Cells and Organelles Flashcards
List the fundamental properties of cells
Cytosol, semi-permeable membrane, golgi, RER, SER, Nuclear Envelope, centrosome, lysosome, cytoplasm, ribosomes, mitochondria
State the approximate size of cells and understand the scale of cells and their components
cells are 0.01 milimeters and components are 0.1 micrometers
descibe the basic features of a eukaryote cell
Eukaryotes are more complex cells with internal compartments, contain organelles and are much bigger
Describe the basic features of a prokaryote cell
Some cells only have enclosing membranes, providing structure to the cell, these are the simplest and smallest known as prokaryotes and are mostly bacteria. They have no internal membranes and do not have a nucleus
Where is DNA packaged in these types of cells
Prokaryotes – in these types of cells DNA is packaged but not enclosed by a membrane.
Eukaryotes – in these types of cells the DNA is packaged AND enclosed by a double membrane (known as the nuclear envelope)
List some diseases caused due to errors in cells
- Hypercholesterolemia (defective uptake of lipoproteins)
- Cystic fibrosis (misfolding of key protein)
- Hypertension (defective cell-cell adhesion in the kidney)
- Congenital heart defects (errors in cell migration during development)
- Muscular dystrophy (defective attachment of the plasma membrane to the cytoskeleton) • Lysosomal storage disease (defective intracellular transport of enzymes)
- Food-borne illness (Salmonella, E. coli)
- Cancer (errors in cell division, migration, cell polarity, growth, etc)
- Ageing
What are the four basic tissue types??
- Epithelia
- Connective tissue
- Muscle
- Nervous tissue
How do static cells attach to each other
These static cells can attach to each other via certain junctions, however these interactions are normally not permenant and can be broken down and reformed.
Roles of mitochondria
- Produce most of the ATP supply to cells
- Allow cells to grow bigger
- They are present in ALL eukaryotic cells
- They are composed of two membranes – the inner membrane folded into interior
- They contain their own DNA – they reproduce by dividing in two (SEPARATE FROM DNA IN NUCLEUS) however not enough to produce all the proteins needed in the mitochondria
- All mitochondria are from the mother
- Mostly made by the nucleus
Formation of a vesicle:
highly regulated process which takes a lot of energy, there is a whole series of proteins involved. The key one is clathrin which forms a type of scaffold coat regulator which aids the formation of the vesicle by forming the membrane around it.
What are the two steps in cell evolution
- Compartmentalization
- Mitochondria
Whats the name for cells dying due to infection or attack on the body
necrosis (abnormal process sends out signals if cell dies abnormally to alert the immune system)
What are the three components of the cytoskeleton?
Microtubules:
Microfilaments:
Intermediate filaments:
Microtubules:
A thickness of 25nm, they are vesicle tracks, they position and move organelles (cell division), they are composed of dynamic subunits known as tubulins. Don’t always make it right to the end of the cell.
Microfilaments:
A thickness of 7nm, they generate contractile forces enabling cells to move, parts of cells to move and for cells to contract. They are also composed of subunits of actin and myosin (motility). Very extensive and stretch right to the edge of the cell.
Intermediate filaments:
A thickness of 10nm, provide strength and support, some are positioned in the cytoplasm (keratins) and some support the nuclear envelope (lamins)
What is the process where by cells take things in
ENDO(IN)CYTOSIS (TO CELL)
Describe the basic structure and function of organelles involved in Uptake and Degredation
Endosome to the lysosome the pH continues to decrease making a very acidic environment.
Uptake is performed by endocytosis (large particles are via phagocytosis = can be vastly enhanced - and molecules by pinocytosis = non-specific).
The membrane/cargo which is internalised is delivered to endosomes and then passed to lysosomes (which have a low pH and contain hydrolytic enzymes) for degradation. Some membrane is recycled back to the cell surface.
Portions of the cell itself can be walled off and digested in lysosomes (this is known as autophagy = self-eating) An internal membrane is formed and it seals itself off then is transported to the lysosome to be degraded.
Secretion pathway:
Protein synthesised in ER is carried to Golgi in vesicles. The Golgi modifies the protein by sorting/packing it, then a new vesicle containing the packaged secretion buds of trans-Golgi, travels along microtubule tracks where it is dispersed at the membrane by exocytosis when stimulated to do so.
What does protein synthesis enable?
Growth and differentiation
What are the two stages of protein synthesis
Transcription and translation
Protein synthesis
The dna with its genes are packaged in the central store called a nucleus
This is enclosed by a double membrane the nuclear envelope (the nucleus is one of a number of cell compartments)
mRNA passes from the nucleoplasm to the cytoplasm via holes called nuclear pores
mRNA is decoded and proteins made on specialised factories known as ribosomes.
What are nuclear pores?
Nuclear pores are selective aqueous channels for transport between nucleus and cytosol (mRNA passage but also proteins in both directions).
What is the role of ribosomes?
these decode mRNA messages and convert them into linear polypeptides (also known as proteins). However, many ribosomes will remain free during translation
RER Ribosomes
All protein synthesis starts in the cytosol, the first stretches of any protein destined for ER/Golgi processing are recognised and ribosome becomes bound to ER to generate ER coated ribosomes – rough ER (RER)(endoplasmic reticulum)(This is makes membrane and is widely spread through most cells)
What are the two choices for protein synthesis
In free ribosomes in the cytosol
or they can choose to go to the rough endoplasmic reticulum when the protein must go into this compartment. You can tether ribosomes to the RER and that allows the proteins to be pushed into the membrane.
