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Cell Biology 2203 > Unit 2- DNA and Gene Expression > Flashcards

Unit 2- DNA and Gene Expression Flashcards

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1
Q

Whose studies determined that DNA was the genetic material instead of Protein?

A

Griffin, Hershey and Chase

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2
Q

Whose Research is this? What was the impact?

A

Griffith. He determined that DNA was the heritbale information in DNA because it was changed and reverted back to its original form.

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3
Q

Whose work was this? What was the impact?

A

Hershey and Chase

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4
Q

Who determined the structure and mechanism of replication of DNA?

A

Watson & Crick

Rosalind Franklin & Wilkins

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5
Q

Building Blocks of DNA

A

Nucleotides

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6
Q

Components of a Nucelotide

A

Deoxyribose

Phosphate

Nitrogenous Base (4 Different Types)

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7
Q

Polarity of DNA

A

5’->3’

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8
Q

Base Pairs in DNA

A

A:T G:C

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9
Q

How many base pairs are in each turn of the Double helix?

A

10

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10
Q

DNA Strands run _____ To each other

A

Antiparallel

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11
Q

How much DNA is in a human cell

A

2m of DNA

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12
Q

How large is a typical Cell?

A

20-40 Micrometers

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13
Q

Packaged DNA consists of

A

Single Molecule of DNA+Associated Packaging proteins (Histones)+ Scaffolding Proteins

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14
Q

Bacteria typically have _____, _____ chromosome.

A

Single, Circular

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15
Q

Name This Image

A

Karyotype

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16
Q

Each Chromosome is made up of

A

Single, long DNA Molecule+accompanying proteins (Chromatin)

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17
Q

Karyotypes are arranged in what pattern?

A

From largest to smallest, except the sex chromosomes, which are always #23

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18
Q

Functions of Chromosomes:

A

To Carry Genes

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19
Q

Replication Origin

A

Sites Where Replication begins

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20
Q

Telomeres

A

help overcome the End-Replication problem

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21
Q

During Mitosos, DNA is compacted to what size?

A

~ 10,000-75000x

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22
Q

During Interphase, DNA is compacted to what size?

A

~500-400x ( Less compacted than in mitosis)

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23
Q

Nucleosome

A

Basic Unit of Eukaryotic Chromosomes that consist of a length of DNA coiled around a core of histones.

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24
Q

Histone core of nucleosomes are made of

A

4 different Histone proteins

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25
Q

What is the function of Linker Histone H1

A

Helps pack nucleosome cores more tightly

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26
Q

Levels of Chromosome Packing

A

DNA-> Nucleosomes

Nucleosomes (beads on a string) packaged into Chromatin Fiber

Chromatin Fiber packaged into folded loops

Folded loops packaged into Mitotic Chromosome

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27
Q

Chromatin-Remodeling Complexes

A

Use ATP to Change DNA POsition along Histone cores of nucleosome

Can make DNA More or less accessible

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28
Q

True or false: Chromatin-remodeling Complexes are actvated during mitosis

A

FALSE

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29
Q

Acetyl groups ___ chromatin, making it more accessible

A

Open

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30
Q

Histone Acetyl Transferases (HATs)

A

Add Acetyl Groups to Histones

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31
Q

Histone Deactylases (HDACs)

A

Remove Acetyl groups from histones

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32
Q

Specific combinations of modifications create docking sites for regulatory proteins that promote _______ or _______

A

Decondensation; condensation

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33
Q

Euchromatin

A

Regions or chromosome that are active and less condensed

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34
Q

Heterochromatin

A

Regions of chromosome that are not active and are more condensed

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35
Q

Regions of euchromatin and heterochromatin are regulated by what?

A

Histone Modifications

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36
Q

Histone Modifications promoting “Condense Me” signals may propagate along DNA until________ is reached

A

Barrier Sequence

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37
Q

Errors in Genetic code

A

Mutations

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38
Q

Mutations are a basis of

A

Evolutionary change

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39
Q

Each strand of DNA serves as a ______ _____ for new complementary strand to be replicated

A

Template Strand

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40
Q

The Human Genome can be replicated in as little as

A

8 Hours

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41
Q

Semiconservative Replication

A

Since one sister strand of new daughter DNA molecules is new and one is old, mechanism of replication is called semiconservative.

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42
Q

Describe this process

A

Semiconservative DNA Replication

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43
Q

True or False: DNA Replication begins at only one site along eukaryotic chromosomes?

A

False

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44
Q

Replication Origins

A

Special Sequences of DNA that recruit initiator proteins to begin DNA replication Process

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45
Q

Replication Machine

A

The DNA Double Helix is opened and more proteins are recruited

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46
Q

Replication Fork

A

Y-Shaped Region along which new DNA strands are synthesized

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47
Q

Bidirectional replication

A

Since replication proceeds in both directions away from the replicaiton origin, the process is bidirectional.

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48
Q

Polymerization

A

Occurs by addition of nucleotide to 3’ end of growing DNA molecule and 5’ end of incoming nucleotide (Continues to grow in 5’ to 3’ direction)

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49
Q

DNA is replicated in opposite directions causing 1 strand to be ______ and another strand to be ______

A

Continuous ; Discontinuous

Or

Leading;Lagging

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50
Q

How is the discontinuously replicated strand produced?

A

Via Backstitching mechanism that allows for unidirectional addition of DNA Nucleotides in an overall bidirectional process

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51
Q

The continuously replicated strand is called the

A

Leading Strand

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52
Q

The discontinuously replicated strand is called the

A

Lagging strand

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53
Q

The small pieces of DNA replicated for discontinuous strand are called

A

Okazaki Fragments

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54
Q

True or False: Okazaki fragments remain disjointed.

A

FALSE: They are put together with DNA Ligase

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55
Q

What is the error rate of DNA Polymerase

A

~1 in 10^7 errors

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56
Q

How does DNA Polymerase maintain its low error rate (high fidelity)

A

Carefully monitoring base-pair before catalyzing nucleotide addition

Proofreading when mistake occurs

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57
Q

When does DNA Proofreading occur

A

Concurrently with DNA Synthesis

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58
Q

What does DNA Polymerase do if an error is detected?

A

The previously added base is removed and polymerase tries again

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59
Q

DNA Polymerase must attach to the 3’ end of the template before

A

placing nucleotides

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60
Q

True or false: Primase has proofreading

A

FALSE

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61
Q

True or False: Chromatin-remodeling complexes are activated during Mitosis

A

False

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62
Q

What is the function of Nuclease?

A

Degrades RNA Primer

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63
Q

What is the function of Repair polymerase?

A

Makes DNA version of complementary strand

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64
Q

What is the function of DNA Ligase?

A

It links Okazaki fragments together.

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65
Q

What are some of the enzymes and proteins that come together to complete DNA Replication?

A

DNA Ligase

Single-Stranded Binding proteins

DNA Topoisomerases

Primase

Polymerase

Sliding Clamp

Clamp Loader

Repair Polymerase

DNA Ligase

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66
Q

What is the DNA End-Replication Problem?

A

As the Replication fork reaches the end of the lagging strand, there is not enough room to replace the final primer with DNA.

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67
Q

Telomeres

A

Long, repetitive sequences at the end of chromosomes that solve the DNA-End replication problem

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68
Q

Telomerase

A

The enzyme that maintains telomeres. It has a short stretch of RNA incorporated into enzyme that serves as template for the telomeric DNA

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69
Q

What are the types of DNA Damage?

A

Deamination

Depurination

Covalent Modifications (Thymine Dimers)

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70
Q

What types of DNA damage would result in a Double-Stranded break?

A

Radiation

Mishap at replication fork

Chemical assaults

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71
Q

What is the basic tool for DNA damage Repair

A

Excision Repair

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72
Q

Name 4 mehtods for DNA damage repair

A

Excision Repair

Mismatch Repair

Nonhomologous End-Joining

Homologous Recombination

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73
Q

What are the steps in a Mismatch DNA Repair?

A

Mistake is recognized

new vs. parental strand is determined

Portion of mutated strand is removed

Filled in by repair polymerase

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74
Q

What is Non-Homologous End Joining?

A

Double-Stranded break repair that occurs soon after the damage occurs. The Enzymes detect damage, “clean” the ends, and ligate them together

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75
Q

True or False: NHEJ will result in loss of some nucleotides

A

True

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76
Q

What is Homologous Recombination

A

A Double-Stranded Break Repair which the 5’ ends of broken DNA are chewed back and DNA repair polymerase extends the broken strand.

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77
Q

What are the consequences of a lack of DNA Repair?

A

Mutation

Sickle-Cell Hemoglobin

Cancer

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78
Q

What is the Central Dogma of Molecular Biology?

A

DNA Serves as Template for RNA Production (transcription) and multiple RNAs function in making proteins (translation)

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79
Q

What is Gene Expression

A

Process whereby information in DNA is turned into useful product

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80
Q

True or False: The entire Genome is transcribed into RNA

A

False:

Entire genome is not transcribed into RNA and cell tightly controls how much of each type of RNA is made

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81
Q

What is the Nucleic Acid associated with RNA

A

Ribonucleotides (as opposed to Deoxyribonucleotides)

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82
Q

What are the Nucleotides associated with RNA (and their Base Pairs)

A

Adenine, Guanine, Cytosine, Uracil

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83
Q

True or False: RNA is Double-Stranded

A

False: RNA is single-Stranded

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84
Q

What are three types of functions that RNA’s single-stranded properties result in?

A

Structural, Catalytic, and Regulatory functions

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85
Q

True or False: Transcription uses Helicase to open the DNA Strand

A

False: The DNA is opened, but there is no Helicase involved.

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86
Q

True or False: RNA transcription has a higher fildelity than DNA replication

A

False

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87
Q

Messenger RNAs (mRNA) Function

A

Code for Proteins

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88
Q

Ribosomal RNAs (rRNAs) function

A

Form the core of the ribosome’s structure and catalyze protein synthesis

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89
Q

MicroRNAs (miRNAs) Function

A

Regulate Gene Expression

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90
Q

Transfer RNAs (tRNAs) function

A

Serves as adaptors between mRNA and Amino Acids during Protein Synthesis

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91
Q

Other Noncoding RNA Function

A

Used in RNA Splicing, gene regulation, telomere maintenance, and many other processes

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92
Q

Promoter’s DNA sequence directs RNA Polymerase as to which DNA strand (does what)??

A

Serves as Template

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93
Q

What are the three types of RNA Polymerases in Eukaryotes?

A

RNA Polymerase I

RNA Polymerase II

RNA Polymerase III

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94
Q

What genes are transcribed by RNA Polymerase I?

A

Most rRNA genes

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95
Q

What genes are transcribed by RNA Polymerase II?

A

All protein-coding genes, MiRNA genes, plus all the genes for other Noncoding RNAs (Spliceosome)

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96
Q

What genes are transcribed by RNA Polymerase III?

A

tRNA Genes

55 rRNA Genes

Genes for many other small RNAs

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97
Q

What process begins when TBP/TFIID complex binds the TATA box of a gene?

A

RNA Polymerase II Transcription

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98
Q

What is a TATA Box?

A

A region of ~25 Bases upstream of transcription start site, made of many T & A Nucleotides

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99
Q

What is the Transcription Initiation Complex?

A

When the Binding of TBP/TFIID recruits the remaining general transcription factors and RNA Polymerase II

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100
Q

TFIIH

A

A kinase that’s part of the Transcription Initiation Complex, which phosphorylates the tail of RNA Polymerase II

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101
Q

What 3 steps must be taken in order for the Pre-MRNA transcript to be processed into mRNA in the nucleus?

A

RNA Capping

Polyadenation

Splicing

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102
Q

What allows some processing proteins to assemble on RNA Polymerase II?

A

The Phosphorylation of the RNA Polymerase II Tail that allows this.

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103
Q

What is RNA Capping?

A

A Modified Guanine Nucleotide is added to the 5’ end of a transcript shortly after transcription begins

Helps protect from Endogenous Nucleases

Helps Get translation started

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104
Q

What is Polyadenation?

A

A sequence within a transcript that tells RNA Polymerase II when to stop.

(Poly-A Signal)

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105
Q

What are Introns?

A

Regions that are not expressed as protein

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106
Q

What are Exons?

A

Regions of a gene that are expressed as protein

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107
Q

True or false: The number and length of introns and exons remains consistent.

A

False: the number and length of introns and exons varies from gene to gene.

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108
Q

RNA Splicing:

A

When Introns are spliced out of pre-MRNA, leaving the Exons behind to code for the protein

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109
Q

True or False: Sequence within Exons and Introns dictates boundaries of introns

A

TRUE

110
Q

What is a Spliceosome?

A

A compltex of small Nuclear RNAs (snRNAs) and associated proteins (snRNPs) that are responsible for removing some introns

111
Q

True or False: All introns are spliced with the Spliceosome.

A

False: Some introns are spliced by the spliceosome, but others are self-splicing

112
Q

What are some examples of Alterations in splicing?

A

Exon Skipped

Alternative Exons

Introns Skipped

113
Q

After processing, where is mRNA going to be exported to?

A

The Cytoplasm

114
Q

Proteins that bind the 5’ Cap, Poly-A Tail, and splice sites facilitate interaction with what area?

A

The Nuclear Pore Complexes.

115
Q

mRNA Half-Life

A

The amount of time required for half the population of mRNA to be degraded

116
Q

True or False: Every mRNA has the same Half-Life

A

False: Different mRNAs have different half-lives.

117
Q

How is the mRNA’s Half-Life determined?

A

By Specific sequences within mRNA, usually within the Untranslated Regions (UTRs)

118
Q

What is the end result of Translation?

A

Proteins

119
Q

What is the process of utilizing information in mRNA to produce Protein?

A

Translation

120
Q

What is the Genetic Code?

A

The 4 different nucleotides that encode the 20 Amino Acids in groups of Non-Overlapping, 3-letter words (Codons)

121
Q
A
122
Q

True or False: Each codon is non-specific

A

False: Each codon is specific

123
Q

True or False: There is redundancy among many of the codons

A

TRUE

124
Q

How does the cell know where to start Translation?

A

There must be a Kozak Sequence and an AUG Start Codon

125
Q

What sets the reading frame for translation?

A

The Kozak sequence and the AUG Start codon

126
Q

True or False: Each Eukaryotic mRNA has more than one reading frame.

A

FALSE: There is only one reading frame. Finding the correct AUG to start is how to find it.

127
Q

What is a point mutation?

A

Addition, Deletion, or Substitution of a single base

128
Q

What types of mutations are frameshift mutations?

A

Additions and Deletions

129
Q

What type of mutatation Substitutes one Amino Acid Codon for another Amino Acid’s Codon

A

Missense Mutation

130
Q

What type of Mutation substitutes an Amino Acid Codon with a Stop Codon

A

Nonsense Mutation

131
Q

What type of mutation substitutes one Amino Acid Codon for the same Amino Acid Codon?

A

Silent Mutation

132
Q

What type of mutation substitutes a Stop Codon with an Amino Acid Codon?

A

NonStop Mutation

133
Q

When an Amino Acid is attached to a tRNA, what is it called

A

Aminoacyl-tRNA^AA

or

Charged tRNA

134
Q

What shape are tRNAs typically in?

A

Cloverleaf shape

135
Q

What are the two important sites (at opposite ends) of a tRNA molecule?

A

Anticodon

Amino Acid Attachment Site

136
Q

What is tRNA Wobble?

A

It means there are not 61 different tRNAs in most species*

137
Q

WWhat are the 20 specific enzymes that match the specific Amino Acid with a specific tRNA?

A

Aminoacyl-tRNA Synthetases

138
Q

What is used to create the high-energy bond between tRNA and the Amino Acid?

A

ATP

139
Q

What are Ribosomes made out of

A

rRNA and Proteins

140
Q

What are the two subunits of a Ribosome called?

A

Large (60s)

Small (20s)

come together to make (80s) when the ribosome is active)

141
Q

What organelle is responsible for the process of translation?

A

Ribosomes

142
Q

True or False: the Ribosome moves along the mRNA 3 codons at a time?

A

FALSE: They move along the mRNA one codon (3 nucleotides) at a time.

143
Q

What are the three Binding sites for tRNA on the Ribosome?

A

A, P, E Sites

144
Q

What is the definition and function of the A site on the Ribosome?

A

Aminoacyl-tRNA Binding Site

Accepts incoming tRNA

145
Q

What is the definition and function of the P site on the Ribosome?

A

Peptidyl-tRNA Binding Site

Holds tRNA that is being attached to the growing polypeptide

146
Q

What is the definition and function of the E site on the Ribosome?

A

Exit site (same answer for both)

147
Q

Describe the Process of Translation in steps:

A

tRNA holding growing polypetide sits in P site •

A site, which had been empty, accepts incoming tRNAAA

• Ribozyme activity of rRNA forms peptide bond between last AA of growing polypeptide and incoming AA •

This severs connection between P site AA and its tRNA and at the same time, releases energy to power this process •

Large subunit shifts forward, shifting spent tRNA to E site and tRNA from A site to P site •

A site ready for next charged tRNA •

Continues until stop codon reaches A site

148
Q

What Amino acid would the initiator tRNA carry?

A

Methionine (MET)

149
Q

What are TIFs?

A

Translation initiation Factors

A group of proteins necessary for translation initiation

150
Q

What makes the initiator tRNA unique?

A

It is able to bind to the P site, whereas the others can only initially bind to the A site.

151
Q

Kozak Sequence Example

A

ACCAUGG

152
Q

What is the initiator tRNA in Bacteria?

A

tRNA^fMET (F-Methionine)

153
Q

True or False: Bacteria have a 5’cap to mediate small subunit and mRNA interaction.

A

FALSE

154
Q

What is a Shine-Delgarno Sequence?

A

occurs just upstream of the AUG in Bacteria. It base-pairs with rRNA nucleotides, this positioning initiator tRNA at the P site.

155
Q

How many coding sequences can a bacterial mRNA have?

A
156
Q

How many coding sequences can a Eukaryotic mRNA have?

A
157
Q

What are the three STOP Codons?

A

UAG, UGA, UAA

158
Q

What happens when a Stop codon enters the A site?

A

Translation Termination

159
Q

What does the release factor protein do in Translation?

A

It binds to teh A site, causing Ribosomes to add water molecule to peptidyl tRNA, resulting in a relase of the polypeptide chain

160
Q

What is a Polyribosome?

A

When a single mRNA is translated by multiple ribosomes simultaneously

161
Q

What is the end result of turning genes on and off or regulating gene expression?

A

Cell Differentiation

162
Q

Complexes of mRNA with several accompanying ribosomes are called?

A

Polyribosomes/Polysomes

163
Q

How long do proteins last?

A

A few moments, minutes, hours, days, months, or years.

164
Q

How are proteins recucled?

A

A process called proteolysis

165
Q

Describe the Proteolysis process

A

Enzymes that break down proteins, called proteases, break peptide bonds in the proteins.

166
Q

A large, cylindrical complex of proteins that perform proteolysis in Eukaryotes

A

Proteasome

167
Q

What do the ends of Proteasomes do?

A

They unfold the incoming proteins and feed linear polypeptide chain into the interior of the complex.

168
Q

Inside the Proteasome, what do proteases do?

A

They break the protein into its individual Amino Acids

169
Q

How are proteins targeted to a proteasome?

A

Ubiquitin

170
Q

What is Ubiquitin?

A

A small polypeptide that when covalently bonded to protein functions to target that protein to the proteasome

171
Q

In order for target protein destruction to occur, what must first happen?

A

Several Ubiquition molecules must be added to the protein

172
Q

A Sequence of Amino Acids that function in targeting the protein for destruction

A

Degron

173
Q

What are the Ubiquitin linked to on the target polypeptide?

A

The Lysine Residues

174
Q

True or False: All genes within an organism have different DNA?

A

False: They all have the same DNA

175
Q

How do cells have different functions?

A

Because they turn particular genes on or off.

176
Q

What controls gene expression?

A

Signals from outside the cell:

Hormones, Tension of Substratum

177
Q

True or False: Different cells respond in different ways to various signals

A

TRUE

178
Q

What is the major mechanism for Gene Expression control?

A

Control of Transcription

179
Q

What is the function of a Promoter in transcription?

A

To bind key transcription factors and RNA Polymerase

180
Q

What binds other transcription regulators that control what happens at the promoter?

A

Regulatory DNA Sequences

181
Q

What are the functions of Regulatory DNA Sequences?

A

May act as simple switches or in more complex ways

Sequences can be thousands of nucleotides away from transcription start site

Located nearby in bacteria, may be far away (distal) in eukaryotes

182
Q

True or False:

Transcriptional Regulators have DNA Binding domains and regions that interact very unspecifically and weakly.

A

FALSE:

They interact very specifically and strongly

183
Q

What are Transcriptional Switches?

A

They are switch-like (on-off) and allow the cell to respond to environmental cues.

184
Q

In bacteria, what are the two switches which control several regulated genes/proteins?

A

Tryptophan Operon

Lac Operon

185
Q

The Lac Operon is a _____ reaction

A

Catabolic (Breaks down)

186
Q

The Tryptophan Operon is a _____ reaction

A

Anabolic

187
Q

Transcriptional Activators

A

When activated, they turn the genes on or activate them

188
Q

Transcriptional repressors

A

When activated, they turn the gene off or repress them.

189
Q

How does the Tryptophan Operon work?

A

When Tryptophan is low, the operon is turned on due to the absence of the repressor at the regulatory seqence

190
Q

When is the Tryptophan Operon repressed?

A

When the concentration of Tryptophan increases.

191
Q

What are the steps of the Tryptophan Operon Repression?

A

The free Tryptophan binds the repressor and activates it, allowing it to bind to the DNA.

Binding to regulatory sequence blocks RNA polymerase from binding the Operon’s promoter

Enzymes for tryptophan production are no longer expressed.

192
Q

How does the Lac Operon work?

A

When Lactose is present and ATP is low, the Lac Operon will be turned On.

193
Q

What operon controls the expression of genes required for breakdown of lactose to monosaccharides which can be used in cellular respiration?

A

Lac Operon

194
Q

What are the differences between the Tryptophan and Lac Operons?

A

The Tryptophan is anabolic, Lac is catabolic

Tryptophan is controlled by a repressor, Lac has an activator and a repressor

195
Q

Which Operon is controlled by an activator and a repressor?

A

Lac Operon

196
Q

What is the Lac Operon’s Repressor Called? How does it work?

A

Lac Repressor;

Repressor binds regulatory DNA (Operator) and will result in no gene expression.

197
Q

What is the Lac Operon’s Activator called? How does it work?

A

Cyclic AMP Activator (CAP Activator)

198
Q

What is cAMP

A

Cyclic Adenosine Monophosphate

199
Q

When is cAMP produced?

A

When ATP is low

200
Q

When can the Cap Activator bind regulatory DNA?

A

Only if it is bound by cAMP

201
Q

Once cAMP binds the CAP Activator, CAP binds DNA (at what site)_____ and can induce transription of the Lac Operon only if what?____

A

CAP Binding Site

Only if it is not repressed by the LAC repressor.

202
Q

In the Lac Operon, if there is a high concentration of Glucose and Lactose, will the operon be off or on?

A

Off

203
Q

In the Lac Operon, if there is a high concentration of Glucose and a low concentration of Lactose, will the operon be off or on?

A

Off

Lactose is required to turn the Operon On

204
Q

If there is a low concentration of Glucose and a low concentration of Lactose, will the Lac Operon be On or Off?

A

Off.

Lactose is required to turn the Operon On.

205
Q

In the Lac Operon, if there is a low concentration of Glucose and a high concentration of Lactose, will the operon be off or on?

A

On.

If there is Low Glucose, there is low ATP.

If there is low ATP, then cAMP is activated. The Lactose will bind the repressor to remove it and transcription will occur.

206
Q

What are regulatory sequences called in Eukaryotes

A

Enhancers

207
Q

Where are enhancers located?

A

They can be thousands of nucleotides away from the transcription start site.

208
Q

True or False:

Enhancers can only be upstream from the Transcription Start Site

A

False:

They can be upstream or downstream of Transcription start site

209
Q

What is located between the enhancer and the Transcription start site?

A

The Spacer DNA

210
Q

Interaction of enhancer sequence with Mediator Protein complex facilitates what?

A

Eukaryotic Transcription

211
Q

Define Pluripotent

A

capable of giving rise to several different cell types.

212
Q

How can cells be induced to de-differentiate?

A

By manipulating which transcription regulators are active or inactive.

213
Q

What are the results of a cell being de-differentiated?

A

It results in loss of cell identity and a cell that can be potentially induced to become any other cell (iPS)

214
Q

What is the result of Epigenetic control of Gene Expression?

A

Differentiated cells stay differentiated and so do their daughter cells due to the modifications to their chromatin.

215
Q

Epigenetic modifications lead to what?

A

Cell Memory- an ability of cells to recall which genes they should express or not

216
Q

How is Epigenetic control of gene expression regulated/mediated?

A

By positive feedback loops in which master gene regulators impact their own gene expression:

Gene A induces the Expression of Gene A

217
Q

What is DNA Methylation?

What is the result of DNA Methylation?

A

Addition of methyl group on specific DNA bases (cytosine) results in silencing of that gene

218
Q

True or False:

DNA Methlyation patterns are not passed from one generation to the next.

A

FALSE:

DNA methylation patterns are passed from one cell generation to next, including gametes in some instances

219
Q

How do histone modifications impact chromatin structure?

A

It can create Euchromatin ( loosely packed) or Heterochromatin (tightly packed) chromatin which can result in a loss of gene expression

220
Q

True or false:

Histone Modifications are passed from parent (cell) to offspring (cell).

A

TRUE

221
Q

Define Epigenetic Inheritance

A

It means that a parent’s experiences, in the form of epigenetic tags, can be passed down to future generations.

222
Q

What is a method of Translational control in Prokaryotes?

A

Some bacteria express proteins that bind Shine-Delgarno sequence of prokaryotic mRNAs and thus block ribosome binding

223
Q

What is a mechanism of Translational Control in Eukaryotes?

A

mRNAs may have regulatory sequences within their 5’UTR that impact 5’ cap from binding small ribosomal subunit

224
Q

Define:

Nonsense-Mediated Decay

A

Nonsense mutation will cause premature termination of translation and an incomplete polypeptide chain

225
Q

How do Eukaryotic cells use Nonsense-Mediated Decay?

A

Eukaryotic cells use nonsense-mediated decay to destroy mRNAs containing premature stop codons

226
Q

In mammals, how are premature stop codons detected?

A

By the Exon Junction Complex (EJC)

227
Q

When is the EJC Deposited?

A

Wherever intron is removed from pre-mRNA, so each spliced mRNA has at least one complex bound to it

228
Q

If mRNA contains a stop codon prior to the final EJC, what happens?

A

Translation is terminated and EJC does not get knocked off the mRNA

229
Q

Define Nonstop Decay in Eukaryotes

A

Translation stalls when the ribosome reaches the end of transcript that lacks a stop codon

230
Q

Nonstop Decay (process)

A

RNA degrading enzyme binds empty A site of ribosome and degrades the defective mRNA

231
Q

Define a nonstop decay in Bacteria

A

Transfer Messenger RNA (tmRNA) binds the A site and directs the addition of amino acids that target the protein for destruction

232
Q

Regulatory RNAs are part of what RNA family?

A

The Noncoding RNA

233
Q

What are the three types of Regulatory RNA found to regulate gene expression at the post-transcriptional level?

A

MicroRNAs (miRNAs)

Small Interfering RNAs (siRNAs)

Long Noncoding RNAs (lncRNAs)

234
Q

How are Micro RNAs expressed?

A

As part of longer RNAs, sometimes as part of introns and exons of other mRNAs

235
Q

True or False:

MicroRNAs (miRNAs) must be processed by Dicer)

A

True

236
Q

Define RISC

A

RNA-Induced Silencing Complex

237
Q

True or False:

MicroRNA (miRNAs) do not have to integrate with RISC in order to function.

A

False:

Must integrate with RISC (RNA-induced silencing complex) in order to function

238
Q

How do MicroRNAs (miRNAs) function?

A

Base-pair with target mRNAs and inhibit expression of target

•Exact, complementary match = target mRNA for immediate destruction

High degree complementary match = sequestration in cell away from translation machinery, eventual degradation

239
Q

True or False:

MicroRNAs (miRNAs) are an inefficient way to control several related genes.

A

FALSE:

It is very efficient because there are several targets possible if the mRNAs all share the target sequence, which would be ideal for targeting several related genes.

240
Q

Describe this process

A

miRNA processing beginning in mRNA and ending in mRNA degrading or sequestering and eventual degrading.

241
Q

What is the Cell’s defense mechanism that eliminates foreign RNAs (i.e. Viral RNAs)

A

RNA Interference (RNAi)

242
Q

What is dsRNA?

A

Forms the genetic material of some viruses (double-stranded RNA viruses). Double-stranded RNA such as viral RNA or siRNA can trigger RNA interference in eukaryotes, as well as interferon response in vertebrates

243
Q

How does Dicer process dsRNA?

A

It generates ssRNA ~22 base pieces (small interfering RNAs, siRNAs) which integrate with RISC and then target viral RNAs for destruction

244
Q

What are siRNAs? what is their function?

A

Small Interfering RNAs, which integrate with RISC and then target viral RNAs for destruction

245
Q

How many base pairs are LncRNAs?

A

At least 200 base Pairs Long

246
Q

What are some of the functions of LncRNAs?

A

Some have been found to regulate gene expression

Xist binds one X chromosome in females and silences that specific chromosome (Barr body) by recruiting chromatin remodeling proteins

Various found to be produced from “wrong” DNA strand of target gene, generating antisense strand complementary to target

Inhibits translation and/or contributes to RNAi-mediated destruction of target

247
Q
A
248
Q

Describe this image:

A

DNA Space-Filling Model

249
Q

Describe this image:

A

The Cell Cycle

250
Q

Describe this image:

A

An Electron micrograph of Nucleosomes (Beads on a string)

251
Q

Detail A-F of this image:

A

A: DNA Double Helix

B: Beads on a string form of Chromatin

C: Chromatin Fiber packed into Nucleosomes

D: Chromatin fiber folded into Loops

E: Entire Mitotic Chromosome

F: Each DNA Molecule has been packaged into a mitotic chromosome

252
Q

Describe the process in this photo:

A

A linker histone helps to pull the nucleosomes together and pack them into a more compact chromatin fiber

253
Q

Describe the processes occurring in this image:

A

Chromatin-Remodeling Complexes

Using ATP to change the position along the histone cores

254
Q

Describe this image:

A

The variation of chromatin structure along an interphase chromosome

255
Q

Describe the image:

A
256
Q

Describe the image:

A

DNA Replication

257
Q

Describe the image:

A

Semiconservative DNA Replication

258
Q

Describe the image:

A

DNA Double Helix is opened at the replication Origin

259
Q

Describe the image:

A

DNA synthesis at the Y-shaped Replication Fork

260
Q

Describe the image:

A

Multiple Replication forks along the DNA

261
Q

Describe the image:

A

DNA Polymerase adds a deoxyribonucleotide to the 3’ end of the growing DNA Chain.

262
Q

Describe the image:

A

At each replication fork, the lagging strand is synthesized in pieces

263
Q

Describe the process in the image:

A

DNA Polymerase proofreading

264
Q

Describe the process in the image:

A

Okazaki fragments are synthesized and ligated to form a continuous strand.

265
Q

Describe the image:

A

The replication machine

266
Q

Describe the image:

A

DNA Topoisomerase relieves the tension that builds up in front of the replication fork (preventing double-stranded breaks)

267
Q

Describe the image:

A

DNA End replication repair

268
Q

Describe the image:

A

DNA telomeres and telomerase adjusting end-replication problem

269
Q

Describe the image:

A

DNA Damage in the form of Depurinaton and Deamination

270
Q

Describe the image:

A

Deamination leads to mutations

271
Q
A

Cell Biology 2203 (5 decks)

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