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

Head and Neck Anatomy Q&A

• 33. Zygomaticus minor muscle insertion: From the anterior portion of the zygomatic bone to the upper lip.
• 34. Buccal nerve innervation: Posterior and inferior portion of the vestibule, buccal side of the gums of premolars and molars, and skin of the cheek.
• 35. Terminal branches of the infraorbital nerve: Palpebral, nasal, and labial.
• 36. Tensor tympani muscle innervation: Medial pterygoid nerve (branch of the trigeminal nerve).
• 37. Cerebellar peduncles connection: Connects the cerebellum with the brainstem.
• 38. Temporalis muscle insertion: Medial side of the coronoid process.
• 39. Main nerves in the sublingual region: Lingual and hypoglossal nerves.
• 40. Arteries arising from the anterior external carotid: Superior thyroid,

Organelles and Functions:

• Rough Endoplasmic Reticulum: Responsible for the assembly of many proteins • Cell Membrane: Controls the movements in & out of the cell and organelles • Golgi Apparatus: Process and bundle macromolecules like proteins and lipids • Mitochondria: Perform cellular respiration 0 Breaks nutrients into energy • Nucleus: Contains a majority of the genetic material • Nucleolus: Rewrite ribosomal RNA and combine it with proteins • Smooth Endoplasmic Reticulum: Makes cellular products like hormones and lipids • Lysosome: Digestion and waste removal • Flagella: Allows cells to move • Vesicle: Transport vesicles move molecules within the cell • Ribosomes: Makes proteins within cells • Cytoskeleton:... Continue reading "Structure of garter and grendel model cell membrane" »

Cell Membrane Transport and Internal Systems

Roles of Membrane Proteins

Membrane proteins perform vital functions necessary for cell survival, communication, and structural integrity.

Adhesion Proteins

• Embedded in the membrane, primarily located on either the outer or inner cell surface.
• They anchor the cell in position within the extracellular matrix or anchor structures inside the cell.

Communication Proteins (Gap Junctions)

• Span the entire membrane.
• Connect to gap junctions in a neighboring cell.
• Form large channels between cells, connecting their cytoplasm.
• Facilitate chemical and electrical signaling between adjacent cells.

Receptor Proteins

• Embedded in the membrane, with the receptor site exposed on one side.
• Signal molecules (i.e., hormones) bind

Cell Transport: Endocytosis vs. Exocytosis

• Similarity and Difference:

• Both are forms of active transport (specifically vesicle transport).
• Endocytosis brings materials into the cell, while exocytosis moves them out.

Cell Response to Solute Concentration

Understanding how a cell reacts to different external solute concentrations:

• Hypertonic: More solute outside the cell than inside. Water travels out of the cell.
• Isotonic: Balanced solute concentration inside and outside the cell. Water travels in and out at the same rate.
• Hypotonic: More solute inside the cell than outside. Water travels into the cell.

The Endosymbiotic Theory

Origin of Eukaryotic Organelles

This theory states that organelles such as chloroplasts and mitochondria were once free-living... Continue reading "Cell Transport and Organelle Evolution Concepts" »

Spermatogenesis

Occurs in the seminiferous tubules, which contain interstitial cells that secrete testosterone. The walls of the tubules contain germ cells. As they multiply, they move towards the end until they mature to become spermatozoa.

Oogenesis

Takes place in the ovaries and is divided into two stages:

1. Fetal Development: The female develops immature ova while still an embryo in the mother's womb. Each ovum is surrounded by cells to form structures called follicles. Follicles with immature ova inside stop developing until the woman reaches puberty.
2. Ovarian Cycle: Occurs in cycles of approximately 28 days. Follicles grow, and the ovum inside matures. The release of the mature ovum from the ovary is called ovulation. Typically, females ovulate

Fat vs. CHO

CHO is both aerobic and anaerobic, BUT it has limited stores. It does, however, have a greater energy yield per unit of O2 (fat is about 10% less).

Sparing CHO

Sparing CHO by upregulating lipid oxidation should be advantageous. This leads to:

• More lipid oxidation
• Decreased sympathetic nervous system activity (recruitment of CHO)
• Increased mitochondrial volume and enzymatic adaptations
• Reduction in signals that activate major CHO metabolic enzymes

In lower exercise intensity, more FFA and TG are present in plasma. The more intense the exercise becomes, the more glycogen/glucose is used. At ~62% of VO2 max, the highest lipid oxidative rate is experienced.

Nutritional Strategies to Improve Lipid Oxidation

• High-fat diets: long term vs. short

Human Nutrition

Human nutrition requires the coordinated function of the digestive, respiratory, circulatory, and excretory systems.

The Human Digestive System

The human digestive system involves the following processes:

• Ingestion: Intake of food.
• Digestion: Mechanical and chemical breakdown of food.
• Absorption: Transfer of nutrients from the digestive tract into the blood or lymph.
• Egestion: Elimination of substances that can't be absorbed.

Organs of the Digestive System

• Mouth: The entrance to the digestive tract.
• Pharynx: A muscular tube that connects the digestive system to the respiratory system.
• Esophagus: A muscular tube around 25 cm long; it is normally closed but opens when food is ingested.
• Stomach: Connected to the esophagus via a sphincter,

Protein Synthesis and Protein Structure

Definition of Proteins

Proteins are large molecules formed by the union of amino acids. There are 20 unique amino acids, of which 8 are considered essential because they cannot be synthesized by living organisms. Proteins differ from each other based on the specific order (sequence) of these amino acids.

Functions of Proteins

• They form part of cellular structures.
• They are involved in cellular metabolism.

The Synthesis Process (Gene Expression)

Protein synthesis occurs in two main phases:

1. Transcription: Information transfer from DNA to mRNA (occurs in the nucleus).
2. Translation: Information transfer from mRNA to Protein (occurs in the cytoplasm, involving ribosomes).

Transcription: DNA to mRNA

Genetic information... Continue reading "Molecular Mechanisms of Gene Expression and DNA Replication" »