Molecules Of Life Flashcards
What is the ECM
Complex network of secreted macromolecules in the extra cellular space
Functions of the ECM
3D framework for organisation of tissues
Structural and biochemical support for cells
Adhesive substrate
Structure
Provides growth factors to their receptors
Sequesters and stores growth factors
Senses and transducers mechanical signals
Regulates, proliferation, differentiation, cell-cell interaction, migration
What does too much ECM cause
Fibrosis
What structure does ECM form when outside the cell
Fibres mesh
How much of the body’s protein is collagen
25%
What structure is formed by the 3 polypeptide chains in collagen
Triple helix
What amino acids are in collagen
Glycine, proline, hydroxyproline
What are the 2 main types of collagen
Fibrillar
Non fibrillary
What structure does fibrillar collagen form
Organised banded fibrils
What structures do non fibrillar collagen form
Microfibrils
Mesh like structures
Purpose of fibrillar collagen
Tensile strength
Purpose of non fibrillar collagen
Anchorage of cells
Filtration
What causes osteogenesis imperfecta
Genetic defect in collagen type 1 synthesis - converts glycine to bulky aa preventing folding
Nucleus purpose
Contains genome
Main site for dna/rna synthesis
Composition of nuclear membrane
Lamin, emerin, and nuclear pores
Nucleolus purpose
Makes ribosomal subunits from RNA & protein
What is a laminopathy
Disease due to defects in genes coding nuclear lamina
What does Hutchinson-Gilford cause
Premature aging
RER purpose
Protein synthesis - translation of rna to proteins
Transport of proteins
Folding of proteins
SER purpose
Carbohydrate and lipid synthesis
Ca2+ store
Contain enzymes that detoxify drugs
Golgi apparatus purpose
Synthesis of hormones and enzymes
Packing of hormones and enzymes
Receives lipids and proteins from er and dispatches to different locations
Lysosomes purpose
Autolysis
Autophagy
Peroxisomes purpose
Metabolism of fatty acids
Detoxification
What is autolysis
Degrading of whole cell after death
What is autophagy
Degrading of cellular organelles
Where are peroxisomes most often found
Liver and kidney
Where do lysosomes originate
Golgi
Mitochondria purpose
Generate ATP
control apoptosis
Components of cytoskeleton
Actin microfilaments
Intermediate filaments
Microtubules
Actin microfilament purpose
Cell movement
Cell shape
Organelle and vesicle transport
Intermediate filaments purpose
Tensile strength
Microtubule purpose
Pull apart cell in mitosis
Track movement of organelles and vesicles
Connective tissue purpose
Connects
Supports
Binds
Separates tissues/organs
What is the ECM
Material outside the cell
What syntheses the ECM
Connective tissue cells
ECM purpose
Scaffolding Cell migration Proliferation Survival Shape
2 main classes of macromolecules in the ECM
Glycosaminoglycans
Fibrous proteins
What is a glycosaminoglycan
Linear chain of 20-100s disaccharides usually linked to a protein to form a proteoglycan
What is produced when GAGs bind with water
Hydrated gels that fill space between cells and resist compressive forces
What do GAGs allow rapid diffusion of
Nutrients
Metabolites
Hormones
Collagen purpose
Tensile strength
Components of elastin
Tropoelastin
Fibrillin
Fibronectin purpose
Binds cells and ECM Matrix organisation Guiding cell migration Development Wound healing
Which tissues is the basement membrane found between
Epithelial
Connective
3 layers of basement membrane
Lamina Lucida
Lamina densa
Lamina fibroreticularis
Basement membrane purpose
Support Anchoring Protection Cell movement Cell signalling
Purpose of tight epithelial junctions
Prevent passage of molecules across epithelium
Purpose of adherens epithelial junction
Tether adjacent cells together
Purpose of desmosomal epithelial junctions
Resist mechanical stress
Purpose of gap junctions
Allow passage of small molecules between cells
Purpose of hernidesmosome epithelial junctions
Anchor epithelium to basal lamina
What are cilia
Motile structures
Project from apical surface of some epithelia
What is the central core of a cilia called
Axoneme
Types of cilia
Pseudopodia
Lamellipodia
Filipodia
Pseudopodia purpose
Temporary projection
Allow crawling
Lamellipodia purpose
Cell migration for wound healing - eg migration of fibroblasts
Filipodia purpose
Sense surrounding environment
Direct fibroblasts in wound healing
Macromolecules in ECM
Collagen
Elastin
Glycoproteins
Proteoglycans
What’s is the ECM
3d gelatinous bed for cells to live in
How many families of collagen are there
19
How much of the total protein mass in the body is collagen
25%
Structure of collagen
Triple helix of 3 peptide chains
Amino acid code of collagen
Glycine-X-Y
Fibril forming collagen types
1 2
Network forming collagen types
4 6
Osteogenesis imperfetta cause
Defect in collagen type 1
Single base change - glycine converted to more bulky acid
Osteogenesis imperfetta effects
Fragile bones Thin skin Abnormal teeth Weak tendons Blue looking sclera
Elastin purpose
Gives flexibility for blood vessels, lungs, ligaments, skin
Which contains more valine - collagen or elastin
Elastin
2 Abundant amino acids in elastin and collagen
Glycine
Proline
Marfan syndrome cause
Fibrillin misfolded causing changes to ECM properties
What covers elastin fibres
Fibrillin
Gives stability
Marfan syndrome symptoms
Tall stature Long arms and legs Spider fingers Loose joints Eye problems
Glycoproteins purpose
Cell surface receptors
Strengthens, supports, and distributes ECM
Fibronectin purposes
Cell adhesion
Migration
Shape
Differentiation
Laminin purpose
Cell adhesion
Cell migration
Cytoskeleton organisation