1. Cell Structure Flashcards
What is the difference between heterochromatin and euchromatin?
Heterochromatin is in a solenoid structure, tightly packaged. It is NOT expressed. It has a dark appearance when stained.
Euchromatin is in the beads on a string structure. It IS expressed. It appears pale/white when stained.
How do prokaryotic cells differ from eukaryotic cells?
- They have no separate nucleus
- Bacteria contain a cell wall and a plasma membrane
- Bacteria lack most organelles
- Structures such as pili or flagella may be present on bacteria
NO internal membranes. All of the biochemical processes of the cell occur in the same compartment.
What is the structure and properties of phospholipids?
A polar, hyodrophoilic phosphate head bound to a non-polar, hydrophilic fatty acid tail.
They are amphipathic!
Create barrier impermeable to most water-soluble molecules.
What is the name for the ‘cell coat’ and what is it made up of?
Glycocalyx.
It is made up of oligosaccharide and polysaccharide side chains on the outside of the plasma membrane.
What does the fluid mosaic model refer to?
The structure of the phospholipid bilayer, with transmembrane proteins embedded.
What are the functions of the plasma membrane/plasmolemma?
- Selective permeability
- Transport of materials along cell surface
- Endocytosis and Exocytosis
- Intercellular adhesion (junctions)
- Intercellular recognition
- Signal transduction
What is the function of the SER and where is it abundant?
Lipid biosynthesis and steroidogenesis.
Adrenal gland, testis, ovary, liver and mammary gland
What is the function of the Golgi apparatus ?
Modify, sort, concentrate and package proteins synthesised on the RER.
Where are lysosomes synthesised and what do they contain? How does this relate to their function?
Lysosomes are generated by the Golgi apparatus and contain many hydrolysis enzymes, such as nucleases, proteases, glycosidases and lipases.
They are highly acidic - pH 5
They play an important role in the destruction of cell waste.
What is the function of peroxisomes?
Peroxisomes detoxify molecules such as fatty acids by oxidation, leading to the production of hydrogen peroxide. They contain catalase enzymes.
They are abundant in cells that detoxify substances, e.g Liver! Detoxify alcohols.
What is the difference between properties of the outer membrane and the inner membrane of the mitochondria?
The inner membrane contains the enzymes for the oxidation reactions of respiration. It is impermeable to small ions.
The outer membrane is permeable by all molecules < 5000Da.
What is a unique feature of mitochondria?
They contain their own genetic information and can divide. This is inherited maternally.
They also possess mitochondrial ribosomes
What are the components of the cytoskeleton?
Microfilaments - actin filaments, 5-9 nm diameter
Network of actin filaments underlying cell membrane.
Intermediate filaments - diameter 10nm
Form tough supporting network
Many proteins - e.g keratin
Common in epithelial cells
Microtubules - long, hollow cylinders made of tubulin protein. Found at sites where structures are moved (e.g mitotic spindles, nerve cells, flagella )
Diameter 25nm
What is the function of the Nucleolus?
Makes ribosomal subunits from ribosomal RNA
What is the limit of resolution?
The minimum distance at which 2 objects can be distinguished.
The resolution improves as the wavelength decreases.
