Notes, summaries, assignments, exams, and problems for Biology

Structural Components of Viruses

• Capsid: Protein shell that encloses a viral genome; may be rod-shaped, polyhedral, or more complex in shape
• Viral envelopes: Membrane that cloaks the capsid that in turn encloses a viral genome

Obligate Intracellular Parasites

Viruses can only reproduce within host cells because they lack metabolic enzymes, ribosomes, and other equipment for making proteins.

• Identifying host cells: "Lock and key" fit between proteins on the outside of the virus and specific receptor molecules on the host's surface (which originally evolved for functions that benefit the host).

Bacterial Defenses Against Phages

While phages have the potential to wipe out a bacterial colony in just hours, bacteria have defenses against phages:

• Natural

Applications and Skills

Comparison of Water and Methane Thermal Properties

Water and methane are small molecules with similar covalent structures, yet their physical properties differ significantly due to water's polarity.

Since water is polar, it has stronger intermolecular attraction (hydrogen bonds) and therefore has a much greater specific heat capacity, latent heat of vaporization, melting point, and boiling point.

Water as a Coolant in Sweat

• Water is essential to living organisms.
• Water

Evolutionary Theories

Punctuated Equilibrium vs. Neo-Darwinism vs. Neutralism

• All three theories propose evolutionary change.
• Punctuated Equilibrium: Evolutionary changes occur rapidly and abruptly.
• Neo-Darwinism: Evolutionary changes occur gradually over time.
• Neutralism: Most mutations have no effect on natural selection.

Barriers to Genetic Isolation

• Geographical
• Sexual
• Physiological
• Chromosomal
• Ethological

Ecological Concepts

Abiotic and Biotic Factors

• Abiotic Factors: Non-living factors that affect ecosystems (e.g., temperature, pH, wind)
• Biotic Factors: Living components that affect ecosystems (e.g., disease, predation, competition)

Biomass

- Total dry weight of organic matter in organisms or ecosystems. - Includes carbohydrates, proteins, etc.

Ecosystems

Water: The Essential Solvent

Water constitutes approximately 80% of the human body and plays a crucial role in biological systems.

Role of Water as a Solvent

Water is an important solvent, a liquid in which substances (or solutes) are dissolved, forming a solution. In a solution, the solvent is typically present in a greater amount than the solute.

Metabolic reactions, which are vital for life, can only take place if the chemicals reacting are dissolved in water.

Other Vital Functions of Water

Water is also essential for other reasons, such as being the primary component of plasma, the liquid part of blood, facilitating transport throughout the body.

Carbohydrates: Energy & Structure

Carbohydrates include starches and sugars, and are composed of... Continue reading "Fundamental Biological Molecules: Water, Carbohydrates, Lipids, Proteins, DNA" »

Proteins

  

∑ - Amino acids are linked together by condensation to form polypeptides.

• Amino acids are then combined to create large polypeptides through condensation reactions which produce many molecules of water (i.e. polypeptides - Hemoglobin and Insulin).

B  Skill: Drawing molecular diagrams to show the formation of a peptide bond.

• Basic dipeptide shown to the right. Students should practice drawing  with a variety of different amino acids (different “R” groups)
  
• Every peptide bond should be between the NH2 (amine group) and the COOH (carboxyl group). One H comes from the NH2 and an –OH group comes from the –COOH group to produce H2O
  
• Condensation reaction
  

∑ - There are 20 different amino acids in polypeptides synthesized on ribosomes.

Complete the statements.

1. There are 206 bones in the skeletal system of an adult.
2. Babies are born with almost 300 bones in their body.
3. The largest bone in the body is the femur.
4. The only floating bone is called the hyoid and it is located under the tongue.
5. The skeletal system has two main jobs: protect and support.

Complete the table with the functions of the skeletal system.

Label the parts of the skeletal system.

• Bones: They

Natural Selection and Sickle-Cell Anemia

This is how natural selection can keep a harmful allele in a gene pool.

• The allele (S) for sickle-cell anemia is a harmful autosomal recessive. It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
• Malaria is a deadly tropical disease.
• Heterozygotes (AS) with the sickle-cell allele are resistant to malaria. Therefore, they are more likely to survive

Fundamental Properties of Muscle Tissue

Muscles possess unique characteristics that allow them to function effectively within the body:

• Excitability: They can receive and respond to stimulation from the brain.
• Contractility: They can contract (shorten) following stimulation.
• Extensibility: They can expand (stretch) through the application of force.
• Elasticity: They return to their original shape and length after being contracted or extended.

Structural Hierarchy of Skeletal Muscle

The connection from bone to the functional unit of the muscle follows a specific hierarchy:

Bones → Muscles (via Tendons) → Fascicle → Muscle Fiber → Myofibrils (containing Sarcomeres)

Neural Control of the Knee-Jerk Reflex

During a reflex action, such as a knee tap,... Continue reading "Muscle Physiology and Cardiac Mechanics Fundamentals" »