains higher sodium in lumen than epithelial 3.) sodium ions diffuse into epithelial through co- transport carrying glucose molecule 4.)glucose passes into blood by facilitated
18 of 28
What are the adaptions of the intestine?
villi, long and folded = large SA, thin epithelium = short diffusion pathway
19 of 28
How are lipids hydrolysed?
By lipases produced by the pancreas -> forms fatty acids and monoglycerol
20 of 28
what are micelles?
Droplets of lipids broken down by bile salts
21 of 28
What is the purpose of emulsification?
to greatly increase surface area for lipases to work
22 of 28
How are try glycerides absorbed [1]
micelles come into contact with epithelial cells lining the villi which get broken down into monoglycerides and fatty acids
23 of 28
How are try glycerides absorbed [2]
These diffuse across membranes into the epithelial where they are transported into the endoplasmic reticulum
24 of 28
How are try glycerides absorbed [3]
Then recombined into triglycerides
25 of 28
How are try glycerides absorbed [4]
the triglycerides associate with cholesterol and lipoproteins to form chylomicrons
26 of 28
How are try glycerides absorbed [5]
chylomicrons move out of the cells of the epithelial cells by exocytosis
27 of 28
How are try glycerides absorbed [6]
Finally, they enter the lacteals in the centre of villus
28 of 28

Other cards in this set

Card 2

Front

What is diffusion?

Back

Particles that move down the concentration gradient -> passive

Card 3

Front

What factors effect rate of diffusion?

Back

Preview of the front of card 3

Card 4

Front

What is facilitated diffusion?

Back

Preview of the front of card 4

Card 5

Front

Why is facilitated diffusion used?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cellular processes resources »