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

T-Cell Coreceptor Specificity

• Helper T-cells require antigen and Class II markers.
• Co-presentation requirements stem from different coreceptors on Killer and Helper T cells:
  • Killer T-cell coreceptor CD8 interacts only with Class I markers.
  • Helper T-cell coreceptor CD4 interacts only with Class II markers.

Interactions: Antigen-Presenting Cells & Lymphocytes

Active Immunity

Primary and Secondary Immune Responses

1. On first exposure to a pathogen, there is a latency of 5-10 days before specific antibodies are made, known as the primary response.
   • Antibody levels plateau after a few days and decline after a few weeks.
2. Subsequent exposure to the same antigen causes a secondary response.
   • Antibody production is much more rapid and sustained.

Clonal Selection

The Mechanism of Photosynthesis and Energy Conversion

Photosynthesis (pronounced FOH-tə-SINTH-ə-sis)^[1] is a system of biological processes by which photopigment-bearing autotrophic organisms, such as most plants, algae, and cyanobacteria, convert light energy—typically from sunlight—into the chemical energy necessary to fuel their metabolism. The term photosynthesis usually refers to oxygenic photosynthesis, a process that releases oxygen as a byproduct of water splitting.

Storing Chemical Energy and Maintaining the Atmosphere

Photosynthetic organisms store the converted chemical energy within the bonds of intracellular organic compounds (complex compounds containing carbon), typically carbohydrates like:

• Sugars (mainly glucose, fructose,

Electrical Fundamentals in Electrotherapy

Electrotherapy involves the use of electric currents for therapeutic purposes, commonly used in physical therapy and rehabilitation. Understanding the electrical fundamentals is crucial for effectively applying electrotherapy techniques.

Basic Concepts of Electricity

• Current (I): The flow of electric charge, measured in Amperes (A). It can be direct (DC) or alternating (AC).
• Voltage (V): The electrical potential difference that drives current flow, measured in Volts (V).
• Resistance (R): The opposition to current flow, measured in Ohms (Ω). According to Ohm's Law: V=I×R.

Types of Electric Currents in Electrotherapy

• Direct Current (DC): A unidirectional flow of electric charge, used in applications like iontophoresis.

Biology Concepts

Cellular Processes and Structure

• 1-A) Ev against abiogenesis.
• 3-C) Cannot maggots developed.
• 4-B) Life forms from non-living matter.
• 5-C) Cells contain organelles.
• 6-B) Move through phospholipid bilayer quickly.
• 7-A) Endocytosis.
• 8- Vacuole: 3, Nucleus: 7, Cytoplasm: 2, Rough ER: 4.
• 9- Synthesize lipids: 5, Convert glucose: 8, Convert sunlight: 1, Modify lipids: 6.
• 10-B) None.
• 11-D) Glucose and Oxygen.
• 12-C) Makes ATP.
• 13-B) Cells, tissues, systems.
• 14-C) Tissues.

Microscopy and Molecular Biology

• 15- 2) Internal structures: Transmission electron microscope (TEM), 3) 2 more lenses: Compound microscope, 4) 3D image: Scanning electron microscope (SEM), 5) Highest magnification: Scanning tunneling microscope (STM).
• 16-D) Mitch.
• 17-A) Starch molecule.

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

Spina Bifida: Definition, Symptoms, and Complications

Spina bifida is a neural tube defect (NTD) that occurs when the spinal column does not close completely during early fetal development, usually within the first month of pregnancy. This condition can lead to physical and neurological complications, depending on the type and severity.

Definition of Spina Bifida

Spina bifida is a congenital defect in which the vertebrae fail to close around the spinal cord, leading to an opening in the spine. It can result in the exposure or protrusion of the spinal cord and membranes, depending on the form.

Types of Spina Bifida

1. Spina Bifida Occulta:

   • Mildest form
   • Small gap in the spine, with no protrusion of the spinal cord or membranes
   • Often asymptomatic

2. Meningocele:

Early Foundations and Key Milestones in Plant Tissue Culture

The science of plant tissue culture originates from the discovery of the cell, followed by the postulation of cell theory. In 1838, Schleiden and Schwann proposed that the cell is the basic structural unit of all living organisms. They envisioned that a cell is capable of autonomy and, therefore, it should be possible for each cell, if given the right environment, to regenerate into a whole plant. Based on this premise, in 1902, German physiologist Gottlieb Haberlandt for the first time attempted to culture isolated single palisade cells from leaves in Knop’s salt solution enriched with sucrose. The cells remained alive for up to one month, increased in size, accumulated starch,... Continue reading "Milestones in Plant Tissue Culture Development" »

Basement Membrane Structure & Function

Covering & Lining Epithelia

Knee Joint Anatomy and Function

This document provides a detailed look at the structure, mechanics, and common clinical aspects of the knee joint.

Type of Joint

• The knee is classified as a synovial hinge joint.
• It primarily allows flexion and extension.
• A small degree of medial/lateral rotation is possible when the knee is flexed.

Bones Involved

1. Femur (thigh bone)
2. Tibia (shin bone)
3. Patella (kneecap)

The fibula is nearby but does not participate in the primary knee joint articulation.

Articulating Surfaces

• The medial and lateral femoral condyles articulate with the tibial condyles.
• The patella articulates with the femoral trochlear groove.

Main Ligaments

1. Anterior Cruciate Ligament (ACL) – Prevents anterior displacement of the tibia relative to the femur.