Evidence for Evolution

Evidence for Evolution

Area: Embryology

Examples: embryo of pig and human

Pro: best evidence because it is the most fundamental or basic

information

Vocabulary: embryo — early stages of developing plants and animalscomparative embryology — study of

different developing organisms.

Comparative Embryology

Comparative Embryology

Evidence for Evolution

Area: Biochemistry

Examples: amino acid sequence of chimpanzee and human

Con: limited access to amino acids of past organisms

Vocabulary: comparative biochemistry — comparing amino acid sequences of

different organisms

Human (H) Chimp (C)

Chromosome comparison

Human (H)

Chimp (C) Orangutan (O)

Gorilla (G)

Chromosomes of Primates

Amino Acid Sequence for Hemoglobin Molecule

What is a Mutation? 

• A mutation is a permanent change in the DNA sequence (ATCG) of a gene.

Mutations in a gene's DNA sequence can alter the amino acid sequence of the protein encoded by the gene.

How does this happen? Like words in a sentence, the DNA sequence of each gene determines the amino acid sequence for the protein it encodes. • The DNA (ATCG) sequence is interpreted in groups of three nucleotide bases, called codons.• Each codon specifies a single amino acid in a protein. 

Mutate a sentence!

We can think about the DNA sequence of a gene as a sentence made up entirely of three-letter words. In the sequence, each

three-letter word is a codon, specifying a single amino acid in a protein. Have a look at this sentence:

  Thesunwashotbuttheoldmandidnotgethishat.

If you were to split this sentence into individual three-letter words, you would probably read it like this:

  The sun was hot but the old man did not get his hat.

This sentence represents a gene.

This sentence represents a gene.

Each letter corresponds to a nucleotide base, and each word represents a codon. What if you shifted the three-letter

"reading frame?" You would end up with

 T hes unw ash otb utt heo ldm and idn otg eth ish at.

Or

Th esu nwa sho tbu tth eol dma ndi dno tge thi sha t.

As you can see, only one of these three "reading frames“ translates into an understandable sentence. In the same

way, only one three-letter reading frame within a gene codes for the correct protein.

Amino Acid Sequence for Hemoglobin Molecule

Evidence for Evolution Area: Genetics

Examples: domesticated plants and animals; DNA sequence; mutations

Pro: changes easily seen in domestic plants/animals; gene links for generation after generation documented.

Con: limited access to past DNA

Vocabulary: population — all organisms within a breeding group.

selective breeding — artificial selection of only the most desirable traits to be bred.

Domesticated Plants and Animals

cattle cats

Selective (artificial) Breeding

Domesticated Plants and Animals

corn

apples

Selective (artificial) Breeding

Domesticated Plants and Animals

Selective (artificial) Breeding

Certificate of Pedigree

Domesticated Plants and AnimalsSelective (artificial) Breeding

Certificate of Pedigree

Certificate of Pedigree

Human (H)

Chimp (C) Orangutan (O)

Gorilla (G)

Chromosomes of Primates

DNA Base Sequence Comparisons