Molecular Genetics gene: specific region of DNA that determines the type of proteins to be made

Nucleic Acids – serve as blueprints for the construction of proteins Two Types 1) DNA (DeoxyriboNucleic Acid) 2) RNA (RiboNucleic Acid)

Nucleic Acids nucleotides: monomers that combine to form nucleic acids Three Parts of a Nucleotide 1)

DNA has 4 nitrogen bases: Adenine A Thymine T Cytosine C Guanine G DNA has deoxyribose as its sugar

RNA also has 4 nitrogen bases: Adenine A Uracil U Cytosine C Guanine G RNA has ribose as its sugar

What does DNA & RNA look like? Rosalind Franklin - worked with X-ray photos of DNA James Watson & Francis Crick - Nobel prize for deciphering structure of DNA RNA = single polynucleotide strand DNA = double helix; 2 polynucleotides wrap around each other (“spiral stairs”)

What does DNA & RNA look like? In DNA, the 2 polynucleotides pair up & bond (H-bond) at nitrogen bases: Complementary Base Pairing in DNA Adenine --- Thymine (A – T) Cytosine --- Guanine (C – G) Long strands of DNA with A-T & C-G base pairing is at the core of genetics, Therefore, in Interphase when chromosomes are replicated, DNA is also replicated

How is DNA replicated? Template Hypothesis Two strands of parent molecule of DNA separate Separated strands now serve as a “template” for free nucleotides to attach; remember nucleotides must match up (A-T or C-G)

Template Hypothesis

DNA polymerase: primary enzyme involved in assembling DNA molecules; also checks for errors (wrong base pairing) DNA Replication

What is a ‘genotype’ or ‘phenotype’ in molecular language? Genotype is gene (DNA) makeup of organism

Two Main Stages of Protein Synthesis 1)Transcription: 2) Translation:

Phenotype is a physical trait of an organism determined by specific proteins with specific functions e.g., some structural proteins comprise hair, therefore, different ‘hair proteins’ determine different hair traits (color, curly, straight, coarse, fine, etc…)

codon: 3-base code that are used to produce amino acids amino acids =

Transcription: DNA to RNA * Base pairing of RNA nucleotides using DNA template (note pairings) – RNA polymerase

Transcription: Nucleotide sequence in DNA starts transcription process promoter --

Transcription: 2 nd Phase = RNA elongates RNA begins to separate from DNA template DNA strands begin to reattach

Transcription: 3 rd Phase – RNA polymerase reaches end of gene

Transcription: For eukaryotes, newly formed RNA molecule is modified to produce messenger RNA (mRNA) mRNA

Transcription: Also remove introns (noncoding region) Resplice exons (coding region = genetic information that is ultimately expressed as trait mRNA now leaves nucleus mRNA

Transfer RNA (tRNA) Serves as translator between mRNA and ribosomes In other words, tRNA translates nucleic acid language (codons) into protein language (amino acids) anticodon: complement to mRNA codon tRNA

ribosomes

Translation

Summary of transcription & translation - 1

Summary of transcription & translation - 2

HIV AIDS HIV has 2 strands of RNA Reverses normal transcription process (retrovirus)

Evolution Charles Darwin Evolution:

Evolution Charles Darwin Evolution:

Descent with Modification

Look at the fossil record…

Macroevolution * Major biological changes in species (found in fossil record) Speciation: origin of new species

Evolution Look at the fossil record… Compare common structures in animals, e.g., forelimbs in human, cat, whale and bat (homologous structures) *

Principles of Darwin’s Thinking 1)All organisms vary from one another & some variations are heritable 2)All organisms have potential to produce many young. 3) Limited resources influence number of young that survive to reproduce

Natural Selection Primary theoretical mechanism of evolution Deals with differential (unequal) survival & reproduction “Survival of the Fittest”

Natural Selection

Population Genetics Microevoltion gene pool: all of the genes in a population at one time; includes all alleles At population level, look for change in allele frequencies over time. If allele frequencies change, gene pool is changing & microevolution is occurring.

Population Genetics Hardy-Weinberg Equilibrium * Hypothetical, non-evolving population * No change in allele frequencies Assumptions: 1) No Natural Selection 2) No Mutation of genes 3) No Migration/No Gene Flow 4) LARGE Population 5) Random Mating

Population Genetics How does Microevolution Occur in a Population? Five Possible Mechanisms

Small Populations genetic drift: certain alleles lost due to chance events Genetic Drift

Small Populations bottleneck effect: some event unselectively removes large part of population; remaining individuals may be genetically similar & subject to genetic drift

Bottleneck Effect

Small Populations founder effect: