General Biology Final Exam Study Guide: Cells, Bioenergetics, Genetics, and Protein Synthesis

Unit 1 – Biomolecules & Cells

Prokaryotic and Eukaryotic Cells

Understanding the differences between prokaryotic and eukaryotic cells is fundamental to cell biology. Both cell types share some features but differ in complexity, structure, and function.

• Prokaryotic cells lack a nucleus and membrane-bound organelles; their DNA is found in the nucleoid region.

• Eukaryotic cells have a true nucleus and various membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum).

• Both cell types possess a plasma membrane, cytoplasm, and ribosomes.

Diagram: Draw and label a prokaryotic cell (e.g., Escherichia coli) and a eukaryotic cell (e.g., animal or plant cell), highlighting the nucleus, organelles, and cell wall (if present).

Phospholipid Bilayer Structure

• Phospholipids are amphipathic molecules with hydrophilic (polar) heads and hydrophobic (nonpolar) tails.

• In aqueous environments, phospholipids spontaneously form bilayers, with tails facing inward and heads facing outward.

• This structure forms the basis of cellular membranes, providing selective permeability.

Example: The plasma membrane of animal cells is a phospholipid bilayer embedded with proteins and cholesterol.

Membrane Proteins and Transport

• Integral and peripheral proteins serve roles in transport, signaling, and structural support.

• Transport mechanisms include passive diffusion, facilitated diffusion, and active transport.

• Different types of molecules (e.g., ions, glucose) use different transport proteins or channels to cross the membrane.

Unit 2 – Bioenergetics & Cell Signaling

Energy Conversion in Cells

Cells convert energy from nutrients into usable forms (ATP) through metabolic pathways such as cellular respiration and photosynthesis.

• Cellular respiration involves glycolysis, the citric acid cycle, and oxidative phosphorylation.

• Photosynthesis occurs in chloroplasts and converts light energy into chemical energy (glucose).

• ATP is the universal energy currency of the cell.

ATP Cycle and Energy Coupling

• ATP is synthesized from ADP and inorganic phosphate ($ADP + P_i \rightarrow ATP$) during exergonic reactions.

• ATP hydrolysis ($ATP \rightarrow ADP + P_i$) releases energy to drive endergonic cellular processes.

• Energy coupling links exergonic and endergonic reactions via ATP.

Cell Signaling Pathways

• Cells communicate via chemical signals (ligands) that bind to specific receptors.

• Signal transduction involves a cascade of molecular events, often including phosphorylation by kinases.

• Responses include changes in gene expression, metabolism, or cell behavior.

Example: The insulin signaling pathway regulates glucose uptake in animal cells.

Unit 3 – Cell Cycle & Genetics

Cell Cycle Phases

The cell cycle is the series of events that cells go through as they grow and divide.

• Interphase: Includes G1 (growth), S (DNA synthesis), and G2 (preparation for mitosis).

• Mitosis: Division of the nucleus, followed by cytokinesis (division of the cytoplasm).

• Checkpoints regulate progression to ensure DNA integrity and proper chromosome segregation.

Genetics: Chromosomes and Gene Expression

• Genes are segments of DNA that code for proteins or functional RNAs.

• Chromosomes are structures composed of DNA and proteins (histones) that carry genetic information.

• Gene expression involves transcription (DNA to RNA) and translation (RNA to protein).

Example: In humans, somatic cells are diploid (2n), containing two sets of chromosomes, while gametes are haploid (n).

Unit 4 – Making Proteins

Transcription and Translation

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

• Transcription occurs in the nucleus (eukaryotes) or cytoplasm (prokaryotes) and is catalyzed by RNA polymerase.

• Translation occurs at ribosomes, where mRNA is decoded to synthesize polypeptides.

• Key steps: initiation, elongation, and termination.

Gene Structure and Regulation

• Genes consist of coding regions (exons), non-coding regions (introns, in eukaryotes), promoters, and regulatory sequences.

• Regulation of gene expression can occur at transcriptional, post-transcriptional, translational, and post-translational levels.

Comparison of Prokaryotic and Eukaryotic Protein Synthesis

Feature	Prokaryotes	Eukaryotes
Location of Transcription	Cytoplasm	Nucleus
RNA Processing	None	5' cap, poly-A tail, splicing
Translation Initiation	Shine-Dalgarno sequence	5' cap recognition
Coupling of Transcription & Translation	Yes	No

Overarching Critical Thinking Questions

• How do the chemical nature of biomolecules and the environment of early Earth facilitate the formation of a cell?

• What are the similarities and differences between prokaryotic and eukaryotic cells in terms of genetic content and compartmentalization?

• How is energy transformed from nutrients into ATP, and how does ATP power cellular work?

• What are the mechanisms of gene regulation, and how do they differ between prokaryotes and eukaryotes?

• How do mutations in DNA affect protein structure and function, and what are the consequences for the organism?

Additional info: Students should be able to draw and label diagrams, explain processes, and compare mechanisms across cell types. Understanding the integration of structure and function is key to mastering these topics.