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

Nervous System Fundamentals

• Nervous System Function: Control and communication.
• Autonomic Nervous System: Regulates internal organs.
• Central Nervous System (CNS): Controls most functions of the body and mind (brain and spinal cord).
• Peripheral Nervous System: Connects the CNS to limbs and organs (cranial and spinal nerves).

Brain and Spinal Structures

• Cerebrum: Senses, thoughts, and movements (frontal, parietal, temporal, occipital lobes).
• Cerebellum: Balance, coordination, and speech (anterior lobe, posterior lobe, primary fissure).
• Diencephalon (Thalamus): Processes sensory and motor signals.
• Diencephalon (Hypothalamus): Links the nervous system to the endocrine system.
• Medulla Oblongata: Controls breathing, swallowing, and heart rate.
• Pons: Connects

Human Receptors and Nervous System

Receptors: Structures that human beings use to detect stimuli.

Interoceptors

Collect information about the body’s internal conditions. Located in the internal environment.

Exteroceptors

Provide information from the body’s outside environment. Located on the surface of the body.

Proprioceptors

Inform about the relative position and condition of each of the body’s muscles. Found in the inner ear’s vestibule and locomotive system.

Eyes/Sight

Detect light stimuli. Photoreceptors

Ears/Hearing

Detect sound waves (Mechanoreceptors) and proprioception.

Nose/Smell

Detect substances dissolved in the air. Chemoreceptors

Mouth/Taste

Detects substances dissolved in liquids found in the oral cavity. Chemoreceptors

Skin/Touch

Detects... Continue reading "Human Receptors and Nervous System: An Overview" »

1. Telomerase is a ribonucleoprotein complex that consists of telomerase RNA (which contains several tandem hexanucleotide repeats complementary to the telomere repeats in the substrate) and a reverse transcriptase. This complex is able to synthesize telomeric repetitive DNA sequences at the end of linear DNA molecules. Telomerase RNA binds to the DNA strand, and complementary dNTPs are incorporated into newly synthesized, extended DNA strands by reverse transcriptase. Thus, dNTPs must also have been present during step 1 of the TRAP assay (step 1).

2. The PCR reaction mixture also contained a heat-resistant DNA polymerase (Taq polymerase).

3. Sample 3 contained cell extract isolated from immortal cells. In the presence of the telomerase, products... Continue reading "Telomerase Activity in Immortalized Cells" »

Blood Composition and Functions

Cells live immersed in a medium that provides them with all the nutrients they need. They also secrete the waste products released during metabolism into this medium. In multicellular organisms like humans, this medium is called the internal milieu and is made up of the interstitial plasma, a fluid found in the space between the cells. The interstitial plasma is renewed thanks to the blood, which continuously circulates around the whole body, providing nutrients and taking away waste products.

What is Blood?

Blood is a viscous fluid with a salty taste that flows inside the vessels that make up the circulatory system.

Blood Components

Blood is made up of cells suspended in a liquid called blood plasma.

• Blood plasma

Understanding Cells: Structure, Functions, and Types

The cell is the smallest unit of a living organism that can carry out vital functions: nutrition, interaction, and reproduction.

Essential Cell Components

All cells possess a plasma membrane, cytoplasm, and DNA.

• Plasma Membrane: This is a very thin and stretchy cover that separates a cell from its environment. Its primary function is to regulate the movement of substances in and out of the cell. It also detects environmental stimuli and allows cells to communicate.
• Cytoplasm: This is the substance contained inside the cell, in which the cell organelles are found. Metabolic processes occur within the cytoplasm.
• Genetic Material (DNA): A complex chemical substance that contains the information needed

Oparin’s Theory of the Origin of Life

1. The primitive atmosphere was made up of gases: ammonia, water vapor, methane, and hydrogen.
2. The energy for the first chemical reactions to occur came from volcanic eruptions, radiation from the sun, and storms.
3. The temperature of the Earth fell, so the water vapor condensed and formed seas.
4. Organic molecules, synthesized by the reactions, accumulated in the water and joined together to form bigger molecules.
5. Coacervates were structures formed by organic molecules insulated from the water.
6. The first cell appeared when the coacervates started to reproduce.

The Endosymbiotic Theory

The Endosymbiotic Theory of Margulis explains the appearance of the first eukaryotic living things from the symbiotic relationships... Continue reading "Origins of Life and Biological Evidence for Evolution" »

Skeletal System: Functions and Joints

Skeletal System Functions

• Support the body structure.
• Protect vital organs.
• Provide points of attachment for muscles.
• Manufacture blood cells (hematopoiesis).
• Store calcium and phosphorus.

Joints: Connections Between Bones

Joints are places where bones connect. They are classified by the degree of movement they permit:

• Fixed Joints (Synarthroses): Do not permit movement (e.g., skull sutures).
• Slightly Movable Joints (Amphiarthroses): Allow limited movement (e.g., vertebrae).
• Freely Movable Joints (Diarthroses): Allow bone movement in all directions (e.g., knee).

Sensory Receptors and Stimuli Perception

Types of Receptors

• Internal Receptors (Interoceptors): Perceive changes occurring inside the body (e.g., blood pressure,

The Origin of Life

The Concept of Life

In biology, life refers to the ability of living organisms to perform vital functions: nutrition, interaction, and reproduction.

These vital functions are common and essential to all living organisms, regardless of their level of complexity or organization. This is known as the constancy principle of vital functions.

Significance of Vital Functions

All living organisms interact with their environment.

The biological significance of vital functions lies in their ability to enable continuous interaction between living organisms and their environment.

The reproduction function allows new organisms to form, ensuring the species' longevity and evolution over time.
The interaction function enables organisms to respond... Continue reading "Life's Journey: From Origin Theories to Evolutionary Mechanisms" »

The Endocrine System

Endocrine glands: are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct.

Hormones: are any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.

Blood vessels: are the part of the circulatory system, and microcirculation, that transports blood throughout the human body.

Target cell: are cells that respond to a hormone because they possess specific receptors for that hormone.

Receptor: A molecule, usually a protein, that binds to a specific hormone, initiating a cellular response.

Endocrine Signaling Pathway Example