Fossil Record
This scientist admitted in Origin of Species that geology does not reveal a finely graduated chain of organisms and blamed the problem on the “imperfection of the geological record.”
Charles Darwin
Charles Darwin spent nearly five years traveling aboard the _____ __________, collecting observations on the island of ____________, that later helped him develop the theory of natural selection.
HMS Beagle, Galapagos
What distinction does Gelernter make between small evolutionary changes and the origin of new species?
He distinguishes between microevolution (small changes within a species, such as variation or adaptation) and macroevolution (the origin of entirely new species or complex biological structures). Gelernter suggests that while small changes are observable, the larger transformations are more difficult to explain.
This enzyme binds to DNA and builds an RNA strand by pairing RNA nucleotides with the DNA template strand.
RNA polymerase
This five-carbon sugar forms part of the backbone of DNA and connects to phosphate groups and nitrogenous bases.
deoxyribose
According to Darwin, vast periods of time before the earliest Silurian (Cambrian) strata where the fossils were found, there must have existed on Earth what..?
vast, unnumerable numbers of living creatures
This evolutionary principle states that individuals with advantageous traits are more likely to survive and reproduce, passing those traits to their offspring.
natural selection (survival of the fittest)
What problem does Gelernter say exists with explaining complex biological structures?
He argues that complex biological systems often require many coordinated parts to function, and he questions whether random mutations combined with natural selection can realistically build such systems step by step.
This type of RNA carries the genetic instructions copied from DNA in the nucleus to the ribosome where proteins are made in the cytoplasm.
messenger RNA (mRNA)
The twisted ladder or spiral staircase shape that describes the overall structure of DNA.
double helix
This Harvard naturalist and critic of Darwin argued that if evolution were correct, there should be countless transitional forms connecting ancestors and descendants.
Louis Agassiz
This idea explains that species change slowly over long periods through the accumulation of many small changes rather than sudden transformations.
gradualism
Why does Gelernter believe the fossil record raises questions about gradual evolution?
He argues that many species appear abruptly in the fossil record and remain relatively unchanged for long periods, rather than showing a continuous chain of transitional forms.
This multi part cellular structure reads mRNA codons and links amino acids together to build a protein.
A. These weak chemical bonds hold complementary nitrogenous bases together in the center of the DNA molecule.
B. These strong chemical bonds hold phosphate together with deoxyribose.
A. hydrogen bonds
B. covalent bonds
Charles Darwin predicted that if evolutionary theory is correct, there should produce these organisms in the fossil record—forms that gradually link earlier species to later ones.
transitional fossils, intermediate fossils
This 18th-century scientist, known as the “Father of Taxonomy,” created the binomial naming system used to classify organisms. He hypothesized an upside down alternative to Darwin's "tree of life"
Carl Linneaus
What did Gelernter say Darwin successfully explained?
Darwin successfully explained variation within species and the process of natural selection, showing how certain traits can become more common in populations over time.
These three-nucleotide sequences on mRNA correspond to specific amino acids during protein synthesis.
codons
This enzyme “unzips” the DNA double helix by breaking the hydrogen bonds between base pairs.
helicase
This evolutionary concept proposes that species remain stable for long periods and then experience rapid bursts of change, leaving few transitional fossils.
This epigenetic process can act like a molecular “switch” that turns genes off by adding methyl groups to DNA.
DNA methylation
Why should scientific theories continue to be questioned?
Gelernter argues that science advances through open debate and testing ideas. Even well-established theories should be examined critically as new evidence emerges.
This type of RNA brings the correct amino acid to the ribosome and uses an anticodon to match the mRNA codon.
transfer RNA (tRNA)
This enzyme builds a new DNA strand by adding nucleotides complementary to the template strand.
DNA polymerase
Darwin explained the lack of intermediate fossils by suggesting this major limitation of paleontology—
incomplete nature of preserved geological history.
This animal was made famous by Darwin, as a prime example of how animals demonstrate evolution in real time
finches
Main argument of the essay:
Gelernter argues that while Darwin’s theory explains some aspects of biological change, it may not fully account for the origin of complex life forms. He believes scientists should be open to questioning the completeness of Darwinian explanations.
This three-letter mRNA codon signals the ribosome to begin translation and codes for the amino acid methionine.
start codon (AUG)
Every cell in your body contains the same genome, yet cells in your eyes, skin, and muscles look and function very differently. How can the same DNA and the same set of genes produce such different physical traits in different types of cells?
Although every cell contains the same DNA and genome, different cells turn different genes on or off. This process is called gene expression. For example, muscle cells activate genes for muscle proteins, while skin cells activate genes related to skin structure. Because different genes are expressed, the cells develop different physical traits and functions.