Multicellular animal

serve as structural components of a cell

Cells produce three types of large macromolecules:

control of gene activity depends on DNA-binding proteins called

transcription factors

bipartite molecules

phospholipid molecules

The bacterial cell wall is composed of layers of

peptidoglycan, a complex of proteins and oligosaccharides

are organelles enclosed by two membranes

the nucleus, mitochondrion, and chloroplast

Three classes of fibers compose the cytoskeleton

microtu- bules (20 nm in diameter), built of polymers of the protein tubulin; microfilaments (7 nm in diameter), built of the pro- tein actin; and intermediate filaments (10 nm in diameter).

1. controls movement of molecules in and out of the cell and functions in cell-cell signaling and cell adhesion.

1. Plasma membrane

1. generate ATP by oxidation of glucose and fatty acids.

1. Mitochondria

1. have an acidic lumen, degrade material internalized by the cell and worn-out cellular membranes and organelles.

1. Lysosomes

1. filled with chromatin composed of DNA and proteins; site of mRNA and tRNA synthesis.

1. contains enzymes that synthesize lipids and detoxify certain hydrophobic molecules

1. functions in the synthesis, processing, and sorting of secreted proteins, lysosomal proteins, and certain membrane proteins.

1. processes and sorts secreted proteins, lysosomal proteins, and membrane proteins synthesized on the rough ER.

1. Golgi complex

1. store secreted proteins and fuse with the plasma membrane to release their contents.

1. increase surface area for absorption of nutrients from surrounding medium

1. Microvilli

1. stores water, ions, and nutrients, degrades macromolecules, and functions in cell elongation during growth. 

1. tubelike cell junctions that span the cell wall and connect the cytoplasms of adjacent plant cells.

the space between the inner and outer nuclear membranes is continuous with the

lumen of the endoplasmic reticulum

The two nuclear membranes appear to fuse at

nuclear pore complexes

________ form a two-dimensional network, called the _________, along the inner surface of the inner nuclear membrane, giving it shape and rigidity

the non-nucleolar regions of the nu- cleus

nucleoplasm

dark areas, which are often closely associated with the nuclear membrane, contain condensed, concentrated DNA that cannot be transcribed into RNA

heterochromatin

During the S phase of the cell cycle....

chromosomes are duplicated, and the daughter “sister chromatids,” each with a complete copy of the chromosomal DNA, remain attached at the centromere.

the endoplasmic reticulum (ER)—an extensive network of closed, flattened membrane-bounded sacs called

cisternae

Newly made membrane proteins remain associated with the rough ER membrane, and proteins to be secreted accumulate in the...

lumen

endocytosis

a sorting station of membrane-limited tubules and vesicles

endosome

The process by which an aged organelle is degraded in a lysosome is called

large, insoluble particles (e.g., bacteria) are enveloped by the plasma membrane and internalized.

All of these lysosomal enzymes are collectively termed

acid hydrolase

Cytosolic and nuclear proteins generally are not degraded in lysosomes, but rather in ______, large multiprotein complexes in the cytosol

a class of roughly spherical organelles 0.2–1.0 μm in diameter.  contain several oxidases:  also contain copious amounts of the enzyme catalase

enzymes that use molecular oxygen to oxidize organic substances and in the process form hydrogen peroxide (H2O2),

small organelles that plants have that oxidize stored lipids as a source of car- bon and energy for growth

glyoxisomes

occupy up to 25 percent of the volume of the cytoplasm

contains proteins that allow many molecules to move from the cytosol to the intermembrane space between the inner and outer membrane.

outer mitochondrial membrane

much less permeable, is about 20 percent lipid and 80 percent protein—a proportion of protein that is higher than those in other cellular mem- branes.

inner mitochondrial membrane

The surface area of the inner membrane is greatly increased by a large number of infoldings

In eukaryotic cells, the initial stages of glucose degradation take place in the

the chloroplast also contains an extensive internal system of interconnected membrane- limited vesicles called

Thylakoids often form stacks called

grana are embedded in an aqueous matrix termed the

thylakoid membranes contain green pigments called

The chromosomes and the DNA they carry are duplicated during the

The rep- licated chromosomes separate during the

The M and S phases are separated by two gap phases, the

during which mRNAs, proteins, lipids, and other cell constituents are made and the cell increases in size.

Proteins from different organisms, but with similar amino acid sequences, are said to be

homologous

The cells of higher plants are encased in a network of cham- bers formed by the interlocking cell walls surrounding the cells and are connected by cytoplasmic bridges called

Animal cells are often “glued” together into a chain, a ball, or a sheet by cell- adhesion proteins on their surfaces, often called

made up of polysaccharides and multiple proteins such as collagen, forms a supporting layer underlying cell sheets and prevents the cell aggregates from ripping apart

The external surfaces of all metazoan animals, as well as the surfaces of their internal organs, are covered by a sheet-like layer of tissue called an

Cells that form epithelial tissues are said to be

Typically, the distinct surfaces of a polarized epithelial cell are the

basal and lateral (collectively, basolateral) surfaces

lumen of a small blood vessel is lined with a sheet-like layer of endothelial cells, or

DNA seg- ments that have the same order of unique DNA sequences and genes along a segment of a chromosome

regions of synteny

Embryonic Development Uses a Conserved Set

of

Master Transcription Factors

these proteins bind to regulatory DNA sequences, are conserved throughout evolu- tion, and control the development of specific types of cells by activating or repressing groups of genes, often at different stages of development.

develop a mouth close to a transient opening in the early embryo (the blastopore)

 a transient opening in the early embryo

develop an anus close to this transient opening in the embryo and have a dorsal central nervous system

Protostomes develop a mouth close to a transient opening in the early embryo (the blastopore) and have a

encode master transcription fac- tors that control expression of other genes and specify the general organization of an organism

is characteristic of stem cells and is critical to the generation of different cell types in the body

molecules that are mirror images of each other, a property called chirality (“handedness,” from the Greek word cheir, meaning “hand”) (Figure 2-4). Such mol- ecules are called optical isomers,

When the van der Waals attraction between two atoms exactly bal- ances the repulsion between their two electron clouds, the atoms are said to be

lipids such as cholesterol must be packaged into special hydrophilic carriers, called

a lock- and-key kind of fit between their shapes, charges, or other physical properties

Thus the binding of a molecule to another has the potential to induce a change in the shape of its binding partner. When the molecular complementarity increases after such interac- tions, the process is called

Polysaccharides are linear or branched polymers of monosaccharides (sugars) such as glucose linked by

the for- mation of a covalent bond between two monomers usually involves the net loss of a

covalent bond forma- tion between monomers can be thought of as a 

The breakdown, or cleavage, of a covalent bond in a polymer that releases a monomeric sub- unit involves the reverse reaction, or the addition of water, called

All amino acids have a characteristic structure consisting of a

With rare exceptions, only the _______ of amino acids are found in proteins

The side chains of alanine, valine, leucine, and isoleucine are linear or branched hydrocarbons that do not form a ring, and they are therefore called

Phenyl- alanine, tyrosine, and tryptophan have large, hydrophobic _______ in their side chains

serve to “cross-link” regions within a single polypeptide chain (intramolecular cross-linking) or between two separate chains (intermolecular cross-linking)

must be included in the diet to permit nor- mal protein production.

One important modification is the addition of (CH3CO) to amino acids, a process known as

Another is the addition of a (PO4) to hydroxyl groups in serine, threonine, and tyrosine residues, a process known as

nucleotides, all have a common structure:

In RNA, the pentose is _______; in DNA, it is ________, which has a________

Adenine and guanine are _______, which contain a pair of fused rings

cytosine, thymine, and uracil are _________ which contain a single ring (see Figure 2-17).

Cells and extracellular fluids in organisms contain small concentrations of ________, combinations of a base and a sugar without a phosphate.

involves the covalent linking of an acid, such as a car- boxylic acid or a phosphoric acid, with an alcohol accom- panied by the release of an hydroxyl (−OH) group from the acid and an H from the hydroxyl group on the other molecule, which together form a water molecule.

Monosaccharides are

covalently bonded combinations of carbon and water in a one-to-one ratio (CH2O)n, where n equals 3, 4, 5, 6, or 7. Hexoses (n = 6) and pentoses (n = 5) are the most common monosaccharides.

Mannose is identical to glucose except that the orientation of the groups bonded to carbon 2 is reversed. Similarly, galactose, another hexose, differs from glucose only in the orientation of the groups attached to carbon 4. Interconver- sion of glucose and mannose or galactose requires the break- ing and making of covalent bonds; such reactions are carried out by enzymes called

The most common storage carbohydrate in animal cells is

The primary storage carbohydrate in plant cells,

Both glycogen and starch are composed of the

Bacterial cell walls con- sist of

consist of a hydrocarbon chain attached to a carboxyl group (−COOH)

Fatty acids in which all the carbon-carbon bonds are single bonds—that is, the fatty acids have no carbon-carbon double bonds—are said to be

Unsaturated fatty acids with more than one carbon-carbon double bond are referred to as

Two “essen- tial” polyunsaturated fatty acids, _____ and ______, cannot be synthesized by mammals and must be supplied in their diet. Mammals can synthesize other common fatty acids.

In phospholipids, fatty acids are covalently attached to another molecule by

In phospholipids, fatty acids are covalently attached to another molecule by esterification. In the combined molecule formed by this reaction, the part derived from the fatty acid is called an

can relieve the torsional stress that develops in cellular and viral DNA molecules during replica- tion and transcription

topoisomerase I

topoisomerase I binds to DNA at ran- dom sites and breaks a phosphodiester bond in one strand. Such a one-strand break in DNA is called a

makes breaks in both strands of a double-stranded DNA and then religates them. As a result, can both relieve torsional stress and link to- gether two circular DNA molecules as in the links of a chain.