Lecture 12: Chapter 15 (Genes and how they work)

Question 1

What did Archibald Garrod (1902) propose after he recognized that alkaptonuria is inherited via a recessive allele and that patients with the disease lacked a particular enzyme?

Answer 1

The ideas connected genes to enzymes

Question 2

When was Beadle’s and Tatum’s experiment?

Answer 2

1941

Question 3

What did Beadle and Tatum study?

Answer 3

They studied a bread mold, Neurospora

Question 4

What did Beadle and Tatum use to damage the DNA of Neurospora?

Answer 4

X-rays

Question 5

In their experiment, what did Beadle Tatum look for, and how did they identify it?

Answer 5

They looked for nutritional mutations by identifying spores unable to grow on minimal media

Question 6

What did Beadle’s and Tatum’s minimal media contain?

Answer 6

glucose+ vitamin (biotin)+ salts

Question 7

What is
Gluatamate–> Ornithine–> cirtuline–> arginosuccinate–> arginine?

Answer 7

The arginine synthesis pathway

Question 8

What strains did Beadle and Tatum isolate?

Answer 8

The strands that could not grow unless fed arginine

Question 9

What did Beadle and Tatum feed the isolated strands to test for growth?

Answer 9

The intermediates in the pathway

Question 10

What was required for the biochemical pathway to produce the amino acid arginine?

Answer 10

enzymes

Question 11

How did Beadle and Tatum identify mutants deficient in each enzyme of the pathway?

Answer 11

By supplementing minimal media with biochemical intermediates

Question 12

What hypothesis did Beadle and Tatum come up with from their experiment?

Answer 12

One-gene/ one-enzyme

Question 13

What has the one-gene/ one enzyme hypothesis been modified to?

Answer 13

one-gene/one- polypeptide hypothesis

Question 14

What does the central dogma describe?

Answer 14

information flow

Question 15

Who was the central dogma first described by?

Answer 15

Francis Crick

Question 16

How does information flow?

Answer 16

DNA–> RNA–> protein

Question 17

What part of the information flow is transcription?

Answer 17

DNA_-> RNA (both nucleic acids)

Question 18

What part of the information flow is translation?

Answer 18

RNA–> Protein (from nucleic acid to protein)

Question 19

How do retroviruses violate the information flow?

Answer 19

They use reverse transcriptase to convert their RNA genome into DNA

Question 20

What are the steps of Transcription?

Answer 20

1. DNA-directed synthesis of RNA
   2.Only one strand of DNA copied as RNA

Question 21

What strand in transcription is copied as RNA?

Answer 21

the template strand (sense)

Question 22

What is the strand in transcription that is used as a template called?

Answer 22

noncoding strand (antisense)

Question 23

In RNA, what is thymine replaced by?

Answer 23

Uracil

Question 24

What is used to direct synthesis of polypeptides in transcription?

Answer 24

mRNA

Question 25

T or F: all RNA is synthesized from a DNA templated by transcription

Answer 25

True

Question 26

What kind of RNA is part of the machinery involved in the processing of "pre-mRNA" in splicing?

Answer 26

small nuclear RNA (snRNA)

Question 27

What kind of RNA is a mediator for proteins synthesized on the rough ER?

Answer 27

signal recognition particle RNA (SRP RNA)

Question 28

What kind of RNA is involved in control of gene expression?

Answer 28

small RNAS

Question 29

What are the two types of small RNAS?

Answer 29

miRNA and siRNA

Question 30

About the genetic code, what did Francis Cric and Sydney Brenner determine?

Answer 30

How the order of nucleotides in DNA encoded amino acid order

Question 31

What is a block of three DNA nucleotides corresponding to an amino acid called?

Answer 31

codon

Question 32

What type of mutation deals with inserting or deleting a single nucleotide?

Answer 32

frameshift mutations

Question 33

If you add or delete 1 or 2 nucleotides, what does it shift?

Answer 33

the genetic message

Question 34

If you add or delete 3 nucleotides, what is the result?

Answer 34

the addition or deletion of a protein

Question 35

What did Crick and Brenner conclude from their experiments of adding and deleting nucleotides?

Answer 35

That the genetic code is read in increments of three nucleotides, and read continuously

Question 36

T or F: Codons specify amino acids

Answer 36

True

Question 37

Who identified the codons that specify each amino acids?

Answer 37

Marshall Nirenberg

Question 38

What do stop codons do?

Answer 38

They terminate translation

Question 39

How many start codons are there, and what are their names?

Answer 39

Three 1. UAA 2.UGA 3. UAG

Question 40

What does the start codon do?

Answer 40

It signifies the start of translation

Question 41

How many start codons are there, and what are their names?

Answer 41

1. AUG

Question 42

Genetic code is ________, which means that some amino acids are specified by more than one codon.

Answer 42

degenerate

Question 43

T or F: Genetic code is practically universal

Answer 43

True

Question 44

What is the most substantial evidence that all living things share a common ancestry?

Answer 44

That genetic code is practically universal

Question 45

What two organelles of the cell have some differences in genetic code?

Answer 45

Mitochondria and chloroplast

Question 46

How many RNA polymerases do prokaryotes have?

Answer 46

a single RNA polymerase

Question 47

What are the two forms of RNA polymerase?

Answer 47

1. core polymerase 2. Holoenzyme

Question 48

Why is the Holoenzyme needed for RNA polymerase?

Answer 48

Because its addition of the sigma subunits is needed to accurately initiate synthesis

Question 49

What does transcription not require?

Answer 49

a primer

Question 50

What forms the recognition and binding site for RNA polymerase in transcription?

Answer 50

the promoter

Question 51

What is the actual site where RNA synthesis begins in transcription?

Answer 51

start site

Question 52

What signals the end of transcription?

Answer 52

The Terminator

Question 53

What is the region from the promoter to the terminator called?

Answer 53

the transcription unit

Question 54

What are some characteristics of the promoter?

Answer 54

1. found upstream of the start site 2. not transcribed 3. it is asymmetrical- it indicates the site of the initial and direction of transcription

Question 55

What are the steps of transcription: elongation?

Answer 55

1. RNA chains grows in the 5' to 3' direction as ribonucleotides are added 2. After the transcription bubble passes, the now-transcribed DNA is rewound as it leaves the bubble

Question 56

What complex contains RNA polymerase, DNA template, and growing RNA transcript?

Answer 56

Transcription bubble

Question 57

T or F: termination occurs at specific sites

Answer 57

True

Question 58

What happens when the stop signal is sequenced to RNA polymerase?

Answer 58

1.RNA-DNA hybrid within the transcription bubble dissociated 2. RNA polymerase release the DNA 3. DNA rewinds

Question 59

What is the series of G-C base- pairs followed by a series of A-T base-pairs in transcription called?

Answer 59

the simplest terminator

Question 60

How does the simplest terminator work?

Answer 60

It forms a hairpin, which results in the dissociation of RNA from DNA in the transcription bubble

Question 61

What does the hairpin cause in transcription?

Answer 61

RNA polymerase to pause at uracil

Question 62

What bonds are the weakest bonds in transcription?

Answer 62

U-A

Question 63

In prokaryotes, what are coupled together?

Answer 63

transcription and translation

Question 64

How are transcription and translation coupled?

Answer 64

mRNA begins to be translated before transcription is finished

Question 65

How many RNA polymerases do Eukaryotes have?

Answer 65

Three

Question 66

In Eukaryotes, what does RNA pol I do?

Answer 66

transcribes rRNA

Question 67

In Eukaryotes, what does RNA polymerase II do?

Answer 67

It transcribes mRNA and some snRNA

Question 68

In Eukaryotes, what does RNA polymerase III do?

Answer 68

it transcribes tRNA an some other small RNAS

Question 69

Each RNA polymerase recognizes its own _____

Answer 69

promoter

Question 70

RNA pol I promoters are ______ specific

Answer 70

species

Question 71

RNA Pol II promoters consist of a ______ promoter which includes the _____ _____

Answer 71

core, tata BOX

Question 72

Where are most RNA pol III promoters found?

Answer 72

within the gene itself

Question 73

IN Eukaryotes, what causes the initiation of transcription?

Answer 73

the pol II promoters

Question 74

Why are RNA pols II required in transcription?

Answer 74

1. they ae necessary to get the RNA pol II enzyme to a promoter to initiate gene expression 2. They interact with RNA polymerase to form initiation complex at promoter

Question 75

What structural feature coordinates elongation complex factors?

Answer 75

the carboxyl terminal domation (CTD)

Question 76

In eukaryotes, the primary transcript must be modified to become ______ mRNA

Answer 76

mature

Question 77

What does mature mRNA consist of?

Answer 77

1. addition of a 5' cap 2. addition of 3' poly- A- tail 3. removal of introns