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Genetics and Evolution. Mary Susan Mardon. Nucleotides. Building blocks of DNA and RNA. Each nucleotide contains: phosphate group. deoxyribose (DNA), ribose (RNA) nitrogen base. * adenine * cytosine

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Genetics and Evolution

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genetics and evolution

Genetics and Evolution

Mary Susan Mardon

  • Building blocks of DNA and RNA.
  • Each nucleotide contains:
  • phosphate group.
  • deoxyribose(DNA), ribose (RNA)
  • nitrogen base.

* adenine * cytosine

* thymine * guanine

RNA only---Uracil

the discovery of dna s structure
The Discovery of DNA’s Structure
  • Rosalind Franklin and Maurice Wilkins at King’s College in England used x-ray diffraction to study the physical structure of DNA.
  • James Watson and Francis Crick worked at Cambridge University in London, England created a structural model of DNA.
the structure of dna
The Structure of DNA
  • Deoxyribonucleic acid(DNA) is located in the nucleus.
  • Double helix.
  • Each side of the helix is composed of a long strand of nucleotides.
  • DNA has four nitrogen bases--adenine, thymine, guanine and cytosine.
dna function
DNA Function
  • Provides genetic information in the form of a genetic code.
  • DNA splits in half
  • Codon is transcribed to mRNA
  • tRNA picks the message up and transfers to the ribosome where the message is translated into amino acids
  • Proteins are then formed
rna function
RNA Function
  • The function of RNA is protein synthesis.
  • Three basic steps to protein synthesis:
  • DNA segment must be copied in the nucleus.
  • The code must be carried from the nucleus into the cytoplasm and to a ribosome.
  • The protein is assembled from the code and released from the ribosome.

Single stranded

  • Ribose
  • Adenine bonds with Uracil
  • Cytosine bonds with guanine
  • Three types of RNA:
  • Transfer
  • Messenger
  • Ribosome
events of the cell cycle
Events of the Cell Cycle
  • Interphase is composed of

G1 phase-----Cell growth, synthesize new proteins, organelles

S phase-----Chromosomes replicated, DNA synthesized

G2 phase-----production of molecules and organelles, shortest of the 3 phases

  • Nuclear division.
  • Cell division results in two daughter cells. (2n)

A process called reduction division in which the number of chromosomes in a human reproductive cell is reduced to 23 chromosomes. These cells are haploid (n).

genetics and probability
Genetics and Probability
  • Gregor Mendel
  • Trait
  • Hybrid or Heterozygous—Hh
  • Purebred or Homozygous—HH, hh
  • Allele: variation of a gene
  • Dominant Trait—HH, Hh
  • Recessive Trait– hh
  • Gamete: Sex cells
  • Genotype: genes represented by letters (HH, Hh, hh)
genetics and probability continued
Genetics and Probability continued
  • Phenotype: traits or characteristics you can see.
  • Punnett Square: A tool to calculate genetic probability.
  • Cross-pollinate: two different parents.
  • Self-pollinate: one parent.
  • True breeders: can self-pollinate to produce identical offspring.
genetics and probability continued1
Genetics and Probability continued
  • Principle of Segregation: The paired alleles separate so that each egg or sperm carries one form of the allele.
  • Principle of Independent Assortment: states that genes for different traits can segregate independently during the formation of gametes.
  • Principle of Dominance: states that some forms of a gene or trait are dominant over other traits, which are called recessive (hides or masks)
genetics and probability continued2
Genetics and Probability continued
  • Incomplete Dominance: one allele is not completely dominant over the other (RR, WW)
  • Co-dominance: Both alleles contribute to the phenotype (BW)
  • Polygenic Traits: more than one gene controls the trait (skin color)

Evolution: Change over time

  • Theory of Natural Selection: Organisms adapted to their environment survive and reproduce























types of natural selection
Types of Natural Selection
  • Stabilizing Selection: environmental change acts to eliminate extremes in a population
  • Directional Selection: occurs in either direction shifting the population towards a new norm.
  • Disruptive Selection: environmental change acts on the most common variety.
requirements of a species
Requirements of a Species
  • Species: group of similar organisms that can breed and produce fertile offspring.
  • Genetic mutations (random changes in the DNA)
  • Genetic drift (change in frequency of alleles in a population)
  • Hybridization
  • Gene Flow: exchange of genes between two populations, development of geographic isolation, ex. Darwin’s finches
animal adaptation
Animal Adaptation
  • Behavioral adaption for survival and reproduction
  • Territoriality is a behavioral adaption that ensures adequate space and resources for reproduction.
  • Courting behavior is a behavioral adaption that helps to ensure beneficial genes are passed along to offspring.
patterns of evolution
Patterns of Evolution
  • Gradualism: species change slowly over many generations; ex. body size of the water buffalo
  • Punctuated Equilibrium: sudden changes in a species; ex. light and dark peppered moth
  • Convergent Evolution: unrelated species develop similar characteristics; ex. porpoise and shark—streamlined bodies and fins
  • Divergent Evolution: many species develop from a common ancestor; ex. homologous structures (beaks) in Darwin’s finches
patterns of evolution continued
Patterns of Evolution, continued
  • Coevolution: two or more organisms in an ecosystem evolve in response to each other; ex. Orchid’s long tube and Hawk moth’s proboscis
evidence of evolution
Evidence of Evolution
  • Anatomical Similarities
  • Homologous structures; ex. human arm, wing of a bird, flipper of a whale
  • Vestigial organs; whales and some snakes have a pelvis and femurs
  • Molecular Similarities: overlap of DNA; ex. DNA of a Horseshoe crab is more closely related to a spider than a crab
  • Embryonic Developmental Similarities:
  • Fossil Record:
  • Extinction
  • Ecological extinction: species does not have a large enough population to sustain genetic diversity; ex. Florida panther, mountain lion
  • Mass extinction: large population becomes extinct in a short period of time