3.4 - Cytoplasm Flashcards
What is the Cytosol?
- Liquid portion of the cytoplasm
What is the composition of the cytoplasm?
- 75-90% water
- Ions
- Glucose
- Amino acids
- Fatty acids
- Lipids
- Proteins
What are the three filaments that make up the cytoskeleton?
- Microfilaments (smallest)
- Intermediate filaments (middle)
- Microtubules (biggest)
What is the function of the cytoskeleton?
- Maintains shape of the cell (microfilaments)
- Organises cellular contents (Intermediate)
- Responsible for cell movements (Microtubules)
What is the structure of a centrosome?
- 9 clusters of 3 microtubules make up a centriole
- 2 centrioles per centrosome
- Pericentriolar material surrounds centrioles
What is the function of a centrosome?
- Organising centre for microtubules
- Forms the mitotic spindle
Describe Cilia and Flagella
- Motile cell surface projections
- Inner core of microtubules
- Cilia: small and hair-like
- Flagella: larger and tail-like
What are the functions of cilia and flagella?
- Cilia: Move fluids over a cell surface
- Flagella: Responsible for cell movement
Describe the structure of ribosomes
- Composed of two subunits (large and small)
- Contain rRNA and proteins
- subunits leave the nucleus separately and come together in the cytosol
What is the function of a ribosome?
- Protein synthesis during mRNA translation
Describe the structure of the RER
- Membranous network of folded membranes
- studded with ribosomes
- continuous with the nuclear envelope
- very extensive
Describe the structure of the SER
- Membranous network of folded membranes
- NOT studded with ribosomes
- continuous with the RER
- very extensive
What is the function of the RER?
- Site of synthesis of glycoproteins and phospholipids
What are the functions of the SER?
- Site of fatty acid and steroid synthesis
- Release glucose into the blood stream
- Metabolism of drugs and toxic substances
- storage of Ca2+ for muscle contraction (sarcoplasmic reticulum)
Describe the structure of the golgi apparatus
- Sac of 3-20 flattened membranous sacs
- Sacs are called cisterns
- More extensive in cells that secrete proteins
What are the functions of the golgi apparatus?
- Accepts proteins from RER
- Forms glycolipids and glycoproteins
- Store, packages and exports proteins
Describe the function of a lysosome
- Vesicle formed from the golgi
- contains digestive enzymes
What are the functions of lysosomes?
- Fuses to and digests contents of vesicles
- Autophagy: digests worn-out organelles
- Autolysis: digests whole cells
- Digests extracellular materials
Describe the structure of peroxisomes
- Vesicles containing oxidative enzymes
What is the function of peroxisomes?
- Detoxify harmful substances
- H2O2, free radicals
Describe the structure of proteasomes
- Barrel shaped structure
- contains protease enzymes
What is the function of proteosomes?
- Degrade proteins by cutting them into smaller peptides
Describe the structure of a mitochondrion
- Two membranes (inner and outer)
- Inner membrane is folded (cristae)
- Inner membrane is studded with enzymes
- Fluid filled cavity inside is called the mitochondrial matrix
- Ribosomes present inside the matrix
What is the function of a mitochondrion
- Powerhouse of the cell
- Production site for ATP
