Chapter 8.
Movement across the Cell
Membrane
Docsity.com
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community
Ask the community for help and clear up your study doubts
University Rankings
Discover the best universities in your country according to Docsity users
Free resources
Our save-the-student-ebooks!
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
Understanding Cell Membrane: Molecule Movement - Diffusion, Osmosis, and Active Transport, Slides of Biology
An in-depth exploration of the cell membrane, its composition, and the movement of various molecules across it through processes such as diffusion, osmosis, and active transport. It covers topics like the role of the 2nd law of thermodynamics, the concept of concentration gradients, and the functions of lipids, proteins, and channels in maintaining the semi-permeability of the membrane.
Typology: Slides
2012/2013
1 / 43
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Understanding Cell Membrane: Molecule Movement - Diffusion, Osmosis, and Active Transport and more Slides Biology in PDF only on Docsity!
Chapter 8.
Movement across the Cell
Membrane
Diffusion
• 2nd Law of Thermodynamics
governs biological systems
- Universe tends towards disorder
Diffusion
movement from high → low concentration
Diffusion
• Move for HIGH to LOW concentration
- “passive transport”
- no energy needed
diffusion osmosis Docsity.com
Cell (plasma) membrane
• Cells need an inside & an outside…
- separate cell from its environment
– cell membrane is the boundary
IN
food carbohydrates sugars, proteins amino acids lipids salts, O 2 , H 2 O
OUT
waste ammonia salts CO 2 H 2 O products cell needs materials in & products or waste out
IN
OUT
Can it be an impenetrable boundary? NO!
Docsity.com
Lipids of cell membrane
• Membrane is made of phospholipids
- phospholipid bilayer
phosphate
lipid
hydrophilic
hydrophobic
inside cell
outside cell
Phospholipids
Phospholipid bilayer
• What molecules can get through directly?
inside cell
outside cell
fats & other lipids
can slip directly
through the
phospholipid cell
membrane, but…
what about other
stuff?
lipid salt
sugar aa H 2 O
NH 3
Simple diffusion across membrane
inside cell
outside cell
Which way will lipid move?
low
high
lipid
lipid
lipid
lipid
lipid
lipid lipid
lipid^ lipid
lipid
lipid
lipid
lipid
lipid
Diffusion through a channel
• Movement from high to low
inside cell
outside cell
sugar
sugar
sugar
sugar
sugar
sugar
sugar sugar
sugar sugar sugar
Which way will sugar move?
low
high
sugar
Semi-permeable cell membrane
• But the cell still needs control
- membrane needs to be semi-permeable
- specific channels allow specific material in & out
inside cell
outside cell
H 2 O aa sugar
NH 3 salt
Why proteins?
• Proteins are mixed molecules
- hydrophobic amino acids
- stick in the lipid membrane
- anchors the protein in membrane
- hydrophilic amino acids
- stick out in the watery fluid in & around cell
- specialized “receptor” for specific molecules
Facilitated Diffusion
- Globular proteins act as doors in membrane
- channels to move specific molecules through cell membrane
“The Bouncer”
open channel = fast transport high
low
Getting through cell membrane
- Passive transport
- diffusion of hydrophobic (lipids) molecules
- high → low concentration gradient
- diffusion of hydrophobic (lipids) molecules
- Facilitated transport
- diffusion of hydrophilic molecules
- through a protein channel
- high → low concentration gradient
- Active transport
- diffusion against concentration gradient
- low → high
- uses a protein pump
- requires ATP
- diffusion against concentration gradient
Facilitated diffusion
• Move from HIGH to LOW concentration
through a protein channel
- passive transport
- no energy needed
- facilitated = with help