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

Cell Structure and Function

Cell Membrane

The cell membrane is a dynamic structure known as the fluid mosaic model, consisting of:

• Phospholipid Bilayer: Forms the basic structural framework.
• Proteins: Integral proteins (embedded in the membrane) and peripheral proteins (attached to the membrane surface).
• Cholesterol: Provides stability and regulates fluidity.
• Carbohydrates: Often attached to proteins (glycoproteins) or lipids (glycolipids) for cell recognition.

Energy Flow and Metabolism

• Energy Flow: From sunlight to producers (photosynthesis) and then through consumers (cellular respiration).
• Matter Cycling: Carbon, nitrogen, and other elements cycle through living organisms and the environment.
• Metabolism Types: Anabolism (building molecules) and Catabolism

Pharyngeal Arches

• First Arch: Mandibular nerve, Meckel's cartilage, muscles of mastication, tensor tympani, mylohyoid, anterior belly of the digastric
• Second Arch: Facial nerve, Reichert's cartilage (hyoid bone), muscles of facial expression, posterior belly of the digastric, stylohyoid, stapedius
• Third Arch: Glossopharyngeal nerve, hyoid bone, stylopharyngeus muscle
• Fourth Arch: Vagus nerve, laryngeal cartilages, soft palate muscles (except tensor veli palatini), pharyngeal muscles (except stylopharyngeus)
• Fifth Arch: Vagus nerve, no specific structure, arytenoid muscle
• Sixth Arch: Vagus nerve (recurrent laryngeal), no specific structure, intrinsic muscles of the larynx (except cricothyroid and arytenoid)

Pharyngeal Pouches

• First Pouch: Auditory tube

Microorganisms: Definitions and Characteristics

Place the correct number in the boxes to match the organism with its definition.

1. Fungus: A spore-producing organism that absorbs nutrients from the environment.
2. Protist: Any eukaryotic organism that is not an animal, plant, or fungus.
3. Bacteria: A prokaryotic organism with peptidoglycan in its cell walls.
4. Archaea: A prokaryotic organism without peptidoglycan in its cell walls.
5. Virus: A microscopic particle that cannot replicate on its own.

Understanding Hosts in Biology

A host is:

• An infected protein
• A prokaryotic organism
• A living thing that a virus or parasite uses for shelter
• A cell destroyed by a virus

Extreme Habitats of Archaea

Label these extreme habitats of Archaea with the correct names from the box:... Continue reading "Microorganisms, Reproduction, and Species Classification" »

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

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