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

Nucleic Acid Structure and Function

• Nucleoside: A part of a nucleotide made up of one sugar (ribose or deoxyribose) and one nitrogenous base (pyrimidine or purine) joined together by N-glycosidic bonds.
• Nucleotide: Simple molecules that form large molecules called nucleic acids. It is formed by a nitrogenous base, sugar, and three phosphate groups.
• Chromatin: Bundles of DNA and proteins; the normal state of the genetic material during interphase.
• Chromosome: Structures formed by the condensation of chromatin that appear when the cell is about to divide.
• Centromere: A bond that joins two sister chromatids; it's where the microtubules are attached to the chromosome during the division process.
• Telomere: The end of the arms of a chromosome, which prevents

• 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

The Nervous System

The nervous system allows us to respond to changes in our environment and coordinate our actions. It consists of two key parts:

• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)

The Peripheral Nervous System

The peripheral nervous system is divided into two components:

• Autonomic Nervous System: Controls unconscious activities. It is further split into the sympathetic nervous system (prepares the body for action) and the parasympathetic nervous system (calms the body down).
• Somatic Nervous System: Controls conscious activities and connects the CNS with the senses.

Neurons and Neurotransmission

Cells of the nervous system are called neurons (nerve cells). They transmit information as electrical impulses throughout the body.... Continue reading "Understanding the Human Nervous System and Brain Functions" »

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