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

Understanding Mitosis and Cell Division

Mitosis is a way of producing new cells. It takes place when organisms are growing or replacing damaged cells. Asexual reproduction is a type of reproduction that involves only one parent. During mitosis, the nucleus of the cell divides so that the daughter cell has an identical set of genes as the parent cell. Genes are carried in the nucleus in long strings called chromosomes. Nearly all cells contain 46 chromosomes in each nucleus. The newly formed cells are called clones, which are exact replicas of the parent cell.

Meiosis and the Production of Gametes

Meiosis is another way of producing new cells. It results in gametes, which have half the number of chromosomes as the parent cell. It happens in the... Continue reading "Cell Division and Human Reproduction Processes" »

Respiratory System

Fetus: developing unborn baby.

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