Biological Anthropology

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 • Produces 2 daughter cells • Genetically identical • diploid Meiosis • Occurs in sex cells (gametes) • Produces 4 daughter cells • 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 5 # of fingers 6 5 cerumen wet dry dry wet A O ABO group A 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. 3,000,000,000 DNA bases • 35,000 – 40,000 genes • Honeybee – 300,000,000 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 • How is the variation present within a species at any time affected by the environment? Darwin • How is variation passed on from one generation to the next? Mendel • 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 (mRNA) – the locks • Transfer RNA (tRNA) – the keys • Ribosome (“locksmith) • Amino Acids

Protein Synthesis 1: Transcription • messenger RNA (mRNA) copy of gene is made • mRNA copy leaves nucleus and goes to cytoplasm

Protein Synthesis 2: Translation • mRNA copy is “read” by ribosomes • Ribosomes match tRNA to codons on mRNA

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 Key words DNA replication Protein synthesis DNA translation Transcription http://www.dnalc.org/resources/ http://www.johnkyrk.com/

Biological Anthropology