BIO130H1 Lecture : Lectures 3 and 4.docx

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lemonsnake834

14 Apr 2012

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Document Summary

Lipid bilayer permeable to some molecules: dependent on hydrophobic tails, core of bilayer = hydrophobic so hydrophobic molecules easily pass through bilayer because they can interact easily with the tail (eg. o2, co2, n2, benzene). High concentration to low concentration (down concentration gradient) More hydrophobic or non polar the molecule, the faster it is able to diffuse across the bilayer by simple diffusion. Lipid bilayer is nonpermeable to some molecules: don"t interact well with hydrophobic tails, require membrane proteins for transport. Important for cellular processes: eg. (large uncharged polar molecules: glucose, sucrose. Passive and active transport: passive transport, channel mediated: gated open or close pass through down concentration gradient, transporter mediated: don"t need nrg just need path across membrane. They specifically bind to a molecule and then undergo conformation changes that lets it across bilayer and protects it from lipid tails. Resting membrane potential: contributes to the ability of ions to move across cell membrane: positive outside, negative inside.

Related Questions

Which types of molecules will dissolve easily in water? CHECK ALL THAT APPLY.

a) Small polar covalent molecules.

b) Ionic compounds.

c) Large, folded protein molecules with exposed polarized regions.

d) Large non-polar molecules such as most hydrocarbons.

e) Highly hydrophobic molecules.

f) Highly hydrophilic molecules.

Please check P1&P2 & help with P3

P1.

A. DNA

B. Glycogen

C. Ribosome

D. miRNA

E1. Triacylglycerol

E2. Cyclic AMP

F. Acetyl CoA

G. Testosterone

H. ATP

I. Tau

1. Which molecules contain nucleotides? A, H, F, E2, D, C?

2. Which molecules contain at least one fatty acid? E1

3. Which molecules contain amino acids? I

4. Which molecules contain a sugar? A, B, H, E2, D, F

P2.

A. Phospholipid

B. Glycolipid

C. Cholesterol

D. None

1. Which molecules are amphipathic? A, B, C

2. Which molecules would decrease fluidity of plasma membrane? A?, B?, C

3. Which molecules are important for cell-cell recognition? B?

4. Which molecules are located solely on the intracellular surface of the plasma membrane, facing the cytosol? D

P3. 1. Describe where the following amino acids would be found in the glucose transporter (GLUT2) - part of the protein exposed to the lipid bilayer or within the interior of the transporter - and provide reasoning.

1A. Valine

1B. Serine

Acidic, basic, nonpolar, uncharged polar

2. Which amino acids form hydrogen bonds that shape tertiary structure?

3. Which amino acids allow transmembrane proteins to span the lipid bilayer?

During active transport in the neuron, the outside of the cell is _________________ and the inside is _______________.

positive, negative

more positive, less positive

more negative, less negative

negative, positive

In active transport, _____________ provides the energy to move molecules against their concentration gradient.

nucleus