General Biology I: Study Guide for Exam 1 – Key Concepts and Learning Objectives

Scientific Method and Science

Understanding the Scientific Method

The scientific method is a systematic approach used in science to investigate phenomena, acquire new knowledge, or correct and integrate previous knowledge. It is based on observable, empirical, and measurable evidence.

• Definition: The scientific method involves making observations, forming hypotheses, conducting experiments, analyzing data, and drawing conclusions.

• Steps:

  1. Observation

  2. Question

  3. Hypothesis

  4. Experiment

  5. Analysis

  6. Conclusion

• Scientific Theory vs. Everyday Theory: In science, a theory is a well-substantiated explanation based on evidence, while in everyday language, "theory" may refer to a guess or speculation.

• Hypothesis: A testable statement that can be supported or refuted through experimentation.

• Example: Testing whether plants grow faster under blue light than red light.

Experimental Design and Data Analysis

Designing Experiments and Interpreting Data

Experiments are designed to test hypotheses by manipulating variables and observing outcomes. Proper experimental design is crucial for obtaining valid and reliable results.

• Experimental Design: Includes control and experimental groups, independent and dependent variables.

• Data Presentation: Data can be presented in graphs, tables, and statistical summaries.

• Correlation vs. Causation: Correlation indicates a relationship between variables, while causation shows that one variable directly affects another.

• Example: Using a scatterplot to show the relationship between temperature and enzyme activity.

Cell Structure and Function

Basic Cell Biology

Cells are the fundamental units of life. They can be classified as prokaryotic or eukaryotic, each with distinct structures and functions.

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles (e.g., bacteria).

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals).

• Cell Organelles: Include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and more.

• Example: The mitochondrion is the site of cellular respiration and energy production.

DNA, Genes, and Chromosomes

Structure and Function of DNA

DNA (deoxyribonucleic acid) is the molecule that stores genetic information in living organisms. Its structure allows for replication and transmission of genetic traits.

• DNA Structure: Double helix composed of nucleotides (adenine, thymine, cytosine, guanine).

• Base Pairing: Adenine pairs with thymine, cytosine pairs with guanine.

• Gene: A segment of DNA that codes for a specific protein.

• Chromosome: A DNA molecule with part or all of the genetic material of an organism.

• Example: Human cells have 46 chromosomes (23 pairs).

Protein Synthesis

Transcription and Translation

Protein synthesis involves two main processes: transcription (DNA to RNA) and translation (RNA to protein).

• Transcription: DNA is transcribed into messenger RNA (mRNA).

• Translation: mRNA is translated into a protein at the ribosome.

• Genetic Code: The sequence of nucleotides in mRNA determines the sequence of amino acids in a protein.

• Example: The codon AUG codes for the amino acid methionine.

Genetics: Mendelian Principles

Inheritance Patterns

Genetics is the study of heredity and variation. Mendelian genetics explains how traits are inherited through dominant and recessive alleles.

• Allele: Different forms of a gene.

• Genotype: The genetic makeup of an organism.

• Phenotype: The observable traits of an organism.

• Homozygous: Two identical alleles for a trait.

• Heterozygous: Two different alleles for a trait.

• Punnett Square: A diagram used to predict the outcome of a genetic cross.

• Example: Crossing two heterozygous pea plants (Yy x Yy) yields a 3:1 ratio of yellow to green peas.

Chromosomes and Cell Division

Mitosis and Meiosis

Cell division is essential for growth, development, and reproduction. Mitosis produces identical cells, while meiosis produces gametes with half the chromosome number.

• Mitosis: One cell divides to produce two genetically identical daughter cells.

• Meiosis: One cell divides to produce four genetically unique gametes.

• Homologous Chromosomes: Chromosomes that have the same genes but may have different alleles.

• Example: Human gametes (sperm and egg) have 23 chromosomes each.

Population Genetics

Gene Pool and Allele Frequencies

Population genetics studies the distribution and changes of allele frequencies in populations, which is fundamental to understanding evolution.

• Gene Pool: The total collection of genes in a population.

• Allele Frequency: The proportion of a specific allele among all alleles in a population.

• Genotype Frequency: The proportion of a specific genotype among all individuals in a population.

• Phenotype Frequency: The proportion of individuals with a specific phenotype.

• Hardy-Weinberg Equation: Used to calculate allele and genotype frequencies in a population not evolving.

Key Equations:

• $p + q = 1$ (where p and q are the frequencies of two alleles)

• $p^2 + 2pq + q^2 = 1$ (genotype frequencies for a gene with two alleles)

Table: Comparison of Mitosis and Meiosis

Feature	Mitosis	Meiosis
Number of Divisions	1	2
Number of Daughter Cells	2	4
Genetic Identity	Identical	Unique
Chromosome Number	Diploid	Haploid
Function	Growth, repair	Sexual reproduction

Additional info:

• Some context and definitions were expanded for clarity and completeness.

• Examples and equations were added to support key concepts.