Fundamental features of eukaryotic cells Flashcards
What are the fundamental features of a eukaryotic cell that you don’t see in prokaryotic cells?
Membranes provide compartments for processes inside the cell
What is the main method of reproduction in Prokaryotes?
Binary fission, mostly asexual
What is the main method of reproduction in Eukaryotes?
Mitosis or meiosis, mostly sexual
What function does compartmentation in the cell serve?
Differences in pH across the membrane inside the cell
Metabolic regulations by keeping enzymes/substrate separate
Isolate toxic substances
What affect does SA:V ration have on a cell?
limits the rate of exchange
Why are cells small?
Need to be able to communicate with the environment, and quick communication within the cell.
What is a coenocyte?
Large cell with multiple nuclei and chloroplast.
What are the main components of the Plasma membrane?
bilayer of phospholipids, with various proteins embedded
What makes up a phospholipid?
hydrophilic phosphate head, glycerol molecule and hydrophobic two fatty acid tails.
What is an amphiphatic molecule?
Has both hydrophilic and hydrophobic parts (polar and non polar)
What is contained within the nucleus?
Most of the genes contained within a eukaryotic cell
Describe the membrane around the nucleus
Is an envelope, perpetuated by pore structures which are lined by protein complexes that regulate entry and exit of materials.
How is DNA organised in the nucleus?
In chromosomes, which are made of chromatin.
How many chromosomes does a human have?
46
What processes take place within the nucleus?
Synthesis of mRNA with the instructions provided by the DNA.
What does the Endoplasmic Reticulum consist of?
network of membranes and tubules called cisternae, connected to the nuclear envelope
What is the role of the SER?
varies within cell type, lots of metabolic processes, e.g.. synthesis of lipids, modification of carbs and detoxification of drugs and poisons
What is different about the RER and SER?
RER has bound ribosomes
How do proteins leave the ER?
In vesicles
What is the name for vesicles in transit?
Transport vesicles
What are the roles of the ER?
protein processing, phospholipid production and membrane production
How is the RER a membrane making factory?
It grows in place by adding membrane proteins and phospholipids to its own membrane.
What is the role of the Golgi apparatus?
centre of manufacturing, modification, sorting and shipping
What is the structure of the golgi apparatus?
flattened membrane sacs, cisternae, all staked up.
What are the cis and trans ends of the Golgi apparatus?
They are the poles, vesicles carrying unprocessed molecules fuse to the cis and, and the trans face gives rise to new vesicles leaving the golgi
What macromolecules does the golgi process?
secretes polysaccharides
What is the cisternae maturation model?
movement of cis to trans face
How are vesicles identified by the cell?
Molecular identification tags, e.g. phosphate groups.
What is the cytoskeleton?
a network of fibres that organise structures and activities inside the cell
What is the role of the cytoskeleton?
Gives support and maintains cell shape
Involved in cell motility
Regulation og biochemical activities inside the cell
How doe the cytoskeleton provide support in the cell?
Stabilised by balance between pressing forces executed by its elements, provides anchorage for organelles
why is the cytoskeleton important in animals?
No cell wall for support
How is the cytoskeleton different to the animal skeleton?
More dynamic, can be quickly dismantled and reassembled.
How is the cytoskeleton involved in cell motility?
Interaction of the cell with motor proteins.
How do motor proteins promote movement of vesicles along cytoskeleton?
Attach to receptors on the and can walk them along the microtubule/filaments, pathways called monorails.
How to motor proteins make filaments move?
Gripping organelles with microtubules and can slide them against one another
Describe the structure of microtubules
Hollow roads made from globular protein tubulin. Each protein is dimer
What does it mean if a protein is a dimer?
made of two subunits
What are the two subunits in the globular protein tubular?
alpha tubulin and beta tubulin
What is the role of microtubules
maintain cell shape, cell motility, chromosome movement, organelle movement
What is the role of the centrosome?
an organelle that serves as the main microtubule organizing center of the animal cell
pulling chromatids apart in cell division
Where is the centrosome often located?
near the nucleus
How are microtubules arranged within the centromere?
There is a pair of centrioles, each composed of nine sets of microtubules arranged in a ring.
What happens to the centriole before division?
replicates
What is kinesin?
a motor proteins found in eukaryotic cells. Kinesins move along microtubule filaments, generally from the centre of a cell to the periphery
What is dyein?
A motor protein. Dyneins are important in sliding microtubules relative to one other during the beating of cilia and flagella
What are ATPases?
class of enzyme that hydrolyse ATP to ADP to drive a chemical reaction