BIO_Class_Notes__2_

5.1 Inheritance

• Gregor Mendel: Known as the "father of genetics" for his experiments with pea plants.

• Pea Plants:

  • Chosen for their ability to self-pollinate, quick reproduction, and control in breeding.

• True Breeding Organisms:

  • Produce offspring that are genetically identical for one or more traits via self-pollination.

• Generations:

  • P Generation: Parental generation differing by one characteristic.

  • F1 Generation: Offspring of P generation, monohybrids differing by one characteristic.

  • F2 Generation: Result of F1 breeding, showing a ratio of 3:1 for dominant to recessive traits.

• Law of Segregation:

  1. Organisms inherit two copies of genes (one from each parent).

  2. Organisms donate one copy of each gene to gametes.

• Alleles:

  • Different forms of a gene; each organism has 2 alleles.

  • Homozygous: Two identical alleles (e.g., two purple flower genes).

  • Heterozygous: Two different alleles (e.g., one purple and one white flower).

  • Genotype: The genetic makeup (e.g., PP, Pp, pp).

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• Phenotypes: The observable characteristics determined by the genotype.

• Punnett Squares: Used to predict allele combinations from both parents.

• Test Cross: A cross to determine an organism's genotype by crossing it with a recessive genotype.

  • Dominant phenotype indicates homozygous dominant; both dominant and recessive phenotypes indicate heterozygous.

Types of Dominance

1. Complete Dominance: Dominant allele fully expressed regardless of the other allele.

2. Incomplete Dominance: Blending of traits (e.g., red and white flowers produce pink).

3. Codominance: Both alleles expressed independently (e.g., type AB blood).

Blood Type Genetics

• Four blood types: A, B, AB, O.

• Controlled by alleles IA, IB, i:

  • Type A: IAIA or IAi.

  • Type B: IBIB or IBi.

  • Type AB: IAIB.

  • Type O: ii.

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• Humans have one set of sex chromosomes (X or Y) and 22 pairs of autosomes.

Pedigree Analysis

• Pedigree: Chart showing genetic relationships across generations.

• Sex Linkage:

  • Sex-linked alleles found on X or Y chromosomes.

  • X-linked: More common in males due to their single X chromosome.

  • Y-linked: Fewer disorders due to limited genes on the Y chromosome.

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Genetic Disorders

• Disorders: Result from mutations in alleles.

  • Recessive gene inheritance can be assessed through carrier testing and genetic screening.

Examples of Genetic Disorders

• Cystic Fibrosis: Causes thick mucus in lungs, leading to infections.

• Breast Cancer: Linked to mutations in BRCA1 and BRCA2 genes.

• Phenylketonuria (PKU): Recessive disorder that leads to the accumulation of phenylalanine, affecting development if untreated.

Multi-Trait Inheritance

• Dihybrid Cross: Cross between two heterozygous genes results in a 9:3:3:1 ratio.

• Law of Independent Assortment: Alleles segregate independently into gametes.

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Variations in Heredity

• Discontinuous Variation: Traits with distinct categories, e.g., gender.

• Continuous Variation: Traits with a range of phenotypes, e.g., skin color.

Nutritional Needs

• Eating: Provides energy for biological processes and maintenance of body functions.

• Metabolism: All chemical reactions in the body.

Energy Measurement

• Basal Metabolic Rate (BMR): Rate of energy use at rest.

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Nutrients

• Macromolecules: Nucleic acids, carbohydrates, proteins, lipids.

• Micronutrients: Vitamins and minerals.

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Digestion Overview

1. Indigestion: Physical intake of food.

2. Digestion: Breakdown of food mechanically and chemically.

3. Absorption: Nutrient transfer to the bloodstream.

4. Egestion: Removing undigested matter.

Digestive Processes

• Physical Digestion: Chewing; breakdown of food via teeth.

• Chemical Digestion: Enzymatic breakdown in the stomach.

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Structure and Function of the Stomach

• Gastroesophageal sphincter: Regulates food entry.

• Chemical Digestion: Gastric juices (HCl and pepsin) break down food into simpler forms.

Common Stomach Issues

• Acid Reflux: When gastric contents back up into the esophagus.

• Stomach Ulcers: Damage to the stomach lining due to acid exposure.

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Digestion in the Small Intestine

• Three sections: Duodenum, Jejunum, Ileum.

• Villi and Microvilli: Increase surface area for nutrient absorption.

Accessory Digestive Structures

• Pancreas: Releases enzymes for digestion and hormones for glucose regulation.

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Nausea and Eating Disorders

• Nausea: Often precedes vomiting; can be treated with antihistamines.

• Eating Disorders:

  • Anorexia Nervosa: Extreme weight loss due to starvation.

  • Bulimia: Binge eating followed by purging.

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Gas Exchange and Respiration

• External Respiration: Gas exchange in the alveoli from atmosphere to blood.

• Internal Respiration: Gas exchange between blood and cells.

Efficiency of Cellular Respiration

• Cells consume oxygen and produce ATP while releasing CO2.

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Respiratory System Anatomy

• Lungs: Enclosed in thoracic cavity, protected by rib cage.

• Airway Structures: Nose, trachea, bronchi, and bronchioles facilitate air movement.

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Gas Exchange Mechanism

• Alveoli: Thin-walled sacs that enable efficient gas exchange.

• Ventilation Mechanics: Inhalation requires contraction of intercostal muscles.

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Breathing Control

• Brain Regulation: Signals contraction for inhalation and relaxation for exhalation.

• Influence of Aerobic Activity: Increased CO2 levels during exercise.

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Respiratory Disorders

• Asthma: Chronic inflammation reducing airflow due to swelling.

• COPD: Long-term condition with bronchitis and emphysema leading to restricted airflow.

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Circulatory System Functions

• Transport: Moves oxygen, nutrients, hormones, and metabolic wastes throughout the body.

Types of Circulatory Systems

• Open Circulatory System: Blood mixes with tissue fluid.

• Closed Circulatory System: Blood circulates within vessels.

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Heart Structure and Circulation

• Heart Chambers: Includes two atria and two ventricles.

• Two-Circuit Circulation: Separates pulmonary (lungs) from systemic (body) circuits.

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Blood Composition

• Blood Components: Made of plasma (liquid) and cellular components (RBCs, WBCs, platelets).

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Arteries and Blood Flow

• Arteries: Carry blood away from the heart under high pressure; consist of three layers.

• Arterioles: Smaller arteries capable of constriction and dilation.

Coronary Artery Disease

• Causes: High blood pressure, cholesterol, and lifestyle factors lead to artery hardening.

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Heart Attack Mechanism

• Myocardial Infarction:

  1. Plaque rupture leads to clot formation.

  2. Blood flow blocked, causing cell death.

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Nutrient Requirements for Plants

• Key elements: Nitrogen, phosphorus, potassium.

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Plant Structure and Function

• Vascular Plants: Roots anchor; stems support; leaves conduct photosynthesis and gas exchange.

• Transport Mechanisms: Nutrients and water are absorbed and transported via osmosis and active transport.

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Plant Reproduction

• Asexual Reproduction: Involves vegetative reproduction and rhizomes.

• Sexual Reproduction: Involves male and female structures (stamens and stigma).

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Plant Growth Factors

• Influenced by light, water, temperature, and nutrients available.

• Phototrophism: Growth direction influenced by light.

Chemical Influences on Growth

• Plant Hormones: Auxins, gibberellins, cytokinins regulate growth responses to environmental changes.