Microbiology Tortora Chapter 8 " Microbial Genetics "

Front 1

________ is the study of heredity.

Back 1

Genetics

Front 2

The genetic information in a cell is called the ___________.

Back 2

genome

Front 3

A cell's genome is organized into ______________.

Back 3

chromosomes

Front 4

_________ carry genes.

Back 4

Chromosomes

Front 5

_______ are segments of DNA that code for functional proteins.

Back 5

Genes

Front 6

_________ are repeating units that compose the macromolecule of DNA.

Back 6

nucleotides

Front 7

What are nucleotides?

Back 7

repeating units that compose DNA

Front 8

What is the structure of a nucleotide?

Back 8

Each nucleotide consists of :

- a nitrogenous base (adenine, thymine, cytosine or guanine)
- deoxyribose ( a pentose sugar)
- phosphate group

Front 9

The ________ is an organism's genetic makeup, the information that codes for all the particular characteristics of the organism.

Back 9

genotype

Front 10

The _________ refers to the actual, expressed properties of an organism

Back 10

phenotype

Front 11

An organism's ________ is its collection of genes.

Back 11

genotype

Front 12

An organism's _______ is its collection of proteins.

Back 12

phenotype

Front 13

The DNA within a cell exists as long strands of _______ twisted together in pairs to form a double-helix.

Back 13

nucleotides

Front 14

The DNA within a cell exists as long strands of nucleotides twisted together in pairs to form a ________.

Back 14

double-helix

Front 15

Each strand of DNA is made up of what?

Back 15

string of alternating sugar and phosphate groups, with a nitrogenous base attached to each sugar in the backbone.

Front 16

What is the sugar phosphate backbone?

Back 16

a string of alternating sugar and phosphate groups, with a nitrogenous base attached to each sugar of the backbone.

Front 17

Adenine always pairs with _________.

Back 17

thymine

Front 18

Thymine always pairs with ________.

Back 18

adenine

Front 19

Guanine always pairs with _________.

Back 19

cytosine

Front 20

Cytosine always pairs with ________.

Back 20

guanine

Front 21

What are the purines?

Back 21

adenine and guanine

Front 22

What are the pyrimidines?

Back 22

cytosine and thymine

Front 23

The base pairings of nucleotides are ________.

Back 23

complementary

Front 24

The two strands of DNA are _________.

Back 24

complementary

Front 25

DNA is synthesized in the _______ direction.

Back 25

5'-------->3'

Front 26

RNA synthesis continues until RNA polymerase reaches a site on the DNA called the _________.

Back 26

terminator

Front 27

What is the terminator?

Back 27

a site on the DNA that "signals" RNA polymerase to stop synthesizing RNA

Front 28

______ are the regions of DNA that are expressed

Back 28

exons

Front 29

_______ are the regions of DNA that do not encode protein.

Back 29

introns

Front 30

What are constitutive genes?

Back 30

their products are not regulated; their products are constantly produced at a fixed rate. Usually these genes are effectively turned on all the time, so they code for enzymes that the cell needs in fairly large amounts.

Front 31

What is repression?

Back 31

the regulatory mechanism that inhibits gene expression and decreases the synthesis of enzymes

Front 32

What term is best described by the following:

" The regulatory mechanism that inhibits gene expression and decreases the synthesis of enzymes is called _______. "

Back 32

repression

Front 33

Repression is mediated by regulatory proteins called ________.

Back 33

repressors

Front 34

What do repressors do?

Back 34

they block the ability of RNA polymerase to initiate transcription from the repressed genes

Front 35

What is the process that turns on the transcription of a gene/genes?

Back 35

induction

Front 36

What is induction?

Back 36

the process that turns on the transcription of a gene/genes

Front 37

A substance that acts to induce transcription of a gene is called an ________

Back 37

inducer

Front 38

what is an inducer?

Back 38

a substance that acts to induce transcription of a gene

Front 39

the combination of an operator, promeoter, and the structural genes they control is known as _______

Back 39

an operon

Front 40

What is an operon?

Back 40

the combination of an operator, promotor, and the structural genes they control.

Front 41

How are inducible operons and repressible operons different?

Back 41

In inducible operons, the structural genes are transcribed when they are turned on, or induced. In repressible operons, the structural genes are transcribed UNTIL they are turned off, or repressed.

Front 42

An example of an inducible operon is the _______ operon.

Back 42

lac

Front 43

An example of a repressible operon is the _________ operon.

Back 43

tryptophan

Front 44

Inhibition of the metabolism of alternative carbon sources by glucose is termed ___________.

Back 44

catobolite repression

Front 45

catobolite repression is also known as the ___________.

Back 45

glucose effect

Front 46

How does catabolite repression work?

Back 46

keeps making C-amp until turned off by realizing that the body has enough glucose.

Front 47

What is a base mutation?

Back 47

a single base at one point in the DNA sequence is replaced with a different base.

Front 48

What is a missense mutation?

Back 48

If a base situation results in an amino acid substitution in the synthesized protein, it is referred to as a missense mutation

Front 49

What term is best described:

" a base situation results in an amino acid substitution in the synthesized protein "

Back 49

missense mutation

Front 50

What term is best described:

" a base substitution resulting in a stop (nonsense) codon "

Back 50

nonsense mutation

Front 51

What is a nonsense mutation?

Back 51

When a base substitution results in a stop (nonsense) codon, preventing the synthesis of a completely functional protein.

Front 52

What is a frameshift mutation?

Back 52

When one or a few of the nucleotide pairs are deleted or inserted in the DNA

Front 53

What term is best described:

" When one or a few of the nucleotide pairs are deleted or inserted in the DNA"

Back 53

frameshift mutation

Front 54

Spontaneous mutations are what?

Back 54

when mistakes occur during DNA replication in the absence of an apparent mutation-causing agents.

Front 55

What term is best described:

" when mistakes occur during DNA replication in the absence of an apparent mutation-causing agent "

Back 55

spontaneous mutation

Front 56

What are mutagens?

Back 56

agents in the environment, such as certain chemicals and radiation, that directly or indirectly bring about mutation

Front 57

How do chemical mutagens work?

Back 57

convert the base adenine (A) to form in such a way that it no longer pairs with thymine (T), but with cytosine (C).

Front 58

How do ionizing radiation cause mutations?

Back 58

causes the formation of ions and free radicals that react with DNA and can break the sugar-phosphate backbone or cause base substitutions

Front 59

UV radiation causes mutations how?

Back 59

by causing bonding between adjacent thymines

Front 60

How are thymine dimers repaired?

Back 60

thymine dimers can be repaired by light-repair enzymes

Front 61

What do light-repair enzymes do?

Back 61

repair thymine dimers

Front 62

_________ is a relatively inexpensive and rapid test for identifying possible chemical carcinogens.

Back 62

Ames test

Front 63

What does the Ames test identify?

Back 63

posisble chemical carcinogens

Front 64

What does the Ames test assume?

Back 64

that a mutant cell can revert to a normal cell in the presence of a mutagen, and that many mutagens are carcinogenic

Front 65

In prokaryotes, transcription occurs in the _________

Back 65

cytoplasm

Front 66

In eukaryotes, transcription occurs in the ________

Back 66

nucleus

Front 67

" ATGCTATTG " is an example of a code for DNA or RNA? How can you tell?

Back 67

DNA: presence of thymines

Front 68

" AUGCUAUUG " is an example of a code for DNA or RNA? How can you tell?

Back 68

RNA: presence of uracil

Front 69

In DNA, adenine pairs with __________.

Back 69

thymine

Front 70

In RNA, adenine pairs with __________.

Back 70

uracil

Front 71

an MRNA is read in what direction?

Back 71

5'------->3'

Front 72

There are _____ codons.

Back 72

64

Front 73

In prokaryotes, __________ can begin before transcription is complete.

Back 73

translation

Front 74

Genes for the enzymes in glycolosis are examples of what type of enzymes?

Back 74

constitutive enzymes

Front 75

Another word for the stop codon is a ________ codon.

Back 75

nonsense