Cells and Organelles Flashcards
What is a cell?
A semi-independent living unit used for metabolism, growth and replication
What is an organelle?
Subunits within cells that perform special activities
What are tissues?
An assembly of cells that carry out similar activities
What are organs?
Assemblies of tissues that perform specific functions
What are organ systems?
Assemblies of organs with specific related activites
What are Prokaryotes?
Single celled organisms with circular DNA and no membranous organelles
What are Eukaryotes?
Multicellular organelles with linear DNA chromosomes enclosed in a nucleus with membrane bound organelles
What are Viruses?
An assembly of nucleic acid proteins. They invade cells and use their machinery. They are not considered cells as they have no plasma membrane or metabolism
Prokaryotes regarding Chromosomes, Chromosome location, Histones, Nucleolus, Extrachromosomal DNA, Ribosomes and Cell Division?
Single circular, nuclear region, absent, absent, in plasmids, 70s and binary fission
Eukaryotes regarding Chromosomes, Chromosome location, Histones, Nucleolus, Extrachromosomal DNA, Ribosomes and Cell Division?
Paired linear, membrane bound nucleus, present, present, in mitochondria and plasmids, 80s cytoplasmic/70s mitochondrial, mitosis or meiosis
Structures present in Prokaryotes?
Cell wall (Internal membrane present in photosynthetic organisms only)
Structures present in Eukaryotes?
Mitotic spindle, sterols in plasma membrane, internal membrane, ER, mitochondria, lysosomes, Golgi, peroxisomes and cytoskeleton
What are the two electron microscopes?
TEM and SEM
The 3 reasons to why the maximum size of a cell is limited?
1) After 50um, diffusion efficiency reduced
2) SA:V ratio as greater size means volume increasing more than SA
3) Distance from nucleus to the periphery
The 3 ways cells can overcome limitations of cell diffusion?
1) Thin processes for direct transport
2) Giant multinucleate cells
3) Gap junctions
Why are membranes important?
Membranes allow specialised environments to exist with different functions and different conditions
What does the cytoskeleton contribute to?
Mechanical strength, Shape control and to Guide movement
The Nucleus
Largest organelle
Visible with a light microscope
Contains packed genetic material
Contains DNA in chromosomes
The Smooth ER
Biosynthesises membrane lipids and sterols
Involved in n-linked glycosylation and detoxification of Xenobiotics
The Rough ER
Coated in ribosomes
Allows proteins for insertion and secretion to cell membrane
Proteins folded forming Cys-Cys bridges
Vesicles bud to the golgi
The Golgi
Consist of 4-8 close stacked cisterna Modifies proteins Synthesises materials Can direct new proteins in vesicles Creates lysosomes
The Peroxisome
Not very electron dense
involved in detoxification
enzymes which generate and degrade H2O2
The Lysosomes
Electron dense spheres
Contain hydrolytic enzymes
Require low pH
Involved in organelle turnover
The Mitochondria
Two layers
Inner membrane forms cristae to increase surface area
Contains DNA
Generates ATP via the krebs cycle
