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

Introduction to Biomolecules

Living organisms are made up of thousands of biomolecules—molecules produced by living systems with distinct properties and functions favored through evolution. Small, simple molecules called micromolecules (or monomers), such as water, minerals, simple sugars, and nucleotides, serve as building blocks for larger macromolecules (or polymers) like proteins, lipids, carbohydrates, and nucleic acids. Biomolecules are classified into inorganic types (e.g., water, minerals, gases) and organic types (e.g., lipids, carbohydrates, proteins, nucleic acids). While biomolecules alone do not exhibit life, they organize into cells and are continuously synthesized and broken down to maintain and perpetuate life.

Water: The Essential

HISTORICAL INTRODUCTION:Intro:Microbiology is the science of living organisms that are only visible under the microscope*Medical microbiology deals with the causative agents of infectious diseases of man his reaction to such infections the ways in which they produce disease and the methods for their diagnosis*The disease is transmitted by contact from man was known since biblical time. Varo and columella (First century BC)*The credit for observation and description of bacterial goes a Antony-Van Leeuwersback (1632-1723)*Father of microbiology (Antony Van Leeuwen hoek (1632-1723) and Logis pastoor (1822-1895)**Scientific development of microbiology*SDM was us by Louis pasteure*perfection ion microbiological studies by robert koch*The Intro of... Continue reading "Laboratory parasitology" »

c) Antigen Processing and Presentation

• Engulf protein antigens, partially digest them, and display polypeptide fragments on the surface for T cells to "see."
• Fragments are associated on the surface with Major Histocompatibility Antigens (MHC II), which are necessary to activate T cells.

d) Dendritic Cell Migration

To increase the chance of interacting with the correct T cells, dendritic cells migrate to secondary lymphoid organs (chemokines are secreted to attract T cells).

VII. Extracellular Killing by the Immune System

A. Natural Killer (NK) Cells

NK cells lyse virus-infected cells, tumor cells, and parasites. They kill cells that do not express MHC class I antigens.

B. Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)

1. In ADCC, NK cells and macrophages

Circulatory System

Blood is a viscous, red, and saline liquid (approximately 5 liters). It is composed of:

• Plasma (55%): A yellowish liquid made of water and substances such as nutrients and hormones.
• Blood Cells: Produced in the bone marrow, there are three types:
  • Red blood cells (erythrocytes): Transport oxygen from the lungs to the cells using a red protein called hemoglobin.
  • White blood cells (leukocytes): Essential components of the immune system.
  • Platelets: Fragments of cells that function to stop bleeding.

Blood Functions

• Transport nutrients
• Transport oxygen and carbon dioxide
• Transport waste products
• Regulate body temperature
• Participate in the immune system
• Prevent hemorrhages

Blood Vessels

• Arteries: Transport blood from the heart to the organs.

Cancer Stem Cells vs. Normal Stem Cells

Both normal stem cells and cancer stem cells (CSCs) share the ability to self-renew through asymmetric division, allowing one daughter cell to remain a stem cell while the other differentiates. They both generate heterogeneous populations of mature cells: normal stem cells produce tissue-specific cell types, while CSCs produce diverse tumor cells. Both rely on similar regulatory signaling pathways such as Wnt, Notch, and Hedgehog, but these pathways are tightly controlled in normal stem cells and dysregulated in CSCs, promoting tumor formation. Both exist as rare subpopulations within tissues, depend on signals from their niche, and can remain quiescent for long periods. CSCs, however, show enhanced resistance... Continue reading "Cancer Stem Cells: Signaling Pathways and Therapeutic Potential" »

Animal Development and Embryology

• Which best describes the blastula development stage? - A hollow ball of cells with a blastocoel.
• In early stages of development through the gastrula stage: Cells divide to increase the number of cells but they don’t increase in size.
• A fertilized egg cell is: Diploid.
• Which best describes the zygote development stage? - A fertilized egg cell.
• Which of the following correctly displays the sequence of developmental stages? - Cleavage-blastula-gastrula.
• The first cavity in an embryo formed during frog development is the: Blastocoel.
• The archenteron of the developing sea urchin eventually develops into the: Digestive tract or gut.
• _____ has determinate cleavage and will not have identical twins: Protostome.
• ____ has the

1. Single-Cell Protein & Alcohol Production

Industrial fermentation harnesses microbial metabolism under controlled conditions to synthesize biomass and primary metabolites on a massive commercial scale.

                  [Raw Material / Carbon Source]
                                 │
                                 ▼
         ┌──────────────────────┴──────────────────────┐
         ▼                                             ▼
 [Biomass Production]                       [Metabolite Production]
  e.g., Single-Cell Protein                  e.g., Ethanol Fermentation
  (Cell body is the product)                 (Secreted fluid is the product)

Lab 8: Temperature and Microbial Growth

Key Concepts

• Psychrophiles grow best between 0–20°C. Often found in cold environments like glaciers.
• Mesophiles prefer 20–45°C. These include human pathogens like E. coli.
• Thermophiles thrive at 55°C or higher. They are often found in hot springs.

Materials and Their Functions

• Tryptic Soy Broth (TSB): A nutrient-rich medium that supports bacterial growth.
• Incubators set to different temperatures (4°C, 25°C, 37°C, 55°C): Used to simulate environmental conditions.
• Spectrophotometer (OD600): Measures turbidity (cloudiness) of a culture to estimate cell density.
• Classification by growth: “+++” indicates heavy growth; “0” means no growth.

In this lab, students investigated how temperature affects... Continue reading "Microbiology Lab Fundamentals: Growth, Metabolism, Genetics" »

Plant Anatomy and Reproduction

The flower, which is responsible for reproduction, has a female part: the carpel, and a male part: the stamen. The female gametes (ovules) are produced in the ovary inside the carpel, while the male gametes are called pollen grains. Petals attract animals and protect the flower, while sepals cover and protect the other parts of the flower.

As a result of fertilization, a seed develops, which is responsible for the survival and dispersal of the plant.

3. Reproduction in Plants

Aquatic organisms often use water as a medium for transporting their gametes and for fertilization. On land, the vast majority of plants have developed mechanisms of reproduction that make their fertilization independent of water. Plants can... Continue reading "Plant Reproduction and Photosynthesis Explained" »

The Tricarboxylic Acid (TCA) cycle, also called the Krebs cycle or citric acid cycle, is a cyclic series of reactions in which acetyl-CoA is oxidized to CO₂, producing reduced coenzymes NADH and FADH₂ and generating energy.

Energetics

For one acetyl-CoA:

• 3 NADH = 3 × 2.5 = 7.5 ATP
• 1 FADH₂ = 1 × 1.5 = 1.5 ATP
• 1 GTP = 1 ATP
• Total = 10 ATP per acetyl-CoA

Since one glucose produces 2 acetyl-CoA:

TCA yield = 20 ATP per glucose

Importance of the TCA Cycle

• Major pathway for the oxidation of acetyl-CoA.
• Produces ATP and GTP.
• Produces NADH and FADH₂ for the electron transport chain (ETC).
• Provides intermediates for amino acid synthesis.

Enzyme Inhibition

Definition

Enzyme inhibition is the reduction in enzyme activity due to the binding of an inhibitor to... Continue reading "TCA Cycle Energetics, Enzyme Inhibition and DNA Replication" »