Biological Anthropology On Cells, DNA, and Proteins
Cell Theory • A set of explanatory principles used to understand cells • Cells are the smallest unit of life • Consist of smaller (non-alive) parts: organelles
A Cell
Two Types of Cells Somatic cells • The vast majority of cells in our bodies • Reproduce through mitosis Sex Cells (gametes) • Only found in ovaries and testes • Reproduce through meiosis
Two Types of Cell Division Mitosis • Occurs in somatic cells Meiosis • Occurs in sex cells (gametes) • Produces 2 daughter cells • Produces 4 daughter cells • Genetically identical • diploid • Genetically unique • haploid
Mitosis • Asexual reproduction • Occurs in somatic cells • Produces 2 genetically identical diploid daughter cells
Meiosis • Occurs in sex cells (gametes) • Produces 4 daughter cells • Genetically unique • haploid
Crossing-Over 6 wet A 5 dry # of fingers 6 cerumen dry O ABO group A 5 wet O
Cell Division Mitosis Meiosis
Karyotype • Species-specific set of chromosomes • Differs from species to species in terms of • The number of chromosomes • The sequences of genes contained in the chromosomes
Human karyotype • 46 chromosomes • Arranged in 23 pairs • 1 set from each parent
Human karyotype • Autosomes • Pairs 1 -22 • Are homologous • same length • same sequence of genes (may be different alleles)
Human karyotype • Sex chromosomes • Pair 23 • X&Y X longer than Y • XX – homologous • XY – partially homologous
So what’s in a chromosome?
Let’s take a look!
A chromosome contains genes
and genes contain… Deoxyribonucleic Acid • Present in all living organisms • Amount varies from organism to organism • Species can read each others’ DNA
DNA • Sugar-phosphate backbone” • Bases are “rungs” adenine = thymine cytosine = guanine
Genome the total DNA/genes of a species • Homo sapiens • app. 3, 000, 000 DNA bases • 35, 000 – 40, 000 genes • Honeybee – 300, 000 DNA bases • Fruit fly – 13, 600 genes • Bacteria – a few hundred to a few thousand genes
DNA Replication • Produces two identical strands from one original strand • Each side of the original is a template for making a new copy of its complement
The Three Problems 1. How is the variation present within a species at any time affected by the environment? Darwin 2. How is variation passed on from one generation to the next? Mendel 3. Where does variation come from? Watson & Crick
But what are genes used for?
Protein Synthesis • A two stage process • Transcription • Translation • Our players: • • Messenger RNA (m. RNA) – the locks Transfer RNA (t. RNA) – the keys Ribosome (“locksmith) Amino Acids
Protein Synthesis • 1: Transcription messenger RNA (m. RNA) copy of gene is made • m. RNA copy leaves nucleus and goes to cytoplasm
Protein Synthesis 2: Translation • m. RNA copy is “read” by ribosomes • Ribosomes match t. RNA to codons on m. RNA
Proteins: the End Result • One gene codes for one protein • Differences between individuals due (in part) to differences in their proteins
Protein Synthesis, once again… • A two stage process 1) transcription 2) translation • The process whereby the DNA message is converted into a protein product
for more information… Web sites http: //www. dnalc. org/resources/ http: //www. johnkyrk. com/ Key words • DNA replication • Protein synthesis • DNA translation • Transcription
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