Biological Basis for Life

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As you work through this set of chapter slides, keep in mind the notations that are included from your instructor. Open, read carefully, download if necessary, and use in conjunction with your reading and video lesson study. All these components supplement each other. The wise student will keep this in mind.

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We’re getting into critical and foundational concepts now that will help clarify so much else in this course. Don’t skimp on your study time! Go for it!

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THE STUDY OF GENETICS:

Modern study & cloning controversy (see Box 3.1)

 

Q. What is the “stuff” of life? “There’s something there, but what is it”

Darwin & Mendel were ”in the dark”

 

* Blood types discovered c. 1900

The term “gene” coined in early 20th century by Johannson

 

HOW GENETICS HAS BEEN APPROACHED BY SOME, EVEN UNWITTINGLY

Example...

* Tentative steps taken by Mendel in mid-19th century! How so?

 

He studied pedigrees & traits of pea plants; what causes a “throw back”? Seven traits: tall/short, violet/blue, etc. Speaks to principles of dominance & recessive.

 

Do the EARLOBES experiment with your friends….How many have “attached” vs. “hanging” earlobes? Why might this variation exist?

 

TERMINOLOGY TO REMEMBER

 

* Cellular genetics: Study of the basic building blocks of life

 

* Population genetics today: Examines genetic variation within & between populations of the same species (e.g., Irish light haired vs. Italian/Irish with darker hair living in Ireland).

 

* Phylogenetics: uses tree-like diagrams to depict relationships between species; uses observable (physical) & molecular/genetic traits.

 

DRAW A SIMPLE “TREE” FROM CHIMP TO HOMINID TO...(see handout listed at course map.

* Behavioral genetics: attempts to gain understanding of human behavior with respect to how it may/may not be influenced by genetics. Example: road rage as an inheritance from our primate ancestors? Fight or flight.

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All cells contain proteins which are are “long chains of amino acids” (20 in all)

 

* Protozoa & Metazoa: these are single celled bacteria vs. multi-cellular organisms. Another distinction is...Prokaryote vs. Eukaryote

 

* Prokaryotic vs. Eukaryotic cells: these are “simple” cells (no nucleus) vs. nucleated cells

 

* Somatic (regular) vs Gametic or sex cells (sperm & ova)

 

* Stem cells (undifferentiated) vs. mature (differentiated) cells; Dolly, etc. Found in fetus & in nasal tissue.

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Look this up in this chapter.

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At the molecular level, the basic unit of DNA is a long strand of nucleotides composed of sets of base pairs of purines & pyramidines.

 

• The “purines” are A & G, while the pyramidines are T & C); a nucleotide will vary depending on the base pairs it carries. That is, does the string go...a t c g or does it go a c g t?

* Chromosomes (Karyotype on p.49) & Cell Division: A chromosome is really two long continuous strings/strands of DNA. One string is called a “chromatid”; together, the two strings form a double helix.

 

 

In the chromosomes (a long string of nucleotides), purine A matches up only w/pyramidine T; purine C only w/pyramidine

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* DNA Replication: Begins inside the nucleus of the cell when two strands “split” to isolate a string of DNA (a gene) and allow or “invite” the transcription of RNA (bits pull up alongside the single strand of DNA). A template is constructed to enable the building or synthesis of a new DNA strand.

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Yeah, this is how it happens.

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* Protein synthesis: When the string of RNA is ready, out it goes into the cytoplasm where it meets a ribosome, which will enable the transcription process (aka protein synthesis) to begin. The tRNA’s carries w/it a particular amino acid. Slowly/precisely, a chain of amino acids is built when the end of the molecule (mRNA) is reached.

 

Mitosis occurs in the somatic cells; diploid (mom & pop’s) Meiosis occurs in gametic/sex cells; haploid (mom or pop’s)

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While in the nucleus, DNA exists as long, single strands (aka chromatid). During mitosis, the long strands coil up (safer) into what we call “chromosomes” and pair up w/the respective homologous chromosome. [“Homologous” means that the two strings are members of same pair (e.g., contain “same” DNA/the “eye color” gene at roughly the same spot along the strand); 23 pairs = 46 total.

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DNA Structure II: Chromosomes and Cell Division (cont’d)

• Mitosis
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase

• Meiosis
• Tetrad formation
• Crossing over
• Recombination
• Reduction division
• Second Meiotic Division

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Chromosomal Abnormalities

• Nondisjunctive Errors: The failure of homologous chromosomes to separate properly during cell division
• Monosomy
• Turner Syndrome
• Trisomy
• Down’s Syndrome

Copyright © 2013 Pearson Education, Inc. All rights reserved.

Molecular Tools for Bioanthropological Research

• Indirect Methods
• Immunological Methods
• DNA Hybridization
• Direct Methods
• DNA Sequencing
• Protein Sequencing

Copyright © 2013 Pearson Education, Inc. All rights reserved.

Molecular Tools for Bioanthropological Research (cont’d)

• PCR

• Mitochondrial DNA (mtDNA)

• Ancient DNA

Copyright © 2013 Pearson Education, Inc. All rights reserved.

Molecular Tools for Bioanthropological Research (cont’d)

• Polymerase Chain Reaction
• The polymerase chain reaction (PCR) is a method for the amplification of minute quantities of DNA
• PCR makes possible the recovery of ancient DNA from bone or fossil material, up to about 100,000 years old, provided that preservation conditions were adequate