Honors Biology Semester 2 Final Review Guide

Flashcards for DNA/Replication/Protein Synthesis, Evolution, Ecology.

Hershey and Chase Discovery

DNA enters bacteria using radioactive phages.

Nucleotide Composition

Sugar, phosphate, and a nitrogen base. Differ by nitrogen bases (pyrimidines: C and T, purines: A and G).

Chargaff's Rule

The amount of adenine is always equal to the amount of thymine, and the amount of guanine is always equal to the amount of cytosine.

DNA Replication

1) Helicase unwinds DNA. 2) DNA primase adds primers. 3) DNA polymerase adds nucleotides (5' to 3', leading and lagging strands, Okazaki fragments). 4) DNA ligase glues fragments, DNA polymerase proofreads.

Why can a large amount of proteins be formed from a small amount of amino acids?

Amino acids can be rearranged.

Transcription

1) RNA Polymerase unwinds DNA, adds complementary RNA nucleotides (A, U, G, C). 2) RNA detaches, becomes pre-mRNA. 3) pre-mRNA (introns and exons), introns removed, exons remain. 4) Final RNA leaves nucleus to ribosome.

Translation

1) mRNA binds to small ribosomal subunit. 2) Ribosome reads codons. 3) tRNA (with amino acid) binds to corresponding codons with anticodons.

Gene Mutation Types

Point: single nucleotide change. Frameshift: nucleotide added/deleted. Block: large chromosome region changes.

Recombinant DNA Technology

Restriction enzymes cut gene of interest and plasmid (creating sticky ends), ligase glues gene into plasmid, put into bacterial cell to clone.

PCR (Polymerase Chain Reaction)

Technique to make many copies of a DNA segment without using living cells.

RFLPs (Restriction Fragment Length Polymorphism)

A particular banding pattern via restriction fragments, used to identify individuals based on unique DNA sequences.

Gel Electrophoresis

Technique to sort DNA fragments by length. Cut DNA, load samples in gel, DNA moves (-) to (+), stain the DNA.

Species Definition

Group of organisms with similar features that breed together and produce fertile offspring.

Natural Selection

Survival and reproduction of organisms best adapted to the environment.

Homologous Structure

Similar structures in species sharing a common ancestor (e.g., limbs of humans, cats, whales, bats).

Gradualism

Evolution occurs slowly and steadily over long periods of time.

Antibiotic Resistance

Some bacteria survive antibiotics due to mutations and reproduce, creating resistant populations.

Causes of Genetic Variation

Mutations, gene recombination, mutagens (e.g., UV radiation).

Genetic Drift

Change in gene pool due to chance. Bottleneck effect: population reduction leads to loss of diversity. Founder effect: colonization of new habitat.

Selection Pressure

Change in environment (e.g. changes in seed size on the Galapagos Islands favor different beak sizes.)

What changes when a species is evolving?

Allele frequencies, gene pool, the species self

Why do Lethal Recessive Alleles persist in populations?

Carriers survive and reproduce, new mutations can introduce alleles into the gene pool.

Classification Order

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Linnaeus' Contribution

Introduced binomial nomenclature (double naming system).

Limiting Factor

Condition that restricts a population's growth (e.g., space, disease, food, water, weather, disasters).

Density Dependent vs. Independent Factors

Density-dependent: limits population more as density increases (e.g., disease, food availability). Density-independent: unrelated to density (e.g., weather, natural disasters).

Carrying Capacity

Number of organisms an environment can maintain.

Types of Population Growth

Exponential, linear, logistic growth. Factors such as resource availability affect the type of growth.

Survivorship Types

Type I: high survivorship, parental care, late death. Type II: constant loss, independent of age. Type III: low survivorship, early death.

Niche

The role an organism plays in its ecosystem.

Factors Determining Biomes

Temperature and precipitation.

Symbiotic Relationships

Parasitism: one benefits, one harmed. Mutualism: both benefit. Commensalism: one benefits, other unaffected.

Ecological Succession

Pioneer species, intermediate species, climax community.

Stable Ecosystem

Diversity, no exotic species, self-maintaining.

Food Chains and Webs

Sun → Producers → Primary Consumers → Secondary Consumers → etc. Energy flows one way, nutrients recycle.

Energy Transfer in Food Chain

10%

Nutrient Cycling

Abiotic -> Biotic factors

Energy Cycling

From sun, then producers, primary consumers, secondary consumers and tertiary consumers.

Exotic Species Impact

Causes competition and alters food webs, disrupting habitats.

Carbon Cycle

Photosynthesis, decaying organisms, dead organisms & waste products, fossil fuels, factories (Combustion)

Nitrogen Cycle

Nitrogen fixation, nitrification, assimilation, ammonification, denitrification.

Global Warming

Increase in Earth's temperature from buildup of carbon dioxide and other gases.