Interactive Map

Victoria Martinelli SalazarSantiago Gomez Montemayor

Interactive Map

Interactive Conclusion

DNA

Genetic Disease: Down syndrome

Gene

Chromosome

Mendelian Inheritance (Simulation)

Mutation

Genetic Disease: Down syndrome

Normally, humans have 46 chromosomes. In Down syndrome, individuals have 47 chromosomes due to an extra copy of chromosome 21. This condition is also called Trisomy 21.

• The chromosomal alteration happens because of a process called nondisjunction during meiosis, when chromosomes fail to separate properly.
• The karyotype of a person with Down syndrome shows three copies of chromosome 21 instead of two.

• Phenotypic consequences may include characteristic facial features, developmental delays, and an increased risk of certain medical conditions such as heart defects.

Mutation

A mutation is a change in the DNA sequence. Mutations can occur naturally or be caused by environmental factors such as radiation or chemicals.

There are different types of mutations:

• Gene mutations: affect the sequence of a single gene. These include substitution, insertion, and deletion.
• Chromosomal mutations: involve structural changes in a chromosome, such as deletion, duplication, inversion, or translocation
• Numerical mutations (aneuploidy): occur when there is an abnormal number of chromosomes.

Mutations can be neutral, harmful, or sometimes beneficial.

Gene

A gene is a specific segment of DNA that contains the instructions to produce a protein. Genes determine physical traits and regulate many biological functions.

• The gene-protein relationship works through gene expression: DNA is transcribed into RNA, and RNA is translated into a protein. Proteins perform essential functions such as building tissues, transporting molecules, and regulating chemical reactions.

• An example is the gene responsible for blood type in the ABO system.
• Genes can exist in different versions called alleles. A dominant allele is expressed even if only one copy is present (A). A recessive allele is expressed only when two copies are present (aa).

Mendelian Inheritance (Simulation)

Mendelian inheritance was studied by Gregor Mendel, known as the father of genetics.

• For example, suppose brown eye color (B) is dominant over blue eye color (b).

If both parents have the genotype Bb, the cross would be:

• Bb × Bb
• The possible combinations are
• BB
• Bb
• Bb
• bb

This means:

• 25% will be BB (brown eyes)
• 50% will be Bb (brown eyes)
• 25% will be bb (blue eyes)

Therefore, 75% of the offspring are expected to have brown eyes and 25% blue eyes. This demonstrates how dominant traits appear more frequently, while recessive traits only appear when two recessive alleles are inherited.

Chromosome

A chromosome is a long, organized structure made of DNA wrapped around proteins called histones. Chromosomes are located in the nucleus of cells.

• Humans have 46 chromosomes arranged in 23 pairs. Each chromosome consists of chromatids joined at a region called the centromere and protected at the ends by telomeres
• Homologous chromosomes are pairs that contain the same genes in the same order, although they may carry different alleles.

There are two main types of chromosomes:

• Autosomes: 22 pairs that determine most body traits.
• Sex chromosomes: 1 pair that determines biological sex (XX for females, XY for males).

DNA

Is the molecule that contains the genetic information of all living organisms. Its structure is made up of small units called nucleotides.

• Each nucleotide has three parts: a phosphate group, a sugar called deoxyribose, and a nitrogenous base. The nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). Adenine always pairs with thymine, and cytosine always pairs with guanine.

• Nucleotides are connected by phosphodiester bonds, forming the sugar-phosphate backbone of DNA. The molecule has a twisted ladder shape known as a double helix, described by James Watson and Francis Crick.
• The main function of DNA is to store and transmit genetic information, control protein production, and allow traits to be passed from parents to offspring.

Interactive Conclusion

DNA is the molecule that stores genetic information. Genes are specific segments of DNA that code for proteins. Chromosomes are structures made of DNA that contain many genes. Mutations are changes in DNA that can affect genes and chromosomes. A genetic alteration can cause disease because genes provide instructions to make proteins. If the DNA sequence changes, the protein may not function correctly, which can disrupt normal development or body functions. In my opinion, studying genetics is very important because it helps us understand how traits are inherited and how diseases can develop. Learning about DNA and mutations shows how small changes in genetic information can have significant effects. It also helps scientists develop better diagnostic tools and treatments. Genetics teaches us to appreciate biological diversity and understand the complexity of life.