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BASIC TISSUES - PARTS OF CELLS (Ribosomes (Complexes of RNA and protein,…
BASIC TISSUES - PARTS OF CELLS
Nucleus
Membrane bound structure that contains hereditary information and controls cell's growth ( cell division) and reproduction
Genes without these chromosomes represent nuclear genome
DNA is in complex with proteins
Regulates gene expression
Consists of nuclear envelope, nucleoplasm, chromatin and nucleolus
Chromatin
Made of DNA and histone proteins
Heterochromatin - condensed "inactive" DNA
Euchromatin - active DNA, relatively extended form and condenses to form chromosomes during cell division
Nuclear envelope
Nuclear pores where 2 membranes fuse
Surrounds nucleus
Double layered membrane
Outer membrane continues with rough ER
Nucleolus
Nucleoli formed around specific genetic loci called nucleolar organizing regions (NORs)
Manufactures and assembles ribosomes = protein producing structures
Well developed in cells active in protein synthesis
Consists largely of RNA and protein
Nuclearmatrix
Network of fibres found inside the nucleus
Contains nuclear proteins, RNA, DNA and phospholipid
Cytoplasm
Material between cell and nuclear membrane
Provides structural framework and individual components for genetic info expressed in nucleus to be translated to cell function
Organelles and cytosol (highly organized in which protein fibres (cytoskeleton) are arranged in complex latticework surrounding the organelle) surround
Site where most cellular activities occur
Cytoskeleton
Highly organized "living gel"
Provides binding sites for protein and enzymes
3 distinct stuctures
Microfilament (thinnest)
Made up of action protein
Is attached to plasma membrane and defines surface morphology of cell
Exhibits polarity and promotes motility
Microtubules (thickest)
Made up of protein tubulin (hollow tubes)
Major role in movement of chromosomes during mitosis
Bound to other cytoskeletal elements and organelles
Intermediate filaments
More stable
Provides cells with mechanical strength
Vacuoles
Membrane bound sac
Functions
Storing water, food, enzymes, waste etc
Digestion
Waste removal
Mitochondria
Double membrane
Smoother outer and folded inner (cristae) for increase surface area
Produce energy
Involved in cell signalling, differentiation and growth
Exclusive maternal inheritance (animals)
Mutations leads to "mitochondrial diseases" often neurological
Ribosomes
Complexes of RNA and protein
Directly involved in protein synthesis
Transcription takes place in cell nucleus
mRNA leaves nucleus and travels to cells ribosomes where translation occurs
Consists of 2 subunits (composed of RNA and protein): small (30S) and larger (50S)
Stationary type: embedded in rough ER
Mobile type: injects proteins directly into cytoplasm
Endoplasmic reticulum
Network of tubules, vesicles and sacs that are interconnected
Smooth ER
Not associated with ribosomes
Involved in storage, action and transport of key enzymes and lipids
Structure allows increased surface area for action or storage of key enzymes and products of these enzymes
Rough ER
Fused to nuclear membrane
Has ribosomes constantly binding and releasing
Functions
Manufacture lysosomal enzymes, secreted proteins, protein glycosylation and folding
Golgi apparatus
Consists of flattened, curved saccules
Modifies proteins and lipids made in ER
Steps
Receives vesicles from ER on cis
Modifies them and repackages in vesicles
Releases from trans
Lysosomes
Contains hydrolytic enzymes
Used to destroy invading matter and unwanted cellular material
Can function to help repair damage to plasma membrane as membrane patch
Derived from Golgi network = primary lysosomes
Primary lysosomes + substance to be digested = secondary lysosome
Numerous in disease fighting cells
Cell/ Plasma Membrane
Interface between inside cell machinery and outside fluid
Selectively permeable lipid bilayer
Made up of primarily protein and lipids (phospholipid bilayer) hydrophobic tail and hydrophilic head
Functions
Structural support
Transport of molecules across membrane
Enzymatic control of chemical reactions
Receptors for hormones and other regulatory molecules that arrive at cell surface
Cell adhesion
Structures associated
Cilia
Tiny hairlike structures on surface of cells
Primary purpose - move fluid, mucous or cells
Respiratory system - defense (move mucous)
Female reproductive system - move egg
Microvilli
Tiny finger like projections of cell membrane
Areas where rapid diffusion ocuurs
Increased surface area
Found in kidney - reabsorption of molecules that are filtered out
Flagella
Whiplike strcuture
Propels sperm