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

Antigen-antibody reactions

Ag + Ab AgAb

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·reversible reaction as there are formed noncovalently biochemical bonds

·strength of such interactions is called affinity

·different immunoglobulins within an individual show a wide range of affinity

·valence - number of epitope-binding sites of one immunoglobulin molecule

·avidity - describes the collective affinity of multiple binding sites (affinity + valence)

·e.g. although IgM has a low affinity, its avidity is quite high due to 10 epitope-binding sites

·...

Primary and secondary immune response

·primary immune response

ofirst contact to a foreign antigen that has to be eliminated from the body

ofirst a lag/induction phase (ca. 7-9 days or even up to months) occurs in which no antibody is produced,... Continue reading "Antibody Reactions, Immune Response, and Immunologic Memory" »

Core Concepts in Biology

Biodiversity

Species that inhabit or have ever inhabited the Earth.

Adaptation

The accumulation of changes in a living being to suit the environment in which it lives.

Types of Adaptation

• Structural: Affects organs and allows for specific functions, e.g., birds' beaks.
• Physiological: Affects the organism's function and metabolism.
• Behavioral: Actions that provide advantages, e.g., migration.

Evolutionary Theories

Biodiversity and Evolution

Slow changes in living beings over millions of years.

Fixism (Georges Cuvier)

Organisms were created through divine creation and became extinct due to catastrophes. This theory posited that species could not change, a view contrasted by later evolutionary theories.

Lamarckism (Jean-Baptiste de

The Digestive System

The digestive system is responsible for the ingestion, digestion, absorption, and elimination of food. It transforms food into nutrients through three main processes:

1. Mechanical Digestion: Chewing, grinding, crushing, and mixing of food to break it down into smaller pieces.
2. Chemical Digestion: Digestive juices break down macromolecules in food into smaller molecules that can be absorbed.
3. Absorption: Nutrients are absorbed into the bloodstream and transported to cells throughout the body.

Ingestion

Ingestion begins when food enters the mouth. Key steps include:

• Mastication (Chewing): Teeth tear and break food into smaller pieces.
• Salivation: Saliva mixes with food, forming a bolus and aiding in swallowing.
• Swallowing: The tongue

Photosynthesis Fundamentals

Photosynthesis: Carbon Compound Production

• Living organisms require complex carbon compounds to carry out life processes and build the structures in their cells.
• Photosynthesis involves the conversion of light energy into chemical energy (carbohydrates, lipids, proteins, and nucleic acids).
• Chloroplasts absorb light energy from the sun and convert this energy into chemical energy (glucose) to be used by the organisms for energy.

Visible Light Spectrum and Wavelengths

• Light from the sun is composed of a range of wavelengths.
• The visible spectrum is the portion of the electromagnetic spectrum that is visible to or can be detected by the human eye.
• Electromagnetic radiation in this range of wavelengths (380 to 750 nm) is called

Inorganic biomolecules

Essential for non-living things.

• Water: The most abundant substance found in living things. It makes up about 65% of the human body.
• Mineral salts: Substances that can be found in living things in the form of dissolved ions, such as sodium ion.

Organic biomolecules

Unique to living things. Structures made up of carbon.

• Carbohydrates: Made of carbon and water.
• Lipids: Fats, phospholipids, and cholesterol.
• Proteins: Chains of amino acids.
• Nucleic acids: Groups of nucleotides.

The cell: Functions

• Structural
• Functional
• Basic
• Biological

Prokaryotic cell

• No nucleus
• Organelles: Ribosomes
• Bacteria are prokaryotes
• Membranes: Cell membrane, cell wall, and bacterial capsule (not always)
• Flagella and Fimbriae

Eukaryotic cell

• Nucleus
• Cell membrane: two

Cell Organelles

Mitochondria: Oval-shaped organelles with two membranes. Through cellular respiration, mitochondria produce energy for the cell.

Vesicles: Small, rounded organelles that store, transport, or digest cellular substances. Lysosomes are rounded vesicles produced by the Golgi body.

Endoplasmic Reticulum: A network of interconnected membranous sacs and channels. There are two types:

• Rough ER: Connected with the nuclear envelope and ribosomes.
• Smooth ER: This type has no attached ribosomes.

Golgi Body: Flat, membranous sacs arranged in layers. Secretory vesicles transport substances out of the cell.

Centrosome: Consists of two centrioles: perpendicular cylindrical structures composed of microtubules. They are surrounded by other microtubules... Continue reading "Cell Organelles and Food Preservation Techniques" »

Human Reproduction: Fundamental Processes

Human reproduction is sexual, meaning that both the mother and father contribute genetic material to their offspring via gametes. Offspring will have a mix of their parents' characteristics, and each person obtains their own unique genetic make-up.

The female gametes, ovules, and the male gametes, sperm, fuse together in the process called fertilisation, inside the female reproductive system, to form a zygote.

The embryo develops from the zygote inside the mother's uterus, undergoing repeated cell divisions. The new cells created specialise to form tissues and organs.

Sexual Characteristics and Puberty

Boys and girls are born with different reproductive organs, which constitute the so-called primary sexual

Cellular Division: Meiosis and Mitosis

Meiosis has two rounds of genetic separation and cellular division, while mitosis only has one of each.

Key Differences

• Meiosis: Homologous chromosomes separate, leading to daughter cells that are not genetically identical.
• Mitosis: The daughter cells are genetically identical to the parent cell, as well as to each other.

Male Reproductive System

Primary Sex Organs

A pair of testes (singular: testis) lying outside the abdominal cavity, enclosed in a sac called the scrotum.

Secondary Sex Organs and Accessory Structures

Seminiferous Tubules

These tubules unite to form a long, coiled structure called the epididymis. They are involved in sperm production.

Epididymis

A long, coiled structure that acts as the main storage

All cells in your body are surrounded by a liquid environment. They depend on it to stay alive. The internal environment is made up of the interstitial fluid and the circulating fluids. Lymph is the fluid that flows through the lymphatic vessels. It is formed from the remaining interstitial fluid. Blood is the fluid in charge of transporting substances through the inside of blood vessels. Interstitial fluid is the fluid that surrounds every cell. Cells extract nutrients, oxygen and release into the waste and carbon dioxide produced in cell metabolism. The circulatory system connects the system involved in the nutrition function with the interstitial fluid that surrounds the cells in the body. It has 2 systems: the cardiovascular system through... Continue reading "Understanding the Circulatory System and Its Functions" »