Principles of Human Cell Biology Flashcards
What is one of the key concepts of human biology?
That everything derived from one cell and human biology stems from a group of cells
What are the similarities and differences between prokaryotic cells and eukaryotic cells?
Prokaryotes:
No membrane-bound organelles
DNA in a nucleoid, not separated from the rest of the cell
Single-celled
Circular DNA with no introns
Smaller
Eukaryotes:
Has membrane-bound organelles
DNA separated from the rest of the cell in the nucleus
Can be single-celled or multicellular
Chromosomal DNA with exons and introns
Larger
Why are viruses not considered living?
They are acellular, they cannot undergo metabolic reactions and they don’t replicate on their own
Approximately how many time larger is a eukaryotic cell compared to a prokaryotic cell?
Approximately over 20 times (at least 50)
50µm eukaryotic cell
1µm prokaryotic cell
What are the two major forms of prokaryotes?
Bacteria and archaea
What are distinct features of a prokaryotic cell?
Prokaryotes have a smaller genome and a single, circular genome
They may also have plasmids, small sections of circular DNA which can be passed between cells
They do not have membrane-bound organelles (such as a nucleus)
What does viral genetic material force cells to do once injected into the cell?
Make/copy the viral DNA and RNA
To produce viral proteins
Why does viral replication negatively affect host cells?
The host cells eventually burst as too many viral proteins have been replicated
What are the four major kingdoms regarding eukaryotes?
Animals
Fungi
Plants
Protists
How are animal cells defined?
By what they lack:
Lack of cell wall
Lack of chloroplasts
Always multicellular
What do eukaryotic cells have to support their function?
All eukaryotic cells have organelles to support their cellular function. The organelles include a nucleus, mitochondria, Golgi body, and both smooth and rough endoplasmic reticulum
Why are many supporting structures like ribosomes, not considered organelles?
They lack complexity and/or have no membrane
In which way could you describe the appearance of a cell?
The cell is surrounded by a membrane (plasma/cell membrane) and contain many membranes in it due to individual organelles, and an endomembrane system
What is an endomembrane system?
A group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins
What are some of the several functions that a membrane provides?
Compartimentalisation
Communication
Partial permeability, therefore acts as a barrier
Why is it beneficial for the cell membrane surrounding the cell being able to act as a barrier?
This then allows for different molecules to pass through and be responsible for cell signaling
What are the three types of membrane proteins?
Integral
Lipid-anchored
Peripheral
Where can each type of membrane protein be found<
Integral: within the phospholipid bilayer (within the membrane)
Lipid-anchored: attached to lipids that are in the membrane (lipoproteins)
Peripheral: bound intermolecularly to the membrane (e.g. Hydrogen bonds) but isn’t directly covalently bonded to the membrane
What are some features of integral membrane proteins?
Amphipathic: has both polar and non-polar regions so has both polar and non-polar regions
Span the membrane
They can be singlepass or multipass (based on how they bond)
They are partially embedded and so are attached to only one side of the membrane
What are some features of lipid-anchored proteins?
Protein is found at the membrane’s surface
Found on both membrane surfaces
Lipid is covalently bonded to the protein within the membrane, therefore lipid-anchored
What are some features of peripheral membrane proteins?
Lack hydrophobic regions
Don’t interact with fatty acid ends of membrane lipids
Not chemically associated with the membrane
Associated with the membrane surface via intermolecular forces, (i.e. electrostatic attraction, hydrogen bonding) to either the proteins or the polar head groups
