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

• Many carbon-based molecules are made of many small subunits bonded together.
• Monomers are the individual subunits.
• Polymers are made of many monomers.
• Four main types of carbon-based molecules are found in living things.
• Carbohydrates are made of carbon, hydrogen, and oxygen. Include sugars and starches. Carbohydrates can be broken down to provide energy for cells. Some carbohydrates are part of cell structure.
• Monosaccharides are simple sugars.
• Polysaccharides include starches, cellulose, and glycogen.
• Polymer (starch)
• Starch is a polymer of glucose monomers that often has a branched structure.
• Polymer (cellulose)
• Cellulose is a polymer of glucose monomers that has a straight, rigid structure
• Many contain carbon chains called fatty acids.
• Fats and oils

Gene and Alleles

• A gene is a unit of heredity that occupies a specific locus on a chromosome.
• A locus is a specific location on a chromosome where a gene is located.
• Alleles are different forms of a gene that occupy the same locus on homologous chromosomes.

Hardy-Weinberg Equilibrium

• The Hardy-Weinberg equilibrium is a population genetics model that describes the frequencies of alleles and genotypes in a population that is not evolving.
• The five conditions for Hardy-Weinberg equilibrium are:
  1. No mutation
  2. No gene flow
  3. No genetic drift
  4. Random mating
  5. No natural selection

Population Genetics

• Population genetics is the study of the genetic variation within populations.
• Genetic variation is the presence of different alleles in a population.
• The gene pool is the

Sternocleidomastoid

Origin:

• Sternal head: Manubrium of sternum
• Clavicular head: Medial 1/3 of clavicle

Insertion: Outer surface of mastoid process, lateral 1/3 of superior nuchal line
Nerve Supply:

• Motor: Accessory nerve
• Sensory: C2, C3

Action:

• Both muscles contract: Flexes neck forward
• One muscle contracts: Bends neck to the opposite side and rotates to the same side

Relations:

• Superficial: Skin
• Deep: Carotid sheath

Digastric Muscle

Origin:

• Anterior belly: Lower border of mandible
• Posterior belly: Digastric notch of mastoid process

Intermediate tendon: Connected to hyoid bone
Nerve Supply:

• Anterior belly: Mylohyoid nerve
• Posterior belly: Facial nerve

Function:

• Anterior belly: Depresses mandible, elevates hyoid bone
• Posterior belly: Elevates hyoid bone, retracts mandible

Relations:

Nutrition: The digestive system (introduces food and transforms it), respiratory system (obtains O₂ and eliminates CO₂), circulatory system (transports nutrients and oxygen), and excretory system (releases waste substances outside the organism). Digestive System The gastrointestinal tract (about 8 meters long, starts in our mouth and ends at our anus) consists of the following parts: oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine. The mucus, produced by an inner cell called the mucous membrane, creates a lubricant substance called mucus. Accessory glands include salivary glands, the liver, and the pancreas. Digestion: This is the process by which foods are transformed into nutrients. Mechanical processes (like... Continue reading "Understanding the Human Digestive and Respiratory Systems" »

Human Tissue Types and Skeletal Components

Muscle Tissue

• Muscle tissue: Cells that can contract.
• Skeletal muscle: Moves bones.
• Smooth muscle: Involuntary muscles found in the digestive system and blood vessels.
• Cardiac muscle: Makes up the heart.

Nervous Tissue

• Nervous tissue: Made of cells that receive and transmit messages.
• Neurons: Specialized nerve cells.

Epithelial and Connective Tissue

• Epithelial tissue: Layers of cells that line internal and external body surfaces.
• Connective tissue: Binds, supports, and protects structures in the body.
• Matrix: Intracellular substance that holds cells in tissue.

Body Cavities

• Cranial cavity: Contains the brain.
• Spinal cavity: Holds the spinal cord.
• Thoracic cavity: The upper part of the torso.
• Abdominal cavity: The lower

Key Terminology of the Human Body

Receptor

Part of the body that receives signals from the environment or other cells and transmits information.

Stimulus

A signal that results in changes in the body.

Feeling

The ability to notice or feel physical sensations.

Eyebrow

A row of hair above the eye.

Eyelash

Small hair on our eyelids which protects our eyes.

Bactericide

A substance that kills bacteria.

Cavity

A hole, for example in bones or teeth.

Temporal Bone

One of a pair of bones forming part of the sides and base of the skull.

Vibration

A small movement, which the body can sense.

Texture

The structure or substance of something and how it feels.

Pressure

Applying force to something.

Pain

A sensation you feel when you are hurt.

Saliva

A colorless liquid which mixes with

Understanding Ecosystems

An ecosystem encompasses all plants, animals, and other organisms in a specific location, along with its climate. It also includes the relationships among organisms (e.g., for food) and between organisms and their environment.

Biotope: The Physical Environment

The Lymphatic System

The lymphatic system is a crucial part of the immune system, especially in the immune response.

• Lymphatic vessels allow accumulating lymph to carry and filter out pathogens through lymph nodes.
• The majority of lymphocytes are found in the lymphatic system. For example, T cells mature in the thymus while B cells mature in the bone marrow.

Humoral Immune System

The humoral response, which occurs in blood and lymph, primarily uses B cells to combat pathogens directly. B cells are triggered and activated by helper T cells before they can fight pathogens. When B cells encounter a pathogen they recognize, they engulf the foreign substance and display the antigens on their cell surface. Helper T cells then bind to these antigens, triggering... Continue reading "The Lymphatic System and Immunity Explained" »

Understanding Cells: The Building Blocks of Life

Cells are the fundamental building blocks of all living organisms.

Cell Structure Essentials

A typical cell consists of several key components:

• Plasma membrane: A very thin, stretchy cover composed of lipids, proteins, and carbohydrates that separates the cell from its external environment.
• Cytoplasm: The jelly-like substance filling the cell, enclosing the organelles.
• Genetic material (DNA): A complex chemical substance containing the genetic information necessary to regulate the cell's functions.

Prokaryotic vs. Eukaryotic Cells

Cells are broadly classified into two types based on the location and organization of their DNA:

Prokaryotic Cell Characteristics

• Kingdom: Monera (bacteria).
• Cellularity: Typically

Cellular Respiration Stages

Glycolysis: Sugar Breakdown

Breaks down a 6-carbon sugar into two 3-carbon groups.

Krebs Cycle Location and Output

Occurs in the inner membrane of the mitochondria.

Forms 2 ATP.

ETC and ATP Synthase Function

Finishes the breakdown of pyruvic acid molecules to CO₂.

Forms 34 ATP.

ATP and ADP Explained

ATP (Adenosine Triphosphate) becomes ADP (Adenosine Diphosphate) when one phosphate is given away, leaving only two.

ADP becomes ATP when one phosphate is added to complete the three phosphates.

Electron Transport Chain Role

A sequence of electron carrier molecules that transfers electrons and releases energy during cellular respiration.

Fermentation: ATP Without Oxygen

When cells exercise and there is not enough O₂, they use fermentation... Continue reading "Biology Essentials: Cells, Respiration, Anatomy" »