Science to Support Our Lifestyles

Applied Science

Chromosomes & DNA

Chromosomes & DNA

Structures in the cell nucleus carrying genetic instructions. Humans have 23 pairs.

Genes

Specific DNA segments coding for traits. Different forms are called alleles (e.g., eye color).

Variation

Alleles can cause different traits (e.g., blue vs. brown eyes).

Double Helix

DNA is structured as two coiled strands.

Base Pairs

Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

Punnett Squares

Predict inheritance probabilities.

Genotype

Genetic makeup (e.g., AA, Aa).

Phenotype

Observable traits (e.g., eye color).

Recessive Allele

Expressed only with two copies (e.g., aa).

Dominant Allele

Masks recessive traits (e.g., A in Aa).

Mutations

Changes in DNA, which can be harmless, beneficial, or harmful.

Inheritance

Mutations in germ cells can be passed to offspring.

Down's Syndrome

Cause: Extra copy of chromosome 21 (trisomy 21).

Effect: Developmental and physical challenges.

Anorexia

Extreme calorie restriction.

Obesity

Excessive weight gain with health implications.

GDA

General daily nutrient recommendations.

RDA

Specific daily nutrient needs.

Food Labelling

Includes traffic light labels, use-by dates.

Insulin

Regulates blood glucose levels.

Type 1 Diabetes

Autoimmune destruction of insulin cells.

Type 2 Diabetes

Insulin resistance and reduced production.

Alpha Radiation

Low penetration, high ionising.

Beta Radiation

Moderate penetration and ionising.

Gamma Radiation

High penetration, low ionising.

External Radiotherapy

Uses X-rays from outside the body.

Internal Radiotherapy

Radioactive sources placed inside or near the tumor.

Criteria for Selection of Radioisotopes

Factors: Half-life, type of radiation, medical purpose.

Chemotherapy

Uses chemicals to kill or inhibit cancer cells. Often combined with radiotherapy.

Medical Imaging

• X-rays: Bones and some organs.

• Ultrasound: Soft tissues, pregnancy monitoring.

• MRI: Detailed images of soft tissues

Ultrasound

Pregnancy monitoring, diagnosing conditions.

X-rays

Two-dimensional images.

CAT Scans

3D imaging, combines multiple X-ray images.

Antigens

Foreign molecules recognized by the immune system.