Molecular Biology - Ch 18

Front 1

Hershey and Chase experiment showed . . .

Back 1

. . . by using radioactive isotopes, they were able to show that DNA from phages ended up in other phages, but proteins did not. ("Waring Blender" experiment)

Front 2

Bacteriophage (phage)

Back 2

Viruses that infect bacteria

Front 3

Bacteriophage components:

Back 3

DNA-filled Head, Hollow Tail, Baseplate, Tail fibers

Front 4

Chargaff's Rule

Back 4

The # of As = # of Ts, and Gs = Cs

Front 5

DNA base composition ______ from species to species

Back 5

DNA base composition _varies_ from species to species

Front 6

DNA isolated from different cells of any species have the same percentage of . . .

Back 6

. . . each of the 4 bases

Front 7

The number of purines ________ the number of pyrimadines

Back 7

The number of purines _equals_ the number of pyrimadines

Front 8

The helix if DNA is ____-handed, meaning it curls __ward to the ____

Back 8

The helix if DNA is _right_-handed, meaning it curls _up_ward to the _right_

Front 9

DNA contains ___ nucleotide pairs per turn

Back 9

DNA contains _10_ nucleotide pairs per turn

Front 10

The two strands of the double helix are held together by _________ bonding

Back 10

The two strands of the double helix are held together by _hydrogen_ bonding

Front 11

Each strand of DNA can function as a ______ dictating the synthesis of a new complementary DNA strand using the base-pairing rules

Back 11

Each strand of DNA can function as a _template_ dictating the synthesis of a new complementary DNA strand using the base-pairing rules

Front 12

two strands of the double helix run ________ to each other

Back 12

two strands of the double helix run _anti-parallel_ to each other

Front 13

Each complete turn of the DNA double helix adds ___ nm to the length of the molecule

Back 13

Each complete turn of the DNA double helix adds _3.4_ nm to the length of the molecule

Front 14

DNA can go back and forth between the _____ state and _____, or relaxed, state

Back 14

DNA can go back and forth between the _supercoiled_ state and _non-supercoiled_, or relaxed, state

Front 15

topoisomerases

Back 15

interconvert DNA between relaxed and supercoiled forms

Front 16

Positive supercoiling involves ____ winding of the DNA helix and therefore ______ opportunities for interaction

Back 16

Positive supercoiling involves _tighter_ winding of the DNA helix and therefore _reduces_ opportunities for interaction

Front 17

Negative supercoiling involves ____ of the DNA helix which give strands ______ access to proteins involved in DNA replication

Back 17

Negative supercoiling involves _unwinding_ of the DNA helix which give strands _increased_ access to proteins involved in DNA replication

Front 18

Type I topoisomerase relaxes supercoiled DNA by . . .

Back 18

. . . introducing transient single-strand breaks by cutting one strand of the double helix, allowing the DNA to rotate and the uncut strand to be passed through the break before the broken strand is resealed

Front 19

Type II topoisomerase relaxes supercoiled DNA by . . .

Back 19

. . . introducing transient double-strand breaks by cutting both DNA strands and then passing a segment of uncut double helix through the break before the broken strand is resealed.

Front 20

Type I & II topoisomerases are able to remove . . . . . from DNA

Back 20

Type I & II topoisomerases are able to remove both negative and positve supercoils from DNA

Front 21

DNA Hybridization

Back 21

Procedures for identifying nucleic acids based on the ability of single-stranded chains with complementary base sequences to bind, or hybridize with each other

Front 22

DNA Melting temperature

Back 22

The temperature at which one-half of the light-absorbance change has been achieved

Front 23

GC base pairs are held together by ___ hydrogen bonds

Back 23

GC base pairs are held together by _3_ hydrogen bonds

Front 24

AT base pairs are held together by ___ hydrogen bonds

Back 24

AT base pairs are held together by _2_ hydrogen bonds

Front 25

probe

Back 25

A purified single-stranded radioactive DNA fragment whose sequence is complementary to the base sequence one is trying to detect

Front 26

Genome

Back 26

A complete copy of all the genetic information of an organism or virus

Front 27

restriction endonucleases are also called . . .

Back 27

. . . restriction enzymes

Front 28

Restriction enzymes

Back 28

proteins isolated from bacteria that cut foreign DNA molecules at specific internal sites.

Front 29

Restriction fragments

Back 29

A specific set of DNA pieces cut by a restriction enzyme

Front 30

Restriction site

Back 30

A specific recognition sequence that a restriction enzyme recognizes, and where it cuts.

Front 31

blunt ends

Back 31

straight cut in DNA by restriction enzyme

Front 32

sticky ends

Back 32

staggered cut in DNA by restriction enzyme

Front 33

gel electrophoresis

Back 33

Method of determining number and lengths of restriction fragments,

Front 34

DNA Sequencing

Back 34

Determining the linear order of bases in DNA

Front 35

dideoxynucleotides

Back 35

Used for DNA sequencing. They stop a DNA strand for growing.

Front 36

DNA polymerase

Back 36

Catalyzes the attachment of nucleotides to the 3' end of the primer, producing a growing DNA strand that is complementary to the template whose sequence is being determined

Front 37

Bioinformatics

Back 37

Merges computer science with biology in an attempt to make sense of data gathered from DNA sequences

Front 38

transcriptomes

Back 38

The entire set of RNA molecules produced by the genome

Front 39

proteomes

Back 39

The structure and properties of every protein produced by the genome

Front 40

SNPs

Back 40

Single Nucleotide Polymorphisms - Differences involving single base pair changes

Front 41

tandemly repeated DNA

Back 41

Multiple copies arranged next to each other in a row (a single unit tends to be 1 to 2000 BPs long)

Front 42

Interspersed repeated DNA

Back 42

Repeated units of DNA scattered throughout the genome (a single unit tends to be hundreds or even thousands of BPs long)

Front 43

Transposable elements (transposons)

Back 43

Genes that move around the genome and leave copies of themselves wherever they stop. Can be cut out and replaced back in the genome

Front 44

RFLPs

Back 44

Restriction Fragment Length Polymorphisms - Differences in DNA fragment lengths

Front 45

nucleoid

Back 45

region of bacterial cell where DNA is bound

Front 46

Plasmids

Back 46

Small, circular DNA found in bacteria

Front 47

Chromatin

Back 47

DNA bound to protein - diffused form of chromatid

Front 48

Histones

Back 48

positively charged amino acids that "ion bind" to DNA, making it more stable

Front 49

Nucleosome

Back 49

nucleosomes, "beads" of histones connected by a strand of DNA

Front 50

"Bead on a String"

Back 50

model of chromatin fibers consisting of repeating nucleosomes

Front 51

Nucleosome Core

Back 51

146 nucleotide base pairs wound around 8 Histone proteins

Front 52

Histone H1

Back 52

Released upon degradation of Linker DNA

Front 53

Linker DNA

Back 53

joins one nucleosome to the next

Front 54

heterochromatin

Back 54

highly compacted segments of chromatin that show up as dark spots on micrographs

Front 55

euchromatin

Back 55

loosely packed, diffuse form of chromatin

Front 56

Perinuclear space

Back 56

space between two walls of nuclear envelope; continuous with ER lumen

Front 57

Nuclear pore

Back 57

specialized cylindrical channel extending through both membranes of the nuclear envelope

Front 58

nucleoplasm

Back 58

interior of the nucleus, other than the nucleolus

Front 59

Nuclear Pore complex

Back 59

2 parallel rings, each housing 8 water-filled channels. can transport small proteins, etc. by simple diffusion

Front 60

Transporter (aka Central Granule)

Back 60

Large selective passageway of the nuclear pore

Front 61

Nuclear Localization Signal

Back 61

amino acid sequence on "cargo protein" that importin binds to in order to bring the cargo into the nucleus

Front 62

importin

Back 62

cytosolic receptor protein - allows "cargo proteins" to cross nuclear pore into nucleus

Front 63

Ran

Back 63

nucleoplasmic GTP-binding protein that dissociates importin from its cargo. Carries GTP/importin complex out of the nucleus

Front 64

exportin

Back 64

nucleoplasmic receptor protein - allows "cargo proteins" to cross nuclear pore out of nucleus

Front 65

RNA leaves the nucleus as . . .

Back 65

. . . an RNA protein complex

Front 66

Nuclear Localization Signals

Back 66

Amino Acid Sequences that enable a protein to be recognized and transported by the nuclear pore complex

Front 67

Nuclear Export Signals

Back 67

Short amino acid sequence in a protein that targets it for export from the cell nucleus to the cytoplasm through the nuclear pore complex

Front 68

Nuclear export usually involves . . .

Back 68

. . . RNA molecules that are synthesized in the nucleus but function in the cytoplasm

Front 69

Nuclear import usually involves . . .

Back 69

. . . proteins synthesized in the cytoplasm but function in the nucleus

Front 70

Release of _________ for reuse is coupled to the _________ of the GTP bound to _____

Back 70

Release of _importin_ for reuse is coupled to the _hydrolysis_ of the GTP bound to _Ran_

Front 71

Nuclear matrix

Back 71

A.K.A. Nucleoskeleton, fibrous network thought to maintain the shape of the nucleus and provide an organizing skeleton for the chromatin fibers

Front 72

Nuclear Lamina

Back 72

Network of intermediate filaments that lines the inner surface of the inner nuclear membrane and confers mechanical strength to the nucleus

Front 73

Constitutive heterochromatin

Back 73

Simple-sequence repeated DNA of a largely structural function

Front 74

Facultative heterochromatin

Back 74

varies with particular activities carried out by the cell. Differs from tissue to tissue, and time to time within a given cell. Specifically inactivated regions of DNA

Front 75

Simple-sequence repeated DNA

Back 75

Short sequences of DNA that repeat tandemly and are not transcribed

Front 76

Heterochromatin

Back 76

Highly compacted chromatin regions bound to certain segments of the nuclear envelope at inner membrance sites

Front 77

nucleolus

Back 77

ribosomal factory of the cell

Front 78

Nuclear Organizing Centers (NORs)

Back 78

A stretch of DNA carrying multiple copies of rRNA genes

Front 79

Granules

Back 79

Ribosomes being assembled from rRNA and protein

Front 80

Nucleic acids absorb ________ because of the absorption by ________.

Back 80

Nucleic acids absorb _ultraviolet light_ because of the absorption by _purines and pyrimidines_.

All DNA absorbs ultraviolet light, with an absorption maximum around 260 nm that is due to absorption by the aromatic rings of purine and pyrimidine bases.

Front 81

DNA fingerprinting can be used to solve murder cases by analyzing ________.

Back 81

varying numbers of tandem repeats in DNA

Non-repeated DNA is likely the genes, which may have significant conservation from one person to another. This material is not useful for DNA fingerprinting.

For DNA fingerprinting, scientists can analyze short repeated DNA sequences called short tandem repeats (STRs). Because STR length varies significantly from person to person, they can be used to identify a specific individual's DNA.

Front 82

Short tandem repeats (STRs) of DNA from mammalian genomes have differing . . .

Back 82

. . . G-C content from the average for the genome they are part of
STRs tend to be localized in patches that are hundreds to millions of base pairs in length.

Front 83

Which answer shows the correct order from smallest to largest?

chromatin fiber
looped domain
heterochromatin
chromosome

Back 83

Chromatin fibers are approximately 30 nm wide and make up looped domains (300 nm wide). These fold into heterochromatin (700 nm wide), which becomes highly condensed to form chromosomes (1400 nm wide).

Front 84

________ provides structural support for the nucleus and attachment sites for chromatin.

It is a thin, dense meshwork of fibers that lines the inner surface of the inner nuclear membrane. It helps support the nuclear envelope and provides attachment sites for chromatin.

Back 84

The nuclear lamina provides structural support for the nucleus and attachment sites for chromatin.

The nuclear lamina is a thin, dense meshwork of fibers that lines the inner surface of the inner nuclear membrane. It helps support the nuclear envelope and provides attachment sites for chromatin.