Callum Cafferty Flashcards
What is primary, secondary, tertiary, quaternary protein structure
What type of bonds
Primary: sequence of amino acids in polypeptide chain with N terminus at start and C terminus at end- Peptide bonds
Secondary: local folding of polypeptide chain into alpha helix or beta pleated sheet- H bonds
Tertiary: 3d folding of protein to generate functional domains due to interactions between R groups- ionic bonds, disulphide bridges, hydrophilic/hydrophobic interactions, H bonds
Quaternary: association of multiple subunits - same bonds as tertiary structure
What is splicing
The selection of of different sections of DNA to be translated- Exons code for protein, Introns are non coding sections, selection of different combinations of exons created different proteins during alternate splicing
What is glycosylation
What are lipid anchors
What is phosphorylation
Attachment of sugar groups to form glycoproteins which facilitate protein interactions such as ligand binding and binding of proteins in ECM
Chemical groups that help proteins attach or associate with a membrane
Reversible addition of phosphate group
What causes amelogenesis imperfecta
3
Mutations in genes (AMELX and ENAM) that encode ECM proteins of enamel
Mutations in genes that encode proteases that remove organic matter from enamel as it matures
Mutations in SLC24A4 which codes for calcium transporter required to deliver calcium to teeth as they develop
What apperance on a childs growth chart warrants investigation
Plateauing of weight or height during childhood
What age does lymphoid tissue reach 100% of its size
7 years
At what age does neural tissue reach 90% of its size
At what age does neural tissue reach 96% of its size
7 years
10 years
What is the post natal growth spurs
What is the pre pubertal growth spurt
Rapid growth observed during first year of life followed by progressive decrease in growth rate till puberty
Rapid growth at onset of puberty occurring at 11 in girls and 13 in boys
Growth hormone/somatotrophin
What is its gland of origin What is its function What happens in excess What happens during deficiency How is its release regulated
Anterior pituitary gland
Stimulated chondocyte proliferation, production of insulin like growth factor 1, bone mineralisation , increases skeletal mass, promotes lipolysis and protein synthesis, antagonises insulin, stimulates immune function
Acromegaly in adults, pituatary gigantism in children
Impaired growth
Relase stimulated by GHRH from hypothalamus and inhibited by somatostatin (from hypothalamus), negative feedback, dietary carbohydrate, glucocorticoids
Thyroid hormones (T3 and T4)
What is its gland of origin What is its function What happens in excess What happens during deficiency How is its release regulated
Thyroid gland
Causes growth of nervous tissue and bone , increases glycogenolysis, increases basal metabolic rate
Hyperthyroidism causes increased bone turnover, accelerated growth, accelerated bone maturing so can lead to short stature
Hypothyroidism leads to cognitive and neurologic abnormalities, short stature and growth retardation, delayed bone maturation
Release stimulated by TSH from anterior pituitary, inhibited by negative feedback
Oestrogen
What is its gland of origin What is its function What happens in excess What happens during deficiency How is its release regulated
Ovaries
Controls puberty in females, strengthens bones, causes pubertal growth spurt
Excess can cause acne, breast cancer, fibroids
Deficiency can cause poor bone growth and menopausal symptoms such as osteoporosis
Release stimulated by FSH from anterior pituitary, inhibited by negative feedback
Androgens - testosterone and androstenedione
What is its gland of origin What is its function What happens in excess What happens during deficiency How is its release regulated
Testes, ovaries, adrenal glands
Testes formation, male pubertal development, inhibits fat deposition, promotes muscle mass
Hyperandrogenism - in females causes hirsutism, alopecia, hidradenitis suppurativa, acne, obesity
Hypoandrogenism- in men causes loss of libido, infertility, genital shrinkage, low muscle mass, osteoporosis
Release stimulated by FSH and LH from anterior pituitary, inhibited by negative feedback
What is endochondral ossification
What is the process 3
The formation of bone from a preceeding cartilagenous matrix which becomes replaced by bone and marrow
- periosteal bud invade cartilage model and allows mesenchymal cells to enter cartilage
- Invading mesenchymal cells mature into osteoblasts
- Osteoblasts deposit bone using the framework of calcified cartilage
What is intermembranous ossification
What is the process 3
Mineralisation of tissue with differentiation of mesenchymal cells to osteoblasts occuring within a membranous plate of mesenchymal cells
- At ossification centre mesenchymal cells differentiate into osteoblasts
- Osteoblasts deposit osteoid
- Thin sheet of woven bone called periosteal collar is deposited around shaft of cartilage model
What type of ossification happens in the cranial vault
Intramembranous ossification
What type of ossification occurs in cranial base growth
Endochondral ossification
What is the cartilage precursor of the cranial base
What age does the spheno ethmoidal synchondrosis close
What age does the spheno occipital synchondrosis close
Chondrocranium
6 years
12-15 years
How does the nasomaxillary complex grow
Initially the nasomaxillary complex grows by intramembranous ossification then grows by apposition of sutures that connect maxilla to cranium and cranial base and surface remodelling
How does the mandible grow
Which cartilage makes the most significant contribution to post natal growth
What area of the mandible allows adaptibility during growth and how does it do this
Endochondral ossification with its preceeder being meckels cartilage
Condylar cartilage
The ramus and condyle- can vary amount and direction of growth to accommodate nasomaxillary and dental height, this involves feedback mechanisms
What are the key facts of growth of lips
4
Follows jaw growth before adolescence then catches up
Lip height short during mixed dentition
Lip incompetence greatest during childhood
Lip thickness greatest during adolescence then decreases with age
What age is nasal bone complete
Why may nose become more prominent during adolescence
10 years
There is considerable Growth in nasal cartilage and soft tissues during adolescent growth spurt
Explain the process of odontoblast and ameloblast histodifferentialtion
7
- During late bell stage at cusp tips mitosis of inner enamel epithelium stops
- Columner cells of inner enamel epithelium elongate and reverse polarity with there nuclei aligned adjacent to stratum intermedium
- As this happens changes are induced in dental papilla by growth factors released by inner enamel epithelium
- Ectomesenchymal cells of papilla differentiate into odontoblasts eliminating acellular zone
- Differentiation of ameloblasts and odontoblasts progresses down cusp slopes
- Odontoblasts move towards centre of papilla leaving behind cytoplasmic extensions around which dentin is formed
- Ameloblasts move out leaving layers of enamel
What are matrix vesicles
How big are they
What is their function
Extracellular membrane bound vesicles released by odontoblasts durring differentiation
100 nanometers
Provide microenviroment with high conc of phosphate and calcium ions- crystals within vesicle grow then vesicle ruptures and crystals fuse with adhacent crystals to form a continous layer of mineralised matrix
What stages do the ameloblasts go through during histodifferentiation and amelogenesis
4
Presecretory stage
Secretory stage
Maturation stage
Reduced enamel epithelium stage
What happens during the pre secretory stage of amelogenesis
2 phases
Morphogenesis phase- cells of inner enamel epithelium cuboidal and undergo frequent mitosis to establish crown pattern of tooth
Differentiation phase- cells of inner enamel epithelium differentiate into ameloblasts by elongating, polarising, shifting their nuclei towards stratum intermedium, increasing size of Golgi and RER and forming Tomes processes which break down basal lamina. Ameloblasts aligned closely by junctional complexes
What happens during the secretory stage of amelogenesis
4
Protein granules migrate to Tomes processes and are released along mantle dentin to form initial aprismatic enamel layer
Ameloblasts migrate away from dentin
The proximal part of Tomes process forms inter rod enamel and distal portion forms enamel rod
Eventually ameloblasts become shorter and lose the distal aspect of Tomes process so final few enamel increments aprismatic
What happens during Maturation stage of amelogenesis
2 phases
Transitional phase- ameloblasts undergo morphologic changes reducing in size, volume and organelle content, some apoptose
Maturation proper- cells show modulation to facilitate the bulk removal of water and organic material. Ruffle ended ameloblasts have tight distal junctions and pump calcium ions into maturing enamel to promote incorporation of inorganic material. Smooth ended ameloblasts have tight proximal junctions and permit exit of proteins and water from enamel
What happens during reduced enamel epithelium stage of amelogenesis
As eruptive movements begin a layer of ameloblasts cover crown of tooth called reduced enamel epithelium for protection
Where is cementum formation initiated
Hertwigs epithelial root sheath (HERS)
What is the process of cementum formation
2 Theories
(3)
- HERS sends inductive message to adjacent mesenchymal pulp cells which differentiate into odontoblasts to produce layer of predentin
- HERS interupted by ectomesenchymal cells from dental follicle coming into contact with predentin
- Dental follicle cells receive inductive signal to differentiate into cementoblasts
- HERS cells differentiate into cementoblasts with some cells of HERS forming epithelial cell rests of malassez
What is the process of root formation
4
- Once crown formation complete inner and outer epithelial cells from cervical loop proliferate to form HERS with the rim of the sheath (epithelial diaphragm) enclosing primary apical foramen
- As dental pulp expands within inner epithelial cells of root sheath they initiate odontoblast differentiation to form dentin of root
- As root formation progresses from advancing root edge HERS disintegrates leaving behind clusters of cells called epithelial cell rests of malassez
- In adults these persist next to root surface within PDL
What is immunocytochemistry
What is the primary method
What is the secondary method
What does DAPI stain
What does Alpha tubilin stain
What does Ki67 stain
Cellular immaging using antigens to label antibodies with fluorescent dye (Fluorophore)
Uses single antibody directly conjugated to fluorophore directed against the target interest
Primary antibody unconjugated and secondary fluorophore conjugated antibody attaches to primary antibody
Nucleic material
Cytoskeletal components
Cell division
What is in situ hybridisation used for
What is the process
4
Used to reveal location of specific nucleic acid sequence on chromosome
- Gene of interest localised and labelled using DNA/RNA probe
- Label hybridised to known target DNA sequence in sample so probe now labelles sequence
- Labelled probe can be detected by antibody linked with fluorophore
- This detects expression of gene ofinterest and its position along DNA or mRNA sequence
What is flow cytometry used for
What is the process of flow cytometry
3
Used to characterise cells within population by surface expression/cell type/TLRs
- Antibodies detect markers usually on cell surface to find if cells contain proteins of interest
- Sample of labelled cells placed into tube of machine
- Cells individually pass through laser light which scatters the light and provides information about cells
What are the disadvantages of flow cytometry
3
Can get non specific binding
Not all machines as sophisticated so can get issues in signal balance causing masking
May be wavelength crossover
What is ELISA used to do
Measures protein expression or secretion via antibody specific binding
What is PCR used to do
What is the process
3
Method of amplification of DNA and RNA using complementary primers
- Separating of strands
- Annealing of primers
- Synthesis of DNA
What are the disadvantages of PCR
4
Susceptible to contamination
Non specific primer binding can occur leading to amplification of multiple products
Self complimentary binding of primers
Selection of reliable reference gene dependent on multiple factors
What is electrophoresis used to do
What is the process
3
What is the difference between western blotting, southern blotting, northern blotting
Separated molecules based on size and charges
- Samples loaded into wells of gel matrix
- Current applied drawing charged particles through gel
- Fragments migrate different distances based on size and charge
Western blotting: detects target molecules using labelled antibodies
Southern blotting: labels complementary DNA using nucleic acid probe
Northern blotting: labels RNA with nucleic acid probe
What does mass spectrometry do
What is the process
5
What are the disadvantages
3
Characterised molecules by mass to charge ration allowing protoenomic profiling
- Sample vapourised and ionised
- Ion execration
- Deflection
- Detection
- Calculation of m/z
Expensive
Masses of data produced
Sensitive to poor technique
