genetics and evolution

• What are mutations in DNA molecules?

  Mutations are changes in the sequence of nucleotides in DNA molecules.
• What are the types of mutations?

  • Insertion/deletion mutations
  • Point mutation/substitution
  • Nonsense mutation
  • Missense mutation
  • Silent mutation
• What occurs during insertion/deletion mutations?

  One or more nucleotide pairs are inserted or deleted from the sequence, causing a frameshift.
• What is a point mutation/substitution?

  A point mutation/substitution occurs when one base pair is replaced by another.
• What is a nonsense mutation?

  A nonsense mutation stops translation early, resulting in a truncated polypeptide due to a premature stop codon.
• What is a missense mutation?

  A missense mutation results in a codon change that produces a different amino acid, altering the protein's tertiary structure.
• What is a silent mutation?

  A silent mutation is a codon change that does not affect the amino acid sequence produced.
• When can mutations have neutral effects?

  Mutations can have neutral effects when they occur in non-coding regions or are silent mutations.
• What is an example of a beneficial mutation?

  Humans developed trichromatic vision through a mutation.
• What is an example of a harmful mutation?

  A mutation in the CFTR protein causes cystic fibrosis.
• How does the environment affect mutations?

  Whether a mutation is beneficial or detrimental depends on the organism's environment.
• At what levels can gene expression be controlled?

  • Transcriptional
  • Post-transcriptional
  • Post-translational
• What is the lac operon?

  The lac operon is a length of DNA that controls the expression of beta-galactosidase in E. coli.
• What is the role of the promoter region in the lac operon?

  The promoter region is the binding site for RNA polymerase to initiate transcription.
• What happens when glucose concentration is high and lactose concentration is low in the lac operon?

  The transcription of structural genes is inhibited due to the binding of the repressor to the operator region.
• What occurs when lactose concentration is high and glucose concentration is low in the lac operon?

  Lactose binds to the repressor, changing its shape and allowing RNA polymerase to bind to the promoter region.
• How do transcription factors control gene expression?

  Transcription factors switch genes on and off by interacting with the promoter sequence of DNA.
• What occurs during post-transcriptional control of gene expression?

  Editing of the primary mRNA transcript occurs, removing non-coding regions called introns.
• How is gene expression controlled at the post-translational level?

  Proteins can be activated by molecules like cyclic AMP after binding to receptors.
• What are homeobox genes responsible for?

  Homeobox genes control the development of body plans and code for transcription factors.
• What is apoptosis?

  Apoptosis is a form of programmed cell death that controls the development of body plans.
• How does apoptosis differ from necrosis?

  Apoptosis is an ordered process of cell death, while necrosis results from damage and releases hydrolytic enzymes.
• What happens to a cell during apoptosis?

  Enzymes break down the cytoskeleton, DNA, and proteins, causing the cell to shrink and fragment.
• What is phenotypic variation?

  Phenotypic variation refers to differences in observable characteristics of organisms.
• What are the two types of phenotypic variation?

  • Discontinuous variation
  • Continuous variation
• What is discontinuous variation?

  Discontinuous variation can be assigned to a particular category, such as blood type.
• What is continuous variation?

  Continuous variation involves quantitative differences between phenotypes, such as height or weight.
• What influences variation in organisms?

  Variation can be influenced by both environmental factors and genetic factors.
• What is meiosis?

  Meiosis is a form of cell division that produces haploid gametes and genetic variation.

  
• How does meiosis contribute to genetic variation?

  • Crossing over of chromatids
  • Independent assortment of chromosomes

  
• What is an allele?

  An allele is an alternative form of a gene.
• What is a locus?

  A locus is the specific position of a gene on a chromosome.
• What is a phenotype?

  A phenotype is the observable characteristics of an organism resulting from genotype and environment.
• What is a genotype?

  A genotype is the alleles present within the cells of an organism for a particular trait.
• What is a dominant allele?

  A dominant allele is expressed in the phenotype if at least one copy is present.
• What is a recessive allele?

  A recessive allele is expressed in the phenotype only if no dominant allele is present.
• What is homozygous?

  Homozygous refers to having two identical alleles for a trait.
• What is heterozygous?

  Heterozygous refers to having two different alleles for a trait.
• What is codominance?

  Codominance occurs when both alleles contribute to the phenotype in a heterozygote.
• What is linkage in genetics?

  Linkage is the phenomenon where genes for different characteristics are inherited together because they are located on the same chromosome.