Introduction to Biology and Chemistry Flashcards 1

A comprehensive set of question-and-answer flashcards covering core biology concepts from the lecture notes, including cell theory, molecular biology, biochemistry, macromolecules, cell structure, and major themes in biology.

What is biology?

The scientific study of life.

List the seven characteristics of life that distinguish living organisms from non-living matter.

Order, reproduction, growth and development, energy processing, regulation, response to the environment, and evolutionary adaptation.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells are smaller and lack a membrane-bound nucleus and organelles; eukaryotic cells are larger and have a membrane-bound nucleus and membrane-bound organelles.

Define homeostasis.

The maintenance of a stable, internal environment despite external changes.

Define metabolism.

All the chemical reactions inside an organism that keep it alive and functioning.

What are emergent properties?

New properties that arise at higher levels of organization that are not present in the individual components.

What is taxonomy?

The science of classifying, describing, and naming organisms.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What is the Central Dogma of biology?

DNA is transcribed into RNA, which is translated into protein (DNA → RNA → Protein).

What is evolution, and why is it considered the core theme of biology?

Evolution is the process by which populations change over time, uniting life’s unity and diversity through natural selection and genetic variation.

What are the three basic steps of natural selection?

Variation among individuals, differential survival and reproduction, and heritable traits increasing in frequency over generations.

What are the main components of the scientific method as outlined in the notes?

Observations, questions, hypotheses, predictions, tests (experiments or observations), analysis, conclusions, and sharing results.

What are the four main macromolecules in biology?

Carbohydrates, proteins, nucleic acids, and lipids.

What is a monomer and what is a polymer?

Monomer is a small building block; polymers are long chains built from monomers through dehydration reactions.

What is dehydration synthesis?

A chemical reaction that links monomers to form polymers by removing a water molecule.

What is hydrolysis?

A chemical reaction that breaks polymers into monomers by adding water.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary structures.

What determines a protein’s primary structure?

The sequence of amino acids in its polypeptide chain.

What stabilizes an alpha-helix and beta-pleated sheet (secondary structure)?

Hydrogen bonds between the backbone atoms of the polypeptide.

What is a peptide bond?

A covalent bond formed between the carboxyl group of one amino acid and the amino group of the next amino acid during dehydration synthesis.

What are the major categories of amino acid side chains?

Nonpolar (hydrophobic), polar (hydrophilic), and electrically charged (basic or acidic).

What is meant by the term 'amphipathic' in relation to lipids?

Having both hydrophobic (water-fearing) tails and hydrophilic (water-loving) heads.

What are the three major types of lipids discussed?

Fats (triglycerides), phospholipids, and steroids.

What is a triglyceride composed of?

Glycerol linked to three fatty acids.

What is a phospholipid bilayer and why is it important?

A two-layered arrangement of phospholipids with hydrophilic heads outward and hydrophobic tails inward; forms the fundamental structure of cell membranes.

What are the roles of the extracellular matrix (ECM) in animal cells?

Provides support, binds cells together, and participates in cell signaling via integrins.

What are the three types of cell junctions in animal tissues?

Tight junctions, desmosomes, and gap junctions.

What is the difference between a plant cell wall and an animal ECM?

Plant cell walls are rigid and primarily cellulose-based; animal cells have ECM made of glycoproteins like collagen and proteoglycans, without cell walls.

What is endomembrane system and which organelles are part of it?

A network of membranes including the nucleus, ER, Golgi apparatus, lysosomes, vesicles, and the plasma membrane involved in the synthesis, distribution, and processing of cellular products.

What is the function of the rough endoplasmic reticulum?

Ribosome-covered region where membrane- and secretory-protein synthesis and processing occur.

What is the function of the smooth endoplasmic reticulum?

Lipid synthesis, toxin processing, and calcium storage.

What is the Golgi apparatus responsible for?

Modifying, sorting, and shipping cell products.

What are lysosomes?

Digestive compartments containing enzymes that break down ingested materials and damaged organelles.

What is the function of mitochondria?

Site of cellular respiration; produce ATP, the cell’s energy currency.

What is the site of photosynthesis in plants?

Chloroplasts.

What are thylakoids, granum, and stroma?

Thylakoids are membrane-bound sacs, granum is a stack of thylakoids, and stroma is the fluid surrounding them in chloroplasts.

What is the role of the cytoskeleton?

Gives the cell shape, anchors and moves organelles, enables cell movement, and organizes the cytoplasm.

What are the three components of the cytoskeleton and their primary functions?

Microfilaments (actin) provide shape and movement; intermediate filaments provide structural support; microtubules serve as tracks for movement and separate chromosomes during division.

What are cilia and flagella made of and what is their function?

Microtubules; they enable cell movement and movement of substances around the cell.

What is the nucleus and what does it contain?

The organelle that stores genetic information as DNA packaged with histones (chromatin) inside the nuclear envelope.

What are ribosomes and where are they located?

Ribosomes are the cellular machines that synthesize proteins; they can be free-floating in the cytosol or bound to the rough ER.

What is the difference between DNA and RNA?

DNA stores genetic information and is typically double-stranded; RNA is typically single-stranded and participates in protein synthesis (mRNA, tRNA, rRNA).

What is the basic structure of a nucleotide?

A sugar (deoxyribose in DNA, ribose in RNA) attached to a phosphate group and a nitrogenous base.

What bases pair in DNA and RNA?

DNA: A-T and C-G. RNA: A-U and C-G.

What is the sugar-phosphate backbone?

The chain formed by alternating sugar and phosphate groups in nucleic acids; provides directionality (5' to 3').

What is the difference between a monosaccharide, disaccharide, and polysaccharide?

Monosaccharides are single sugars; disaccharides are two sugars linked; polysaccharides are long chains of many sugar units.

Name two storage polysaccharides and two structural polysaccharides.

Storage: starch (plants), glycogen (animals). Structural: cellulose (plants), chitin (insects and fungi).

What are glycosidic linkages and how do they differ?

Glycosidic bonds link sugar monomers; alpha linkages form helical structures (e.g., starch), beta linkages form straight, rigid structures (e.g., cellulose).

What is a lipid bilayer and why is it important for membranes?

A two-layered arrangement of phospholipids forming the fundamental structure of cell membranes, creating a barrier and functional compartments.

What are the three main types of lipids and their general roles?

Fats (energy storage), phospholipids (membranes), steroids (signaling molecules and membrane components like cholesterol).

What is ATP and why is it important?

Adenosine triphosphate; the cell’s main energy currency used to power endergonic reactions.

What is the endosymbiotic theory?

The idea that mitochondria and chloroplasts originated as free-living prokaryotes that were taken inside a host cell, evolving into organelles.

What evidence supports the endosymbiotic theory?

Mitochondria and chloroplasts have their own circular DNA, ribosomes similar to bacterial ones, reproduce by binary fission, and have double membranes.

What is the basic layout of the hierarchical organization of life (from molecules to biosphere)?

Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere.

What is an emergent property in the context of biological hierarchy?

A property that emerges at a higher level of organization and is not present in the components alone.

What is a buffer and why are pH buffers important in biology?

A substance that minimizes changes in pH by neutralizing added acids or bases; buffers help maintain cellular homeostasis.

What determines whether a molecule is hydrophilic or hydrophobic?

Polarity: polar and ionic substances are hydrophilic and mix with water; nonpolar substances are hydrophobic and do not mix well with water.

What is meant by 'polarity' in water and how does it affect water’s properties?

Water is polar; its unequal electron distribution leads to hydrogen bonding, high cohesion, solvent capabilities, and temperature stability.

Why are nucleic acids essential for heredity and protein synthesis?

DNA stores genetic information; RNA translates that information into proteins (DNA → RNA → Protein).

What is meant by the directionality of a polynucleotide backbone?

The backbone has a 5' to 3' direction; one end has a free 5' phosphate group and the other has a free 3' hydroxyl group.

What is the role of enzymes in macromolecule metabolism?

Enzymes catalyze biochemical reactions, including polymerization and hydrolysis of macromolecules.

What is the significance of enzymes in digestion and metabolism?

Enzymes accelerate hydrolysis and synthesis of polymers, enabling digestion and synthesis of biomolecules.

What is the major difference between prokaryotic and eukaryotic cell organization?

Prokaryotic cells lack a nucleus and most membrane-bound organelles; eukaryotic cells have a true nucleus and many organelles enclosed by membranes.

What is a transient feature of plant cells that animal cells lack?

Cell wall and plasmodesmata (channels between plant cells) provide structural support and intercellular communication.

What is the role of vesicles in the cell?

Vesicles transport materials between organelles and to/from the cell membrane as part of the endomembrane system.

What is the role of ribosomes in the cell?

Ribosomes synthesize proteins according to the genetic instructions carried by mRNA.

What are the three types of plant and animal cell junctions and their functions?

Tight junctions (seal leaks), desmosomes (anchor cells together), gap junctions (allow cell-to-cell communication via channels).

What is the role of the ECM in tissue organization and signaling?

ECM binds cells together, supports the plasma membrane, and signals to cells via integrins to regulate behavior.

What is the function of chloroplasts in plant cells?

Chloroplasts carry out photosynthesis, converting light energy to chemical energy stored in sugars.