Biological membranes

Created by

Larissa N

Cards (32)

What should you assess before proceeding with an experiment?
All safety risks
Why is it important to cut away from yourself when using a scalpel?
To avoid cutting yourself
What should you use to remove hot test tubes after an experiment?
Tongs
How can you investigate cell membrane permeability using beetroot?
Use beetroot cells containing colored pigment
Measure pigment leakage to assess permeability
Experiment with variables like temperature and solvent concentration
What happens to the pigment in beetroot cells when membrane permeability increases?
More pigment leaks out
What is the procedure to investigate temperature effects on beetroot membrane permeability?
Cut five equal pieces of beetroot
Rinse to remove pigment
Place in test tubes with water at different temperatures
Measure absorbance of released pigment
What is the purpose of using a colorimeter in the experiment?
To measure light absorption
What should you do before using the colorimeter?
Allow it to stabilize for five minutes
What wavelength filter is used in the colorimeter for this experiment?
Blue filter at 470 nm
Why is it important to wipe the cuvette before using it in the colorimeter?
To ensure accurate light passage
What does a higher absorbance reading indicate in the experiment?
Higher membrane permeability
How does temperature affect cell membrane permeability?
Below 0°C: Membrane is rigid, proteins denature
Between 0°C and 45°C: Membrane is partially permeable, increased movement
Above 45°C: Membrane melts, proteins denature, increased permeability
What happens to phospholipids at temperatures below 0°C?
They are packed closely together
What occurs to channel proteins at low temperatures?
They denature and increase permeability
What happens to the phospholipid bilayer at temperatures above 45°C?
It starts to melt
How does cholesterol affect membrane fluidity?
It makes the membrane less fluid and more rigid
What are the main components of a cell membrane?
Phospholipids
Proteins (integral and peripheral)
Cholesterol
Glycolipids
Glycoproteins
What is the role of phospholipids in the cell membrane?
Form a barrier to water-soluble substances
What is the function of glycoproteins in the membrane?
Act as cell surface receptors
What is the thickness of the phospholipid bilayer?
About 7 nm
What are the types of movement across cell membranes?
Diffusion
Facilitated diffusion
Osmosis
Active transport
Exocytosis and endocytosis
Co-Transport
What is diffusion?
Passive movement from high to low concentration
What is osmosis?
Diffusion of water through a partially permeable membrane
What is required for active transport?
Energy in the form of ATP
How do exocytosis and endocytosis differ?
Exocytosis releases particles; endocytosis takes them in
What is co-transport in epithelial cells?
Using ions to move substances across membranes
What factors increase the rate of gas exchange by diffusion?
Increased surface area, decreased distance, increased gradient, higher temperature
What is the fluid mosaic model of the cell membrane?
Describes the arrangement of molecules in the membrane
Phospholipid bilayer is fluid and constantly moving
Proteins are scattered like tiles in a mosaic
What are the functions of cell membranes?
Control movement of substances in and out
Act as barriers between compartments
Contain receptors for signaling molecules
Enable cell adhesion
What is the significance of membrane fluidity?
Allows movement of proteins and lipids
Facilitates cell signaling and transport
Maintains cell shape and integrity
What is the role of cholesterol in cell membranes?
Regulates membrane fluidity
Provides stability against temperature changes
Creates a barrier to polar substances
What are the roles of glycolipids and glycoproteins?
Glycolipids: Cell recognition
Glycoproteins: Cell surface receptors and adhesion