Unit 1

Question 1

Systems Biology

Answer 1

An approach to studying biology that aims to model the dynamic behavior of whole biological systems based on a study of the interactions among the system’s parts

Question 2

Cell theory

Answer 2

The theory states that all living organisms are made of cells, which are the basic unit of life. In fact, the actions of organisms are all based on the activities of cells.

Question 3

Cell characteristics

Question 4

Prokaryotic cells

Answer 4

Prokaryotic cells are found in two groups of single-celled microorganisms, bacteria (singular, bacterium) and archaea (singular, archaean). In contrast to eukaryotic cells, a prokaryotic cell lacks a nucleus or other membrane-enclosed organelles. Furthermore, prokaryotic cells are generally smaller than eukaryotic cells

Question 5

Eukaryotic cells

Answer 5

A eukaryotic cell contains membrane-enclosed organelles (Figure 1.4). Some organelles, such as the DNA-containing nucleus, are found in the cells of all eukaryotes; other organelles are specific to particular cell types.

Question 6

Organelles

Answer 6

Any of a number of organized or specialized structures within a living cell.

Question 7

What is a DNA strand made up of?

Answer 7

Arranged in a double helix, each chain is made up of four kinds of chemical building blocks called nucleotides, abbreviated A, T, C, and G (Figure 1.7). Specific sequences of these four nucleotides encode the information in genes.

Question 8

What is RNA?

Answer 8

Protein-encoding genes control protein production indirectly, using a related molecule called RNA as an intermediary. The sequence of nucleotides along a gene is transcribed into mRNA, which is then translated into a linked series of protein building blocks called amino acids.

Question 9

Genome

Answer 9

The entire “library” of genetic instructions that an organism inherits is called its genome. A typical human cell has two similar sets of chromosomes, and each set has approximately 3 billion nucleotide pairs of DNA.

Question 10

Feedback regulation

Answer 10

The regulation of a process by its output or end product

Question 11

Negative feedback

Answer 11

The response reduces the initial stimulus

-Release of insulin

Question 12

Positive feedback

Answer 12

positive feedback, in which an end product speeds up its own production.

-formation of a scab

Question 13

Descent with modification

Answer 13

As species adapt to different environments over time, they accumulate differences from their ancestors.

Question 14

Natural selection

Answer 14

Is a primary cause of descent with modification

Darwin reasoned that individuals with inherited traits that are better suited to the local environment are more likely to survive and reproduce than less well-suited individuals. Over many generations, a higher and higher proportion of individuals in a population will have the advantageous traits. Evolution occurs as the unequal reproductive success of individuals ultimately leads to adaptation to their environment, as long as the environment remains the same.

Question 15

The Origin of Species articulated two main points

Answer 15

The first point was that, as species adapt to different environments over time, they accumulate differences from their ancestors. Darwin called this process “descent with modification.” Darwin’s second main point was his proposal that “natural selection” is a primary cause of descent with modification.

Question 16

Cohesion

Answer 16

The linking together of like molecules, often by hydrogen bonds

Question 17

Surface tension: cause and result

Answer 17

Although the arrangement of molecules in a sample of liquid water is constantly changing, at any given moment many of the molecules are linked by multiple hydrogen bonds. These linkages make water more structured than most other liquids. Collectively, the hydrogen bonds hold the substance together, a phenomenon called cohesion.

Question 18

Moderation of Temperature by Water

Answer 18

Compared with most other substances, water has an unusually high specific heat. Because of the high specific heat of water relative to other materials, water will change its temperature less than other liquids when it absorbs or loses a given amount of heat. This makes water is effective as a heat bank because it can absorb or release a relatively large amount of heat with only a slight change in its own temperature. We can trace water’s high specific heat, like many of its other properties, to hydrogen bonding. Heat must be absorbed in order to break hydrogen bonds; by the same token, heat is released when hydrogen bonds form. A calorie of heat causes a relatively small change in the temperature of water because much of the heat is used to disrupt hydrogen bonds before the water molecules can begin moving faster. And when the temperature of water drops slightly, many additional hydrogen bonds form, releasing a considerable amount of energy in the form of heat.

Question 19

Why does ice float

Answer 19

Hydrogen bonding in water molecules causes the molecules to become locked into a crystalline lattice, each water molecule hydrogen-bonded to four partners. The ability of ice to float due to its lower density is an important factor in the suitability of the environment for life. If ice sank, then eventually ponds, lakes, and even oceans could freeze solid

Question 20

Solute vs solvent

Answer 20

Solute: the substance that is dissolved

Solvent: the substance dissolves

Question 21

Hydrophilic

Answer 21

Any substance that has an affinity for water is said to be hydrophilic (from the Greek hydro, water, and philos, loving). In some cases, substances can be hydrophilic without actually dissolving.

Question 22

Hydrophobic

Answer 22

Substances that are nonionic and nonpolar (or otherwise cannot form hydrogen bonds) actually seem to repel water. The hydrophobic behavior of the oil molecules results from a high number of relatively nonpolar covalent bonds, in this case bonds between carbon and hydrogen, which share electrons almost equally. Hydrophobic molecules related to oils are major ingredients of cell membranes.

Question 23

Buffer

Answer 23

A buffer is a substance that minimizes changes in the concentrations of and in a solution. It does so by accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solution when they have been depleted. Most buffer solutions contain a weak acid and its corresponding base, which combine reversibly with hydrogen ions.

Question 24

Nucleotides

Answer 24

A compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.

Question 25

Structural isomers

Answer 25

Structural isomers differ in the covalent arrangements of their atoms.

Question 26

Cis-trans isomers

Answer 26

carbons have covalent bonds to the same atoms, but these atoms differ in their spatial arrangements due to the inflexibility of double bonds.

Question 27

Enantiomers isomers

Answer 27

Enantiomers are isomers that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon, one that is attached to four different atoms or groups of atoms.

Question 28

ATP

Answer 28

An adenine containing nucleoside treiphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells

Question 29

Amino Acid

Answer 29

An amino acid is an organic molecule with both an amino group and a carboxyl group (see Figure 4.9); the small figure shows the general formula for an amino acid. At the center of the amino acid is an asymmetric carbon atom called the alpha carbon. Its four different partners are an amino group, a carboxyl group, a hydrogen atom, and a variable group symbolized by R.

Question 30

monosaccharides

Answer 30

The simplest carbohydrate active alone or serving as a monomer for disaccharides and polysaccharides. Also called simple sugars, monosaccharides have molecules formulas that are generally some multiple of CH2O

Question 31

What are the four main classes of large biological molecules? Which class does not consist of polymers?

Question 32

Phospholipid

Answer 32

A lipid containing a phosphate group in its molecule

Question 33

Steroids

Answer 33

A type of lipid characterized by carbon skeleton consisting of four fused rings with various chemical groups attached

Question 34

Lipids

Answer 34

A macromolecule of hydrocarbons that are hydrophobic and store energy

Question 35

DNA transcription

Question 36

RNA tanslation

Question 37

Autotrophs

Answer 37

-Obtain carbon and energy from inorganic sources

-Photosynthetic organisms (think plants)

Question 38

Heterotrophs

Answer 38

Obtain carbon & energy from organic compounds