Biology Exam 5

Front 1

RNA synthesis from a DNA template

Back 1

Transcription

Front 2

Synthesis of a polypeptide (protein)using the gentic information encoded in an mRNA molecule

Back 2

Translation

Front 3

Flow of information from gene to protein is based on a ______________

Back 3

Triplet code

Front 4

mRNA sequence is _________ to the DNA template

Back 4

complementary

Front 5

AUG codes for

Back 5

start

Front 6

UAA, UGA, UAG dont code for an amino acid, they are __________ codons

Back 6

stop

Front 7

The codon sequence that is determined by reading nucleotides in groups of three from some specific start codon

Back 7

Reading frame

Front 8

T/F: Genetic code is nonoverlapping

Back 8

T

Front 9

mRNA is transcribed from the ___________ strand of a gene

Back 9

Template

Front 10

Enzyme that transcribes DNA into RNA

Back 10

RNA polymerase

Front 11

Initiation, Elongation, Termination

Back 11

Three stages of transcription

Front 12

RNA polymerase binds to a DNA and initiates transcription

Back 12

Initiation

Front 13

A specific nucleotide sequence in DNA that indicates where to start transcription and to which RNA polymerase binds

Back 13

Promoter

Front 14

T/F: Transcription(elongation) proceeds in the 5’ to 3’ direction with local unwinding of the DNA helix (10-20 nucleotides at a time).

Back 14

T

Front 15

Segments of RNA (noncoding sequences called introns) are removed and the coding sequences (exons) are spliced together

Back 15

RNA splicing

Front 16

RNA splicing is carried out by an assembly of proteins and small nuclear RNAs called _______

Back 16

Splicesome

Front 17

Synthesis of a polypeptide (amino acid sequence)using the genetic information encoded in an mRNA molecule (nucleotide sequence)

Back 17

Translation

Front 18

Occurs in cytoplasm, function of ribosomes

Back 18

Translation

Front 19

Interpreters of nucleotide sequence to amino acid sequence

Back 19

tRNA

Front 20

Covalent attachment of an amino acid to the tRNA is an ____________ reaction, requiring the hydolysis of ATP

Back 20

Endergonic

Front 21

Located in cytoplasm, sites of protein synthesis

Back 21

Ribosomes

Front 22

_RNA is the most abundant kind of RNA

Back 22

rRNA

Front 23

holds the tRNA carrying the growing polypeptide

Back 23

P site

Front 24

holds the tRNA carrying the next amino acid

Back 24

A site

Front 25

tRNAs that have discharged their amino acid, leave the ribosome via this site

Back 25

E site

Front 26

A protein that binds to the stop codon in the A site and adds water rather than an amino acid to the polypeptide chain

Back 26

Release factor

Front 27

A stretch of amino acids that targets proteins to specific destinations in eukaryotic cells

Back 27

Signal peptide

Front 28

Changes in the genetic material

Back 28

Mutations

Front 29

Changes in one or a few base pairs

Back 29

Point mutations

Front 30

The replacement of one nucleotide and its partner in the complementary DNA strand with another pair of nucleotides

Back 30

Base-pair substitution

Front 31

Mutations that have no effect on the gene product

Back 31

Silent mutations

Front 32

Altered codon codes for an amino acid but not the correct ones, it still makes sense but not the right sense

Back 32

Missense mutations

Front 33

Altered codon is a stop signal rather than coding for an amino acid

Back 33

Nonsense mutation

Front 34

Addition or loss of one or more nucleotide pairs

Back 34

Insertions and deletions

Front 35

Alteration in the reading frame (triplet code) due to an insertion or deletion

Back 35

Frameshift mutation

Front 36

Chemical or physical agents that cause mutations

Back 36

Mutagens

Front 37

commonly used procedure to test for the mutagenicity (carcinogenicity) of chemicals based on their ability to cause mutation in Salmonella (a bacterium) after incubation with a liver extract.

Back 37

Ames test

Front 38

An infectious particle consisting of nucleic acid enclosed in a protein coat

Back 38

Virus

Front 39

A virus that infects bacteria

Back 39

Phage

Front 40

Protein shell that encloses the viral genome

Back 40

Capsid

Front 41

Protein subunits that make up the capsid

Back 41

Capsomeres

Front 42

Membranes surrounding capsid of some viruses that are derived from the host cell but contain proteins and glycoproteins or viral origin

Back 42

Envelope

Front 43

Capable of reproducing only within a host cell (Ex: Virus)

Back 43

Obligate intracellular parasites

Front 44

Mode of replication that results in the lysis (breaking open; death) of the host cell

Back 44

Lytic cycle

Front 45

Mode of replication in which the viral genome incorperated into the bacterial host chromosome as a prophage

Back 45

Lysogenic cycle

Front 46

Phage that reproduces only by a lytic cycle

Back 46

Virulent virus

Front 47

Phage that is capable of reproducing by both the lytic cycle and lysogenic cycle

Back 47

Temperate virus

Front 48

endonucleases that cut DNA at specific sequences

Back 48

Restriction endonucleauses

Front 49

Harmless varients or derivativesof pathogenic microbes that stimulate the immune system to mount defenses against the pathogen

Back 49

Vaccines

Front 50

Ineffective against viruses since they use mostly host enzymes and processes

Back 50

Antibiotics

Front 51

Mutation, spread from one host to another, dissemination from small island population

Back 51

Processes that contributed to emergence of new viral diseases

Front 52

Hepititis B virus can cause what kind of cancer?

Back 52

Liver cancer

Front 53

Epstein-Barr virus can cause what kind of cancer?

Back 53

Mononucleosis and Burkitt's lymphoma

Front 54

Papilloma viruses can cause what kind of cancer?

Back 54

Cervical cancers

Front 55

HTLV (retroviruses)can cause what kind of cancer?

Back 55

Adult leukemia

Front 56

Genes that are directly involved in triggering cancerous characteristics in cells.

Back 56

Oncogens

Front 57

Plant is infected from an external source of the virus (usually gain entrance by insects or damage)

Back 57

Horizontal transmission

Front 58

Plant inherits viral infection from parent (Asexual propogation or infected seeds)

Back 58

Vertical transmission

Front 59

Viruses spread throughout plant by passing through the __________

Back 59

Plasmodesmata

Front 60

naked circular RNA molecules that dont code for proteins but disrupt metabolism of plant cells and stunt plant growth

Back 60

Viroids

Front 61

Infectious proteins that cause degenerative brain disease

Back 61

Prions

Front 62

4.6 X 106 bp and 4300 genes (100 times more than a typical virus; 1000 times less than the average eukaryotic cell)

Back 62

E. Coli

Front 63

Generation time of approx. 20 min

Back 63

E. Coli

Front 64

Bacteria divide by _______

Back 64

Binary fission

Front 65

Spontaneous mutation rate in any gene is approximately _______ per cell division

Back 65

10^-7

Front 66

Major mechanism for genetic variation in bacteria

Back 66

New mutations

Front 67

the alteration of a bacterial cell’s genotype by the uptake of naked DNA from the environment
e.g., Streptococcus pneumonia and rough to smooth transformation

Back 67

Transformation

Front 68

Transfer of bacterial genes from one host to another by a phage

Back 68

Transduction

Front 69

random pieces of host DNA are packaged within a phage capsid and the phage particle injects this DNA into another cell

Back 69

Generalized transduction

Front 70

a prophage exits the chromosome incorrectly, taking adjoining bacterial DNA at the expense of phage DNA

Back 70

Specialized transduction

Front 71

Bacterial version of sex, transfer of genetic material between two bacterial cells that are temporarily joined

Back 71

Conjugation

Front 72

“male” E. coli has specialized appendages called sex pili, which are used to attach to a recipient (“female”) E. coli, forming a cytoplasmic bridge through which the “male” transfers DNA to the “female”

Back 72

Conjugation

Front 73

(ability to form sex pili and donate DNA during conjugation) depends on presence of an F factor (fertility factor)

Back 73

Maleness

Front 74

genetic elements (like the F plasmid; l phage) that can replicate either as a plasmid or as part of the bacterial chromosome

Back 74

Episomes

Front 75

plasmids that carry genes conferring antibiotic resistance

Back 75

R plasmids

Front 76

transposable genetic element; piece of DNA that can move from one location to another in a cell’s genome

Back 76

Transposon

Front 77

Transposition occurs as a type of recombination between transposon and a target ___ site

Back 77

DNA

Front 78

Transposon is cut out from one location in the genome and pasted into a different location

Back 78

Cut and paste transposon

Front 79

Transposon is replicated and the new copy is inserted at a different location while the original copy remains at the original site

Back 79

Replicative transposition

Front 80

Carry other genes besides those necessary for transposition

Back 80

Composite transposons

Front 81

A DNA region at one end of an operon that acts as the binding site for repressor protein

Back 81

Operator

Front 82

A set of adjacent structural genes whose mRNA is synthesized in one piece, plus the adjacent regulatory signals that affect transcription of the structural genes

Back 82

Operon

Front 83

A protein that suppresses the transcription of a gene

Back 83

Repressor

Front 84

A small molecule that cooperates with a repressor to switch off a gene or operon

Back 84

Corepressor

Front 85

Human somatic cells have

Back 85

6 x 10^9 bp of DNA

Front 86

How many genes do human somatic cells ahve?

Back 86

35,000

Front 87

The complex of DNA and proteins that make up a eukaryotic cell

Back 87

Chromatin

Front 88

Very basic proteins (high lysine and arginine content; positive charge)responsible for the first level of DNA packaging in eukaryotic chromatin

Back 88

Histones

Front 89

Highly condensed state

Back 89

Heterochromatin

Front 90

Less condensed regions of chromosomes

Back 90

Euchromatin

Front 91

In general, genes in heterochromatin are __________ while genes in euchromatin are ___________.

Back 91

Not transcribed; transcribed

Front 92

A typical human cell only expresses ___% of its gene at any given time

Back 92

20%

Front 93

Only __% of the human genome codes for mRNA (protein)

Back 93

1.5%

Front 94

Mental retardation, short stature, facial anomalies; acetyl groups added to certain histones, causing inappropriate transcription of some genes

Back 94

Rubinstein-Taybi syndrome

Front 95

inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence

Back 95

Epigenetic inheritance

Front 96

Chromosomal structure & DNA methylation are both involved in

Back 96

Epigenetic inheritance

Front 97

a specific nucleotide sequence in DNA (includes a TATA box for protein-encoding genes) that binds RNA polymerase and general transcription factors and indicates the start of transcription

Back 97

Promoter

Front 98

DNA sequences close to the promoter to which more specialized transcription factors bind, resulting in a higher rate of transcription.

Back 98

Proximal control elements

Front 99

DNA sequences more distal (farther away; may be thousands of nucleotides, upstream or downstream or even within an intron) from the promoter to which activator proteins bind and stimulate transcription by interacting with mediator proteins that interact with proteins at the promoter.

Back 99

Enhancers

Front 100

operons are the rule (genes encoding proteins of related function are adjacent, share a promoter and control elements, and are transcribed as a single mRNA)

Back 100

Prokaryotes

Front 101

operons rarely found; genes encoding proteins of related function are often scattered on different chromosomes; coordinate expression is dependent upon presence of similar control elements

Back 101

Eukaryotes

Front 102

different RNA molecules (and proteins) can be produced from the same primary transcript, depending on which exons are selected

Back 102

Alternative RNA splicing

Front 103

small single-stranded RNA molecules that can bind to complementary sequences of mRNAs, leading to degradation or inactivation of the mRNAs

Back 103

Micro RNAs

Front 104

normal cellular genes, closely related to oncogenes, that encode proteins that stimulate normal cell growth and division

Back 104

Proto-oncogenes

Front 105

Cancer causing genes

Back 105

Oncogenes

Front 106

Cancer is caused by _________ that alter genes that normally regulate cell growth and division.

Back 106

Mutations

Front 107

genes that encode products that normally help prevent uncontrolled cell growth. Some encode proteins involved in DNA repair, control of the cell cycle, and control of adhesion of cells to each other or an extracellular substrate

Back 107

Tumor suppressor genes

Front 108

Encodes a G protein
Mutated in about 30% of human cancers

Back 108

Ras proto-oncogene

Front 109

Tumor suppressor that is mutated in about 50% of human cancers

Back 109

p53

Front 110

Why does cancer incedence increase with age?

Back 110

Mutations accumulate

Front 111

Contribute to approximately 15% of human cancer cases by integrating into the genome of the host cell

Back 111

Viruses

Front 112

Eye tumor in children; inherit a single mutant Rb gene, which encodes a tumor suppressor

Back 112

Retinoblastoma

Front 113

Autosomal recessive; defective DNA repair

Back 113

Xeroderma pigmentosum

Front 114

Defective in another type of DNA repair

Back 114

Hereditary nonpolyposis colorectal cancer

Front 115

5-10% due to defective BRCA1 or BRCA2 genes, encoding products involved in DNA repair

Back 115

Breast cancer

Front 116

Transposon element-related sequences in primates; account for 10% of human genome; many are transcribed

Back 116

Alu elements