Study sheet: Human Biology Exam 1

📋 Course Outline

1. Structural Organization and Homeostasis
2. Chemistry of Life
3. Biological Molecules and Enzymes
4. Cell Membranes and Organelles
5. Genes and Protein Synthesis

📖 1. Structural Organization and Homeostasis

🔑 Key Concepts & Definitions

• Homeostasis : the maintenance of a relatively stable internal environment through dynamic equilibrium

📝 Essential Points

• 🔄 The body's structural hierarchy proceeds through:

  1. atoms
  2. molecules
  3. organelles
  4. cells
  5. tissues
  6. organs
  7. organ systems
  8. organism

• The characteristics of life are: organization, cellular composition, metabolism, responsiveness and movement in response to stimuli, homeostasis, development, reproduction, evolution through mutations

• A feedback loop consists of a receptor detecting a change, a control center processing the information, and an effector producing a response.

📌 Negative feedback opposes an initial change to help maintain homeostasis, whereas positive feedback reinforces the initial change, as in childbirth.

💡 Memory Hook

Atoms → molecules → organelles → cells → tissues → organs → organ systems → organism

📖 2. Chemistry of Life

🔑 Key Concepts & Definitions

• Atomic number : the number of protons in an atom's nucleus
• Chemical bond : an attraction that holds atoms together through ionic, covalent, hydrogen, or Van der Waals interactions

★ Must-know

📌 Isotopes are atoms of the same element with different numbers of neutrons, whereas ions have gained or lost electrons and therefore carry a charge.

📌 Hydrophilic substances interact with water, whereas hydrophobic substances do not interact readily with water.

Further detail

• Reaction rate is affected by:
  • concentration
  • catalysts
  • temperature

📌 In redox reactions, oxidation is associated with exergonic reactions, whereas reduction is associated with endergonic reactions.

💡 Memory Hook

Hydrophilic substances interact with water, whereas hydrophobic substances avoid it.

📖 3. Biological Molecules and Enzymes

🔑 Key Concepts & Definitions

• Protein denaturation : the alteration of a protein's structure that can impair its function

📝 Essential Points

📌 Carbohydrates provide a class of organic compounds with characteristic properties and examples, whereas lipids include saturated and unsaturated forms.

• Amino acids join through peptide bonds to form proteins that can have primary, secondary, tertiary, and quaternary structures.

• Protein functions include:

  • catalysis
  • movement
  • transport
  • cell recognition
  • cell adhesion

• An enzymatic reaction proceeds through three steps: the substrate binds to the enzyme, the reaction occurs, and the products are released.

📌 ATP and cAMP are nucleotides, whereas DNA and RNA are nucleic acids involved in genetic information and protein synthesis.

📖 4. Cell Membranes and Organelles

🔑 Key Concepts & Definitions

• Plasma membrane : a cell surface structure composed of lipids and proteins that separates the cell from its surroundings

★ Must-know

• Membrane proteins function as:
  • enzymes
  • channel proteins
  • receptors
  • components of second-messenger systems
  • cell-identity markers
  • carriers

📌 Diffusion moves substances down a concentration gradient without carrier-mediated energy input, whereas active transport moves substances using energy.

• The listed cell organelles include:
  • lysosomes
  • the Golgi complex
  • ribosomes
  • peroxisomes
  • mitochondria

Further detail

• Vesicular transport includes phagocytosis, which takes in particles, and pinocytosis, which takes in fluid.

• Cell surface extensions include:

  • cilia
  • flagella
  • microvilli

📖 5. Genes and Protein Synthesis

★ Must-know

• DNA is a polymer of nucleotides containing phosphate, deoxyribose, and a nitrogenous base, with adenine pairing with thymine and guanine pairing with cytosine.

📌 A gene is a segment of genetic information, whereas the genome is the complete genetic material of an organism.

• Protein synthesis uses transcription to produce RNA from DNA and translation to use RNA information to assemble a protein.

• 🔄 Translation proceeds through:

  1. initiation
  2. elongation
  3. termination
  4. packaging or export

Further detail

• In the given genetic example, the DNA triplet CCT corresponds to the mRNA codon GGA, which specifies glycine.

• Mitosis is associated with DNA replication and cellular division.

💡 Memory Hook

DNA replication → transcription → translation → protein packaging or export

📊 Synthesis Tables

Major Genetic Molecules

Molecule	Role or feature
DNA	Stores genetic information
RNA	Participates in protein synthesis
ATP	Nucleotide
cAMP	Nucleotide