Bio 1 exam 1 notes - Summary General Biology I PDF

Preview

Summary

Comprehensive notes for material covered in exam 1...

Description

Bio 1 exam 1 notes Origin of life Random inorganic chemical reactions led to the formation of molecules able to reproduce themselves and create larger molecules. Life arose around 3.8 billion years. For 2 billion years all organisms were unicellular prokaryotes. About 2.5 billion years ago, some prokaryotes acquired the ability to photosynthesise. As oxygen concentration rose in the atmosphere, aerobic metabolism was made possible. About 1.5 billion years ago, some cells had surviving smaller cells within them. These were early eukaryotic cells. 1 billion years ago Two developments made multicellular evolution possible:   

The ability of a cell to change its structure and function to meet the challenges of a changing environment. The ability of cells to stick together after they have divided, and act in a coordinated manner.

Oxygen concentration rising lead to ozone accumulation in the upper atmosphere. 800 million years ago, ozone shield allowed movement of organisms to land. timeline 3.8 billion years ago, life arose 2.5 billion years ago, photosynthesis in prokaryotes 1.5 billion years ago, eukaryotic cells 1 billion years ago, multicellular organisms 800 million years ago, ozone allows land organisms 450 million years ago, land plants. 365 million years ago, land animals. 250 million years ago, dinosaurs. 200 million years ago, land mammals. 140 million years ago, flowering plants. 65 million years ago, mass extinction event. Extremophiles love harsh conditions.

Hierarchy in biological systems

External

Internal Atom Molecules Macromolecules Cells Tissues Organs Organ systems

      

Scientific Method 1. 2. 3. 4. 5.

Observation Questions Hypothesis Prediction Testing

Hypotheses must be testable and have the potential to be rejected.

Evolution Genes and Alleles Eye colour – trait or phenotype Gene codes for phenotype. Multiple Alleles (forms) of a gene. Humans are diploid, so have two copies of each gene. Punnet square used to predict genotype of offspring. Mutations= changes in chemical structure of DNA. Mutations can:   

Cause no change Alter function of gene Create new function of gene.

Processes of evolution Charles Darwin and Alfred Russel Wallace created the idea of evolution.

    

Individual Population Community Ecosystem Biosphere

Charles Darwin went to south America, aboard hms beagle 5 year journey. Went to Galapagos islands. Organisms differed slightly between islands, adapted to different environments. Darwin’s hypothesis: Organisms came from different islands, and each island represented a different environment that the organisms adapted to.

  

Species change over time Divergent species share a common ancestor Natural selection is the mechanism that produces these changes.

Differential survival of organisms is due to variation in traits. As more organisms in a population acquire new adaptive traits, the characteristics of the population evolve.

Individuals do not evolve, populations do. Population: a group of individuals of the same species that live and interbreed in a particular area. Members of populations become adapted to the environment in which they live.

Gene pool- Sum of all copies of all alleles at all loci in a population. Allele frequency- Proportion of each allele in the gene pool. (measure amount of genetic variation) Genotype frequency- Proportion of each genotype among individuals in the population. (Show how such variation is distributed among members of the population.) Organism moves to new area = founder effect Migration of individuals between populations results in gene flow, which can change allele frequencies. Genetic drift: changes in allele frequency from one generation to the next due to random sampling. Affects both large and small populations. Population Bottleneck: Large reduction in size of a population, with an accompanying reduction in genetic variation. Allele frequency equations P= 2N(AA)+N(Aa)/2N

p= frequency of A allele

Q= 2N(aa)+N(Aa)/2N

q= frequency of a allele

Hardy Weinberg equation P^2 + 2pq + q^2 = 1 A population in which allele and genotype frequencies do not change from generation to generation is said to be at hardy Weinberg equilibrium.

5 assumptions:     

Mating is random Population size is very large No migration between populations No mutations Natural selection doesn’t affect alleles under consideration.

Populations in nature never meet the conditions of hardy Weinberg equilibrium

Natural Selection Stabilizing selection: favours average individuals Directional selection: favours individuals which vary in one direction from the mean Disruptive selection: favours individuals which vary in both directions from the mean.

Phylogeny Evolutionary history of organisms and their relationships with other species. A taxon is any group of species that we name to study. A taxon consisting of all of the descendants of a common ancestor is called a clade. Features shared by descendants of a common ancestor are called homologous. Features that differ from their ancestral forms are said to be called derived traits. Synapomorphies are derived traits among a group, which act as evidence of the common ancestry of the group. Similar traits generated by convergent evolution or evolutionary reversals are called homoplasies. These make constructing phylogenies harder because they are deceptive about relation.

Classification criteria:     

Morphology DNA, Genes, Proteins Fossils Behaviour Development

Kids play catch over farmer grime’s stable. Kingdom, Phylum, Class, Order, Family, Genus, Species. Group without common ancestor: Polyphyletic.

Group without all descendants: Paraphyletic. Expected to be normally Monophyletic.

Speciation

Factors affecting speciation rates:     

Ecological specialisation, eg. Diet Population bottlenecks, eg. Founder effect Types of pollination Rapid environmental changes Sexual selection

Allopatric speciation: geographical speciation. Sympatric speciation: multiplication of chromosome numbers. Polyploid organisms cannot interbreed with parent species. Mostly in plants.

Hybrids can develop if barriers to gene exchange fail to develop during allopatry. Hybrids may form if separated populations rejoin without sufficient genetic differences having accumulated.

Prezygotic reproductive barriers:     

Mechanical Temporal Behavioural Habitat Gametic

Post-zygotic reproductive barriers:   

Hybrid zygote abnormality Hybrid infertility Low hybrid viability

Reinforcement: poor survivability of hybrids, development of more prezygotic barriers.

Atoms and Molecules Phosphorus can form 3 or 5 bonds. PONCHS= phosphorus, oxygen, nitrogen, carbon, hydrogen, sulfur.

Sulfur forms 2 bonds. Electronegativity difference greater than 0.5 = polar covalent.

Cells contain 4 major types of macromolecules:    

Proteins Nucleic acids Carbohydrates Lipids

Polymers form via condensation reactions. Break apart via hydrolysis reactions. Carbohydrates Source of stored energy. Structural molecules that give organisms their shapes. Recognition molecules inside and on the surfaces of cells. Monomers are called monosaccharides. Linked by glycosidic bonds. Commonly pentose or hexose cyclic sugars. Several hydroxyl groups. Starch and glycogen have 1.4 and 1.6 glycosidic bonds. Cellulose has only 1.4. This causes branching in starch and glycogen. Lipids Composed mainly of hydrocarbons. Very nonpolar and insoluble in water. They store energy, form cell membranes, and act as thermal insulation.

1. Triglycerides: include fats and oil. Three fatty acids and a glycerol molecule. Fatty acids are amphipathic. They have a hydrophilic head and a hydrophobic tail. Fats tend to have saturated fatty acids. Oils tend to have unsaturated fatty acids. 2. Phospholipids: Two fatty acid chains, a phosphate group and glycerol. Have a hydrophilic head and a hydrophobic tail. Assemble into phospholipid bilayers naturally. 3. Sterols

Acids donate hydrogen. Acids become negatively charged after donating hydrogen. Ph= how many hydrogen ions in solution Pka= how willing an acid is to give up hydrogen ions. Buffers resist small changes in Ph Strong acids tend to be completely deprotonated in water. Smaller pKa = stronger acid. If pka is lower than Ph, it will deprotonate.

Metabolism is all the chemical reactions that happen in an organism Anabolism = building up. Catabolism – breaking down. Endergonic reactions require energy. = positive delta g nought Exergonic reactions release energy. = negative delta g nought Spontaneous reactions = always an increase in entropy. Catabolic and Anabolic reactions are often linked. Delta G nought = energy Positive delta g nought – requires energy

In which direction will the reaction move overall? Delta G nought In which direction do we expect it to move at this moment? Delta G

Left to right (over all)= negative delta g nought Left to right (now) = negative delta g...