Differentiated Cell Flashcards
How should one interpret a heterochromatic nucleus?
That only a short portion of the genome is being utilized, but know that the cell may still be very active in utilizing this portion.
What is the structure of the nucleoli?
1+ fibriller centers
A euchromatic granular component.
A heterochromatic dense fibrillation component.
What is the nucelolar organizing region?
One or more nucleolar organizing regions compose the fibrillation center, and the NORs exist on the ends of acrocentric chromosomes. Each NOR is mainly tandem retreats of genes encoding pre-rRNA.
What can be discerned from a cell with a large nucleolus, or several nucleoli?
It is a cell actively engaged in protein synthesis, as many ribosomal subunits must be created within the nucleolus.
What are the main functions of the sER?
Steroid synthesis
Breakdown of lipid soluble toxins and drugs.
Calcium sequestration.
What structures exist within steroid secreting cells?
Extensive sER
Lipid droplets
Mitochondria with tubular rather than flat cisternae.
Describe the role of the sarcoplasmic reticulum.
Calcium is required for action of actin and myosin during muscle contraction, so SR sequesters calcium so this does not occur constantly. Stimulation via a nerve causes release and function.
What are the three major sources of acidophilia within a cell?
Lysosomes
Mitochondria
Secretory vacuoles.
All due to high protein content.
What does a cell with a large golgi suggest?
Large amounts of secretory proteins are being produced.
Many lysosomes are being produced, and the cell is phagocytic (note for macrophages lysosomes are produced throughout cell life, for neutrophils all lysosomes are produced in development so extensive golgi in mature neutrophil is not needed).
What are forms in which glycogen will be found in a cell?
Smaller beta particles, or aggregated large alpha particles.
Where is glycogen often located within the liver?
Near the sER, as G6-phosphatase is on the sER membrane.
