lecture 3 Flashcards
What are two main types of cell?
Somatic cells: cells are components of body tissues
Gametes: are sex cells (ova, sperm), when sex cells unite you get a zygote
What is the central dogma of molecular biology?
Central dogma: DNA is transcribed into RNA and translated into proteins
define mutation
Mutation: is a change in the genetic code
Mutations are both the sustainer of life and the cause of great suffering. Explain this statement.
Adaptation depends on genetic variation and mutations are partly responsible for this variation in genes that is then selected for by natural selection which leads to evolution. So, mutations are the raw genetic material used for adaptations. Although all mutations are not good mutations and so that can lead to suffering.
What is a single nucleotide polymorphism? Describe an example of a single nucleotide polymorphism that leads to disease.
SNP: is when one base pair is switched for another
Sickle cell anemia is a great example of an SNP because one base pair is switched for the protein coding for hemoglobin which causes the cell to deform into a sickle shape.
what are indels?
Indels: are the insertions and deletions of nucleotide base pairs which can lead to frameshifts in the gene reading area which can also result in a stop codon being formed and therefor you get a truncated protein.
What are frameshift mutations? Describe a situation in which frameshift mutations might not lead to disease.
Frameshift mutation: are changes in genes that cause a shift in the reading frame for the gene so the reading region changes therefore you can get premature stop codons, so the protein synthesis stops prematurely resulting in a truncated protein
Insertions and deletions containing 3 nucleotide bases doesn’t result in a frameshift so they are called in frame insertions and in frame deletions
What are short tandem repeat polymorphisms? Describe a situation in which this type of polymorphism might lead to disease.
Short tandem repeats: repetition of 2-6 base pairs in the genome
Huntington’s disease: an increase in the number of nucleotide base pairings (repeats) on the coding part of the gene produces a toxic protein that has extra glutamine residues (CAG)
Mutations have different phenotypic effects. What are three possible phenotypic effects in general?
Loss of function mutation: an alteration to the structure of the protein that causes complete or partial absence of a protein
Gain of function mutation: causes the cell to produce a protein or gene product that’s not usually present at an inappropriate time in development or in the wrong location
Silent mutation: there is a change in the protein or gene but the function stays the same
What is a suppressor mutation? Describe two classes of suppressor mutation
Suppressor mutation: a genetic change that hides or suppresses the effects of another mutation, the individual is a double mutation because they have the original mutation and the suppressor mutation but exhibit the phenotype of a nonmutated wild type
Intragenic suppressors: suppressing a frameshift mutation, mutation within a gene,
Intergenic suppressors: mutation between genes, one mutation on one gene results in a new phenotype
Describe two kinds of spontaneous mutations
Tautomeric shift: in one strand makes a mutation in the complimentary strand
Nonstandard base pairings or Wobble pairings: non complimentary base pairs are paired
define mutation rate
Mutation rate: the frequency at which a wild type allele changes into a mutant allele and the probability that an offspring carries a new mutation
Mutation rates vary among species. Give two examples to show that this statement is true.
E. coli: a chance that a DNA base in a daughter cell carry a new point mutation, the mutation rate for a single base pair is μ = 0.45 × 10−10 mutations per nucleotide per generation
Achondroplasia: All people carrying the mutant allele or alleles manifest the disorder fully, the mutation rate is 4/100,000 or 0.00004, mutations per gamete
- Organisms with larger genomes tend to have higher mutation rates
Despite the huge range of effects that mutations have, they show two general features. Describe these two general features. Also, include an example for one of these features.
Pleiotropy: a single mutation affects multiple traits like in achondroplasia
Deleterious mutations: have negative affects on the individuals fitness and reproductive ability yet they still persist in populations like sickle cell anemia because Beneficial mutation is attached to deleterious mutation so the deleterious mutation increases frequency, or because Genetic drift can be a cause for deleterious mutations to survive where only a mall portion of the population survives but happens to carry a high frequency of the gene, or They can survive because the deleterious mutations have been covered up so they are silent.
Describe three examples of nongenetic inheritance
Maternal affects: the genotype or phenotype of the mother directly influences the phenotype of her offspring like breastfeeding where milk provides important effects in child’s development and in turn the milk coming from the mother depends on her physiological condition and genotype
Cultural inheritance: song dialects of white crowned sparrows where young males hear the local song dialect from their fathers and other males, can inherit traits from family and unrelated individuals
Epigenetic affects: chemical tags that are added to histones that affect the chromatin or DNA but don’t play a role in genetic expression and are inherited
