Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

DNA Structure and Function

DNA is a large molecule formed by the union of simpler molecules called nucleotides. The nucleotides correspond to the links of a long chain and consist of:

• A molecule of phosphoric acid
• A carbohydrate called deoxyribose
• A nitrogenous base (adenine (A), guanine (G), cytosine (C), or thymine (T))

The DNA sequence is the order of DNA nucleotides. Each DNA molecule is composed of two long chains of nucleotides coiled up in a double helix. The two strands are chemically complementary. This is because the nitrogenous bases are joined and locked inside the double helix, with specific pairings: (A = T), (T = A), (C = G), and (G = C).

DNA Replication

The DNA molecule is the only molecule in living beings that can make an exact copy...

Mendel's Laws

Mendel explained the observations made during years of crossing different types of peas in the gardens of a monastery. He collected the general laws of inheritance that later became known as Mendel's laws.

Double Helix DNA

DNA carries the genetic information. DNA is a molecule composed of four simple units, repeated often and combined in different ways (called nucleotides). There are four types of DNA nucleotides: cytosine, guanine, thymine, and adenine. A single DNA molecule is formed by two chains of nucleotides linked and facing each other, with a structure that forms a spiral staircase: a double helix.

Replication of DNA

DNA contains genetic information. When the cell divides, it is capable of making an exact copy of the entire...

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)

Carbohydrates: Structure and Classification

Classification

• Monosaccharides: Single sugar unit (e.g., glucose, fructose).
• Disaccharides: Two sugar units joined (e.g., sucrose = glucose + fructose).
• Polysaccharides: Many sugar units linked (e.g., starch, glycogen).

Aldose vs. Ketose

• Aldose: Contains an aldehyde (-CHO) group (e.g., glucose).
• Ketose: Contains a ketone (>C=O) group (e.g., fructose).
• Number of Carbons: Triose (3C), Tetrose (4C), Pentose (5C), Hexose (6C).

Structural vs. Stereoisomers

• Structural Isomers: Same molecular formula, different bonding patterns or structure.
• Stereoisomers: Same connectivity, different spatial arrangement of atoms.

Chiral Carbons

• Chiral Carbon: A carbon atom bonded to four different groups, creating an asymmetric center.

Describe the sources, targets, and primary effects of the hormones of calcium metabolism

The parathyroid gland is the hormone that affects Ca2+ concentration. When Ca2+ concentration is too low in the plasma, the parathyroid hormone secretion is stimulated, and vice versa. This parathyroid hormone can have several effects. It can send a signal to the bones and the osteoblasts will break down and more Ca2+ enters the blood. It can also stimulate the formation of 1,25 (OH)₂D to reabsorb Ca2+ in the intestines and kidneys so less Ca2+ is excreted, it also increases the excretion of phosphate ions. It also stimulates the reabsorption of Ca2+ in the GI tract. Calcitonin is a peptide hormone secreted by parafollicular cells in the thyroid gland. Calcitonin...

Wood Structure and Properties

Sapwood and Heartwood

Sapwood

• Width varies with species, growth rate, and tree age.
• Typically represents 20-50% of the total radius (except in very young trees).

Heartwood

• Formed from former sapwood cells.
• Acidity increases, extractives form, and color changes.
• Resistance to fungal and insect attack increases.
• Many timbers develop gums and resins in the heartwood.

Functions of Cells in a Growing Tree

• Primary function: Conduction of water and dissolved minerals from roots to leaves.
• Secondary function: Mechanical support of the tree.
• Tertiary function: Food storage for spring growth.

Characteristic Differences between Softwoods and Hardwoods

• Hardwoods: Water-conducting elements distributed throughout the annual ring.
• Softwoods:

Energy and Matter in Ecosystems

How Does Energy Flow?

Ecosystems maintain an open flow of energy because producers, like plants, transform solar energy into chemical energy through photosynthesis. This energy is then used and degraded as it passes through the trophic levels of consumers (herbivores, carnivores) and decomposers (bacteria, fungi). Ultimately, the activities of all living organisms in the ecosystem generate thermal energy as heat, which dissipates into the environment.

This energy flow is unidirectional because the solar energy entering the ecosystem is transformed into chemical energy within living organisms and eventually lost as heat.

Key Points:

• Typically, no more than 10% of the energy from one trophic level is transferred to

Infectious Diseases

Definition

Temporary or permanent loss of health caused by microorganisms.

Types of Microorganisms

• Bacteria: Unicellular prokaryotic organisms that multiply and can destroy cells and tissues.
• Viruses: Not considered living organisms. They reproduce by entering cells and using their resources, causing damage.
• Protozoa: Single-celled eukaryotes. Some cause disease.
• Fungi: Unicellular and multicellular eukaryotes. Some can cause disease in weakened individuals.
• Parasites: Multicellular organisms that live at the expense of a host, weakening but not killing it.
• Prions: Misfolded proteins that accumulate and cause neuron degeneration.

Non-Infectious Diseases

Nonspecific Defenses

Mechanisms that prevent the entry of microorganisms:

• Skin: Acts

What are Plant Hormones?

Plants require light, carbon dioxide, water, and minerals, including nitrogen, for growth. Utilizing energy from the sun, they produce much of their own substance, transforming simple materials into complex organic compounds. Hormones play a crucial role in regulating plant growth and development by stimulating or inhibiting specific processes. Among the most important internal factors are plant hormones. By definition, hormones are substances produced in one tissue and transported to another, where they exert highly specific effects.

Types of Plant Hormones

Among the many plant hormones identified, the best known are auxins, cytokinins, gibberellins, abscisic acid, and ethylene.

Auxins

Auxins are a group of plant hormones...

Cellular Immunity

Cellular immunity involves two main types of lymphocytes: T lymphocytes and B lymphocytes. It also involves non-T, non-B cells. This system effectively destroys:

• Foreign cells
• Tumor cells
• Virus-infected cells
• Cells infected by intracellular pathogens

T Lymphocytes

T4 Lymphocytes

T_H Lymphocytes: These cells stimulate other T cells and B lymphocytes.

T_D Lymphocytes: These cells increase the number and activity of macrophages.

T8 Lymphocytes

T_C Lymphocytes: These cells destroy target cells.

T_S Lymphocytes: These cells regulate and suppress excessive or inappropriate immune responses. They deactivate lymphocytes once antigenic agents are controlled.

A phagocyte captures a foreign element, digests it, and presents it as an antigen-presenting...