6. Cell structure and function Flashcards
What are the relative sizes of human egg, bacteria, plant cell, human cell, virus and which microscopes can be used to visualise these objects?
Name all prokaryote ogranelles
What are the eukaryote kingdoms?
Plants, animals, fungi
Name all organelles of a plant cell
Name the organelles of a fungi cell
Name organelles of an animal cell
Less rigidly structured than plant and fungi cells
Describe the strucuture of the nucleus
Pores for entering - exiting the nucleus (mRNA)
What is the site of the dogma of life?
Nucleus until mRNA then transported to cytoplasm for translation in ribosomes
Desribe the structure of a ribosome
Where can ribosomes be found in a cell?
Free ribosome - in cytosol
Bound ribosome - rER (most are bound)
What are the functions of the proteins translated by free and by bound ribosomes?
Desribe the Golgi body structure and function
Vesicles arrive at CIS side and exit Golgi through TRANS side - put into other vesicle and transported to other parts of the cell - PROTEIN SORTING
What are the possible pathways for secretion from Golgi out of the cell?
Consecutive - constant secretion
Regulated - only if a signal is received - secretion is regulated
Lysosomal - excrete lysozyme - enzymes secreted for outside digestion or inside a vesicle -> waste excreted
What are the main skeletal fibers inside a cell?
Tubulin - cell division + movement of organelles
Intermediate filaments - support of cytoskeleton
Microfilaments - dramatically changing the direction of the cell + connecting neighbouring cells + organelles move inside the cell (actin - muscle contraction)
Explain the movement mechanism of tubulin
Motorprotein attaches to the tubulin and the cargo (organelle / vesicle) - carries it along the tube
Motorproteins: kinesin (moves in the positive direction - away from the nucleus), dynein (moves in the negative direction - towards the nucleus)
Describe actin (microfilament)
In muscle cells makes up 20%
Describe mitochondria
Describe chloroplasts
Divide by binary fission
Explain cell junctions
Gap junctions - for chemical communication between cells, made up from 6 connexin proteins (very small molecules can pass)
Anchoring junctions - adherence junctions (cells linked by actin-actin filaments via cadherin or integrins) - desmosomes (cells linked keratin-keratin via cadherin) - hemidesmosomes (cytokskeleton of cells linked to extracellular matrix via integrins)
Tight junctions - allow movement of water and solutes to move between epithelial cells (outer cell line of organs) - tight epithelia (many tight junctions - where water transport must be regulated) - leaky epithelia (little or no tight junctions water and solutes can pass easily)
Explain the structure of connexin protein
What are cadherin and integrins?
Cadherin and inetrgin are adhesion receptors
Integrins mediate adhesion between the cell and its extracellular matrix (ECM)
Cadherins mediate homotypic adhesion between cells
