Unit 1 Biology Study Guide Flashcards

Flashcards based on the Unit 1 Study Guide covering Water, Carbohydrates, Lipids, Nucleic Acids, Proteins, and Cells.

What makes a water molecule polar?

A water molecule is polar because oxygen is more electronegative than hydrogen, creating partial negative charges on oxygen ($\delta^-$) and partial positive charges on hydrogen ($\delta^+$) due to unequal electron sharing.

How does hydrogen bonding occur between water molecules?

The partially negatively charged oxygen bonds with the partially positively charged hydrogen of an adjacent water molecule.

What is cohesion in water, and what is its role in biological transport?

Cohesion is the attraction between water molecules of the same type via hydrogen bonds; it allows water molecules to form a continuous column when transported upwards through plant xylem vessels.

What is adhesion in water, and how does it assist plant transport?

Adhesion is the attraction between water molecules and other polar or charged molecules; it allows water to adhere to the cellulose walls of xylem vessels to counteract gravity.

What is capillary action?

Capillary action is the movement of water through narrow spaces or tubes without external forces, driven by the combined effects of adhesion to vessel walls and cohesion between water molecules.

What is surface tension, and how does it work in water?

Surface tension is the cohesive force among water molecules at the liquid surface, creating an elastic-like membrane effect due to hydrogen bonding that allows small organisms to walk on water.

Why is water considered an effective solvent and medium for metabolism?

Water is a polar solvent that dissolves ionic and polar solutes, enabling biochemical reactions to occur in aqueous solution within cells and facilitating substance transport throughout organisms.

How do buoyancy, viscosity, thermal conductivity, and specific heat capacity compare in water versus air?

Water has higher buoyancy, higher viscosity, higher thermal conductivity, and a higher specific heat capacity than air, providing stable aquatic environments and structural support.

What is the general chemical formula for carbohydrates?

The general chemical formula for carbohydrates is $\text{C}_n(\text{H}_2\text{O})_n$ or $\text{C}_x\text{H}_{2y}\text{O}_y$.

What is the difference between $\alpha$-glucose and $\beta$-glucose?

$\alpha$-glucose has the hydroxyl group ($\text{-OH}$) on carbon 1 pointing downward relative to the ring, whereas $\beta$-glucose has the hydroxyl group on carbon 1 pointing upward.

Why is glucose widely used as an energy source in living organisms?

Glucose is highly soluble in water, chemically stable, easily transported in blood or sap, and yields substantial ATP energy during cellular respiration.

What are anabolism and catabolism?

Anabolism is the synthesis of complex molecules from simpler ones through endergonic condensation reactions; catabolism is the breakdown of complex molecules into simpler ones through exergonic hydrolysis reactions.

What occurs during a condensation reaction between two monosaccharides?

Two monosaccharides join together by forming a covalent glycosidic bond, releasing a molecule of water ($\text{H}_2\text{O}$).

What occurs during a hydrolysis reaction in carbohydrates?

A complex molecule like a disaccharide or polysaccharide is broken down into smaller units by adding a molecule of water ($\text{H}_2\text{O}$) to break the covalent bond.

What are the three main types of lipids?

The three main types of lipids are triglycerides, phospholipids, and steroids.

How are triglycerides formed?

Triglycerides are formed by condensation reactions between one glycerol molecule and three fatty acid chains, producing three ester bonds and releasing three water molecules.

How do saturated fatty acids differ from unsaturated fatty acids?

Saturated fatty acids have single carbon bonds, and unsaturated fatty acids have double carbon bonds.

What is an amphipathic molecule, and how does this property apply to phospholipids?

An amphipathic molecule contains both hydrophilic and hydrophobic regions; phospholipids have a hydrophilic phosphate head and two hydrophobic fatty acid tails, forming the structural basis of cell membranes.

What is the importance of steroids in the phospholipid bilayer?

Steroids like cholesterol intercalate between membrane phospholipids to modulate membrane fluidity and stability across varying temperatures.

What are the three components of a nucleotide?

Pentose sugar, nitrogenous base, phosphate group

What are the main structural differences between DNA and RNA?

DNA contains deoxyribose sugar, thymine, and is double-stranded, whereas RNA contains ribose sugar, uracil instead of thymine, and is typically single-stranded.

Where are thymine and uracil found in nucleic acids?

Thymine is found exclusively in DNA, whereas uracil is found exclusively in RNA.

What does it mean for DNA strands to be antiparallel?

Antiparallel means the two complementary strands of a DNA double helix run in opposite directions, one in the $5'$ to $3'$ direction and the other in the $3'$ to $5'$ direction.

What factors contribute to the structural stability of DNA?

DNA stability is provided by hydrogen bonds between complementary base pairs, hydrophobic stacking interactions between aromatic bases, and the covalent sugar-phosphate backbone.

What is the basic structure of an amino acid?

An amino acid consists of a central alpha carbon bound to an amino group ($\text{-NH}_2$), a carboxyl group ($\text{-COOH}$), a hydrogen atom ($\text{-H}$), and a variable side chain ($\text{R-group}$).

What bond links amino acids together in a polypeptide chain?

Amino acids are linked together by covalent peptide bonds formed between the carboxyl group of one amino acid and the amino group of another via a condensation reaction.

What is the difference between essential and non-essential amino acids in human diet?

Essential amino acids cannot be synthesized by the human body and must be obtained through dietary sources, whereas non-essential amino acids can be synthesized internally.

How do temperature and pH affect protein structure?

Can cause denaturation within proteins, causing them to lose their form and function

What are the four levels of protein structure?

Primary, secondary, tertiary, quaternary

What is the difference between conjugated and non-conjugated proteins?

Non-conjugated proteins consist entirely of polypeptide chains, whereas conjugated proteins contain a non-polypeptide prosthetic group (such as heme in hemoglobin).

How do fibrous and globular proteins differ in structure and function?

Fibrous proteins are elongated, insoluble, and serve structural roles (e.g., collagen), whereas globular proteins are spherical, water-soluble, and serve functional roles like catalysis or transport (e.g., enzymes, hemoglobin).

What are the three core principles of Cell Theory?

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

Which structural components are present in all cellular life?

All cells possess a plasma membrane, cytoplasm, genetic material (DNA), and ribosomes.

How is DNA stored in prokaryotes versus eukaryotes?

Within prokaryotes, the DNA is not enclosed by histone proteins and floats freely within the cell. In eukaryotes, the DNA is enclosed in histone proteins, and is contained to the nucleus

How does eukaryotic cell structure differ among Animals, Plants, and Fungi?

Animal cells lack cell walls; Plant cells have cellulose cell walls and chloroplasts; Fungi have chitin cell walls and lack chloroplasts.

What are examples of discrepant cells that challenge typical Cell Theory definitions?

Red blood cells, skeletal muscles

What is a disulfide bond in protein tertiary structure?

A disulfide bond (or disulfide bridge) is a strong covalent bond formed between the sulfhydryl ($\text{-SH}$) groups of two cysteine amino acids in a polypeptide chain.

What is an emulsion?

When a liquid is hydrophobic and does not disperse in another liquid, forming “beads”

What is adipose tissue and what is its primary function?

Adipose tissue is specialized connective tissue composed of adipocytes that stores energy in the form of triglycerides, provides thermal insulation, and cushions internal organs.

What is a glycoprotein?

A protein with one or more oligosaccharide carbohydrate chains covalently attached, serving key roles in cell recognition, signaling, and cell adhesion.