Structure of cell
Cell is elementary structural, functional and genetic unit, which make up basis of life activity and development the living organisms.
Organelles are life-important parts of cell. It constant be present in cell and fulfil fixed functions.
Cell structure of animals and plants is similar. In cell body discern: cytoplasm (greek – cytos – cell, plasma – formation) and karyoplasm (greek – karyon – nucleus).
Cell consist of: 1) superficial apparatus; 2) cytoplasm; 3) nucleus.
Superficial apparatus contains of:
membrane, which consist of 2 layers of lipids. Molecule of protein are included in this layers.
Overmembrane complex – Glycokalyx – fuzzy coat found outside the plasma membrane of animal cells, made of sticky oligosaccharides covalently bonded to proteins and lipids of the plasma membrane.
Cytoskeleton: microtubules, microfilaments (microfibrilles) are gives mechanical support to the cell, helps maintain its shape and for movement.
Cytoplasm contains of:
Hyaloplasm, it’s a colloidal solution with enzymes system.
Organelles of general significance:
Endoplasmic Reticulum (ER): smooth and uneven; ER – extensive membranous network of tubules and sacs (cisternae) which sequesters its internal lumen (cisternal space) from the cytosol.
Golgi apparatus = organelle made of stacked, flattened membranous sacs (cisternae), that modifies, stores and routes products of endoplasmic reticulum.
Mitochondria = are the sites of cellular respiration, a catabolic oxygen-requiring process that uses energy extracted from organic macromolecules to produce ATP.
Ribosomes = a cytoplasmic organelle which functions in protein synthesis.
Lysosomes: primary and secondary = an organelle which is a membrane-enclosed bag of hydrolytic enzymes that digest macromolecules.
Plastids = a group of plant and algal membrane-bound organelles that include :
1) chloroplasts (chloro = green) - chlorophyll-containing plastids are sites of photosynthesis.
2)chromoplasts (chromo = color) – pigment-containing plastids which responsible for the color of fruits, flowers and autumn leaves.
3) amyloplasts (amylo = starch) – colorless plastids that store starch; found in roots and tubers.
3) Organelles of special significance:
a) flagella b) cilia c) myofibrilles d) neurofibrilles
Inclusion - non-constant components of cell
Reserve b) secretional c) specific
Nucleus is a membrane-bound cellular organelle in a eukaryote; contains most of the genes that control the entire cell.
nuclear envelope 2) nucleolus 3) nucleoplasm 4) chromatin structures