Cells Flashcards
Describe the structure and function of the bilipid membrane
- Amphipathic phosholipid bilayer
- impermeable to water soluble molecules
- protein molecules dissolved within bilayer mediate most other functions of cell membrane
What are the main functions of the plasma membrane?
- selective permeability
- transport of materials
- endocytosis and exocytosis
- intercellular recognition
- signal transduction
- intercellular adhesion
What is the glycocalyx? What is the function?
- Cell coat made up of polysaccharides and oligosaccharides
- Side chains give cell specificity
What is the function of the nucleolus?
Synthesising ribosomes
What is the function of the ribosomes?
Protein synthesis
What is the function of the nucleus?
- Storing cell DNA
- Co-ordinating cell activity
What is chromatin?
condensed form of cells DNA that organises to form chromosomes in mitosis
What is the nuclear envelope and what does it do?
- double layered membrane
- separates nucleus contents from rest of cellular cytoplasm
- attached to endoplasmic reticulum
What is the function of nuclear pores?
they allow specific types and sizes of molecules to pass
What is the function of lysosomes?
- they contain acid hydrolases at pH 5 that digest cellular material
- primary lysosomes bind with endocytosed material, membrane bound vesicles, autophagosomes or with excess secretory product to form secondary lysosomes
What is the function of mitochondria?
-ATP production
What is the lineage of mitochondria?
Maternal only
What is the function of the golgi apparatus?
Sorting, modifying, packaging and processing proteins
How does the golgi apparatus work?
- Vesicles bud off RER
- They bind to convex cis face of golgi body
- Vesicles leave trans face
What is the structure and function of peroxisomes?
Roughly spherical with granular matrix
They are the sites of oxygen utilisation and hydrogen peroxide production
RH2 + 02 –> R + H202
Which enzyme uses the hydrogen peroxide to oxidise other substances?
Catalase
What are microfilaments?
- 5nm diameter
- Two actin strings twisted together
- Contractile
- Can associate and disassociate
What are intermediate filaments?
- Not dynamic
- 10-12nm diameter
- common in neurological and nerve cells and epithelial cells
- made up of cytokeratin
- they form a tough supporting mesh in cytoplasm
- anchored to the membrane by desmosomes
What are microtubules?
- 13 alpha and beta subunits that originate from centrosomes
- attach to organelles via attachment of dynein and kinesin to move them
What is the function of the RER?
- Synthesis of lysosomal enzymes and proteins
- Site of glycosylation
What is the function smooth ER?
-Lipid synthesis and steroid genesis
Where is smooth ER found?
- Liver
- Mammary Gland
- Ovaries
- Testes
- Adrenal glands
What are the main differences between eukaryotic and prokaryotic cells?
Prokaryotic cells are found only in bacteria. They have a cell wall, no nucleus (only a plasmid), may have flagella
What is the difference between heterochromatin and euchromatin?
- Light-staining areas of the nucleus are called “euchromatin”. Abundant euchromatin denotes an active cell.
- Dark-staining areas of the nucleus are called “heterochromatin”. There is always a rim of heterochromatin under the real nuclear membrane. Abundant heterochromatin with only scanty euchromatin denotes an inactive cell.
