Notes, summaries, assignments, exams, and problems for Biology

Basement Membrane Structure & Function

Covering & Lining Epithelia

Plasmids pBR322 and pUC18/19

pBR322

pBR322, developed in 1977, is a foundational plasmid in molecular biology. Key features include:

• Size: ~4,361 base pairs (bp)
• Origin of Replication: Allows independent replication within bacteria.
• Selection Markers:
  • ampR: Confers ampicillin resistance.
  • tetR: Confers tetracycline resistance.
• Cloning Sites: Multiple sites for inserting foreign DNA.
• Applications: Gene cloning, expression, and manipulation.

pUC18/19

pUC18/19, derived from pBR322 in the early 1980s, simplifies cloning. Key features include:

• Size: ~2,686 bp
• Origin of Replication: High-copy-number pMB1 ori for increased yield.
• Selection Marker:
  • lacZ: Beta-galactosidase gene; enables blue/white screening for insert identification.
• Cloning Sites: Multiple cloning

1. Brain Abscess

• Gross Morphology

  Localized area of liquefactive necrosis filled with yellow pus, surrounded by a thin fibrous capsule and edematous, inflamed brain tissue.

• Pathology

  Caused by hematogenous spread of bacterial infection, direct trauma, or contiguous spread (e.g., from sinuses). Represents focal suppurative inflammation of the brain.

2. Neurinoma (Schwannoma)

• Gross Morphology

  Well-circumscribed, encapsulated globoid mass with a soft, tan “fish-flesh” appearance, often with cysts or hemorrhage. Cut surface may show yellow patches.

• Pathology

  A benign tumor of Schwann cells, often seen in cranial nerves (especially CN VIII) and associated with neurofibromatosis type 2. Grows slowly and may compress adjacent structures.

3. Fibrinous

Aggressive Periodontitis: Localized vs. Generalized

This section outlines the key similarities and differences between Localized Aggressive Periodontitis (LAP) and Generalized Aggressive Periodontitis (GAP).

Localized Aggressive Periodontitis (LAP)

• Circumpubertal onset.
• Robust serum antibody response to infecting agents.
• Localized first molar/incisor presentation with interproximal attachment loss on at least two permanent teeth, one of which is a first molar.
• Lack of clinical inflammation.
• Presence of deep periodontal pockets.
• Amount of plaque inconsistent with the amount of periodontal destruction.
• Plaque forms a thin biofilm, rarely mineralizing into calculus.
• Distolabial migration and diastema formation.
• Increasing mobility of first molars.
• Sensitivity

Mineral Trioxide Aggregate (MTA) Applications

Pulp Therapy

• Pulp capping
• Furcation repair
• Strip perforation repair
• Root resorption repair
• Immature teeth
• Root end filling material

Elements of Pulp Regeneration

Therapy for exposed dental pulps using stem cells and a biofunctional scaffold, inhibiting or eliminating infection to facilitate pulp generation.

Nickel-Titanium (NiTi) Rotary Instruments

Advantages of NiTi Reciprocation

• Mimics manual movement
• Reduces risks associated with continuous rotation in curved canals

Types of Posts

1. Carbon fiber epoxy resin posts
2. Zirconia posts
3. Glass fiber reinforced posts
4. Ultra-high strength polyethylene fiber reinforced posts

Advantages of NiTi Rotary

• Gradual, evenly tapered radicular preparation
• Fewer instruments required
• Reduced

Metabolic and Biochemical Processes

BMI Calculation: BMI = Kg/M². Interpretation: <25 = Normal, 25-30 = Overweight, >30 = Obese. Ethanolamine (Ethan-NH₃), Choline = N(CH₃)₃

Leptin and Adipose Tissue

Leptin is released from adipose tissue when mass is high. It travels through the blood to the arcuate nucleus, binds to neuronal cells, and activates the JAK-STAT pathway. This increases gene expression of POMC, which produces alpha-MSH (a neurotransmitter). Alpha-MSH reaches neurons connected to adipose tissue, releasing norepinephrine. Norepinephrine binds to beta-adrenergic receptors on adipose tissue, promoting an increase (via the G-protein coupled receptor pathway and activation of PKA). This leads to upregulation of UCP1 expression and... Continue reading "Metabolic Pathways and Liposome Drug Delivery" »

To sort the diversity of life using a rating system. Kingdom, phylum. sub class, super, order, sub groups, sub, genus, species, sub. Hierarchical binomial nomenclature, the greater the taxa categories. To reconstruct the phylogeny of a group uses a character that varies among members (ancestral character.) Is also used to compare outgroup (outgroup ) This is phylogenetically close, but not part of the study group. For any phylogenetic reconstruction we need to consider the characters that we use in our analysis and determine which is the primitive condition that presents the common ancestor of several. In this sense, we use the apomorphies that
refer to a derived or specialized character. In contrast, plesiomorphic, is a primitive character.

Common Oral Benign Lesions and Tumors

6. Peripheral Giant Cell Granuloma (PGCG)

Reactive lesion.

Key Features:

• Prevalence: More common in females and older individuals.
• Site: Exclusively on the gingiva or alveolar mucosa.
• Etiology: Local irritation or trauma.

Clinical Characteristics:

• Color: Dark red.
• Surface: Often hemorrhagic and may be ulcerated.
• Appearance: Sessile or pedunculated mass.

Radiographic Features (X-ray):

• May show superficial bone resorption, sometimes described as "saucerization" or a "cupping effect".
• Can appear as an ill-defined radiolucent (RL) area if bone is involved.

Histopathology:

Characterized by three zones:

1. Zone of Hyperplastic Stratified Squamous Epithelium: Often shows acanthosis and hyperkeratosis.
2. Giant Cell-Free Zone: A band

Full Crown Veneer

Indications:

• Extensive destruction from caries or trauma
• Endodontically treated teeth
• Existing restorations
• Correction for occlusal plane

Contraindications:

• Less than maximum retention
• Esthetics

Advantages:

• Strong
• High retentive quality
• Easy to obtain
• Adequate resistance form

Disadvantages:

• Removal of large amount of tooth structure
• Adverse effect on tissues
• Vitality testing not readily feasible
• Display of metal

Porcelain-Fused-to-Metal (PFM) Crown

Indications:

• Esthetics if all-ceramic is contraindicated
• Gingival involvement

Contraindications:

• Large pulp chamber
• Intact buccal wall

Advantages:

• Superior esthetics compared to complete cast crown

Disadvantages:

• Removal of substantial tooth structure
• Subject to fracture
• Difficult to obtain accurate occlusion
• Shade

Biodiversity Origins: Early Theories

Fixist Theory: Species Immutability

Proposes that species are immutable and have remained unchanged throughout time. Variations include:

• Creationism

  The belief that living things were created by a divine entity. This idea is largely rejected by the scientific community.

• Intelligent Design

  A creationism movement asserting that a creative intelligence is responsible for the complexity of the universe and life. Proponents argue that some biological characteristics are too intricate to have arisen from natural processes, a claim widely considered pseudoscience.

• Catastrophism

  Proposed by Georges Cuvier, this theory suggests that Earth has experienced several catastrophic events, leading to the extinction of species and