HISTO LEC: Module 1 - PART II

DO NOT EXPLOIT.

Endoplasmic Reticulum

It is involved in protein transport and maturation.

Smooth ER

It has no ribosomal granules (agranular); serves as the lipid synthesis, steroid formation, and detoxification of drugs and alcohol.

Rough ER

It has ribosomes attached (granular); mostly found in pancreatic cells, formation of digestive enzymes, fibroblasts, collagen synthesis and plasma cells.

Golgi complex

• It is the site of accumulation, concentration, packaging of secretory product of the cell; known as dictyosome.

• Processes and packages macromolecules such as proteins and lipids after their synthesis

Fibrils

It is found in nearly all types of connective tissues for cell rigidity, tensile strength, and cell movement.

Microtubules

• It serves as a cytoskeleton to maintain cell shape and formidability; major component of flagella and cilia.

• Forms mitotic spindle in mitosis; diffusion channels for water and metabolites.

Peroxisome

Contains enzyme catalase that is responsible for breakdown of hydrogen peroxide → water and oxygen; it is referred to as microbodies.

Vacuoles

Storage cavities which expels waste and water from cell pigment; also known as vesicles.

Lipid

The storage site for triglycerides and hormone precursors; known as fat droplet.

Glycogen

Storage of glucose; the energy source of organisms upon its conversion to glucose and with granules.

Pigment Granule

These are pigmented deposits of naturally colored material which includes melanin, lipofuscin, hemosiderin, and hemoglobin.

Exogenous

Pigment granule formed outside the body.

Endogenous

Pigment granule formed within the body.

Melanin

Dark brown/black granules found in the skin and it protects from UV radiation.

Lipofuscin

These are pale-brown granules found in non-dividing cells. It is also known as the “wear & tear pigment” or H pigment.

Hemosiderin

These are golden-brown, iron containing pigment from breakdown product of hemoglobin.

Hemoglobin

Breakdown products such as hemosiderin and bilirubin.

Secretory/Zymogen Granules

• These are precursors of digestive enzymes such as pepsin, amylase and trypsin.

• Abundant in pancreatic cells

• Chief cells of stomach and salivary glands (rich in mucoproteins)

Mucigen droplets

It is rich in mucoproteins and it is the precursor of mucin which forms upon hydration (lubricant).

Nucleus

• It contains DNA material for directing protein synthesis and the genetic makeup.

• Shape varies but it is usually spherical or ovoid.

• Mostly found in all cells except in mature erythrocytes (RBC) and platelets.

Binucleated and multinucleated

Nucleus is usually single but it is _______ in hepatic cells, and ________ in skeletal cells and osteoclasts.

Nuclear membrane

It facilitates exchange of materials between cytoplasm and nucleoplasm. It is also the skin around the nucleus.

Nucleoplasm (Karyoplasm)

It is a semi-fluid solution of the nucleus where chromatin and nucleolus are suspended.

Nuclear chromatin or chromatin granules

It carries the genes or hereditary.

Nucleolus

It is the site of RNA synthesis.

G1 phase

It is the growth of new daughter cells with active synthesis of RNA and protein, but not DNA. It takes about 10 hours of period.

S phase

It is the active DNA and histone synthesis. There is also a probable replication of 2 centrioles and it is about 9 hours of period.

G2 phase

It is the time between DNA synthesis and resumption of mitosis. It is about 4 hours of period.

Mitotic phase

It refers to active cell division; involves cytokinesis (division of cytoplasm) and karyokinesis (division of nucleus).

Cell division

It occurs in all adult cells except the cells in the Central Nervous System (CNS).

Mitosis

• Occurs in somatic cells; parent cell divides to form 2 new cells identical with one another and to the parent cell.

• Involves 1 cell division.

Meiosis

• Found in gametes or sex cells; parent cell divides to form new cells not identical with one another and to the parent cell, and also necessary for sexual reproduction.

• Involves 2 cell division.

Interphase

The cell is in a resting state and it is also the preparation of cell division, chromosomes duplicate from 23 pairs to 46 pairs.

Prophase

• The stage where each chromosome separates longitudinally in half (chromatid) and each half attaches in a centromere.

• Formation of spindle fibers between separating centrioles.

• Nuclear envelop and nucleolus starts to disappear.

Metaphase

Chromosomes align along the equatorial plate and the chromosome starts to pass between the spindle fibers.

Anaphase

• Chromosome splits in half; cell elongation: spindle fibers pull chromatids to opposite poles.

• Constriction starts to form (cleavage furrow).

Telophase

• Chromosomes detach from chromosomal microtubules at each pole of cell; microtubules disintegrates.

• Chromosomes start to elongate or disperse.

• Nucleoli reappears and the nuclear envelope reforms.