Lecture 1 & 2 Intro to Biology, Scientific Communication, and Biological Chemistry

flashcards cover cell basics, cell types, classification, basic chemistry, properties of water, pH, molarity, and buffers.

What is the basic unit of life?

Cells

What is the main difference between prokaryotic and eukaryotic cells?

Prokaryotic cells have no nucleus or membrane-bound organelles; eukaryotic cells have a membrane-enclosed nucleus and organelles.

Where is DNA located in prokaryotic cells?

DNA is located in the cytoplasm (nucleoid region), not in a membrane-bound nucleus.

Where is DNA located in eukaryotic cells?

DNA is contained within a membrane-bound nucleus.

Do eukaryotic cells contain membrane-bound organelles?

Yes; prokaryotic cells lack membrane-bound organelles.

What is the approximate size scale shown for cells in the notes?

About 1 micrometer (1 μm).

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

Name some kingdoms within the domain Eukarya.

Plantae, Fungi, Animalia, and Protists.

Is biological classification hierarchical?

Yes; Domain, Kingdoms, and lower ranks form a hierarchical system.

List the main domains mentioned.

Bacteria, Archaea, Eukarya.

List the kingdoms mentioned under Eukarya.

Plantae, Fungi, Animalia, and Protists.

What are the levels of biological organization from molecules to organisms?

Molecules → Organelles → Cells → Tissues → Organs → Organism.

What are the two main types of covalent bonds?

Non-polar (electrons shared equally) and polar (electrons not shared equally).

What determines whether a covalent bond is polar?

Differences in electronegativity; asymmetrical differences and molecular shape cause partial charges.

Where is electronegativity highest on the periodic table?

Toward the right side of the periodic table.

Is water polar or non-polar?

Polar.

What is Van der Waals force?

A weak, transient attraction between molecules that is not a true bond and can be easily broken.

What is hydrogen bonding?

A weak, transient attraction where hydrogen atoms bound to electronegative atoms are attracted to charges on nearby molecules.

What central properties of water allow life?

Cohesion, temperature moderation, expansion upon freezing, and solvent versatility.

What does cohesion mean in water?

Water molecules sticking together via hydrogen bonds (important for transport in plants).

What does adhesion refer to?

Sticking of water to other substances.

What is surface tension?

The cohesive forces at the surface of a liquid that enable a surface to resist external forces.

Why can water regulate temperature effectively?

Because of high specific heat and high heat of vaporization; also evaporative cooling.

Why does ice float on water?

Ice is less dense than liquid water, so it floats and insulates the water below.

Why is water a good solvent?

It is a polar solvent capable of hydrating ions and large molecules.

What is a solution?

A completely homogeneous liquid mixture.

What is a solvent?

The dissolving agent in a solution.

What is a solute?

The substance dissolved in a solution.

What are hydrophilic substances?

Water-loving; soluble in water (e.g., salt).

What are hydrophobic substances?

Water-fearing; insoluble in water (e.g., fat).

What does hydration mean in aqueous solutions?

Ions and large molecules can be hydrated (surrounded by water molecules).

What happens when water self-ionizes?

A small amount forms OH- and H+ (hydronium, H3O+), important for pH.

What does pH measure?

The negative log of the hydrogen ion concentration, representing [H+].

What is the product [H+][OH-] at 25°C?

1 x 10^-14.

What is the pH of pure water at 25°C?

7 (neutral).

If [H+] > [OH-], what is the pH and acidity?

pH < 7; the solution is acidic.

If [H+] < [OH-], what is the pH and basicity?

pH > 7; the solution is basic.

What is a mole?

6.02 x 10^23 units (the amount of substance).

What is molarity?

Moles per liter (mol/L).

What does log base 10 mean in pH calculations?

pH uses base-10 logarithms; pH = -log([H+]).

If [H+] = 1x10^-3 M, what is pH?

3.

How can you calculate [OH-] from [H+]?

[OH-] = 1x10^-14 / [H+].

What is a pH buffer?

Substances that resist pH changes by absorbing/donating H+ ions.

What is an example of a buffering system in biology?

Carbonic acid/bicarbonate buffer: H2CO3 ⇄ H+ + HCO3^-; blood pH around 7.4.

What happens when [H+] falls or rises in the carbonic acid buffering system?

If [H+] falls, H2CO3 dissociates to produce more HCO3^-; if [H+] rises, more H2CO3 is produced.

What is hydronium and why is it important?

H3O+ (hydrated proton); the form in which H+ is represented in water; very reactive and central to acid/base chemistry.

What is the relationship between pH and acidity?

Lower pH indicates higher acidity; higher pH indicates basicity.