Diversity of organisms

• What is a species?


  A species is a group of organisms with shared traits.
• What is the defining feature of life regarding variation between organisms?

  No two individuals are identical in all their traits.
• When do monozygotic twins form?

  Monozygotic twins form when a zygote or early-stage embryo divides and develops into two individuals.
• Why do monozygotic twins acquire differences despite having the same genes?

  They acquire differences through mutations and because their environments are never identical.
• What is the morphological species concept?


  • Species are defined as a group of organisms that share a particular outer form and inner structure.
  • Pioneered by Carl Linnaeus.
• According to the biological species concept, what defines a species?

  A species is a group of organisms that can breed and produce fertile offspring.
• What is an example of hybridization that challenges the biological species concept?

  Captive lions and tigers can hybridize, producing ligers or tigons.
• What is speciation?


  • Speciation is the splitting of one species into two or more.
  • It usually happens gradually rather than by a single act.
  • Populations become more different in their traits over time.
• What happens when two populations do not interbreed over time?

  They can diverge and develop recognizable differences, potentially becoming different species.
• What is the chromosome number for humans?

  Humans have 46 chromosomes.
• What is the chromosome number for chimpanzees?

  Chimpanzees have 48 chromosomes.
• What are diploid and haploid cells?

  • Diploid (2n): Body cells with two sets of chromosomes, one from each parent.
  • Haploid (n): Sex cells with one set of chromosomes that can combine to form a diploid cell.
• Why do diploid cells have an even number of chromosomes?

  Diploid cells have an even number of chromosomes due to sexual reproduction, where male and female gametes fuse.
• What is a karyotype?


  • A karyotype is the characteristic types of chromosomes in a species.
  • It is represented in an image called a karyogram.
• How do scientists study chromosomes in an organism?

  Scientists stain cells that are currently dividing and photograph and arrange the chromosomes digitally in a karyogram.
• What are the three types of differences used to classify chromosomes?

  • Banding patterns
  • Size
  • Position of the centromere
• What is the significance of the banding patterns in chromosomes?

  Banding patterns help in identifying and classifying chromosomes.
• What is the fusion hypothesis regarding human chromosome 2?

  The hypothesis suggests that human chromosome 2 was formed from the fusion of two chromosomes in a primate ancestor.
• What are telomeres and their significance?

  • Telomeres are the ends of chromosomes with many repeats of the same short DNA sequence.
  • They protect the chromosome from deterioration.
• What is a genome?


  A genome is all the genetic information of an organism, including all of its DNA.
• What are genes?


  A gene is a length of DNA carrying a sequence of hundreds or thousands of bases.
• What causes diversity within a species?

  Diversity within a species is caused by alternative forms of a gene called alleles.
• What are single-nucleotide polymorphisms (SNPs)?


  SNPs are positions in a gene where more than one base may be present, and they are the main factor in making humans different from each other.
• How many SNPs are typically found within one individual human?

  Typically, there are about 4,000-5,000 SNPs within one individual human.
• How do genomes vary in size and sequence?

  • Genomes vary in overall size, determined by the total amount of DNA and measured in base pairs.
  • Large genomes can contain a large amount of non-functional DNA.
  • Variation between species is much larger than variation within a species.
• What is the genome size of Homo sapiens?

  The genome size of Homo sapiens is 3,080 million base pairs.
• What is the genome size of Pan troglodytes?

  The genome size of Pan troglodytes is 3,175 million base pairs.
• What is the genome size of Apis mellifera?

  The genome size of Apis mellifera is 217 million base pairs.
• What is the genome size of Paramecium tetraurelia?

  The genome size of Paramecium tetraurelia is 27 million base pairs.
• What is whole genome sequencing?

  • Whole genome sequencing is determining the entire base sequence of an organism’s DNA.
  • It was first done in the 1990s but was slow and expensive.
• How has whole genome sequencing changed over time?

  The speed has increased and costs have decreased, allowing for the sequencing of thousands of species.
• What was the cost to sequence one human genome in 2001?

  It cost $100 million to sequence one human genome in 2001.
• What is the current cost to sequence one human genome?

  The current cost to sequence one human genome is less than $1,000.
• What are the current and potential future uses of whole genome sequencing?


  Current uses:

  • Research into evolutionary relationships.
  • Identifying relationships between species and tracing diverging pathways.

  
  

  Potential future uses:

  • Personalized medicine for predicting health problems and prescribing appropriate drugs.