1. Plasma Membrane Part 1 Flashcards
What are the functions of the plasma/cell membrane? What are the benefits of membrane-bound organelles in Eukaryotes?
- Acts as a boundary to control what enters and exits the cell
- Separates the internal and external environments
- Different parts of the cell can have varied conditions to allow specialisation
Describe phospholipid heads:
- Are hydrophilic (hydro=water) and polar
- Love water
Describe fatty acid tails:
- Are hydrophobic and non-polar
- Hate/fear water
Explain the Fluid Mosaic Model:
- Fluid= Because the phospholipids are moving
- Mosaic= Proteins sit in the phospholipids like tiles in a mosaic
What is the function of sterols, what are their different types and where are they located
- Change the fluidity of the membrane so that it is able to remain stable.
- Phytosterol in plants and animals and only Chlorestoral in animals
- Located in the hydrophobic region of the membrane
What are the 2 types of membrane proteins?
Can be integral (permanent parts of the membrane) or peripheral (temporary)
List the 6 functions of membrane proteins:
- Transport substances across the membrane
- Secure the cytoskeleton to the membrane
- Are enzymes
- Are receptors
- Responsible for cell-to-cell adhesion
- Act as identity marks
Describe the internal environment of multi-cellular organisms:
Contain interstitial/tissue (extracellular) fluid between cells (fluid bathes the cells, as well as blood plasma.
Describe the internal environment of unicellular organisms:
Contain only the internal environment of the cell itself.
What is a solute?
A substance dissolved in a liquid.
What is a solvent?
A liquid
What is a solution?
A solute and a solvent
What is a concentration gradient?
Describes the difference between relative amounts of solute and solvent in two solutions.
What does polar refer to? Give an example:
When one end of a molecule has a different charge to the other.
Eg. Water
What does non-polar refer to? Give an example:
When one end of a molecule has the same charge as the other.
Eg. Oil
What are vesicles?
Small storage compartments of membrane which transport solids or liquids across membranes
What is exocytosis and does it require energy?
- Exiting the cell
- Requires energy
What is endocytosis and does it require energy?
- Entering the cell
- Requires energy
What is the difference between eukaryotes and prokaryotes?
- Eukaryotes are complex cells which contain membrane-bound organelles, DNA present as chromosomes, and can be either unicellular or multicellular
- Prokaryotes are primitive cells which lack membrane-bound organelles, nuclei, and can only be unicellular.
What are ribosomes? What cells are they present int?
They are made of proteins and ribosomal RNA (rRNA) and assemble to translate mRNA (messenger RNA) into protein.
-Present in prokaryotic, animal, and plant cells
What is the rough endoplasmic reticulum and why is it called this? What cells are they present in?
Its surface is used to create protein to export. Is called ‘rough’ because of the presence of ribosomes.
-Present in animal and plant cells
What is the function of the Golgi Apparatus? What cells are they present in?
Packages and modifies proteins for transport to other organelles or to secrete from the cell.
-Present in animal and plant cells
Name the 2 types of endocytosis:
- Phagocytosis
- Pinocytosis
What is phagocytosis?
The bulk transport of solids into a cell
What is pinocytosis?
The bulk transport of liquids into a cell
Describe the process of producing and transporting protein:
- DNA is transcribed into mRNA in the nucleus
- mRNA leaves nucleus and ribosomes assemble to translate the message into protein
- Protein is either made in the cytosol or moved into the rough endoplasmic reticulum
- Protein moves via vesicles to the Golgi Apparatus
- Golgi sorts protein into correct vesicles to move either out of the cell or into other organelles
