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Genetics Lecture 9
Exam 2
| Question | Answer |
|---|---|
| What are the three main types of Mutations? | Single-gene, Chromosome, Genome |
| What is single gene mutation? | Small changes in DNA structure that occur within a particular gene (promoter or transcriptional unit) |
| What is a chromosome mutation? | Changes in chromosome structure |
| What is Genome mutations? | Changes in chromosome number (deleted or added) |
| allele | one of the different forms of a gene that exist at a single locus |
| locus | location of the gene on a chromosome |
| What is genetic recombination? | 1) the process in which chromosomes bre broken and then rejoined to form a novel genetic combination 2) the process in which alleles are assorted and passed to offspring in combinations that are different from teh parents |
| What is genetic variation? | genetic differences among members of the same species or among different species |
| what is meant by wild type (wt)? | designated as the standard (either in nature or lab) |
| what is forward mutation? | any change away from wt |
| what is reverse mutation? | any change back to the wt allele (aka reversion or back mutation) |
| Mutation is the foundation... | of diversity found in nature and agriculture |
| According to evolution theory... | all genes are mutant genes |
| What causes gene mutation? (List all five) | DNA replication, chemical reactions, reactive cellular metabolites, high energy radiation (UV light), Mobile Genetic elements |
| What is the number one cause of gene mutations? | DNA replication |
| What is a point mutation? | a change in a SINGLE base pair that involves base substitution |
| What is a transition (for gene mutation)? | a change of a pyrimidine (C, T) to another pyrimidine or a purine (A, G) to another purine |
| What is a transversion (for genetic mutation)? | a change of a pyrimidine (C, T) to a purine or vice versa |
| What is more common: Transitions or transversions? | Transitions |
| Can mutations change (add, delete) short sequences of DNA? | Yes |
| What are examples of Point mutations? | Silent, Missense, Nonsense, Frameshift |
| What is a silent mutation? | same codon but different letters (CCG vs CCC- but both code for Pro) |
| What is a missense mutation? | base substitution in which an amino acid change does occur (ACC-Thr, where A changes to C, CCC-Pro |
| What is a nonsense mutation? | change from a normal codon to a termination codon |
| What is a frameshift mutation? | A deletion or addition of a number of nucleotides (that is not divisible by three b/c called a missense mutation) |
| What is a neutral mutation? | a misssense mutation that substitutes an amino acid with a similar chemistry as the original amino acid (acid that is neg. charged, similar side chain structures) |
| suppressor change | second mutation that produces a mutant tRNA anticodon that suppresses a codon mutation |
| slippage mutation | DNA replication can "slip" at repeated bases and either add or delete |
| What is trinucleotide repeats (TNRE)? | refers to phenomenon that s sequence of 3 nucleotides can increase from one generation to the next |
| What type of diseases are caused by TNRE? | Huntington's Disease |
| Fragile X Syndrome | a change in a SINGLE base pair that involves base substitution |
| what two features do TNRE disorders have in common? | 1) the severity of the disease tends to worsen in future generations |
| 2) the severity of the disease depends on whether it is inherited from the father or mother (paternal imprinting) | a change of a pyrimidine (C, T) to another pyrimidine or a purine (A, G) to another purine |
| In Huntington's Disease, is TNRE more likely to occur if inherited from mother or father? | Father |
| In Myotonic Muscular Dystrophy, is TNRE more likely to occur if inherited from mother or father? | Mother |
| What is anticipation (for TNRE)? | severity of the disease tends to worsen in future generations |
| TNRE may produce... | alternations in DNA structure (stem-loops) which lead to errors in DNA replication |
| If TNRE occurs within coding sequence... | encoded protein will contain long tracks which can cause aggregation and cause disease to progress |
| If TRNE is NOT within coding... | abnormal changes in RNA and causes disease symptoms |
| Cancers occurs more often in... | quickly dividing cells (skin, lungs, digestive tract, mammary glands, liver, reproductive organs) |
| Mutation Rate | likelihood that a gene will be altered by a new mutation--often expressed as the number of new mutations in a given gene per generation |
| Is mutation rate for a given gene constant? | No it can be increased by the presence of mutagens |
| Do mutation rates vary? | Yes between species and within different strains of the same species |
| Can genes mutate at different rates within the dame individual? | Yes--some genes are larger than others which provide a greater chance for mutation |
| what are hot spots | locations in some genes within the chromosomes that make them more susceptible to mutation (can be found with in a single gene) |
| Mutation Frequencies | the number of mutant forms of this gene divided by the total number of these genes in a population |
| What are the two classes of gene mutation? | Somatic mutation, Germinal mutation |
| What is somatic mutation? | mutation in vegetative cells, therefore usually not passed on to next generation (involved in aging and cancers) |
| What is germinal mutation? | source of new alleles which can be passed on to the next generation |
| What is a genetic mosaic? | an individual who has somatic regions that are genotypical different from each other |
| Name the three Mutant Types... | 1)Loss-of-Function 2)Gain-of-Function (rare) 3) Silent |
| What is a loss of function mutation? | the effects of gene mutations that eliminate the function of a gene |
| What is a Gain of Function mutation? | a mutation that causes a gene to be expressed in an additional place where it is not normally expressed, or during a stage of development when it is not normally expressed |
| Loss of function mutations occur most in... | null or leaky |
| usually recessive or incomplete dominant | refers to phenomenon that s sequence of 3 nucleotides can increase from one generation to the next |
| Gain of Function mutations mostly occur in... | Dominant or codominant |
| Silent mutations occur in... | only genotypic not phenotypic change |
| How is cancer caused? | Somatic cell mutations (can be gene or chromosome mutations) |
| Most cancer cells must (List all 3)? | 1) gain rapid cell division (forms a tumor) 2) gain new blood supply 3) gain ability to move and invade other tissues (metastasis) |
| What is the most common mutant type? (Loss of function, Gain of function, or silent) | Loss of function |
| TNRE may produce... | alternations in DNA structure (stem-loops) which lead to errors in DNA replication |
| If TNRE occurs within coding sequence... | encoded protein will contain long tracks which can cause aggregation and cause disease to progress |
| If TRNE is NOT within coding... | abnormal changes in RNA and causes disease symptoms |
| Cancers occurs more often in... | quickly dividing cells (skin, lungs, digestive tract, mammary glands, liver, reproductive organs) |
| Mutation Rate | likelihood that a gene will be altered by a new mutation--often expressed as the number of new mutations in a given gene per generation |
| Is mutation rate for a given gene constant? | No it can be increased by the presence of mutagens |
| Do mutation rates vary? | Yes between species and within different strains of the same species |
| Can genes mutate at different rates within the dame individual? | Yes--some genes are larger than others which provide a greater chance for mutation |
| what are hot spots | locations in some genes within the chromosomes that make them more susceptible to mutation (can be found with in a single gene) |
| Mutation Frequencies | the number of mutant forms of this gene divided by the total number of these genes in a population |
| What are the two classes of gene mutation? | Somatic mutation, Germinal mutation |
| What is somatic mutation? | mutation in vegetative cells, therefore usually not passed on to next generation (involved in aging and cancers) |
| What is germinal mutation? | source of new alleles which can be passed on to the next generation |
| What is a genetic mosaic? | an individual who has somatic regions that are genotypical different from each other |
| Name the three Mutant Types... | 1)Loss-of-Function 2)Gain-of-Function (rare) 3) Silent |
| What is a loss of function mutation? | the effects of gene mutations that eliminate the function of a gene |
| What is a Gain of Function mutation? | a mutation that causes a gene to be expressed in an additional place where it is not normally expressed, or during a stage of development when it is not normally expressed |
| Loss of function mutations occur most in... | null or leaky usually recessive or incomplete dominant |
| Gain of Function mutations mostly occur in... | Dominant or codominant |
| Silent mutations occur in... | only genotypic not phenotypic change |
| How is cancer caused? | Somatic cell mutations (can be gene or chromosome mutations) |
| Most cancer cells must (List all 3)? | 1) gain rapid cell division (forms a tumor) 2) gain new blood supply 3) gain ability to move and invade other tissues (metastasis) |
| What is the most common mutant type? (Loss of function, Gain of function, or silent) | Loss of function |
| What are the three main types of Mutations? | Single-gene, Chromosome, Genome |
| What is single gene mutation? | Small changes in DNA structure that occur within a particular gene (promoter or transcriptional unit) |
| What is a chromosome mutation? | Changes in chromosome structure |
| What is Genome mutations? | Changes in chromosome number (deleted or added) |
| allele | one of the different forms of a gene that exist at a single locus |
| locus | location of the gene on a chromosome |
| What is genetic recombination? | 1) the process in which chromosomes bre broken and then rejoined to form a novel genetic combination 2) the process in which alleles are assorted and passed to offspring in combinations that are different from teh parents |
| What is genetic variation? | genetic differences among members of the same species or among different species |
| what is meant by wild type (wt)? | designated as the standard (either in nature or lab) |
| what is forward mutation? | any change away from wt |
| what is reverse mutation? | any change back to the wt allele (aka reversion or back mutation) |
| Mutation is the foundation... | of diversity found in nature and agriculture |
| According to evolution theory... | all genes are mutant genes |
| What causes gene mutation? (List all five) | DNA replication, chemical reactions, reactive cellular metabolites, high energy radiation (UV light), Mobile Genetic elements |
| What is the number one cause of gene mutations? | DNA replication |
| What is a point mutation? | a change in a SINGLE base pair that involves base substitution |
| What is a transition (for gene mutation)? | a change of a pyrimidine (C, T) to another pyrimidine or a purine (A, G) to another purine |
| What is a transversion (for genetic mutation)? | a change of a pyrimidine (C, T) to a purine or vice versa |
| What is more common: Transitions or transversions? | Transitions |
| Can mutations change (add, delete) short sequences of DNA? | Yes |
| What are examples of Point mutations? | Silent, Missense, Nonsense, Frameshift |
| What is a silent mutation? | same codon but different letters (CCG vs CCC- but both code for Pro) |
| What is a missense mutation? | base substitution in which an amino acid change does occur (ACC-Thr, where A changes to C, CCC-Pro |
| What is a nonsense mutation? | change from a normal codon to a termination codon |
| What is a frameshift mutation? | A deletion or addition of a number of nucleotides (that is not divisible by three b/c called a missense mutation) |
| What is a neutral mutation? | a misssense mutation that substitutes an amino acid with a similar chemistry as the original amino acid (acid that is neg. charged, similar side chain structures) |
| suppressor change | second mutation that produces a mutant tRNA anticodon that suppresses a codon mutation |
| slippage mutation | DNA replication can "slip" at repeated bases and either add or delete |
| What is trinucleotide repeats (TNRE)? | refers to phenomenon that s sequence of 3 nucleotides can increase from one generation to the next |
| What type of diseases are caused by TNRE? | Huntington's Disease, Fragile X Syndrome |
| what two features do TNRE disorders have in common? | 1) the severity of the disease tends to worsen in future generations 2) the severity of the disease depends on whether it is inherited from the father or mother (paternal imprinting) |
| In Huntington's Disease, is TNRE more likely to occur if inherited from mother or father? | Father |
| In Myotonic Muscular Dystrophy, is TNRE more likely to occur if inherited from mother or father? | Mother |
| What is anticipation (for TNRE)? | severity of the disease tends to worsen in future generations |
| TNRE may produce... | alternations in DNA structure (stem-loops) which lead to errors in DNA replication |
| If TNRE occurs within coding sequence... | encoded protein will contain long tracks which can cause aggregation and cause disease to progress |
| If TRNE is NOT within coding... | abnormal changes in RNA and causes disease symptoms |
| Cancers occurs more often in... | quickly dividing cells (skin, lungs, digestive tract, mammary glands, liver, reproductive organs) |
| Mutation Rate | likelihood that a gene will be altered by a new mutation--often expressed as the number of new mutations in a given gene per generation |
| Is mutation rate for a given gene constant? | No it can be increased by the presence of mutagens |
| Do mutation rates vary? | Yes between species and within different strains of the same species |
| Can genes mutate at different rates within the dame individual? | Yes--some genes are larger than others which provide a greater chance for mutation |
| what are hot spots | locations in some genes within the chromosomes that make them more susceptible to mutation (can be found with in a single gene) |
| Mutation Frequencies | the number of mutant forms of this gene divided by the total number of these genes in a population |
| What are the two classes of gene mutation? | Somatic mutation, Germinal mutation |
| What is somatic mutation? | mutation in vegetative cells, therefore usually not passed on to next generation (involved in aging and cancers) |
| What is germinal mutation? | source of new alleles which can be passed on to the next generation |
| What is a genetic mosaic? | an individual who has somatic regions that are genotypical different from each other |
| Name the three Mutant Types... | 1)Loss-of-Function 2)Gain-of-Function (rare) 3) Silent |
| What is a loss of function mutation? | the effects of gene mutations that eliminate the function of a gene |
| What is a Gain of Function mutation? | a mutation that causes a gene to be expressed in an additional place where it is not normally expressed, or during a stage of development when it is not normally expressed |
| Loss of function mutations occur most in... | null or leaky; usually recessive or incomplete dominant |
| Gain of Function mutations mostly occur in... | Dominant or codominant |
| Silent mutations occur in... | only genotypic not phenotypic change |
| How is cancer caused? | Somatic cell mutations (can be gene or chromosome mutations) |
| Most cancer cells must (List all 3)? | 1) gain rapid cell division (forms a tumor) 2) gain new blood supply 3) gain ability to move and invade other tissues (metastasis) |
| What is the most common mutant type? (Loss of function, Gain of function, or silent) | Loss of function |
| Proto-oncogene | a normal cellular gene that does not cause cancer, but which may incur a mutation or become incorporated into a viral genome and thereby lead to cancer |
| Tumor suppressor gene | a gene that functions to inhibit (prevent) cancerous growth |
| Oncogene | an abnormally activated gene that leads to uncontrolled cell growth |
| Mutator Genes | genes involved with DNA repair if mutated allow higher levels of mutation in general |
| Telomerase genes | if mutated to turn on when it should be turned off, could lead to immortal cells |
| Multiple duplications can create | high copy # of genes which can no longer be regulated |
| Deficiency (or deletion) | the loss of a chromosomal segment |
| Duplication | the repetition of a chromosomal segment compared to the normal parent chromosome |
| Inversion | a change in the direction of the genetic material along a single chromosome (flipping of a section) |
| Translocation | a segment of one chromosome becomes attached to a different chromosome |
| Simple translocation | one way transfer |
| Reciprocal translocation | two way transfer |
| Position effect | when a gene is intact but its expression altered because of its new location |
| Two examples of position effect | 1)movement next to regulatory sequences 2)movement to a heterochromatic region |
| Do duplications produce changes in the phenotype? | they may or may not |
| Chromosomal rearrangements, if not detrimental... | provides an opportunity for gene evolution without the loss of the original gene product |
| Lysozyme | degrades the cell wall of bacteria and is normally found in the tears of mammals |
| Lysozyme mutation | allows gene to be expressed in stomach instead of tear glands in the Langur Monkey |
| Monoploid number (X) | number of sets of chromosomes (# genomes--humans are 2 mom and dad) |
| Haploid Number (n) | the number found in gametes (humans are 46) |
| What is the most common form of euploids? | diploid |
| Eupolid | describes an organism in which the chromosome number is an exact multiple of a chromosome set |
| The higher the eupolid... | the rarer they are in nature |
| Polyploids | an organism or cell with three or more sets of chromosomes |
| Name the two different types of polyploids | autopolyploids and allopolyploids |
| Autopolyploids | multiple chromosome sets from one species |
| Allopolyploids | chromosome sets from different species and must be HOMEOLOGOUS |
| Homeologous | describes the analogous chromosomes from evolutionarily related species (wheat and rye) |
| Triploids | an organism or cell that contains three sets of chromosomes and can result from a cross of a tetraploid (4X) with a diploid (2X) |
| What is the problem of Triploids | they are sterile due to problems pairing during meiosis (other odd number of chromosomes will give similar results) |
| Aneuploidy | chromosome number differs from wt by part of a chromosomal set (NOT euploid) |
| Aneuploidy is generally | deleterious which places things out of balance |
| Aneuploidy is caused by... | nondisjunction during meioses or mitosis |
| What is an example of Aneuploidy? | Down syndrome (extra copy of autosome #21 & is the most common type in humans) |
| Somatic Aneuploids occur | during mitosis in early development |
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