bio wai

Chapter 1: Cell Structure and Organization

The Cell Theory

• Basic Unit of Life:

  • The cell is recognized as the basic unit of structure and organization in living organisms.

  • All organisms consist of one or more cells.

  • Cells arise from pre-existing cells.

What Are Cells?

• Cells are the building blocks of life and possess all characteristics of life.

Types of Cells:

1. Animal Cell

• Organelles include:

  • Endoplasmic Reticulum

  • Cytoplasm

  • Mitochondrion (plural: mitochondria)

  • Nucleus

  • Golgi Body

2. Plant Cell

• Organelles include:

  • Cell Wall

  • Large Central Vacuole

  • Chloroplast

  • Cell Surface Membrane

Key Functions of Cells

• Red Blood Cells (RBC):

  • Perform respiration to release energy.

  • Structure aids binding and transport of oxygen (no nucleus, biconcave shape).

• Root Hair Cell:

  • Increase surface area for absorption of water and minerals.

Cell Function and Structure Relation

• Differentiation:

  • Allows cells to specialize and adapt for specific functions (e.g., muscle cells vs. nerve cells).

Characteristics of Protoplasm

• Living material in cells consists of three parts:

  • Nucleus

  • Cytoplasm

  • Cell Surface Membrane

Cell Surface Membrane

• Also known as the plasma membrane.

• Partially Permeable:

  • Controls the exchange of substances in and out of the cell.

Nucleus

• Contains chromatin (DNA structure) which carries hereditary information.

• Surrounded by a nuclear envelope and contains nucleoli (sites of ribosome production).

Endoplasmic Reticulum (ER)

• Rough ER: Contains ribosomes for protein synthesis.

• Smooth ER: Synthesizes lipids and detoxifies certain chemicals.

Golgi Body

• Chemically modifies and packages substances for secretion.

Proteins

• Function in energy sources, synthesis of antibodies and hormones, and enzymes (e.g., amylase).

Carbohydrates

• Organic molecules primarily composed of carbon, hydrogen, and oxygen.

  • Classified into:

    • Monosaccharides: Simple sugars (e.g., glucose).

    • Disaccharides: Composed of two monosaccharides.

    • Polysaccharides: Long chains (e.g., glycogen, starch).

Food and Nutrition

• Nutrients provide energy for vital activities and maintain health.

Malnutrition

• Causes include imbalances or deficiencies in the diet.

  • Marasmus: Severe nutrient deficiency.

  • Kwashiorkor: Severe protein deficiency.

Page 2: Food Tests and Nutrient Identification

Test for Reducing Sugars

Reagent: Benedict's Solution

1. Add 20 cm³ of liquid food sample to a test tube.

2. Add 2.0 cm³ of Benedict's solution and shake.

3. Boil in a water bath for 2 minutes.

Observations & Results:

• Blue solution: Reducing sugar absent.

• Green to brick red precipitate: Indicates amounts of reducing sugars.

Test for Fats

Reagent: Ethanol

1. Crush solid food sample and mix with ethanol.

2. Shake and decant.

3. Add water.

Observations:

• Clear mixture: Fat absent.

• Cloudy white emulsion: Fat present.

Test for Proteins

Reagents: Biuret Solution

1. Add 2.0 cm³ of liquid food sample to a test tube.

2. Add Biuret solution drop by drop and shake.

Observations & Results:

• Blue solution: Protein absent.

• Violet solution: Protein present.

Functions of Proteins

• Source of energy, aid in synthesis of protoplasm, antibodies, hormones, and enzymes.

Starch Test

Reagent: Iodine Solution

1. Prepare crushed sample and add iodine.

Observations:

• Yellow-brown: Starch absent.

• Blue-black: Starch present.

Nutritional Sources of Fats and Proteins

• Animal Sources of Proteins: Dairy products, meat, eggs.

• Plant Sources of Proteins: Soybeans, nuts.

• Fats Classification:

  • Saturated: Found in animal fat, raises cholesterol levels.

  • Unsaturated: Found in plants (e.g., olive oil).

Structure of Proteins

• Made from long chains (polymers) of amino acids, formed by peptide bonds.

• Can denature when exposed to heat or acidic conditions.