Cell biology 2 Flashcards
What is connective tissue? What does it consist of?
Tissues that lies between two other tissues. Consist of extracellular matrix and cells
What are the different categories of connective tissue? Give examples for each category
Loose connective tissue: Serous membrane Adipose Blood Dense connective tissue: Dermis of the skin Bone and cartilage
Which cells can be found in connective tissue? Where are they synthesised?
•Fibroblast • Adipocytes-fat • Chondrocytes-Cartilage • Osteocytes-Bone • Haemopoietic (blood) cells Synthesised in extra cellular matrix
What is categorised as the Extracellular Matrix? What is the Extracellular Matrix’s function?
Material outside the cell is the ECM The ECM determines a tissues physical properties It is also involved in cell migration, shape, proliferation and survival
What are the two main types of macromolecules found in the ECM?
- Polysaccharide chains called glycosaminoglycans, (GAGs), usually linked to a protein - proteoglycans (gel in which cells and fibrous proteins are embedded ) 2. Fibrous proteins – collagen, elastin, fibronectin (structure, strength, flexibility, adhesion, cell positioning)
Where are proteoglycans produced? How do they enter the ECM?
Production- ER and Golgi Delivery-constitutive secretion
How are proteoglycan gels produced?
When proteoglycans combine with water
Name 2 main functions of GAG & proteoglycan gels
- Resist compression 2. Permit rapid diffusion of nutrients, hormones and metabolites
List the 4 main groups of GAG’ s and describe what each group does
- Heparin sufate- cell adhesion, regulation of cell proliferation, cancer metastasis 2. Chondroitin sulfate/dermatan sulfate- migration for wound repair Inhibition of axonal growth brain development, 3. Keratan sulfate- Within cornea Anti-adhesive (cell motility) 4. Hyaluronic acid Component of synovial tissues and fluid Lubricant- resists compression
How are Proteoglycans formed? Give examples of 3 different kinds
One or more glycosaminoglycan (GAG) chains attached to a core protein.
- Aggrecan
- biglycan
- Syndecan
Describe the sturcture, distribution and abundance of collagen
Amino acids which form elongated fibrils
Mostly found in fibrouse tissue- tendons, ligaments and skin
The most abundant protein
Describe the 5 most common types of collagen
Type 1- (most abundant)- skin, tendons, organs, bones
Type 2- Cartilage
Type 3- Retinaculate (spleen liver bone marrow)
Type 4- basila lamina (found alonside type 1)
Type 5- cell surfaces, hair and placenta- diameter of type 1
Describe the sturcture and function and distribution of elastin
Structure- Associated with fibrillin and rich in the amino caids- glycine and proline
Function- Forms the main component of elstaic conncetive tissue. Found most in the dermis if the skin and arteries
What is marphan syndrome?
Mutation in fibrillin gene
Effects conncetive tissue rich in elsatic fibers
severe case- Aorta is prone to rupture
Describe the sturcture and function of Fibronectin
Structure- glycoprotein dimer
Function- Binds to intergrins, involved in cell adhesion, growth mibration and differentiation
Binds to collagen
Extracellular matrix is connected to the inside of the cell by fibronectin. Collagen signals tension, and initiates cell activation or deactivation
Describe the structure and function of the basal lamina
Structure- layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits
Made of type 4 collagen, heparun sulfate, laminin, nidogen
Has 2 layers- lamina densa and lamina lucida
Function- provides sturctural support, relays messages, separates epithelial cells from the underlying connective tissue and supports, anchors, protects, selective cell movement, molecular filtering, and signaling.
The ECM and cancer
Tumour invasion involves the desctruction of ECM and basal lamina by enzymes enbaling the cell to enter the blood stream and surrounding tissues
List the different types of epthilial junctions
Tight junctions
Adherens junctions
Desmosome junctions
Gap junctions
Hemidesmosome junctions
Function of tight junctions? What happens in a diseased state?
Holds cells together
Maintain osmotic balance and used in material trasport
prevent the passage of molecules and ions through the space between plasma membranes of adjacent cells, so materials must actually enter the cells (by diffusion or active transport) in order to pass through the tissue.
Diseased- Viruses and bateria can effect tigh junction and functions
Altertaions in expresion of tigh junction proteins has been found in nuerological disorders e.g. multiple sclerosis, stroke, Alzheimer’s disease, Parkinson’s disease and epilepsy.
Function of desmosomes junctions? What happens in a diseased state?
Cells in tissues are joined by desmosomes
They connect intermidiate filaments in one cell to those in the next
Occure in the lateral side of plasma membarnes
Found in tissues with insense mechnical stress e.g. cardica muscle
Diseased state- causes compromised cutaneous and/or cardiac function, cardomyopthay
Can be broken down by autoantibdoies leading to fluid accumilation and blisteres of the skin. Pemphigus vulgaris.
Function of Adherens junctions and manigestations in a diseased state
Connects actin filaments in adjacent cells
They support both strong cell–cell adhesion and rapid cell–cell contact remodeling during development and wound healing
Diseased state- contributes to endothelial dilator dysfunction in arteries
Function of gap junctions
Directly connect the cytoplasm of two cells
Allows passage of small water solubale molecules from cell- cell
Play a vital role in electrical conduction of cardiac muscles
Composed of connexin proteins which form channels
Key features of neural synapses
Proteoglycans in the ECM regulate synapse formation and synaptic plasticity.
CNS synapses lack Basement membranes,
Structure and function of Pseudopodia
Temporary cytoplasm-filled projection of an eukaryotic cell membrane
Used for motility or ingestion
extend and contract by the reversible assembly of actin subunits.
cell surface projects lamellipodium, Cytoplasm flows into the lamellipodium, forming the pseudopodia.
Structure and function of Lamellipodia and Filopodia
Broad flat protrusions which surge forward and adhere to surfaces, allowing cells to gain traction and move
filopodia extend several micrometers ahead of the cells, explore extracellular surfaces, sense guiding cues, and direct the rest of the cell. There is abundant filopodia in invasive cancer cells
Extension of both lamellipodia and filopodia is powered by polymerization of actin into filaments by ATP
Structure and function of Microvilli
- cell surface extension of secretory and absorptive epithelia
- Increase the surface area of cells by approximately 600 fold, for absorption and secretion. Digestive enzymes (glycosidases).
Conatin enzymes on surface- e.g hydrolyze carbohydrates
What is the effect of toxins on microvillie?
cause destruction of intestinal microvilli and intestinal tight junctions resulting in inhibition of water-reabsorption.
What is the effect of infection on microvillie
E.coli infections enabled by- Celiac disease, Microvillus Inclusion Disease
consequence
–Malabsorption of nutrients and persistent osmotic diarrhoea, often accompanied by fever, and a failure to thrive. Classic symptoms include gastrointestinal problems such as chronic diarrhoea, abdominal distention, malabsorption, loss of appetite.
Structure and function of cilia? List condistions in the case of genetic defects
There are two types of cilia: motile cilia and nonmotile.
Non-motile cilia are found on nearly all cells as sensory antennae, chemosensors, photosensors, mechanosensors; signallers.
Motile cilia are usually present on a cell’s surface in large numbers and beat in coordinated waves e.g., in the trachea or fallopian tubes.
genetic ciliopathies eg. - Bardet–Biedl Syndrome; polycystic kidney disease; lack of cilia in fallopian tubes – ectopic pregnancy
