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

Lamarck: The Evolution of Giraffes

1. The ancestors of giraffes had shorter necks and legs than nowadays.
2. As giraffes tried to reach the leaves on the top branches of the trees, their necks and legs grew.
3. Offspring inherited these characteristics.

Darwin: Natural Selection and Giraffe Evolution

1. Giraffes originally had some variation in the length of their necks and legs.
2. Natural selection favored the giraffes with longer necks and legs, leading to increased offspring.
3. As a result, the number of giraffes with long necks and legs increased.

Amniocentesis: Prenatal Genetic Anomaly Detection

Amniocentesis is a technique used in prenatal diagnosis to search for possible genetic anomalies. It involves extracting a sample of amniotic fluid and studying the fetal... Continue reading "Evolution of Giraffes and Human Ancestors: Lamarck vs Darwin" »

Polygenic Inheritance vs. Monogenic Inheritance

Polygenic inheritance refers to the kind of inheritance in which a trait is produced from the cumulative effects of many genes. This is in contrast to monogenic inheritance, wherein a trait results from the expression of one gene (or one gene pair). In humans, height, weight, and skin color are examples of polygenic inheritance, which does not follow a Mendelian pattern of inheritance.

Linkage Groups, Sex Chromosomes, and Autosomal Chromosomes

• Linkage group: A pair or set of genes on a chromosome that tend to be inherited together.
• Sex chromosomes are the ones that determine your gender. These are X and Y (XX in females, XY in males).
• Autosomal chromosomes are the remaining chromosomes that are not

Key Plant Cell Terms: A Comprehensive Glossary

Amyloplast

Amyloplasts are non-pigmented organelles found in some plant cells. They are responsible for the synthesis and storage of starch granules through the polymerization of glucose. Amyloplasts also convert this starch back into sugar when the plant needs energy.

Cell Wall

The cell wall is a tough, usually flexible but sometimes fairly rigid layer that surrounds certain types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, in addition to acting as a filtering mechanism. A major function of the cell wall is to act as a pressure vessel, preventing over-expansion when water enters the cell.

Nucleus

The nucleus is a membrane-enclosed... Continue reading "Key Plant Cell Terms: A Comprehensive Glossary" »

Amylase begins the digestive process by breaking down starch when you chew your food, converting it into a smaller carbohydrate. Pepsin helps digest the proteins in food because amylase is at the mouth and the pepsin at the stomach.

Chyle

Is a body fluid in the small intestine. It is turbid and milky due to the presence of emulsified fats. Is formed from the chyme during the digestion of fatty foods.

Intestinal Flora

Is the symbiotic bacteria occurring naturally in the gut.

Defecation

Is the final action of digestion, by which organisms eliminate solid, semisolid, or liquid waste material from the digestive tract via the anus.

Mechanical Digestion

This is the enzymatic breakdown of large, complex molecules found in food into smaller, simpler, more... Continue reading "Understanding Digestion, Blood Composition, and the Endocrine System" »

What is a Plasma Membrane, and Do All Cells Have One?

The plasma membrane encloses the cytoplasm and the cell's genetic material. It regulates what enters and exits the cell. Yes, all cells have a plasma membrane.

What Are the Two Central Tenets of Cell Theory?

• All organisms are composed of cells.
• Cells come only from preexisting cells.

What Are the Two Main Types of Cells?

• Prokaryotic cells lack a membrane-bound nucleus.
• Eukaryotic cells have a nucleus that houses DNA.

Where Do Prokaryotic Cells Store Their Genetic Material?

In the nucleoid.

What Domains Do Prokaryotic Cells Belong To?

Archaea and Bacteria.

What Are Three Characteristics of Prokaryotic Cells?

• They are much smaller and simpler than eukaryotic cells.
• They reproduce very quickly and effectively

Essential Medical Concepts

Key Definitions in Health and Immunity

What is Health?

Health is a combination of physical, mental, and social well-being, indicating a state where an individual is not suffering from a disease.

Understanding Antigens

An antigen is a substance that is perceived by lymphocytes and triggers a specific immune response.

Phagocytes: Immune System Defenders

A phagocyte is a specific type of white blood cell that activates when a pathogen crosses the first line of defense.

The Body's Defense Mechanisms

Understanding Immunity and Protection

Non-Specific Immune Response

When a pathogen crosses the first line of defense, the second line of defense is activated. This non-specific response is carried out by specific white blood cells, such... Continue reading "Human Body Defenses and Therapeutic Interventions" »

Characteristics of Living Organisms

Movement

A change of position or place.

Respiration

A chemical process in which oxygen is used to release energy from sugar molecules. Most of it happens in the mitochondrion.

Sensitivity

The ability to detect or sense changes in the environment (stimuli) and to make responses.

Growth

A permanent increase in size by increasing cell number, cell size, or both.

Reproduction

The process that makes more of the same kind of organism.

Excretion

The removal of toxic materials, waste products, and excess substances from an organism.

Nutrition

The process in which nutrients are taken into the body and converted into simpler substances used for energy, growth, and tissue repair.

Cell Structure and Organization

Cells can be classified... Continue reading "Fundamental Concepts of Biology: Cells & Life Processes" »

Pharmacology 2

Dependence: physical response, addiction: behavioral.

Pharmacodynamic principle Placebo effect: patient experiencing relief of symptoms or effect that cannot be attributed to medication. Receptor theory; receptor site, binding site for drug molecule, lock & key. Responses agonist(enhances support encourages response) antagonist( inhibits response drug fits receptor but fails to initiate) neutral(no response). Dose response relationship: inc drug concentration =inc potential receptor site=inc biological effect. Steady state: maintaining blood levels within therapeutic range.

Anti-inflammatories: Steroids: end in -one. NSAIDS: selective(COX2 inhibit celebrex) non selective: upset stomach (salicylates, propionic acid, enolic acid,... Continue reading "Pharmacology 2: Pharmacodynamics, Anti-inflammatories, and Homeostasis" »

The Digestive System

The digestive system transforms food into nutrients that are the right size to reach body cells and be absorbed. To carry out this function, the digestive system consists of a group of organs and structures: the digestive tract and the accessory glands.

The Digestive Tract

The digestive tract, in order from top to bottom, includes:

• Mouth: The entry point of the digestive tract. It contains:
  • Teeth to bite and break food into small pieces.
  • A tongue to mix and swallow food, and enable the sense of taste.
  • Salivary glands.
• Pharynx: A cavity shared by the digestive and respiratory systems. Food passes towards the esophagus. The epiglottis, a small, flexible cartilage, prevents food from reaching the respiratory tract.
• Esophagus: A tube

What is VSG and why is it important in pathogenesis caused by Trypanosoma?

VSG stands for Variant Surface Glycoprotein, and it plays a crucial role in the pathogenesis caused by Trypanosoma, the parasitic protozoa responsible for diseases like African trypanosomiasis.

The importance of VSG lies in its ability to undergo antigenic variation. Trypanosomes have a dense coat of VSG on their cell surface, providing a protective barrier against the host's immune system. The parasite, however, can continually switch between different VSG variants, making it challenging for the host's immune system to mount an effective and lasting defense.

This antigenic variation is a key survival strategy for Trypanosoma during the course of infection. As the immune... Continue reading "VSG and Winterbottom's Sign in Trypanosoma Pathogenesis" »