Module 3 Vocab Flashcards
(96 cards)
1
Q
What is a mutation
A
Change in the genetic material (DNA)
2
Q
Alkaptonuria
A
-One of the first disease phenotypes correlated with a genotype
-Absence of homogentisate oxidase activity
-Archibald Garrod
3
Q
Phenylketonuria (PKU)
A
-Accumulation of phenylpyruvic acid in the brain
-Newborns are screened
4
Q
Albinism
A
-Inability to produce melanin pigment
-Recessive disorder
5
Q
Wildtype
A
Naturally occurring variations of genes
6
Q
Mutation - Loss of Function
A
-Causes complete or partial absence of protein function
-Loss of function mutations are recessive acting
7
Q
Mutations - Gain of Function
A
-Causes the cell to produce a protein that is not normally present
-Gain of function mutations are dominant acting (ex. cancer cells)
8
Q
Transition Point Mutation
A
-Purine to Purine
-Pyrimidine to Pyrimidine
9
Q
Transversion Point Mutation
A
-Purine to Pyrimidine
-Pyrimidine to Purine
10
Q
Missense (nonsynonymous) Point Mutation
A
Changes the amino acid
11
Q
Nonsense Point Mutation
A
Changes codon so that it becomes a STOP codon
12
Q
Silent (synonymous) Point Mutation
A
Codes for the same amino acid
13
Q
Readthrough Point Mutation
A
STOP codon is changed to a codon that codes for amino acid
14
Q
Types of Spontaneous Point Mutations
A
-Depurination
-Deamination of Cytosine
-Wobble Base Pairing
15
Q
Depurination
A
-Removes the glycosidic bond at either G or A bases
-Results in an apurinic site (missing purine)
16
Q
Deamination of Cytosine
A
-Results in Uracil
-Causes GC to AT transition
17
Q
Wobble Base Pairing
A
-Mispairing due to flexibility in helix
-Results in transitions after replication
-AC or TG can wobble
18
Q
5-bromouracil
A
Normally pairs with adenine, but can also pair with guanine
19
Q
2-aminopurine
A
Normally pairs with thymine, but can also pair with cytosine
20
Q
Mutations that alter DNA bases
A
-Alkylating agents
-Deamination
-Hydroxylamine
21
Q
Frameshift Mutations
A
-The insertion/deletion of one or more base pairs in the gene, shifting the reading frame in all codons following the mutation site
-Can alter the stop/start site
22
Q
Cystic Fibrosis
A
-Mutation in a structural protein
-Mucus with high viscosity and leads to respiratory infections
23
Q
Fragile X Syndrome
A
-Extra copies of trinucleotide repeat (CGG) on the X chromosome
-More frequent in males than females
-Long face/jaw bone and loose joints
-Number of Repeat Copies: 50-1500
24
Q
Huntington Disease
A
-Extra copies of CAG
-Nerve cells in the brain decrease over time
-Number of Repeat Copies: 37-121
25
Impact of UV Light
-Impacts mainly Thymine dimers (Pyrimidine Dimer Formation)
-Distort the helix and inhibit replication
26
Xeroderma Pigmentosum
-A human disorder where a repair mechanism is defective.
-Results in tumors on the skin surface. (Impacts Pyrimidine Dimer Formation)
27
Transposable Genetic Elements "Jumping Genes"
-Can move from one site to another site
-Can move to a different chromosome
-Can alter phenotypes by disrupting a gene or disrupting a regulatory area
28
Ac (Activator) in Maize
Complete transposable element with functional transposase and repeats
29
Dx (Dissociation) in Maize
Lacking functional transposase gene (deletion) so it requires the AC transposase to move
30
Arabidopsis (Transposons)
Transposase derived proteins regulate plant genes required for plant growth
31
Humans (Transposase)
Mechanism for antibody formation may have evolved from transposons
32
Drosophila (Transposase)
Telomerase enzyme is not present in Drosophila, but ends of chromosomes have transposon type sequences and mechanism of telomerase is similar to that of transposons
33
Direct Repair of Mutations in Bacteria
-Photoreactivation Repair of Pyrimidine Dimers
-Enzyme Photolyase absorbs light and clips dimer
34
Methyltransferase
Restores correct form to incorrectly methylated guanine bases
35
Proofreading during Replication
1) DNA Polymerase stalls
2) Exonuclease removes incorrect nucleotide
3) DNA Polymerase inserts the correct nucleotide
36
Mismatch Repair (MMR)
1) Mismatch repair proteins recognize abnormal helical structure and ID the incorrect base
2) Exonucleases remove the area
3) DNA polymerase fills the gap
4) Ligase seals the nick
-Does NOT remove lesions
37
Nucleotide Excision Repair (NER)
1) SSB separates and holds DNA apart
2) DNA Polymerase fills the gap
3) DNA ligase seals nick
-CAN remove lesions
38
Base Excision Repair (BER)
1) Glycosylases recognize and removes defective bases resulting in an AP site (apurinic/apyrimidinic site)
2) AP endonuclease causes a nick in the phosphodiester bond then removes the rest of the nucleotide
3) DNA polymerase fills the gap
4) DNA ligase seals the nick
-Removes modified bases
39
Homologous Recombination Repair (Double Strand Break Repair)
-Uses sister chromatid to repair the break
-Uses many of the same enzymes as homologous recombination of meiosis
-BRCA1, BRCA2
40
Nonhomologous End Joining (Double Strand Break Repair)
-Often used in G1
-Joins broken ends
-Often leads to translocations, deletions and insertions
41
Translesion DNA Polymerases
-Specialized polymerases that can bypass lesions on the DNA during replication
-Often make errors
-Allow replication to proceed at the cost of introducing mutations
42
Terminal Deletion
Produces acentric fragment which is lost during cell division
43
Interstitial Deletion
Required 2 breaks
44
Deletions
Missing parts of a chromosome
45
Effects of Deletions
-Segments that do not contain a centromere (acentric fragments) are lost
-May cause an imbalance in the amount of gene products produced
-May allow the recessive allele to become "visible" causing mutant phenotype
46
Haploinsufficiency
Single copy of gene is not enough to allow the wildtype phenotype to occur
47
Pseudodominance
Expression of normally recessive phenotype because there is no homologous allele due to a deletion
48
Duplications
Extra copy of part of the chromosome
49
Types of Duplications
-Tandem
-Reverse Tandem
-Displaced (homobrachial) - same arm
-Displaced (hetrobrachial) -different arm
50
Inversions
Have a segments of a chromosome that is removed, turned 180 degrees, and reinserted back into the chromosome
51
Paracentric Inversion
Inverted area does not include centromere
52
Pericentric Inversion
Inverted area does include centromere
53
Dicentric Bridges
Are common in anaphase I when a crossover occurs in a paracentric inversion loop
54
Reciprocal Translocations
-Two nonhomologous chromosomes exchange arms (or part of arms)
-No gain/loss of DNA
55
Non-Reciprocal Translocations
-A segments from one chromosome is moved to a nonhomologous chromosome
-No gain/loss of DNA
56
Robertsonian Translocations
-Two telocentric chromosomes combine to make one larger chromosomes
-Some small amount of DNA is lost but often not noticeable
-Isochromosomes - two chromosomes joined are homologs
57
Familial Down Syndrome
-Caused by Robertsonian translocation or isochromosomes
-Joining chromosomes 14 and 21
58
Isochromosome
Two chromosome 21's join together
59
Burkitt's Lymphoma
-Abnormal function of B cells (secrete antibodies)
-Reciprocal translocation between chromosomes 8 and 14
60
Position Effect
Same genes are present, but chromosomal location alters the phenotype
61
Structural Genes
Encode proteins that are used in metabolism or play a structural role in the cell
62
Regulatory Genes
Encode products that interact with other sequences and affect the transcription a/o translation of these sequences
63
Regulatory Elements
DNA sequences that are not transcribed, but play a role in regulating other nucleotide sequences
64
Regulatory Mechanisms for Transcription
-Rapid turn ON/OFF
-Sequential gene expression (cascades)
-Constitutive expression/housekeeping genes (continuously expressed under normal conditions, such as rRNA and tRNA)
65
Positive Control (Transcription)
Regulatory protein (activator) binds to DNA to stimulate transcription
66
Negative Control (Transcription)
Regulatory protein (repressor) binds to DNA to prevent transcription
67
Inducible Control (Transcription)
Transcription is normally turned off and is turned on when a small molecule binds the regulatory protein
68
Repressible Control (Transcription)
Transcription is normally on and is turned off when a small molecule binds the regulatory protein
69
Operon
A segment of DNA containing controlling regions and structural genes controlled by those controlling regions
70
Cis Acting (Lac Operon)
-Action of an element affects only the genes adjacent to it
ex) operator and promoter elements
71
Catabolite Repression
Glucose is preferred so there is no need for the lac operon to function if glucose is present
71
Anti-sense RNA
Small RNA molecules complementary to pats of the mRNA. They base pair to the mRNA and inhibit translation.
71
Attenuator
Located in the leader sequence and responsible for decreasing transcription when trp is present
72
Riboswitches
Are RNA sequences in the mRNA that affect the translation of that mRNA (regulate at the level of translation)
73
Changes in Chromatin
-Histone modification
-Chromatin remodeling
-DNA methylation
74
DNasel Hypersensitive sites
-Small regions typically upstream from start of transcription
-Nucleosome is missing
-Binding sites for regulatory proteins
75
Methylation of tails of histones
Can either increase or decrease transcription depending on which amino acids are methylated
76
Acetlyation of tails in histones
Weakens interaction with DNA and may allow transcription factors to bind DNA
77
Histone Deacetylation (lys)
-Enzyme: Histone Deacetylases (HDAC)
-Tightens association between histones and DNA
-"tighten it up"
78
Histone Acetylation (lys)
-Enzyme: Histone Acetyl Transferase (HAT)
-Loosens DNA - histone association by neutralizing the positive charge on the histones
-"loosen it up"
79
Histone Code
Is the combination of modifications present that help regulate chromatin structure and transcription
80
Histone Methylation
Can activate or repress expression of a gene (usually repress)
81
DNA Methylation
By DNA methyl transferases, tends to cause genes to be turned OFF (silencing)
82
Epigenetics
-The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself
Ex) royal jelly + honeybees
83
Transcription Factors
-Bind to DNA at transcription factor binding sites (enhancers, silencers, regulatory promoter)
-Interact with the transcription apparatus
-Can be activators or repressors
84
Insulators
Are cis DNA elements that block transcription factors from interacting with the wrong gene
85
Northern Blot
Shows relative amounts of RNA present
86
Somatic Recombination
DNA processing to choose constant region, joining region and variable region for both the heavy and light chains
87
Maternal Genes (Egg Polarity Genes)
-Establish anterior/posterior polarity and dorsal/ventral polarity
-Transcribed during egg development
-Translated after fertilization
88
Segmentation Genes
-Affect the number and polarity of segments
-Gap genes, Pair Rule genes, Segment Polarity genes
89
Homeotic Genes
Determine the identity of each segment
90
Gap Genes
Divide embryo into broad segments
91
Pair-Rule Genes
Affect same part of the pattern in every other segment
92
Segment Polarity Genes
Affect anterior/posterior polarity of each segment
93
Autopolyploidy
Extra sets of chromosomes are identical to normal chromosome set (all sets are from the same species)
94
Allopolyploidy
Combination of sets of chromosomes from different species
