UNIT 1.5

Question 1

All living cells fall into one of three broad categories

Answer 1

Archaea, Bacteria and Eukarya

Question 2

Archaea and bacteria are referred to collectively as

Answer 2

prokaryotes.

Question 3

are single-celled organisms that lack nuclei and other organelles

Answer 3

prokaryotes.

Question 4

prokaryotes are grouped together as members of the kingdom

Answer 4

Monera

Question 5

Despite great diversity in form and function, cells and organisms share much bio-chemistry in common. This commonality and diversity has been substantiated by the results of

Answer 5

whole genome sequencing,

Question 6

Any minimum gene set must encode all the information necessary for cellular metabolism, including the vital functions essential to reproduction. The simplest cell must show at least

Answer 6

(1) some degree of metabolism and energy production;

(2) genetic replication based on a template molecule that encodes information (DNA or RNA?); and

(3) formation and maintenance of a cell boundary (membrane).

Question 7

reported lowest number of protein coding genes in or order for a cell to function

Answer 7

105 protein-coding genes.

Question 8

heat- and acid-loving bacteria

Answer 8

thermoacidophiles

Question 9

salt-loving bacteria

Answer 9

halophiles

Question 10

bac-teria that generate methane from CO2 and H2

Answer 10

methanogens

Question 11

Prokaryotes are typically very small, on the order of several microns in length, and are usually surrounded by a

Answer 11

rigid cell wall

Question 12

Prokaryotic cells have only a single membrane, the

Answer 12

plasma membrane or cell membrane.

Question 13

they possess a distinct nuclear area where a ______ is localized

Answer 13

single circular chromosome

Question 14

some prokaryotes have an internal membranous struc-ture called a

Answer 14

mesosome

Question 15

In _______, flat, sheetlike membranous structures called lamellae are formed from cell membrane infoldings.

Answer 15

cyanobacteria

Question 16

are the sites of photosynthetic ac-tivity, but they are not contained within plastids

Answer 16

lamellae

Question 17

Some bacteria have _______, single, long filaments used for motility.

Answer 17

flagella

Question 18

Mechanical support, shape, and protection against swelling in hypotonic media. The _________ is a porous nonselective barrier that allows most small molecules to pass.

Answer 18

cell wall

Question 19

Molecular Composition of cell wall

Answer 19

peptidoglycan

Question 20

is a highly selective perme-ability barrier that controls the entry of most sub-stances into the cell. Important enzymes in the generation of cellular energy are located in the ______.

Answer 20

cell membrane

Question 21

The cell membrane molecular composition

Answer 21

45% lipid and 55% protein.

Question 22

Where does this happen?

DNA provides the operating instructions for the cell; it is the repository of the cell’s genetic infor-mation. During cell division, each strand of the double-stranded DNA molecule is replicated to yield two double-helical daughter molecules.

Answer 22

Nuclear area or nucleoid

Question 23

Nuclear area or nucleoid Molecular Composition

Answer 23

a single, tightly coiled DNA molecule 2 nm in diameter

Question 24

are the sites of protein synthesis.

Answer 24

Ribosomes

Question 25

Ribosomes Molecular Composition

Answer 25

Bacterial cells contain about 15,000 ribosomes. Each is composed of a small (30S) subunit and a large (50S) subunit.

Question 26

When needed as metabolic fuel, the monomeric units of the polymer are liberated and degraded by energy-yielding pathways in the cell.

Answer 26

Storage granules

Question 27

is the site of intermediary metabo-lism, the interconnecting sets of chemical reac-tions by which cells generate energy and form the precursors necessary for biosynthesis of macro-molecules essential to cell growth and function.

Answer 27

Cytosol

Question 28

are supramolecular complexes of nucleic acid, either DNA or RNA, en-capsulated in a protein coat and, in some instances, surrounded by a membrane envelope

Answer 28

Viruses

Question 29

Viruses infecting bacteria are called

Answer 29

bacteriophages

Question 30

Mature virus particles arise by encapsulating the nucleic acid within a protein coat called the

Answer 30

capsid

Question 31

Often, viruses cause disintegration of the cells that they have infected, a process referred to as

Answer 31

cell lysis.

Question 32

It is their cytolytic properties that are the basis of viral dis-ease. In certain circumstances, the viral genetic elements may integrate into the host chromosome and become quiescent. Such a state is termed

Answer 32

lysogeny.

Question 33

This complex coating is cell specific, serves in cell–cell recognition and communication, creates cell adhesion, and provides a protective outer layer.

Answer 33

Extracellular matrix

Question 34

Extracellular matrix Molecular Composition

Answer 34

flexible and sticky layer of complex carbohydrates, proteins, and lipids.

Question 35

is a selectively permeable outer boundary of the cell, containing specific systems—pumps, channels, transporters, receptors—for the exchange of materials with the environment and the reception of extracellular information. Impor-tant enzymes are also located here.

Answer 35

Cell membrane (plasma membrane)

Question 36

Cell membrane (plasma membrane) Molecular Composition

Answer 36

Roughly 50:50 lipid:protein as a 5-nm-thick continuous sheet of lipid bilayer

Question 37

is the repository of genetic information encoded in DNA and organized into chromosomes. During mitosis, the chromosomes are replicated and transmitted to the daughter cells.

Answer 37

Nucleus

Question 38

Molecular Composition Nucleus

Answer 38

The DNA is com-plexed with basic proteins (histones)

Question 39

is a labyrinthine organelle where both membrane proteins and lipids are synthe-sized. Proteins made by the ribosomes of the rough ER pass through the ER membrane into the cisternae and can be transported via the Golgi to the periphery of the cell.

Answer 39

Endoplasmic reticulum (ER) and ribosomes

Question 40

Flattened sacs, tubes, and sheets of internal membrane extending throughout the cytoplasm of the cell and en-closing a large interconnecting series of volumes called

Answer 40

cisternae

Question 41

Involved in the packaging and processing of macro-molecules for secretion and for delivery to other cellular compartments.

Answer 41

Golgi apparatus

Question 42

are the power plants of eukaryotic cells where carbohydrates, fats, and amino acids are oxi-dized to CO2 and H2O. The energy released is trapped as high-energy phosphate bonds in ATP.

Answer 42

Mitochondria

Question 43

function in intracellular digestion of materials entering the cell via phagocytosis or pino-cytosis.

Answer 43

Lysosomes

Question 44

act to oxidize certain nutrients, such as amino acids. In doing so, they form potentially toxic hydrogen peroxide, H2O2, and then decompose it to H2O and O2 by way of the peroxide-cleaving enzyme catalase.

Answer 44

Peroxisomes

Question 45

determines the shape of the cell and gives it its ability to move. It also mediates the internal movements that occur in the cytoplasm, such as the migration of organelles and mitotic movements of chromosomes.

Answer 45

cytoskeleton

Question 46

Protection against osmotic or mechanical rupture. The walls of neighboring cells interact in cement-ing the cells together to form the plant.

Answer 46

Cell wall

Question 47

function in transport and storage of nutrients and cellular waste products. By accumu-lating water, the vacuole allows the plant cell to grow dramatically in size with no increase in cyto-plasmic volume.

Answer 47

Vacuole