Lecture Slides

THIRD EDITION

Essentials of Physical

Anthropology

Clark Spencer Larsen

Genetics: Reproducing Life and Producing

Variation

• Larsen. Essentials of Physical Anthropology

3

Genetics: Reproducing Life and Producing Variation

• Questions addressed in this chapter: – What is the genetic

code?

– What does the genetic code (DNA) do?

– How does understanding genes help us understand variation?

The Cell: Prokaryotes

• Prokaryotes

– 3.5 billion years old

– Single-celled bacteria

– No nucleus or organelles

M.I. Walker/Science Source

The Cell: Eukaryotes

• Eukaryotes

– 1.2 billion years ago.

– Some single-celled; all multicellular organisms (including humans)

– DNA contained in a nucleus

– Organelles

Eye of Science/ Science Source

The Cell: Somatic Cells and Gametes

• Somatic cells

– Body cells have full DNA (humans: 46 chromosomes)

– Mitosis

Michael Abbey/ Science Source Biophoto Associates/ Science Source

(c1): Michael Abbey/Science Source; (c2): SPL/ Science Source Jim Zuckerman/Media Bakery

The Cell: Somatic Cells and Gametes

• Gametes

– Eggs (ova) and sperm

– Half DNA (humans; 23 chromosomes)

– Meiosis

Eye of Science/ Science Source

Chromosomes

• DNA packaged in chromosomes

• Chromosome number varies by species

Biophoto Associ-ates/ Science Source; (camel): Richard Nowitz/National

Geographic Image Collection; (guinea pig): Corbis; (salamander):

Wolfgang Thieme/ dpa/ Corbis; (house fly): Nigel Cattlin/ Science

Source; (apple): Evans Caglage/ Dallas Morning News/ Corbis; (potato):

DK Limited/ Corbis; (petunia): Roy Morsch/ Corbis; (algae): JP Nacivet/

Getty Images; (lemur): Millard H. Sharp/ Science Source; (colubus

monkey): Mark boulton/ Science Source; (orangutan): Robert Garvey/

Corbis

DNA: The Blueprint of Life

• DNA Genes Chromosomes Genome

• Nuclear DNA: homoplasmic

DNA: The Blueprint of Life

• Mitochondrial DNA

DNA: The Blueprint of Life

• DNA structure

– Sugar

– Phosphate

– Nucleotide base • Adenine (A)

• Thymine (T)

• Guanine (G)

• Cytosine (C)

– A with T

– C with G

» CAAAT

» GTTTA

The DNA Molecule: Replicating the Code

Chromosome Types

• Homologous pairs

– Autosomes (22 pairs)

– Sex chromosomes (1 pair) • X and Y

• Male determines sex

• Karyotype

Steve Gschmeissner/ Science Source L. Willatt/ Science Source

Mitosis

Mitosis

Steve Gschmeissner/ Science Source

Meiosis

• Haploid: 23 chromosomes (no pairs)

• Recombination via crossing over – Haplotypes

• Translocations and nondisjunctions

Law of Independent Assortment

Law of Independent Assortment

DNA and Protein Synthesis

Clouds Hill Imaging Ltd./ Corbis

Visuals Unlimited/ Corbis

Transcription and Translation

• Transcription

– DNA transcribed into mRNA in the nucleus of the cell

• Translation

– mRNA translated into an amino acid chain at the ribosomes

Transcription

Translation

Regulatory Genes

• On/off switches for genes

– Marfan syndrome

– Chicken teeth

– Human hair

– Lactose intolerance or persistence

John Radcliffe Hospital/ Science Source

Bettmann/Corbis

Homeotic (Hox) Genes

Law of Segregation and Codominance

Polymorphisms: Variations in Specific Genes

• Exercises:

– Can mother with blood type A and father with blood type B have a baby with blood type O?

– Can a man with blood type AB be the father of a baby with blood type O?

Polygenic Traits and Pleiotropy

• Many traits polygenic – Height, skin color

• Many genes pleiotropic – Sickle-cell

• All traits a product of genes AND environment – Height and

nutrition

– Epigenetics

Lecture Slides

Essentials of Physical Anthropology

Clark Spencer Larsen

THIRD EDITION