Biology for Science Majors I: Key Concepts in Organization, Genetics, and Molecular Biology

Hierarchy of biological organization

molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem

Biological community

All of the organisms living in a particular ecosystem.

Primary source of energy for producers

light energy.

Biosphere

All the living things on Earth along with all the places where life exists.

Hierarchy of biological organization (small to large)

cells → organisms → populations → communities → ecosystems

Domains classified as prokaryotes

bacteria and archaea.

Eukarya

Domain that includes multicellular photosynthetic organisms.

Single-celled organism from ancient peat bog was found to have a cell wall and nucleus

Most likely a member of the domain eukarya.

Common genetic language of DNA

All living things share a common genetic language of DNA because they share a common ancestry.

Evidence of common ancestry

The existence of a nearly universal genetic code.

Unity among all organisms

DNA structure and function.

Example of unity in diversity

The forelimbs of all mammals have the same basic structure, modified for different environments.

Hypothesis in science

The hypothesis is testable and falsifiable.

Scientific theory

It generates testable hypotheses, is supported by a large body of evidence, and is broad in scope.

Prokaryotic cells

Separated into two Domains: Bacteria and Archaea.

Bacteria

The most diverse and widespread prokaryotes.

Archaea

Most of the prokaryotes known as Archaea live in extreme environments, such as salty lakes.

Protists

A diverse collection of mostly single-celled eukaryotes, sorted into several kingdoms to reflect their evolutionary relationships.

Kingdom Plantae

Consists of multicellular eukaryotes that produce their food by photosynthesis.

Kingdom Fungi

Includes eukaryotic organisms that mostly decompose organic wastes and absorb nutrients into their cells.

Kingdom Animalia

Consists of multicellular eukaryotes that obtain their food by ingesting (eating) other organisms.

Scientific inquiry

A general process used by scientists to ask and answer questions about nature.

Inductive reasoning

A generalized conclusion can often be drawn from a large number of specific observations.

Hypothesis

A proposed explanation for a set of observations that leads to predictions that can be tested.

Deductive reasoning

Uses 'if . . . then' logic to proceed from a general hypothesis to specific predictions.

Falsifiable

There must be some observation or experiment that could show that it is not true.

Controlled Experiment

Involves both an experimental group and a control group, which are alike except for the one variable being tested.

Theory

Broader in scope than a hypothesis, supported by a large body of evidence, and generates many new hypotheses.

Adhesion

The attraction between molecules of different substances, causing them to stick together.

Cohesion

The attraction between molecules of the same substance, causing them to stick to themselves.

Elements making up 96% of human body mass

Carbon, hydrogen, nitrogen, oxygen.

Element

A substance that cannot be broken down into other substances by ordinary chemical procedures.

Difference between carbon-12 and carbon-14

Carbon-14 has two more neutrons than carbon-12.

Reactivity of an atom

Arises from the existence of unpaired electrons in the valence shell.

Covalent bonding

Involves the sharing of electron pairs between atoms.

Ionic bonding

Involves the transfer of electrons from one atom to another.

Covalent bond

Formed by sharing a pair of electrons between two atoms.

Carbon dioxide solubility in water

CO2 + H2O ↔ H2CO3.

Carbonic acid

A weak acid represented by H2CO3.

Why ice floats in liquid water

Hydrogen bonds stabilize and keep the water molecules of ice farther apart than the water molecules of liquid water.

Molar mass of glucose

180 g/mol.

Making a 0.5 M solution of glucose

Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.

0.01 M solution with pH of 2

Strong acid that ionizes completely in water.

pH increase from 5 to 8

The concentration of OH- is 1000 times greater than what it was at pH 5.

True statement about buffer solutions

They maintain a relatively constant pH when either acids or bases are added to them.

Effect of increasing H2CO3 concentration in oceans

pH decreases.

Effect of acidification of seawater on marine organisms

Acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals.

Commonality of ocean acidification and coral reef calcification

Increasing of CO2 level.

Acid

A substance that increases the hydrogen ion concentration of an aqueous solution.

Covalent bonds formed by nitrogen

A nitrogen atom must form covalent bonds with 3 hydrogen atoms to complete its valence shell.

Most organic compounds contain

Carbon and hydrogen.

Functional group for energy transfer

Phosphate (ATP).

Main categories of large biological molecules

Proteins, nucleic acids, carbohydrates, and lipids.

True statement about functional groups

Amino and carboxyl.

Methyl functional group

A methyl group consists of a carbon bonded to three hydrogen atoms.

Functional group that behaves as a base

Amino group.

Characteristic of thiols

Sulfhydryl group (-SH).

Functional group that behaves as an acid

Carboxyl group (-COOH).

Dehydration reactions

Assemble polymers.

Hydrolysis reactions

Break down polymers.

Diversity of large biological molecules

Explained by the many ways that monomers of each class can be combined into polymers.

Cellulose

A primary structural component of plant cell walls.

Glucose units in cellulose

Cellulose is composed of β-D-glucose units, forming long, straight chains ideal for structural support.

Lactose

A disaccharide composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule.

Saturated fatty acid

A molecule that contains no double bonds between carbon atoms.

Hydrocarbons

Insoluble in water due to nonpolar covalent carbon-to-hydrogen linkages.

Phospholipids

Large biological molecules that will self-assemble into a bilayer when mixed with water.

Lipids

Hydrophobic substances that do not dissolve readily in water.

Amino acids

Always contain carboxyl and amino functional groups.

Structural feature of amino acids

Different side chains (R groups) attached to an alpha carbon.

Secondary structure of proteins

Examples include alpha helix and beta pleated sheet.

Changing a single amino acid

Alters the primary structure and sometimes alters tertiary structure or function.

Monomer/polymer pairing

Amino acid/polypeptide.

Monomeric carbohydrate subunits

Approximately 32 different subunits are found in various natural polysaccharides.

Proteins

Composed of 20 different amino acids.

DNA and RNA synthesis

Each is synthesized from four nucleotides.

Functional variety of biological polymers

Proteins have the greatest functional variety due to 20 different amino acids.

Primary structure of proteins

Linear order of amino acids determines secondary and tertiary structures.

Peptide bond

Joins the monomers in a protein's primary structure.

Secondary structure formation

Results from hydrogen bonds.

Tertiary structure dependence

Not directly dependent on peptide bonds.

5' ends of RNA molecules

Have phosphate groups attached to the number 5 carbons of ribose.

3' end of RNA molecule

Typically has a hydroxyl functional group.

Nitrogenous base attachment in RNA

Attached at carbon #1 of the ribose sugar.

Ribose vs. deoxyribose

Ribose has a hydroxyl group at the 2' carbon while deoxyribose has a H atom.

Function of RNA molecules

Involved in the synthesis of proteins.

Nucleotide composition

Composed of a nitrogenous base, a phosphate group, and a pentose sugar.

Purines

Nitrogenous bases that include guanine and adenine.

Pyrimidines

Include cytosine (C), thymine (T), and uracil (U).

Sugar difference between DNA and RNA

The sugar in DNA contains one less oxygen atom than the sugar in RNA.

5'-GAACUT-3' sequence

May be found in neither DNA nor RNA.

DNA directionality

DNA goes from 5' to 3'.

Flow of genetic information

Goes from DNA to RNA to protein.