Membranes Flashcards by Susan Merfeld

Define hydrophobic

Water repels

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Define hydrophilic

Water attracts

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Define membrane

Outer substance of the cell

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What is a polar head attracted to?

Attracted to other polar (charged) molecules

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What is a non polar tail attracted to?

Repelling charged molecule, therefore prevent passage of ions through the membrane

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What are lipids

Fats, oils, do not mix with water

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More info on oil…

Base molecular membrane
Oil is thicker, slighter higher viscosity
Reason why there is life
They separate themselves as much as possie

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Define phospholipids

Phosphates that are fats and it’s another name for cell membrane

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Break down the meaning of phospholipid bilayer

Phospho- phosphates
Lipids- fats

Bi- 2
Layer- layers

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What is a polar head

Phosphate head

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What is a non-polar tail?

Fatty (oil) acid

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Explain how hydrophobic and hydrophilic properties of phospholipids help maintain the structure of the cell

When surrounded by water, the molecular properties phospholipids will cause them to form structures in which the lipid tails are not in contact with water

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What’s a metaphor for a phospholipids?

Magnets, north likes south and polar likes non polar

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Are phospholipids glued together?

No, they are very flexible. They act very similar to magnets

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What happens when the tails meet?

When the tails meet, the fatty acids will meet up to feel balanced and stable

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What does it mean to be selectively permeable?

It means that selectively means “controlled” and permeable means “entry/exit of molecules”

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What is selectively permeable also called?

Semi-permeable

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Some molecules pass through easily because of…..

Diffusion

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Some molecules go through a protein tunnel because of…

Facilitated diffusion (too polar or too big)

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Other molecules need energy to get trough the membrane because of…

Active transport

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Large molecules use their own membrane to get through a phospholipids because of…

Endo/exo-cytosis

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What are the 6 functions of the plasma membrane

1) hold the cell together
2) control what goes in and out
3) protect the cell
4) allow the cell to recognize and be recognized
5) bind to other cells and molecules
6) a site for biochemical reactions

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List 7 functions of membrane proteins.

1) hormone binding
2) fixed enzymes
3) cell adhesion
4) channels for facilitated diffusion
5) cell receptors for communication
6) active transport pumps
7) electron carriers in photosynthesis and cell respiration

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What is the fluid mosaic model?

The fluid mosaic model tells us that the structure of the membrane is flexible, adaptable and in motion. It is not solid, or fragile like skin of a balloon

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Break down "fluid mosaic model"

Fluid- always moving, not solid Mosaic- collection of things stuck together Model- representation of real life

Is it hard to break the cell membrane? Why/why not?

Yes, because a plasma membrane has the fluid properties of the phospholipid bilayer allows the membrane to reform very easily

What are the names and functions of these parts of the plasma membrane?

Integral proteins, glycoprotein, channel "integral" protein, cholesterol, and peripheral protein

What does a integral protein do for the plasma membrane?

It has enzymes to site for chemical reactions and pumps for active transport of molecules

What does the glycoprotein do for the plasma membrane?

It combines with carbon hydrates to make chemical receptors

What does channel "integral" proteins do for the plasma membrane?

It carries molecules through the plasma membrane

What does cholesterol do for the plasma membrane?

It affects membrane fluidity at different temperatures

What does peripheral proteins do for the plasma membrane?

They act as receptors and 'recognize' other cells

What are receptors?

They are lock keys 'bouncers' to let things into the cell

Define proteins

Molecules, amino acids make up proteins. They came in many shapes and sizes and try can range from very small to very large

7) functions of membrane proteins do

1) hormone binding sites 2) fixed (immobilized) enzymes 3) cell adhesion 4) channels for facilitated diffusion 5) cell receptors for communication 6) active transport pumps 7) electron carriers in photosynthesis and cell respiration

Define diffusion

Passive bet movement of particles from areas of high concentration to low concentration. This is often a partially permeable membrane

Define osmosis

Passive movement of water molecules are a passive that move from different areas of high solute to low solute, through a SEMI-PERMEABLE MEMBRANE

What does a concentration gradient do?

A concentration gradient meaning the differences in concentration of substance between two locations

What is isotonic?

When two solution s have the same concentration of solutes

What is hypertonic?

A solution with greater concentration of solutes

What is hypotonic?

A solution with lower concentration of solutes

Define facilitated diffusion

The passive movement of molecules across the cell membrane down the concentration gradient

What is passive transport?

When molecules move through the membrane without energy

What does a carrier protein do for the phospholipid bilayer?

It has parts that are polar and non polar so that phospholipid bilayer can adjust well with the carrier protein

What are integral proteins?

Enzymes: sites for chemical reactions. Pumps for active transport molecules

What are glycoproteins?

Combines with carbohydrates to make chemical receptors

What are channel proteins?

Carries molecules through the plasma membrane

What does cholesterol do for the membrane?

It affects membrane fluidity at different temperatures

What are peripheral proteins do for the membrane?

Try act as receptors and 'recognize' other cells (assist the glycoproteins)

Define vesicles

A bubble that surrounds the protein when being moved from the rough ER to the Golgi apparatus

Break down endocytosis

Endo - enter Cyto - cell Sis - process

Break down exocytosis

Exo - exit Cyto - cell Sis - process

What is endocytosis?

The import of molecules into the cell

What is exocytosis?

The export of cells

Name 3 types of endocytosis

1) phagocytosis 2) pinocytosis 3) receptor mediated endocytosis

What is phagocytosis?

The ingestion of large, solid molecules

What is pinocytosis?

The ingestion of liquids and solutes

What are receptor mediated endocytosis?

It requires binding to receptors on the outside if the cell membrane

What does endocytosis and exocytosis require?

ATP

What does ATP mean?

Adenosine Tri-Phosphate

What does ADP mean?

Adenosine Di-Phosphate

How does a protein pump get energy?

When ATP goes to ADP. ADP is when ATP loses a phosphate

Where does ADP go to?

To mitochondria

What is the only molecule that can go through things?

O2. It can diffuse .5 into objects