BIO1000 Exam 1 Comprehensive Study Guide Flashcards

Flashcards covering all core concepts, application scenarios, and study guide questions for BIO1000 Exam 1.

What is cancer and how is it defined?

Cancer is a group of diseases characterized by uncontrolled cell division and growth, leading to the formation of malignant tumors that can invade surrounding tissues and spread throughout the body.

What percentage of Americans will be diagnosed with some form of cancer in their lifetime?

Approximately 40% (or 39.5%) of Americans will be diagnosed with some form of cancer in their lifetime.

How do environmental/lifestyle factors compare to inherited genetic factors in cancer risk?

Environmental and lifestyle exposures (such as smoking, UV radiation, and diet) strongly influence cancers like lung and skin cancer, whereas inherited genetic components involve mutations passed down through families that increase susceptibility to cancers such as hereditary breast or ovarian cancer.

What is the defining structural difference between a benign tumor and a malignant tumor (cancer)?

A benign tumor is a non-cancerous growth of cells that stays localized and does not invade surrounding tissue or spread, whereas a malignant tumor (cancer) invades nearby tissues and has the ability to metastasize.

How do normal cells regulate growth, and how is this control lost in cancer cells?

Normal cells regulate growth using cell cycle checkpoints, growth factors, and contact inhibition; cancer cells lose these controls by ignoring stop signals, evading apoptosis, and dividing indefinitely.

What are metastasis and angiogenesis?

Metastasis is the spread of cancer cells from the primary tumor location to distant tissues via blood or lymph vessels; angiogenesis is the formation of new blood vessels to supply oxygen and nutrients to a growing tumor.

How is a tumor classified across Stage I, Stage II, Stage III, and Stage IV?

Stage I: small, localized tumor confined to origin; Stage II: localized growth with minor tissue/lymph node involvement; Stage III: larger regional growth with significant lymph node involvement; Stage IV: distant metastasis to other organs.

Apply It #1: A biopsy confirms cancer cells in two lymph nodes near a patient's primary tumor, but imaging shows no tumors elsewhere in the body. What stage is this cancer at and why?

Stage III, because the cancer has spread to nearby regional lymph nodes near the primary tumor, but has not metastasized to distant organs.

What are the three cancer types with the highest number of new diagnoses in males and females?

In males: prostate, lung & bronchus, and colorectal cancer. In females: breast, lung & bronchus, and colorectal cancer.

Apply It #2: Lung & bronchus cancer is not the single most-diagnosed cancer, but it is the leading cause of cancer death. What does this suggest about its risk factors or detection?

It suggests that lung cancer is strongly linked to a major modifiable risk factor (tobacco smoking) and is typically caught late in advanced stages due to a lack of early symptoms and routine early screening.

What are the general purposes of a biopsy, MRI, CT scan, and PET scan in cancer diagnosis?

Biopsy: direct removal and microscopic evaluation of tissue; MRI: detailed soft-tissue imaging using magnetic fields; CT scan: cross-sectional X-ray imaging of body structures; PET scan: metabolic imaging using radioactive tracers to identify active cancer cells.

What are the three broad categories of cancer treatment?

Surgery (physical removal of tumor tissue), radiation therapy (high-energy radiation to destroy cancer cell DNA), and chemotherapy (systemic chemical drugs targeting rapidly dividing cells).

What is an atom and what are its three subatomic particles, their charges, and their locations?

An atom is the basic unit of matter. Protons (positive charge, $+1$) and neutrons (no charge, $0$) sit in the central nucleus, while electrons (negative charge, $-1$) orbit in surrounding electron shells.

What is the difference between an element and a molecule?

An element is a pure substance made of only one type of atom, whereas a molecule consists of two or more atoms bound chemically together.

What is the difference between atomic number, atomic mass, and an isotope?

Atomic number is the number of protons in an atom; atomic mass is the combined mass of protons and neutrons; an isotope is an atom of an element with the same atomic number but a different number of neutrons.

How do electron shells fill, and what is a valence electron?

Electrons fill the innermost shell first (up to 2 electrons) before filling outer shells (up to 8 electrons each); a valence electron is an electron located in the outermost shell that determines chemical reactivity.

How do you calculate the number of valence electrons given an atom's atomic number?

Fill electron shells from inside out ($2$ in the 1st shell, $8$ in the 2nd shell, $8$ in the 3rd shell); the remainder in the outermost shell represents the number of valence electrons.

What makes an atom chemically inert (stable) versus reactive?

An atom is chemically inert if its valence shell is full (e.g., noble gases), whereas an atom is reactive if its valence shell is incomplete and needs to share, gain, or lose electrons.

How does an atom's valence electron count relate to the number of covalent bonds it can form?

The number of covalent bonds an atom can form is equal to the number of additional electrons needed to complete its valence shell.

What is electronegativity and how does it determine bond type?

Electronegativity is an atom's measure of pull on shared electrons. Equal electronegativity forms nonpolar covalent bonds, moderate differences form polar covalent bonds, and extreme differences result in electron transfer forming ionic bonds.

How many electron pairs are shared in a single covalent bond?

A single covalent bond consists of 1 shared pair of electrons (2 electrons total).

How do nonpolar covalent, polar covalent, ionic, and hydrogen bonds differ regarding electron interaction?

Nonpolar covalent: electrons shared evenly; polar covalent: electrons shared unevenly; ionic: electrons transferred from one atom to another; hydrogen bond: weak attraction between a partially positive hydrogen atom and a partially negative atom on another polar molecule.

What are cations and anions, and how do they relate to ionic bonding?

A cation is a positively charged ion formed by losing electrons; an anion is a negatively charged ion formed by gaining electrons. Ionic bonding is the electrostatic attraction between opposite charges of cations and anions.

How does water's polarity give rise to cohesion, adhesion, and high specific heat?

Water's polar covalent bonds create partial charges that form hydrogen bonds between molecules, allowing water molecules to stick to each other (cohesion), stick to polar surfaces (adhesion), and absorb high amounts of thermal energy without rapid temperature changes (high specific heat).

What is the difference between hydrophobic and hydrophilic substances, and what solvents dissolve each?

Hydrophilic substances are polar or charged and dissolve in polar solvents (such as water); hydrophobic substances are nonpolar and dissolve in nonpolar solvents (such as oil).

What element must be present for a molecule to be classified as organic?

Carbon.

Apply It #3: Two atoms form a bond where one atom pulls shared electrons much closer than the other. What bond type is this, and will it dissolve in water or oil?

This is a polar covalent bond. The resulting polar molecule is more likely to dissolve in water (a polar solvent) than in oil.

What are the basic building blocks of a fat (triglyceride) and how are they connected?

A fat consists of one glycerol molecule linked to three fatty acid chains via covalent ester bonds.

How do saturation, unsaturation, and hydrogenation change a lipid's structure and physical state at room temperature?

Saturated fats have no double bonds, straight tails, pack tightly, and are solid at room temperature; unsaturated fats have double bonds, kinked tails, pack loosely, and are liquid; hydrogenation adds hydrogen atoms to make unsaturated fats more solid.

What is a steroid and what is one of its biological functions?

A steroid is a lipid composed of four fused carbon rings; functions include maintaining membrane fluidity (cholesterol) or acting as signaling hormones (estrogen, testosterone).

How do phospholipids differ structurally from fats, and why does this matter for their body localization?

Phospholipids have two fatty acid tails and a polar phosphate head attached to glycerol, making them amphipathic, which causes them to form biological membranes rather than energy-storage fat droplets.

What does amphipathic mean, and which parts of a phospholipid are hydrophilic vs. hydrophobic?

Amphipathic means possessing both hydrophilic and hydrophobic regions; the phosphate head is hydrophilic, and the fatty acid tails are hydrophobic.

What are the monomer and polymer units for carbohydrates, proteins, and nucleic acids?

Carbohydrates: monosaccharides (monomers) form polysaccharides (polymers); Proteins: amino acids (monomers) form polypeptides (polymers); Nucleic Acids: nucleotides (monomers) form polynucleotides/DNA/RNA (polymers).

To which macromolecule class do glucose, amino acids, nucleotides, and fatty acids belong?

Glucose: carbohydrates; amino acids: proteins; nucleotides: nucleic acids; fatty acids: lipids.

Apply It #4: A cell increases the proportion of unsaturated fatty acid tails in its membrane phospholipids. What happens to membrane fluidity and why?

Membrane fluidity increases because kinks in unsaturated fatty acid double bonds prevent phospholipids from packing tightly together.

What are the defining structural differences between prokaryotic and eukaryotic cells?

Eukaryotic cells have a membrane-bound nucleus and membrane-bound organelles and are larger; prokaryotic cells lack a nucleus and membrane-bound organelles and are smaller.

What is the sequence of organelles followed by a newly made protein along the secretory pathway?

Rough Endoplasmic Reticulum (RER) $\rightarrow$ Transport Vesicle $\rightarrow$ Golgi Apparatus $\rightarrow$ Secretory Vesicle $\rightarrow$ Plasma Membrane.

What is the endosymbiotic theory and what evidence supports it?

The endosymbiotic theory states that mitochondria and chloroplasts originated from ancestral prokaryotes engulfed by early eukaryotic cells. Evidence includes their double membranes, circular DNA, prokaryotic-like ribosomes, and self-replication by binary fission.

Which organelles are responsible when a cell cannot detoxify chemicals, generate ATP, or package proteins for secretion?

Chemical detoxification: Smooth Endoplasmic Reticulum; ATP generation: Mitochondria; Protein packaging for secretion: Golgi apparatus.

What is the fluid mosaic model, and what is the difference between integral and peripheral membrane proteins?

The fluid mosaic model describes the cell membrane as a fluid phospholipid bilayer embedded with diverse proteins; integral proteins span or penetrate the lipid bilayer, while peripheral proteins are loosely attached to membrane surfaces.

Why do phospholipids arrange into a bilayer in an aqueous environment?

Phospholipids align so that their hydrophilic heads face outward toward water inside and outside the cell, while their hydrophobic fatty acid tails shield themselves inward away from water.

Which types of molecules cross the lipid bilayer easily versus those that require transport protein help?

Small, nonpolar molecules (such as $O_2$ and $CO_2$) cross easily through simple diffusion; large, polar, or charged molecules (such as glucose, ions, and $H_2O$) require transport proteins.

How does cholesterol impact cell membrane fluidity, and how does its role change with temperature?

At high temperatures, cholesterol restricts phospholipid movement to prevent the membrane from becoming too fluid; at low temperatures, it prevents tight packing of phospholipids to maintain fluidity.

How does lateral movement of phospholipids within a bilayer compare to flip-flop movement between leaflets?

Lateral movement within a single leaflet occurs frequently and rapidly, while flip-flop movement between the outer and inner leaflets is rare.

What is the difference between diffusion and osmosis?

Diffusion is the passive movement of solute particles from high to low concentration; osmosis is the specific movement of water molecules across a selectively permeable membrane toward higher solute concentration.

How do hypertonic, hypotonic, and isotonic solutions differ, and which direction does water move in each relative to a cell?

Hypertonic: higher solute outside cell, water moves out causing cell to shrink; Hypotonic: lower solute outside cell, water moves in causing cell to swell; Isotonic: equal solute concentration, no net water movement.

What distinguishes passive transport (simple and facilitated diffusion) from active transport (pumps)?

Passive transport moves substances down their concentration gradient without cellular energy; active transport uses ATP and pump proteins to move substances against their concentration gradient.

Apply It #5: A cell is placed in a solution and immediately shrinks. Is the surrounding solution hypertonic, hypotonic, or isotonic, and by what process is water moving?

The surrounding solution is hypertonic relative to the inside of the cell, and water is moving out of the cell by osmosis.

Apply It #6: A drug blocks all pump proteins in a cell membrane. Which transport type is disrupted, and what happens to movement against concentration gradients?

Active transport is directly disrupted, preventing the cell from moving substances against their concentration gradient.

What are the phases of the cell cycle in order, and when is DNA replicated?

The order is Interphase ($G_1$, $S$, $G_2$), followed by Mitosis (M) and Cytokinesis. DNA is replicated during the $S$ phase of interphase.

What are the four stages of mitosis in order, and what happens to chromosomes during each?

Prophase: chromatin condenses into visible chromosomes; Metaphase: chromosomes align along the metaphase plate; Anaphase: sister chromatids separate to opposite poles; Telophase: nuclear envelopes re-form around separated chromatin.

What is the difference between a chromosome and a sister chromatid?

A chromosome is a individual double-stranded DNA structure; sister chromatids are identical replicated copies of a chromosome linked together at the centromere.

What is the biological purpose of mitosis?

To produce two genetically identical daughter cells for cellular growth, tissue repair, and asexual reproduction.

What is a cell cycle checkpoint, where do major checkpoints occur, and why is regulation necessary?

A checkpoint is a regulatory control point where signals determine if a cell proceeds with division; major checkpoints occur near the end of $G_1$, at $G_2$/M transition, and during Metaphase (M) to prevent mutated or damaged cells from dividing.

Apply It #7: Under a microscope, you see a cell with two separate nuclei that have just re-formed, but the cytoplasm has not finished dividing. What stage is this cell in?

Telophase / Cytokinesis (specifically telophase of mitosis with ongoing cytokinesis).