Bio120 Notes for Exam 1

Biology 120 Notes

Living Organisms

  • Cellular Composition:

    • Organisms are made of membrane-bound cells.

  • Reproduction:

    • All organisms are capable of reproduction.

  • Hereditary Information:

    • All organisms process hereditary information within genes and acquire information from the environment.

  • Energy Utilization:

    • Organisms require energy to stay alive.

  • Evolution:

    • Populations of organisms are continually evolving.

Scientific Method

  1. Formulate a Hypothesis:

    • A hypothesis is a testable statement.

  2. Gather Evidence:

    • Conduct experiments that allow researchers to test effects for observable results.

  3. Draw Conclusions:

    • Analyze the data to draw conclusions.

Definitions

  • Hypothesis: A testable statement made before conducting an experiment.

  • Prediction: A measurable outcome expected from a hypothesis.

Hypothesis Testing Steps

  1. State the hypothesis and list predictions.

  2. Design a study to test the predictions.

  3. If data disproves, reformulate hypothesis.

Good Experimental Design Criteria

  • Includes a control group.

  • Tests alternative hypotheses.

  • Maintains experimental conditions as constant.

  • Essential to repeat tests with a large sample size.

Theories in Modern Biological Science

  1. Cell Theory:

    • All living organisms are composed of cells.

  2. Theory of Evolution by Natural Selection:

    • Explains how species evolve over time.

  3. Chromosome Theory of Inheritance:

    • Explains how hereditary information is transmitted from one generation to the next.

Null Hypothesis

  • A hypothesis indicating no effect; specifies what is observed when the hypothesis is incorrect.

Ant Experiment Example

  • Experiment Setup: A team of scientists studied ants to test the "pedometer hypothesis".

    • Groups Created:

    • Group with stumps (very short legs).

    • Group with normal legs.

    • Group with stilt legs (bristles glued to legs).

  • Hypothesis Results:

    • If the hypothesis is incorrect, there should be no correlation with stride length and the number of steps.

Chapter 3: Protein Structure and Function

  • Four Classes of Macromolecules:

    • Proteins

    • Nucleic Acids

    • Carbohydrates

    • Lipids

  • Three Fundamental Attributes of Life:

    • Information

    • Replication

    • Evolution

Proteins

  • Building Blocks:

    • Composed of amino acids.

Amino Acid Structure

  • Components:

    • Central carbon atom bonded to:

    • Hydrogen atom

    • Amino functional group (NH2)

    • Carboxyl functional group (COOH)

    • Variable side chain (R-group)

  • Forms of Amino Acids:

    • Ionized forms in water, affecting their chemical reactivity.

Polymerization of Amino Acids

  • Amino acids polymerize through a condensation reaction forming peptide bonds:

    • Peptide Bond: A covalent bond between the carboxyl group of one amino acid and the amino group of another.

    • Terminology:

    • Oligopeptide: Few < 10-20 peptide bonds.

    • Polypeptide: ≥ 50 amino acids in a chain.

    • Protein: Complete functional form of a molecule formed from amino acid chains.

Protein Diversity

  • Primary Structure: Unique sequence of amino acids; diverse sequences can create thousands of variations.

  • Secondary Structure: Formed by hydrogen bonds between carbonyl group and amino group of different amino acids, resulting in:

    • Alpha-helix

    • Beta-pleated sheet

  • Tertiary Structure: Overall three-dimensional shape of a protein, influenced by interactions between R-groups, causing bending and folding.

  • Quaternary Structure: Formed by the binding of two or more polypeptide subunits, leading to the formation of dimers (two identical subunits) or heterodimers (two different subunits).

Protein Interactions

  • Various interactions contribute to the protein's tertiary and quaternary structures:

    1. Hydrogen Bonds: Form between polar side chains and strong, opposite partial charges.

    2. Hydrophobic Interactions: Nonpolar side chains congregate due to water's properties.

    3. Van der Waals Interactions: Weak electrical interactions between hydrophobic side chains.

    4. Covalent Bonds: Disulfide bonds between side chains of cysteine residues.

    5. Ionic Bonds: Between groups with full, opposing charges.

Protein Folding

  • Protein folding is spontaneous and results in more stable molecular configurations. Molecular chaperones aid in this process by preventing inappropriate interactions.

Nucleic Acids

  • Components:

    • Nucleotides (consist of phosphate group, five-carbon sugar, and a nitrogen base).

    • RNA Monomer: Ribonucleotide

    • DNA Monomer: Deoxyribonucleotide

DNA Structure

  • DNA strands form an antiparallel double helix with a sugar-phosphate backbone.

  • Base pairs form hydrogen bonds, contributing to the stability of the structure.

  • Functions of DNA:

    • Stores information for growth and reproduction.

    • Used to create new strands through complementary base pairing during replication.

DNA Replication Process

  1. Strands separate.

  2. Free deoxyribonucleotides bond with complementary bases.

  3. Phosphodiester linkages form to create a new strand.

RNA Structure and Function

  • Characteristics:

    • Contains ribose instead of deoxyribose; has uracil instead of thymine.

    • More reactive and less stable than DNA.

  • Roles of RNA:

    • Involved in protein synthesis as mRNA; can regulate production and act as catalysts in some reactions.

Carbohydrates

  • Essential for cell structure, energy storage, and identity in organisms.

  • Types:

    1. Monosaccharides

    2. Oligosaccharides

    3. Polysaccharides

  • Forms & Functions:

    • Carbohydrates consist of carbonyl and hydroxyl groups with a general formula (C(H2O))n.

    • Monosaccharides are the simplest sugars and are critical in chemical evolution (e.g., ribose for nucleotide formation).

Sugar Structure Differences

  • Differentiated by:

    1. Location of the carbonyl group (aldose or ketose).

    2. Number of carbon atoms (trioses, pentoses, hexoses).

    3. Variations in spatial arrangement and hydroxyl groups.

    4. Linear vs. ring forms.

Di- and Polysaccharides

  • Formed through glycosidic linkages constructed from condensation reactions of hydroxyl groups.

    • Common examples include starch, glycogen, cellulose, and chitin.

Lipids

  • Carbon-containing compounds that are hydrophobic and form integral parts of cell membranes and energy storage.

  • Types of Lipids:

    1. Fats (triglycerides)

    2. Phospholipids

    3. Steroids

Fats

  • Composed of fatty acids and glycerol; formed via ester linkages.

  • Can be saturated (single bonds, solid at room temperature) or unsaturated (double bonds, liquid at room temperature).

Phospholipids

  • Comprise glycerol linked to two fatty acids and a phosphate group; form the cell membrane.

Cell Membranes

  • Function as selective barriers allowing the entry of nutrients and preventing harmful materials from entering.

Key Takeaways

  • Carbohydrate Functions: Serve as energy sources, structural support, and are critical in cell signaling and identity. Derived from photosynthesis in plants.

  • Energy Storage: Glucose is broken down through cellular respiration to release ATP for energy.