Mcb 3020C Exam 2 Vandenbergh

Front 1

Define the field of Genetics.

Back 1

Field of biology that studies the transfer of traits from one generation to another.

Front 2

What is the Central Dogma?

Back 2

The flow of information in the cell, DNA to RNA and eventually to proteins.

Front 3

What is a Gene?

Back 3

The information containing region of the chromosome. It is transcribed into an RNA message.

Front 4

Typical E. Coli contains how many genes?

Back 4

3,000-4,000 different genes.

Front 5

Define Genome.

Back 5

The total complement of genes found within the cell.

Front 6

Define Genotype.

Back 6

The genetic composition of an organism.

Front 7

Define Phenotype.

Back 7

When an organism expresses observable characteristics.

Front 8

The genetics information contained in the DNA is first copied into _______ in a process called Transcription.

Back 8

mRNA

Front 9

Describe Translation.

Back 9

When mRNA relays information to synthesize protein molecules.

Front 10

True or False? Prokaryotic mRNA is often polycistronic.

Back 10

True.

Front 11

True or False? Polycistronic encodes for multiple proteins.

Back 11

True.

Front 12

What are codons?

Back 12

Four bases (A, G, U, & C) arranged into three letter words.

Front 13

How many codons are in the genetic code?

Back 13

64.

Front 14

How many of the 64 codons in the genetic code are for amino acids?

Back 14

61. 3 (UAA, UAG, & UGA) are nonsense, start or stop codons.

Front 15

True or False? The genetic code is NOT degenerate.

Back 15

False. The genetic code IS degenerate. Many amino acids ARE represented by more than one codon.

Front 16

Which codon position is the most degenerate?

Back 16

The third (last) position is the most degenerate.

Front 17

What years were there important experiments showing that DNA was in fact the genetic material?

Back 17

1928 (Griffith), and 1944 (Avery, MacLeod, & McCarty).

Front 18

Which experiment showing that DNA was in fact genetic material led to transformed recipients?

Back 18

The 1944 experiment performed by Avery, MacLeod, & McCarty.

Front 19

What did we learn about DNA from the Watson and Crick experiment in 1953?

Back 19

DNA consists of 2 polynucleotide chains arranged in a double helix. Helix diameter is 20A, and makes a complete rotation every 34A. 10bp per rotation. Hydrogen bonds link bases.

Front 20

What is the size of the diameter of the DNA double helix?

Back 20

20A.

Front 21

DNA makes a full rotation every _____A.

Back 21

34A.

Front 22

DNA has _____bp per rotation.

Back 22

10bp.

Front 23

DNA bases are linked together by what type of bonds?

Back 23

Hydrogen bonds.

Front 24

DNA with a high percentage of G+C bonding tends to be more stable or unstable to unwinding or denaturation into single strands?

Back 24

More stable.

Front 25

As DNA denatures there is a sharp increase in their absorbance at _____nm.

Back 25

260nm.

Front 26

DNA has a net ______ charge.

Back 26

Net negative charge.

Front 27

E. Coli chromosome has 4.7*10^6bps, with a MW of 2.5*10^9 daltons. The molecule is 550 times longer than the E. Coli cell length. Thus the molecule is __________ and _________.

Back 27

Twisted and supercoiled.

Front 28

In 1958, Meselson and Stahl made a ________ replication of DNA.

Back 28

Semiconservatie.

Front 29

True or False? DNA replication is sequential and bi-directional?

Back 29

True.

Front 30

What is a Theta Replication DNA pattern?

Back 30

A circular molecule with two replication forks.

Front 31

What do initiator proteins recognize and bind to in DNA replication?

Back 31

A specific DNA sequence of about 300 bases near the origin of replication.

Front 32

What does the DNA helicase do?

Back 32

It unwinds short sections of DNA helix in front of the replication fork.

Front 33

What do DNA topoisomerases do?

Back 33

They assist in unwinding and rejoining of DNA during DNA replication.

Front 34

Enzymes that catalyze DNA synthesis only add nucleotides to the ________ end of the molecule.

Back 34

3'-OH.

Front 35

Okazaki fragments, found in 1964, demonstrated that ___________?

Back 35

One of the DNA daughter strands was synthesized discontinuously in short segments of 1,000 to 2,000 nucleotides in a 5’ to 3’ direction. These fragments are formed in onlyone of the daughter strands, called the lagging strand, in replication.

Front 36

How many DNA Polymerase enzymes are there?

Back 36

3.

Front 37

DNA Polymerase enzymes add nucleotides to which end of a growing polynucleotide?

Back 37

3'-OH.

Front 38

DNA Polymerase III will add up to _________ nucleotides per minute.

Back 38

30,0000 nucleotides.

Front 39

DNA Polymerase I, also known as the Kornberg Enzyme, is involved in DNA repair from what?

Back 39

UV damage.

Front 40

The Rolling Circle Mechanism of DNA replication is found in __________________?

Back 40

Bacterial viruses, bacteriophages, and during DNA replication in conjugation. One of the strands is nicked at a specific site and the free 3’-OH end generated is extended by a DNA polymerase.

Front 41

Uracil replaces ________.

Back 41

Thymine. The sugar is a ribose, and it usually exists in the single stranded form.

Front 42

What are the 3 forms of RNA?

Back 42

mRNA, tRNA and rRNA.

Front 43

All 3 forms of RNA are transcribed from a DNA template by ___________________?

Back 43

DNA dependent RNA Polymerase.

Front 44

True or False? RNA Polymerase is a multi-subunit enzyme.

Back 44

True. These 4 subunits form a complete enzyme, or halo enzyme.

Front 45

______ (greek letter) is the initiation factor for RNA Polymerase.

Back 45

Sigma. This subunit is required for promoter binding, once polymerization begins this subunit dissociates from the core enzyme.

Front 46

True or False? RNA Polymerase is a small enzyme.

Back 46

False. It is one of the largest known enzymes.

Front 47

True or False? RNA Polymerase is a point of difference between the different phylogenic groups Bacteria, Archaea, and Eukarya.

Back 47

True.

Front 48

Bacteria have ___ types with ____ different subunits.
Archaea has ___ types with ____ different subunits.
Eukarya has ___ types with ____ different subunits.

Back 48

Bacteria: 1 type, 6 different subunits.
Archaea: several types, 8-12 different subunits.
Eukarya: several types, 12-14 different subunits.

Front 49

mRNA is the _____ varied of the 3 RNA forms. It forms ____% of all RNA.

Back 49

Most varied. 5% of all RNA.

Front 50

mRNA has a lifespan of ________ in a bacterial cell.

Back 50

A few minutes.

Front 51

mRNA does what?

Back 51

Carries the genetic message from the DNA template to the ribosomes.

Front 52

In bacteria, mRNA commonly contain information for the amino acid sequence for several different polypeptide chains, ________________ mRNA.

Back 52

Polycistronic mRNA.

Front 53

True or False? All of the base sequences in mRNA are translated into amino acid sequences for polypeptides.

Back 53

False.

Front 54

What is the "Leader" region of mRNA?

Back 54

The region of mRNA behind where translation starts. (usually 5-20 bases)

Front 55

What are "Spacer" regions in Polycistronic mRNA?

Back 55

Sequences which are 10 bases long that separate coding sequences.

Front 56

What are the 3 types of rRNA molecules found in prokaryotic organisms?

Back 56

5S and 23S, found in the 50S ribosomal subunit. 16S, found in the 30S subunit.

Front 57

Ribosomes contain ____% protein, and ____% rRNA.

Back 57

33% protein and 66% rRNA.

Front 58

The intact particle is called a ____ ribosome in bacteria.

Back 58

70S ribosome.

Front 59

What role does rRNA have in a ribosome?

Back 59

They contribute to structure of the ribosome and have a function in protein synthesis.

Front 60

In bacteria 16S rRNA pairs with _____ ______ site on the mRNA and positions the mRNA on the ribosome.

Back 60

Initiation sequence.

Front 61

In bacteria 23S rRNA is believed to be peptidyl transferase associated with ________ _________ _______ during protein synthesis.

Back 61

Peptide bond formation.

Front 62

True or False? tRNA is the largest of the RNA structures.

Back 62

False. tRNA is the smallest of the RNA structures. Cloverleaf structure folded back on themselves. This unique structure is maintained by internal base pairing which results in the loops. tRNA has modified bases ie methylated forms, pseudouridine, dihydrouridine are examples.

Front 63

True or False? tRNA is involved in the translation of genetic messages?

Back 63

True.

Front 64

tRNA is an _____ of amino acids to mRNA codons at the ribosome incorporating into growing proteins.

Back 64

Adapter.

Front 65

True or False? Any tRNA can carry any amino acid.

Back 65

False. Each tRNA carries a specific amino acid.

Front 66

How is amino acid tRNA activated? Is ATP required to link the tRNA to the appropriate amino acid?

Back 66

It is activated by an enzyme, Synthase. Yes, ATP is required.

Front 67

Recognition at the ribosome involves which tRNA loop?

Back 67

The anticodon loop.

Front 68

What do the two tRNA loops, pseudouridine and dihydrouridine, do?

Back 68

They are involved in the binding of the ribosome and the aminoacyl-tRNA synthase.

Front 69

True or False? Around 20% of chromosomal DNA encodes for synthesis of rRNA and tRNA in the cell.

Back 69

False. Around only 1% of chromosomal DNA encodes for synthesis.

Front 70

True or False? rRNA and tRNA are more stable than mRNA?

Back 70

False. mRNA is more stable than rRNA or tRNA.

Front 71

We all know that DNA is synthesized in the 5'-3' direction. What about RNA?

Back 71

RNA is also synthesized in the 5'-3' direction.

Front 72

True or False? Only one of the DNA stands is transcribed in any given DNA region.

Back 72

True.

Front 73

True or False? RNA synthesis begins with the binding of RNA polymerase to a promoter on DNA.

Back 73

True.

Front 74

What is a promoter?

Back 74

A promoter is a specific DNA sequence, usually 20-200 bases long.

Front 75

How were promoters discovered?

Back 75

They mixed RNA polymerase with DNA. Then they treated this mixture with an enzyme that digested DNA. This left the DNA bound to the RNA Polymerase intact. They then sequenced this DNA region and discovered the promoter regions.

Front 76

What is the beginning step of RNA synthesis?

Back 76

It begins with binding of the RNA polymerase to the promoter, this causes the DNA strands to separate.

Front 77

What is Rho independent termination?

Back 77

When the RNA polymerase synthesizes a polyU sequence, which results in a hairpin formation in the new chain.

Front 78

What is Rho dependent termination?

Back 78

Rho binds to the RNA and moves along until it catches up with the RNA polymerase at a terminator, where it unwinds the RNA-DNA hybrid.

Front 79

What is the first stage of RNA synthesis?

Back 79

Promoter recognition. (-10, -35)

Front 80

What is the second stage of RNA synthesis?

Back 80

Local unwinding. The RNA Polymerase forms an "open promoter complex".

Front 81

What is the third stage of RNA synthesis?

Back 81

Chain initiation.

Front 82

What is the fourth stage of RNA synthesis?

Back 82

Chain elongation.

Front 83

What is the fifth, and last, stage of RNA synthesis?

Back 83

Chain termination.

Front 84

Define Protein Synthesis.

Back 84

A multistep process that takes place in the ribosome.

Front 85

How many distinct steps are there in Protein Synthesis?

Back 85

Three. Initiation, Elongation, and Termination.