BIOL 161 Exam 1

Describe the structure of an atom and use atomic number and electrical charge to interpret atomic diagrams and periodic-table information.

protons, neutrons, electrons. Nucleus contains protons + neurons, electrons on the outside. Atomic number determined by # of protons. + charge = cation; - charge = anion

Compare and contrast the terms: atom, molecule, and element.

An atom is a single unit of matter made up of subatomic particles: protons, neutrons, electrons.

A molecule is made of 2 or more atoms chemically bonded to each other.

An element is a pure substance of the same atom, defined by having a particular # of protons

Explain ionization and distinguish among neutral atoms, cations, and anions.

Ionization: the process in which an atom gains or loses electrons and becomes electrically charged

Neutral: # protons = # electrons; charge = 0

Cations: Positively charged ions; lost >= 1 electrons

Anions: Negatively charged ions; gains >= 1 electrons

Explain why ions are physiologically important and describe their roles in membrane voltage and electrical current.

Ion concentration gradients: differences in ion concentration across a membrane

Electrical Gradients: differences in charge across a membrane

Electrochemical gradients: the combined influence of concentration and electric gradients

Compare ionic, polar covalent, nonpolar covalent, and hydrogen bonds in terms of how atoms or molecules interact.

Ionic bond: one atom transfers >= 1 electrons to another atom —> created charged ions that attract each other

Polar covalent bond: when atoms share electrons unqeually

Nonpolar covalent bond: when atoms share electrons equally or nearly equal

Hydrogen bonds: weak attractions between slightly positive hydrogen atom and slightly negative atom (no sharing of electrons)

Use molecular diagrams to distinguish among the major types of chemical bonds discussed in this lecture.

Explain the polarity of water and relate water's polarity to hydrogen bonding.

Water has an uneven distribution of charge (positive hydrogen, negative oxygen)

The O-H bonds within one water molecule are covalent and polar.

Distinguish monomers from polymers and identify the four major categories of organic molecules.

Monomer: smaller molecular subunit that can be joined to other similar subunits

Polymer: a larger molecule made of repeating or linked subunts called monomers

carbohydrates, lipids, proteins, nucleic acids

Describe the basic organization of carbohydrates and relate carbohydrates to their major biological functions.

Carbohydrates: organic molecules composed primarily of carbon, hydrogen and oxygen. Provide/store usable energy, contributing to structural support, participating in cell recognition or cell-surface interactions

Monosaccharides: single sugar units

Disaccharides: two sugar units joined together

Polysaccharides: long chains or sugar units

Describe the structure of a triglyceride and relate its structure to its physiological functions.

One glycerol molecule + three fatty acid chains attached to glycerol by as ester bond

Triglycerides are largely nonpolar and hydrophobic so they do not dissolve well in water

Long term energy storage: hydrocarbon rich fatty acid chains contain substantial energy

Insulation: stored adipose triglycerides can reduce heat loss

Cushioning and protection: adipose tissue can help protect organs

Compare saturated and unsaturated fatty acids in terms of their structure and biological significance.

Saturated: have no carbon-carbon double bonds. maximum # of hydrogen atoms

Unsaturated: one or more carbon-carbon double bonds (liquid room temp)

Monounsaturated: one double bond

Polyunsaturated: two or more double bonds

Describe the structure of a phospholipid and relate its organization to cell and organelle membranes.

Three major parts: glycerol back bone, two fatty acid tails, phosphate-containing polar head

Amphipathic b/x both hydrophobic and hydrophillic

Describe the structural features of steroids and explain the physiological roles of cholesterol and steroid hormones.

4 fused carbon rings

Generally lipic-soluble and can cross the phospholipid bilayer

Different steroids have different function because of differences in: attatched chemical groups, side chains, functional groups]

Cholesterol differs from other steriods b/c of hydrocarbon-containing tail + hydroxyl group

Cholesterol: helps regulate the fluidity + stability of cell membranes, served as a precursor for steroid hormones

Describe how amino acids are organized into proteins and relate protein structure to protein function.

Shape determines function

Amino acids are joined by peptide bonds to form polypeptide chains

Interpret a protein-structure figure to distinguish primary, secondary, tertiary, and quaternary structure.

Primary: the amino acid sequence (bracelet beads)

Secondary: folding (alpha helix, beta sheet)

Tertiary: 3 dimensional shape

Quaternary: association of multiple polypeptide chains (if present)

Describe the organization and major functions of nucleic acids.

Polymers made of repeating nucleotide monomers

Sugar, phosphate group, and nitrogen containing base

Information storage, information transfer, and protein function

Interpret the gene-expression diagram and distinguish transcription from translation.

Information is transferred from a gene to an RNA molecule, then used to produce a protein

Explain how genetic information determines the primary structure of a protein.

DNA stores genetic info → transcription turns that info into RNA transcript → translation makes the nucleotide sequence from RNA according to genetic code → amino acid order is the primary structure

Interpret the ATP hydrolysis diagram and explain the physiological significance of the process.

Hydrolysis uses water to split ATP into ADP, releasing energy

Can often be coupled to process requiring energy like: active transport, muscle contraction, movement of cellular components, and synthesis of larger molecules

Predict the electrical charge of an atom after it gains or loses electrons.

Gaining electrons makes an atom more negative, producing a negative ion

Losing electrons makes an atom more positive, producing. a positive ion

Predict how changing the distribution of shared electrons within a covalent bond would affect molecular polarity

Nonpolar covalent: equally shared

polar covalent: unequal sharing

Predict how altering the hydrophilic or hydrophobic regions of a phospholipid would affect its behavior in a membrane.

hydrophilic, polar heads interacts w/ water

hydrophobic, nonpolar tails avoid water

Changes can affect: phospholipid orientation, bilayer formation, membrane formation, membrane fluidity, permeability, and interactions with other membrane components

Predict how a change in the amino acid sequence of a protein could affect protein function.

Amino acid is primary structure

changes could affect: chemical interactions among amino acid side chains, protein folding + 3D shape, stability, active sites/bonding sites, cellular location, and interactions w/ other molecules

Predict how disrupting transcription or translation would affect protein production.

Transcription produces an RNA copy of genetic information, while translation uses RNA information to assemble an amino-acid sequence.

Disrupting either process affects: RNA production/availability, protein production, the amount or structure of protein produced, and potentially cell function