DNA Structure, Function, and Mutations
DNA Composition
DNA is a biomolecule composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus. It is a polynucleotide made of repeating units called nucleotides (deoxyribonucleotides). DNA stores and transmits hereditary information, forming the molecular basis of heredity.
Chemically, DNA consists of:
- A pentose sugar (deoxyribose).
- A nitrogenous base (adenine, guanine, cytosine, or thymine).
- A phosphate group.
DNA Structure
Primary Structure
The primary structure of DNA is the sequence of nucleotides
Read MoreHuman Body Functions: Metabolism, Respiration, and Excretion
Metabolism
- Formation of complex substances from simpler ones, e.g., protein synthesis from amino acids.
- Glucose and other organic compounds.
- Burning nutrients to release energy.
- Note: The term “consumption” is not accurate for energy, as it transforms (e.g., chemical energy in organic substances to heat).
- In winter, it’s colder.
- Chewing expends energy.
- Calculation example: (7.4 x 42 + 428 x 1.65 + 572 = 1589)
- Consuming a varied diet is important.
- Diseases: Beriberi, malaria, and rickets.
- Global distribution
Nutrition and Digestion in Animals: From Cells to Systems
Types of Nutrition
Autotrophs have the capacity to use inorganic substances as raw materials for nutrition. Energy acquisition methods include:
- Chemosynthetic: Using energy from chemical reactions (bacteria).
- Photosynthetic: Using solar energy (cyanobacteria and plants).
Heterotrophs require organic matter and nutrients (bacteria, fungi, animals). The processing and utilization of nutrients occur inside the cell in a complex chain of metabolic reactions:
- Catabolism: Degradation of substances and energy
Evolutionary Theories: From Lamarck to Punctuated Equilibrium
Hypotheses of Evolution
Lamarckism
Lamarck’s transformisme theory proposed that organisms evolve through the inheritance of acquired characteristics. For example, a worm transforming into a beetle over time or an animal adapting to a contaminated environment.
Evidence of Evolution
Darwin posited that living beings are products of a process involving successive modifications from a common ancestor, driven by natural selection.
Paleontological Evidence
Fossil remains of extinct flora and fauna demonstrate
Read MoreHuman Body Systems: Diseases, Illnesses & Health
Health and IllnessWhat is Health?Health, as the absence of illness, is the state of well-being of the body. When healthy, the body carries out all its functions correctly. Healthy habits help us stay healthy and prevent illnesses. A healthy diet is one of the most important habits. What is Illness?An illness is an abnormal process that alters, modifies, or prevents the activity of part of our body or the complete organism.
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Bacterial Genetics and Physiology
Transposable Elements: Transposons
The genes in living organisms are not static and may change their sequence under certain conditions, for example, through insertion sequences.
- Insertion occurs through single-strand breakage by the enzyme transposase.
- Transposons, or “jumping genes,” are DNA segments that can move within the genome, or between chromosomal DNA and plasmids.
- The transposon attaches to the ends of single strands and repairs them after replication.
- Transposition is important because these