Topic 14: Cell diversity Flashcards
Describe the theories on cell evolution
- Ancient prokaryotic cell: has DNA floating near plasma membrane and membrane-bound ribosomes
- Ancient eukaryotic cell:
+ the plasma membrane of prokaryotic cell move inwards, stick and bring ribosomes inwards
+ the plasmas membrane wraps around the DNA, then form:
i) inner and outer membrane with nuclear pores around the nucleus
ii) endoplasmic reticulum (in conjuction with the nuclear membrane)
+ no ability to utilize all the energy obtained from organic matter/food - Anaerobic pre-eukaryotic cell (ancient eukaryotic cell):
+ engulf and develop endosymbiosis with aerobic prokaryotic cell (have enzymes to break down pyruvic acid)
+ form membrane around the new organelle
+ mitochondria develop and replicate inside the cell
–> early aerobic eukaryotic cell
Distinguish between prokaryotic and eukaryotic cells; bacteria and archea
- Prokaryotes:
+ No membrane-bound nucleus
+ No membrane-bound organelles (like mitochondria, lysosomes, etc.)
+ Not all DNA is in chromosomes, some is in plasmid - rings of DNA
+ Bacteria: have sugar and amino acid lattice as cell wall, act as protection
+ Archea: NO sugar and amino acid cell wall; live in extreme conditions - Eukaryotes:
+ Membrane-bound nucleus
+ Membrane-bound organelles
+ No cell wall
Describe the composition and function of phospholipid bilayer of cell membrane
- Cell membrane is made out of mainly phospholipids with
+ hydrophilic heads (with CH2 structure like triglycerides and phosphate group with (-) charge –> hydrophilic)
+ hydrophobic tails
–> the tails cluster together and stay away from the water environment outside and inside of the cell - Phospholipid bilayer is quite fragile –> have integrated molecules to maintain structure, including
+ integral proteins (only interact with either outside or inside of cell)
+ transmembrane proteins (interact with both outside and inside of cell)
+ glycoprotein (usually attached to the proteins)
+ carbohydrates
+ cholesterols - Many integral proteins, mostly transmembrane, interact with cytoskeleton to reinforce the strength of membrane
–> able to withstand stress, friction, etc. - Function of membrane and integral molecules:
+ Receive information/signals (receptors)
+ Allow import/export of molecules (carrier proteins, channels, transporters, etc.)
+ Shape, size and movement (the integrale molecules interact with fibre tissues/cytoskeleton –> movement and expansion)
Explain the importance of cholesterols in cell membrane
- Cholesterols stabilize cell membrane
+ the carboxyl is attracted to the phosphate group of phospholipid molecule
+ the steroid part helps stiffen parts of the hyrdrophobic tails
–> give the mebrane the viscosity
Identify key differences between animal and plant cell
Chloroplast
Big central vacuole
Cell wall
Describe the composition of plant cell wall
- Made up of cellulose - long chains of sugars/carbohydrates
+ aka fibre - good for guts - Gives plant cell defined structure
Which structure on the nucler membrane allow the proteins to move in and out of the nucleus?
The nuclear membrane has nuclear pores - allowing proteins like transcription factors to move.
Explain the roles of compartmentalisation in cellular function or
How does the formation of internal membrane/membrane-bound organelles affect cell’s function?
Internal membrane allows formtion of intracellular components –> able to perform specialized function without interupting others
What is the role of fibre tissues?
- Like train tracks for vesicles to transport molecules
- Interact with integral proteins in membrane to maintain cell strcture and allow movement
