Biology (Cell membrane)

thin flexible barrier surrounding the cell

What is the cell membrane

selective permeability - controls what enters and leaves, maintaining homeostasis
Physical barrier - separates external and internal environment of cell
Holds cytoplasmic organelles in place

functions of membrane + purpose

Phospholipids are fluid, so they can move sideways
Proteins can drift in between

Describe fluid part of fluid mosaic

Has many different molecules (carbs, lipids, proteins)

Describe mosaic part of fluid mosaic

Temperature
Double bonds (saturation of fat)
Cholesterol

What affects membrane fluidity

Prevents from being too fluid or rigid
In hot, acts as a brace to prevent tails from moving too freely
In cold, wedges between tails so they can’t stack neatly

How does cholesterol help membrane in diff temps?

Cold - phospholipids pack, little protein movement, transport slows down
Heat - Too fluid, Ions/molecules can leak out, proteins may fall apart

What happens to membrane without cholesterol in diff temp

Area around the cell (blood)
extracellular fluid
Chemical waste is released here to release

What is environment of cell and its importance

Cold - membrane proteins can’t change shape, prevents proper transport
transporting molecules slow down
small molecules can no longer pass easily
Heat - Proteins can denature
Can no longer control what enters and leaves

Temperature affect on membrane

Integral/transmembrane/intrinsic protein - spans fully from external to internal environment, often known as transport proteins
Peripheral/extrinsic protein - Partially embedded in membrane. Helps sticks cells together and hold its shape

Types of proteins in bilayer + location

Acts as gatekeepers
Acts as channels to allow molecules in and out of cell
Can use ATP to pump molecules against gradient

Transport proteins

Part of protein exposed to outside of cell
Specific binding site shape to only allow 1 type of molecule fit
Sends messages to cell

Receptor site

Active binding sites
Shape is specific to substrate

Enzymes (on protein)

molecule being worked on by the enzymes

Substrate

Sticks cell to cell or extracellular matrix
Allows cells to form tissue
Helps cells form a protective barrier

Cell adhesion

attaching to microfilaments

How do proteins help cell structure support

Carbohydrate molecule that surrounds the cell
sticks outward into environment
Cell recognition

Glycocalyx

Protein with carb attached to it
Blood markers
Helps with identification

Glycoprotein