Chap 1 Introduction: Themes in the Study of Life

DNA.html: 01_07DNAGeneticMaterial_L.jpg

  1. DNA double helix. A DNA molecule takes the three-dimensional form of a double helix, made of building blocks called nucleotides.
  2. Single strand of DNA. Genetic information is encoded in specific sequences of four types of nucleotides.

adaptations.html: 01_22BatFormFitsFunction_UP.jpg

blowfly.html: _BED_/sketches/sounds/Arthropoda/fly.wav 01_blowfly.jpg

cell.html: 01_08CellTypesCompared_LP.jpg
The cell is the basic unit for life. Eukaryotic cells contain membrane–enclosed organelles, including a DNA –containing nucleus. Prokaryotic cells lack organelles, and are usually smaller than eukaryotic cells.

cell_reproduction.html: 01_05NewtLungCell_LP.jpg
A lung cell from a newt divides into two smaller cells that will grow and divide again.

cover.html: 01_cover.jpg

deductive.html: 01_25ScientificExperiment_L.jpg
Deductive reasoning is the process of using general principles to explain individual observations.

Often this involves "if... then..." logic and can be used to make predictions.

domains.html: 01_15ThreeDomains.jpg
Domains Bacteria and Archaea are prokaryotes and possess no nucleus.
Domain Eukarya is split into 4 kingdoms: Protista, Plantae, Fungi, and Animalia.

edison.html: 01_edison_bulb.jpg

eukarya.html: 01_14ClassifyingLife_L.jpg
Each group in this hierarchy of organisms is a clade (taxon) with shared derived characters.

For example, animals in order Carnivora posses carnassials : the last upper premolars and the first lower molars adapted for shearing food a scissor-like manner.

eye.html: 01_eye.jpg

eye2.html: _BED_/sketches/sounds/Arthropoda/fly.wav 01_eye.jpg

feedback_negative.html: 01_11NegativeFeedback_L.jpg
Negative feedback. This three–step chemical pathway converts substance A to substance D. A specific enzyme catalyzes each chemical reaction. Accumulation of the final product (D) inhibits the first enzyme in the sequence, thus slowing down production of more D.

feedback_positive.html: 01_12PositiveFeedback_L.jpg
Positive feedback. A product stimulates an enzyme in the reaction sequence, increasing the rate of production of the product.

hier1.html: 01_EM01_03a.jpg

hier2.html: 01_EM01_03b.jpg

inductive.html: 01_24JaneGoodall.jpg
Jane Goodall collecting qualitative data on chimpanzee behavior. Goodall recorded her observations in field notebooks, often with sketches of the animals' behavior. From these specific observations she can make generalized inductions about chimpanzee behavior.

life.html: 3714601010.jpg

natural_selection.html: 01_20NaturalSelectionSumm_L.jpg
Most populations tend to overproduce offspring, but due to limited resources, individuals struggle for existence and populations remain stable in size over time. Members of the population exhibit herotable variation in their characteristics. Those individuals with heritable traits best suited to the local environment will generally produce more offspring - natural selection. Over the generations, heritable traits that enhance survival and reproductive success tend to increase in frequency among a population's individuals. The population adapts to its environment and evolves.

saturn-ring.html: 01_saturn-ring.jpg

saturn.html: 01_saturn.jpg

snake.html: 01_27CoralAndKingSnakes_CL.jpg

Is mimicry a falsifiable hypothesis?

snakes.html: 01_28ArtificialSnakes_LP.jpg