2.4 Embryonic Development BYK

A multicellular organism in the early stages of development.

• Zygote

• Embryo

• Fetus

• Chromosome

How does a zygote develop into an embryo?

• cell divisions

• The zygote develops into an embryo as it grows through many...

• As the embryo develops cells...

• specialize in their...

• structure and function.

Undifferentiated cells that can develop into highly specialized cells by turning on and off certain genes. These are the cells that all specialized cells derive from.

• Skin Cells

• Zygote Cells

• Embryonic Cells

• Stem Cells

Why do so many embryos look similar during the early stages of development?

• Scientists believe that all organisms share a common ancestor from which they developed a similar pathway of development.

• Scientists know that all organisms have the same DNA and therefore will look the same in early stages of development.

• Scientists hypothesize that all organisms have the same parents and therefore develop similarly.

• Scientists believe that since all organisms start as one cell they will have the same traits and characteristics.

A rod made of cartilage that runs the length of the embryos body, found in all vertebrates.

• Spinal Cord

• Vertebrae

• Notochord

• Tailbone

Explain why some structures change drastically or even disappear toward the end of development, while others stay consistent throughout development.

• As development continues some structures are...

• replaced with structures specific to the species.

• backbone.

• the notochord is replaced with the....

• For Example...

When parts of different organisms have the same relative position and structure.

• Homosapien

• Homologous

• Homogeneous

• Homozygous

The bones in the picture are very similar, what do you think this suggests?

• These bones suggest that these animals are all mammals.

• These bones suggest that these animals all share descent from a common ancestor.

• These bones suggest that these animals are all able to fly and walk on land.

  
  

• These bones suggest that humans may soon evolve into horses and whales.

Reorder the organisms to match the embryos.

• Cow

• Cat

• Horse

• Human

A field of study that looks at internal and environmental factors that guide how cells look at pieces of DNA in order to make new cells.

• Epigenetics

• Polygenetics

• Human Genome

• Mendelian Genetics