BIOLOGI Kelas 12 - Hereditas pada Manusia | GIA Academy

Introduction

This tutorial covers the topic of human heredity, specifically designed for 12th-grade biology students. It breaks down the key concepts of physical traits, gender, hereditary diseases, and blood groups. Understanding these topics is vital for grasping basic genetic principles and their applications in medicine and biology.

Step 1: Understanding Physical Traits and Gender

• Physical Traits: These are characteristics that can be observed, such as eye color, hair type, and height. They are determined by genetic inheritance from parents.
• Gender Determination: Gender is a biological characteristic influenced by chromosomes. Males typically have XY chromosomes, while females have XX chromosomes.

Step 2: Exploring Hereditary Diseases

Hereditary diseases can be classified based on their genetic transmission pathways: through gonosomes (sex chromosomes) and autosomes (non-sex chromosomes).

Gonosomal Diseases

These diseases are linked to the X and Y chromosomes. Common examples include:

• Color Blindness: Difficulty in distinguishing colors.
• Hemophilia: A bleeding disorder due to lack of blood-clotting factors.
• Anadontia: The absence of teeth.
• Webbed Toes: A condition where toes are fused together.
• Hirsutism: Excessive hair growth in women.
• Brown Teeth: Discoloration of teeth due to genetic factors.
• Hypertrichosis: Excessive hair growth on the body.

Autosomal Diseases

These diseases are inherited through non-sex chromosomes. Key examples include:

• Albinism: Lack of pigmentation in skin, hair, and eyes.
• Phenylketonuria (PKU): A metabolic disorder causing brain damage if untreated.
• Thalassemia: A blood disorder reducing hemoglobin production.
• Sickle Cell Anemia: A genetic blood disorder causing deformed red blood cells.
• Polydactyly: Having extra fingers or toes.
• Brachydactyly: Short fingers or toes.
• Anonychia: Absence of nails.
• Taste Blindness: Inability to taste certain flavors.
• Dentinogenesis Imperfecta: A genetic disorder affecting tooth development.
• Cataracts: Clouding of the lens in the eye.
• Baldness: Hereditary hair loss.

Step 3: Understanding Blood Groups

Blood groups are determined by specific antigens present on red blood cells. The main systems include:

ABO System

• Blood types are classified as A, B, AB, or O.
• The presence or absence of A and B antigens determines the blood type.

MN System

• This system is based on the presence of M and N antigens.

Rhesus Factor

• Determines whether blood type is positive or negative based on the presence of the Rhesus (Rh) antigen.

Conclusion

In summary, understanding heredity in humans involves recognizing how traits and diseases are passed down through generations. Key takeaways include the differentiation between gonosomal and autosomal diseases, the classification of blood groups, and the genetic basis of physical traits. For further learning, consider exploring genetic counseling or a deeper study into genetic engineering and its implications in modern medicine.