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

Applications of Proteins

Rubisco

• Catalyzes the CO₂ fixation reaction in the Calvin cycle.
• Full name: ribulose bisphosphate carboxylase.
• One of the most abundant and important enzymes.

Insulin

• Hormone produced by pancreatic beta cells.
• Reduces blood glucose levels by promoting glucose absorption.
• Binds reversibly to cell membrane receptors.

Immunoglobulins (Antibodies)

• Y-shaped proteins produced by plasma B cells.
• Identify and neutralize foreign pathogens.
• Act as markers for pathogen destruction by phagocytes.
• Each antibody is specific to a particular pathogen.

Rhodopsin

• Biological pigment in retinal photoreceptor cells.
• Consists of a retinal molecule surrounded by an opsin polypeptide.
• Light absorption changes its shape, sending a nerve impulse to the brain.

Balanced Diet and Nutrients

We need to eat a wide variety of foods to obtain all the necessary substances. A diet that includes a variety of foods is called a balanced diet. Carbohydrates, proteins, fats and oils (lipids), vitamins, and minerals are essential nutrients. These nutrients provide the raw materials our bodies need to function properly.

Food Testing

We can conduct tests to identify the substances present in our food. For example, starch turns iodine a blue-black color.

Nutrition Information Labels

Nutrition information labels on food products tell us about the food's composition and the amount of energy stored within it. Energy is measured in kilojoules (kJ). A person's daily energy needs depend on several factors:

• Level of activity
• Age
• Gender

Food... Continue reading "Balanced Diet and Nutrition: A Guide to Healthy Eating" »

The Nervous System

Central Nervous System (CNS)

Brain

Located inside the head, the brain is divided into three regions:

• Cerebrum: Receives and interprets information from the sense organs. Language, memory, learning, and thinking are located here.
• Cerebellum: Plays an important role in motor control and motor learning. It acts in coordination and precision.
• Brain Stem: Joins the brain and spinal cord. It controls involuntary actions.

Spinal Cord

A long, thin tube running inside the backbone, the spinal cord transports information from the brain to the nerves and carries reflexes.

Protection of the CNS

• Hard: Bones protect the CNS. The brain is protected by the skull, and the spinal cord is protected by the backbone.
• Soft: Meninges, a system of membranes

Population Dynamics and Carrying Capacity

Population dynamics refers to how populations change over time in response to environmental factors.

• The Carrying Capacity of a Habitat

  The carrying capacity (K) is the maximum number of individuals in a population that a specific environment can support sustainably.

• When the carrying capacity of a habitat is reached, the population size varies around that value due to two main causes:

  • Fluctuations: These are non-periodic changes caused by unpredictable environmental factors (e.g., disease, drought).
  • Cyclical Changes: These are predictable changes, such as seasonal variations (winter, spring) or the regular interaction between predators and prey populations.

Population Growth Strategies (K and R Selection)

The Function of Reproduction

Reproduction is a fundamental biological process involving several key stages:

• Gametogenesis: The formation of gametes (sex cells) which takes place in the gonads.
• Fertilization: The joining of two gametes to form a zygote, typically an internal process in humans.
• Embryo Development: Cell division increases the number of cells that make up the zygote, which becomes an embryo. This continues developing and eventually becomes a fetus.
• Childbirth: The birth of the baby, which is fully formed and alive.
• Development: The baby grows and reaches maturity (adulthood).

Sexual Maturity and Development

Sexual maturity involves significant changes, including the development of primary and secondary sex characteristics.

Puberty

Between... Continue reading "Human Reproduction: Stages, Systems, and Development" »

Antigen-antibody reactions

Ag + Ab AgAb

←

·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