Biology- plasma membrane

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What kind of role do proteins have?

A functional role

What kind of role do phospholipids have?

A structural role

What do rip and rib stand for?

All plasma membrane functions R reaction site(cellular Chem reactions) I insulation P protection R recognition I in and out B boundary

What is a gLyco protein

Any protein that has carbohydrates attached to phospholipids

Why do scientists describe the plasma membrane as a fluid mosaic

Because the proteins embedded in the lipid bilayer can move around or float amount the lipids and because so many different kinds of molecules make up the plasma membrane

What occurs when these lipids are mixed with water

Fatty acid tails cluster together Heads attracted to water Lipid bilayer =result

Describe the two parts of a lipid bilayer.

Fatty acid tails- hydrophobic "water-hating" Phosphate head-hydrophilic "water-loving"

What do some of the proteins do?

Form channels and pumps that help move material across the cell membrane

What does the lipid bilayer do?

Gives plasma membrane flexible structure and forms a strong barrier between the cell and its surroundig

What are the two parts of phospholipids?

Head (glycerol and phosphate group) and tails

What is the function of transport proteins

Help transport ions, macromolecules, and other substances incapable of entering a cell by themselves across plasma membrane -charged particles, small polar -large molecules need special processes to get through

What is the function of proteins in the membrane?

Hormone binding sites Election carriers Pumps for active transport Channels for passive transport Enzymes Cel signaling Cell adhesion

Membrane acts as an attachment point for ...

Intracellular cytoskeleton and if present cell wall

What kind of cells produce a plasma membrane and cell wall?

Prokaryotes(plants) Algae Fungi Not animals

What do most plasma membranes contain?

Protein molecules that are embedded in the lipid bilayer

What are channels in plant cells?

Pits

What do pits contain?

Plasmodesmata (continuous strands of cytoplasm) that Connect cytoplasm of neighboring cells slowing movement of water soluble materials from cell to cell

The cell wall is ______ enough to allow____,____,___, to pass through easily

Porous Water,oxygen,carbon dioxide, and certain other substances

What else does cholesterol do?

Prevents cells from freezing when your body temp gets very low. That's why animals in post areas have larger amounts of cholesterol

Do all cells have a plasma membrane? What does it do?

Yes Regulates what enters/exits cell Protects and supports cells

Are organelles also composed of phospholidpids

Yes. Mitochondria are bounded by double membrane

What is plasma membrane analogous for?

Our skin

Where is the cell wall located?

Outside the cell membrane

Structure of lipid bilayer

-Head groups of lipids in bilayer exposed to water -fatty acid tails form oily layer inside membrane from which water is excluded

What is the function of the cell wall?

-provide support and protection for the cell

What is the function of the plasma membrane?

-regulate what enters and exits the cell -protects and supports the cell -acts as wall to keep organelles inside -helps cell control chemical and electrical properties -help maintain cell hlmeostasis

What are gap junctions

Channels formed by embedded proteins in the plasma membrane of adjacent cells Allows small water soluble substances to pass directly from cell to cell

What do carbohydrates molecules act like?

Chemical identification cards, allowing individual cells to identify one another

What is the plasma membrane composed of?

Double-layered sheet called a lipid bilayer

What are Desmosomes?

Links intermediate filaments of neighboring cells Acts as rivets but allows passage of substances through spaces between cells

What do carb chains do?

Located outside bilayer Used to identify the cell -Determines blood type depending on which type is bonded to membrane

What is the function of cholesterol in plasma membranes?

Make the membrane more rigid but still flexible - too much can cause hardened arteries

What are the properties of lipids?

Many have oily fatty acid chains attached to chemical groups that interact strongly with water

Can all substances cross biological membranes?

No, some re too large or too strongly charged to cross lipid bilayer

Most biological membranes are _____ meaning some substances can pass across them and others cannot

Selectively permeable

Selectively permeable membranes are also called...

Semi permeable membranes

What kind of molecules pass through the plasma membrane easily?

Small, uncharged molecules Water, glycerol, ethanol Small, nonpolar has molecules Nitrogen, oxygen,carbon dioxide

What is an extra cellular matrix

Solution of macromolecules outside the cell (extra cellular space) - may help regulate behavior of cell in contact with matrix

What are junctions?

Specialized regions in plasma membranes where cells can be connected to one another

What are phospholipids called phospholipids

The lipid has only two fatty acids, the third being replaced by a phosphate group

What happens if substance is able to cross membrane

The membrane is determined as permeable to it - membrane is impermeable to substances that cannot pass across it

What are tight junctions

When plasma membranes are fused Substances cannot move through spaces between cells


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