Lecture 2a - Biomolecules, Cells, and Tissues

What are the common features of all Earth organisms?

They share biological molecules, maintain homeostasis, evolve, and require liquid water.

What 4 elements make up 96% of all biomass?

Oxygen, Carbon, Hydrogen, Nitrogen

What are atoms made of?

Protons (+), Neutrons (neutral) in the nucleus, and Electrons (–) in orbitals

What determines an atom’s chemical behavior?

Electrons, especially those in the outer (valence) shell

What are isotopes?

Forms of an element with the same number of protons but different neutrons

What are the three main chemical bonds?

Ionic (transfer of e⁻), Covalent (sharing e⁻), Hydrogen (weak attraction)

Why is water a good solvent?

It is polar; dissolves salts and hydrophilic molecules

What does hydrophobic mean?

"Water-hating"; nonpolar molecules (like oil) that do not dissolve in water

List 4 remarkable properties of water

Cohesion, Adhesion, Denser as liquid than solid, Absorbs heat energy

What does the pH scale measure?

Concentration of hydrogen ions (H⁺). pH < 7 = acidic, pH = 7 neutral, pH > 7 basic

What keeps cell pH stable?

Buffers (donate or absorb H⁺ to resist changes)

What are the 4 classes of macromolecules?

Proteins (amino acids), Nucleic acids (nucleotides), Carbohydrates (monosaccharides), Lipids (fatty acids)

Why is carbon essential for life?

Can form 4 bonds, builds complex macromolecules

What are the three tenets of cell theory?

1. All living things are made of cells.
2. All cells come from preexisting cells.
3. Cells are the smallest units of life.

What are the 3 main parts of a typical human cell?

Plasma membrane, Cytoplasm, Nucleus

What is the plasma membrane made of?

Phospholipid bilayer (hydrophilic heads, hydrophobic tails), proteins, cholesterol

What is the function of the nucleus?

Stores DNA, controls activities (protein synthesis, division, metabolism)

Where are ribosomes located and what do they do?

Free in cytoplasm or on RER; synthesize proteins

Difference between Smooth ER and Rough ER?

RER = protein synthesis; SER = lipid synthesis, detoxification, carbohydrate metabolism

What is the role of the Golgi apparatus?

Modifies, sorts, and packages proteins for secretion or lysosomes

What is the function of mitochondria?

Produce ATP via cellular respiration; have their own DNA

What do lysosomes do?

Digest waste & damaged organelles; autophagy and autolysis

What do peroxisomes do?

Detoxify harmful molecules using oxygen and catalase

What are the 3 cytoskeletal elements?

Microfilaments (actin), Intermediate filaments (support), Microtubules (movement & shape)

What are cilia vs flagella vs microvilli?

Cilia = short, move substances; Flagella = long, locomotion (sperm); Microvilli = increase absorption area

What is the flow of genetic information?

DNA → RNA → Protein

What are the steps of protein synthesis?

Transcription (DNA → mRNA) and Translation (mRNA → protein)

What is an Okazaki fragment?

Short DNA fragment on the lagging strand during replication

What enzyme joins Okazaki fragments?

DNA ligase

What are the steps of the cell cycle?

Interphase (DNA replication), Mitosis (chromosome separation), Cytokinesis (cell divides)

List the 4 stages of mitosis

Prophase (chromosomes condense, spindle forms),
Metaphase (chromosomes align),
Anaphase (chromatids separate),
Telophase (nuclear envelopes reform)

What are the 4 main tissue types?

Epithelial, Connective, Muscle, Nervous

Characteristics of epithelial tissue?

Avascular, tightly packed cells, basement membrane, apical/basal sides

What are the classifications by shape?

Squamous, Cuboidal, Columnar, Transitional

What are the classifications by layers?

Simple (1), Stratified (2+), Pseudostratified (appears layered but is 1)

What are the 3 glandular secretion types?

Merocrine (exocytosis), Apocrine (apical portion pinches off), Holocrine (cell dies and releases contents)

What is the extracellular matrix made of?

Protein fibers (collagen, elastin) + ground substance

What are the 3 classes of connective tissue?

Proper (loose, dense), Supporting (cartilage, bone), Fluid (blood, lymph)

What are the 3 types of muscle tissue?

Skeletal (voluntary, movement), Cardiac (involuntary, heart), Smooth (involuntary, organs)

What are the 2 main cell types?

Neurons (electrical signals) and Glial cells (support)