cells, organelles, stem cells Flashcards
What are the roles of the cell membrane?
- regulate transport of solutes
- mediate cell to cell communication
What are the roles of mitochondria?
- site of ATP generation
- clustered in cells that have high energy
Describe the structure of mitochondria?
- permeable outer membrane
- less preamble inner membrane, folded into cristae
- inside is the matrix
What is the role of the golgi apparatus?
modify, package, sort, proteins and lipids
What are lysosomes and their role?
- small irregular cytoplasmic vesicles
- packed with degradation enzymes
- principal sites of intracellular digestion
What is the main function of peroxisomes?
- oxidation reactions for the breakdown of fatty acids
- detoxify toxic substances such as ethanol (via catalase)
What are peroxisomes?
- small cytoplasmic vesicles
- contained environment for reactive H202 generation
What is the main function of cytosol?
- contains meany metabolic pathways
- protein synthesis
What is the main function of the nucleus?
- contains main genome
- DNA and RNA synthesis (nucleolus)
What are the main functions of the endoplasmic reticulum?
- synthesis of most lipids
- synthesis of proteins for distribution to many organelles and to the plasma membrane
What is the main function of endosomes?
sorting of endocytosed material
What are the functions of the cytoskeleton?
- pulls chromosomes apart during mitosis
- guides the intracellular traffic of organelles, proteins and RNA
- supports plasma membrane
- enables some cells to move
What are the 3 major components of the cytoskeleton?
- intermediate filaments
- microtubules
- actin filaments
Describe the intermediate filaments in the cytoskeleton
- twisted into ropes and provide tensile strength
- needed to maintain cell shape
Identify the fibrous proteins used in the intermediate filaments in various cells
- KERATIN: epithelial cells
- VIMENTIN: many other cells
- NEUROFILAMENT: neurones
- IAMINS: nucleus
Describe the microtubules in the cytoskeleton
- polymers of tubulin dimers
- form the spindle fibre in mitosis
- important in cell shape and movement
What are haemopoietic stem cells?
stem cells that can differentiate into all type of blood cells
What are the advantages of Induced pluripotent stem cells (IPS)?
- cells taken from patient should not elicit immune response
- fewer ethical issues
- any cell type could be replaced (theoretically)
What are the disadvantages of IPS?
- more basic research needs to be done on developmental pathways
- transplanted stem cells could develop into cancer cells
What are the two ways a cell can die?
- apoptosis
- necrosis
What is apoptosis?
- programmed cell death
- normal pathway for cell death
- triggered as signalling processes within the cell activate intracellular suicide proteases
How do intracellular suicide proteases carry out apoptosis?
- degrade intracellular structures and organelles
- collapse the cytoskeleton
- fragment the cell into mini-cells, which are then engulfed by phagocytes
Why is apoptosis the normal pathway for cell death?
the apoptosic cell dies neatly without damaging its neighbours
What is necrosis?
where cells simply lyse and burst
How is necrosis carried out?
- cell membrane integrity is destroyed
- cell soluble contents are released into the tissue fluids
- cell components are degraded by the action of extracellular enzymes
- phagocytic cells enfold fragment remains
What kind of stem cells do adults have?
multipotent
