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

Infrared Spectra of Alkanes

Alkanes, being saturated hydrocarbons, only contain Carbon-Carbon (C-C) and carbon-hydrogen single bonds. Their IR spectra are relatively simple due to the absence of strong functional groups.

C-H Stretching

The most prominent peaks in an alkane's IR spectrum are due to C-H stretching vibrations. These sharp, strong bands typically appear in the range of 2850-2960 cm^-1. The exact wavenumber can vary slightly depending on the specific alkane and its branching.

Infrared Spectra of Alkenes

Alkenes contain at least one carbon-carbon double bond (C=C), along with C-H bonds. The presence of the double bond introduces distinct features in their IR spectra compared to alkanes.

C=C Stretching

The stretching vibration of the C=C... Continue reading "Infrared Spectroscopy of Organic Compounds: A Comprehensive Guide" »

Steps in Root End Surgery

• Local anesthesia and hemostasis
• Management of soft tissue
• Management of hard tissue
• Surgical access (visual and operative)
• Access to root structure
• Periradicular curettage
• Root end resection
• Root end preparation
• Root end filling
• Soft tissue repositioning and suturing
• Post-surgical care

Root End Preparation

Preparing a cavity to receive root end filling.

According to Carr and Bentkover, this involves a Class I preparation at least 3mm into root dentin with walls parallel to and coincident with the anatomic outline of the pulp space.

Key requirements:

1. The apical 3mm of the root canal must be freshly cleaned and shaped.
2. The preparation must be parallel to and coincident with the anatomic outline of the pulp space.
3. Adequate retention form

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

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

Human Body and Homeostasis

Cells and Their Functions

Cytoplasm: The material between the plasma membrane and the nucleus, composed of cytosol (largely water with dissolved proteins) and cytoplasmic organelles.

• Mitochondria: Provide ATP (energy).
• Ribosomes: Sites of protein synthesis.
• Endoplasmic Reticulum: Manufactures proteins and catalyzes reactions.
• Golgi Body: Concentrates and packages proteins.
• Lysosomes: Contain digestive enzymes; degrade unwanted substances.
• Cytoskeleton: Provides structural support.
• Nucleus: Control center of the cell; contains genes.
• Centriole: Plays an active role in cell division.
• Microvilli: Increase surface area for absorption.
• Vacuole: Membrane-bound organelle that stores and excretes substances.

Plasma Membrane: Separates... Continue reading "Human Body Systems: A Comprehensive Overview" »

Benign Epithelial Lesions

Squamous Cell Papilloma

Age: Mid-age
Site: Palate, uvula, cheek, lip, tongue, gingiva
Characteristics:

• Color: White to pinkish (depending on keratinization)
• Shape: Cauliflower-like
• Surface: Rough, irregular (finger-like projections)
• Texture: Firm or soft (depending on keratinization)
• Sessile or pedunculated

Histological Features:

1. Hyperplastic stratified squamous epithelium
2. Acanthosis and hyperkeratosis
3. Intact basal layer
4. Thin central branching core of connective tissue carrying nutrition

Verruca Vulgaris (Wart)

Reactive lesion, autoinoculation
Etiology: HPV 2, 4, 6
Histological Features:

1. Intranuclear inclusion bodies
2. Koilocytes
3. Cupping effect of rete ridges
4. Granular cell layer

Keratoacanthoma

True, self-limiting lesion
Age: Older males
... Continue reading "Benign Epithelial and Mesodermal Lesions of the Oral Cavity" »