General Biology: Homeostasis, Diabetes, Scientific Method, and Gene Expression Flashcards

Comprehensive flashcards covering key topics from Module 1 through Module 3: human hierarchy of life, cell theory, homeostasis, blood glucose regulation (insulin/glucagon), Type 1 and Type 2 diabetes, the scientific method, nutrition, DNA structure, protein synthesis, gene expression, and cancer.

What are the three core principles of the Cell Theory?

1. All living things are made of one or more cells.
2. The cell is the basic unit of structure and organization.
3. All cells arise from pre-existing cells.

What is the structural hierarchy of human organization from simplest to most complex?

Atoms, molecules, macromolecules, organelles, cells, tissues, organs, organ systems, and the whole organism.

How is a tissue defined in human biology?

An integrated group of similar cells that work together to perform a specific function.

What are the four major types of tissues found in the human body?

Muscle tissue, nerve tissue, epithelial tissue, and connective tissue.

Which tissue types are depicted in this diagram?

Epithelial tissue, nerve tissue, muscle tissue, and connective tissue.

How is an organ defined?

A structure consisting of two or more types of tissues that work together to perform a specific function.

How many major organ systems exist in the human body?

$11$ organ systems (Skeletal, Muscular, Circulatory, Nervous, Immune/Lymphatic, Endocrine, Respiratory, Digestive, Urinary, Reproductive, and Integumentary).

What is homeostasis?

A "steady state" in which the internal conditions of the body remain relatively constant regardless of changes in the external environment.

How does negative feedback control maintain homeostasis?

A deviation from an optimal setpoint is sensed, an action is triggered to bring the condition back to the setpoint, and the corrective action terminates once baseline is restored.

What is a positive feedback loop, and what is a physiological example of it?

A feedback mechanism that amplifies changes and moves the body further away from homeostasis, such as oxytocin release stimulating increasingly frequent contractions during labor.

What are the four essential components of a negative feedback control system?

Stimulus, sensor, control center, and effector.

What is the normal fasting range for human blood glucose?

Between $70$\text{ mg/dl} and $100$\text{ mg/dl}.

How does the human body respond when blood glucose levels spike above normal?

The pancreas senses the spike and releases insulin, which signals cells to absorb glucose from the blood and directs the liver and muscles to store excess glucose as glycogen.

How does insulin facilitate the entry of glucose into body cells?

Insulin binds to insulin receptors on the cell surface, acting like a key that unlocks and opens closed glucose channels in the plasma membrane.

How does the human body respond when blood glucose levels drop below normal?

The pancreas releases the hormone glucagon, which signals the liver to break down stored glycogen into glucose and release it into the bloodstream.

In what tissues and molecular forms is excess glucose stored in the body?

Excess glucose is stored as glycogen in muscle and liver tissue, and as lipids in fat cells.

What are the immediate physical symptoms caused by a complete lack of effective insulin?

Weight loss, fatigue, weakness, hunger, frequent urination, dehydration, excessive thirst, and increased susceptibility to infections.

What is Type 1 diabetes, and what causes it?

An autoimmune disease in which the immune system attacks and destroys the insulin-producing cells of the pancreas, resulting in a total absence of insulin production.

What is the prevalence of Type 1 diabetes in the United States?

About $5$ in every $1000$ adults and $4$ in every $1000$ children.

What is insulin resistance?

A condition in which target cells (particularly muscle and fat cells) fail to respond normally to insulin, preventing glucose from being cleared efficiently from the blood.

What percentage of diabetes cases in the US are Type 2 diabetes?

$90\%$ to $95\%$ of all diabetes cases.

What proportion of adult Americans are estimated to have prediabetes?

About $38\%$ of adult Americans.

What is the primary approach for treating and reversing insulin resistance in Type 2 diabetes?

Lifestyle changes, particularly improvements in diet and physical exercise.

What is the difference between a primary scientific source and a secondary scientific source?

A primary source is a peer-reviewed, original research paper written by scientists, whereas a secondary source interprets, summarizes, or translates primary scientific findings for a broader public audience.

What are the core steps of the scientific method in sequential order?

Observation, Question, Hypothesis, Experiment, Results, and Conclusions.

What is a scientific hypothesis?

A proposed explanation for an observation or a proposed answer to a testable empirical question.

What is the distinction between an independent variable and a dependent variable?

The independent variable is the factor being intentionally manipulated or changed as a potential cause, while the dependent variable is the measured outcome, effect, or response under investigation.

What is the role of a control group in a scientific experiment?

To serve as a baseline comparison group that does not receive the active experimental treatment, isolating the experimental variable and verifying the validity of the results.

What is the placebo effect?

A psychological or physiological response in which a participant shows improvement simply because they believe they received an active treatment.

How do single-blind and double-blind experimental designs differ?

In a single-blind study, experimental information is withheld from participants; in a double-blind study, information is withheld from both participants and experimenters to reduce bias.

Why does correlation not equal causation?

Because two variables moving together in pattern does not prove that one variable causes the other; unconsidered confounding variables may be responsible.

What is the chemical composition of the human body by percentage?

$70\%$ Water, $24\%$ Organic Compounds, and $6\%$ Inorganic Compounds.

What are the four major categories of organic macromolecules found in living organisms?

Proteins, Carbohydrates, Lipids, and Nucleic Acids.

How do macronutrients differ from micronutrients?

Macronutrients (proteins, carbohydrates, lipids) are required in large quantities to provide energy and structural building blocks; micronutrients (vitamins, minerals) are needed in smaller amounts for essential metabolic functions.

What is metabolism?

The sum total of all chemical reactions occurring within an organism.

What monomers form proteins, and how many common ones do cells utilize?

Amino acids; cells utilize about $20$ common amino acids.

What three distinct structural parts make up a nucleotide monomer?

A pentose sugar, a phosphate group, and a nitrogenous base.

What are the base-pairing rules for DNA?

Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C).

How many total chromosomes are contained inside the nucleus of a human somatic cell?

$46$ chromosomes.

What is a gene?

A specific sequence or section of DNA that contains instructions for constructing one protein or a polypeptide chain.

What are the two steps of protein synthesis, where do they occur, and what templates do they use?

1. Transcription: DNA is used to make mRNA inside the nucleus.
2. Translation: mRNA is read to build a polypeptide chain at ribosomes in the cytoplasm.

How does RNA differ structurally from DNA in its nitrogenous bases?

RNA is single-stranded and contains Uracil (U) instead of Thymine (T).

What is a codon in translation?

A three-nucleotide sequence on mRNA that codes for a specific amino acid.

What is gene expression?

The process by which a gene is turned "on," transcribing its DNA into mRNA and translating it into a functional protein.

What are the two major phases of the cell cycle and their relative time proportions?

Interphase ($90\%$ of the cell's lifespan, spent performing normal functions) and the Mitotic phase ($10\%$ of the time, spent actively dividing).

What fundamental biological failure leads to cancer?

Uncontrolled cell division caused by genetic mutations in the genes that regulate the cell cycle.