DNA and Replication
What are the 3 components of a nucleotide?
Base, sugar, phosphate
Where in the cell does transcription take place?
What is the term for a random change in a DNA sequence that introduces new traits?
Mutation
What do we call structures that have a similar underlying bone anatomy but different functions (e.g., human arm vs. whale flipper)?
Homologous Structures
Why are invasive species detrimental to an ecosystem?
They don't have any natural predators and outcompete native species for resources
If a DNA strand has the sequence ATTGCA, what is the complementary DNA strand?
TAACGT
Translate this mRNA codon into its amino acid: AUG. (What is its special role?)
Methionine; it is the "Start" codon that signals the beginning of translation
How does natural selection "choose" which traits are passed on?
Organisms with traits best suited to their environment are more likely to survive and reproduce, passing those advantageous alleles to their offspring.
Whales have tiny, unused pelvic bones. What type of structures are these?
Vestigial Structures
Classify these limiting factors as density-dependent or density independent:
Volcanic Eruption
Highly contagious respiratory illness
Volcanic: density independent
Illness: density dependent
Why is DNA replication described as semi-conservative?
Because each new DNA molecule consists of one original (parental) strand and one newly synthesized strand
If a DNA strand reads TAC-GGC, what will the resulting mRNA sequence be?
AUG-CCG
Difference between natural selection and genetic drift.
Natural selection is based on fitness and adaptation to the environment (not random). Genetic drift is a change in allele frequencies due to purely random, chance events.
How does comparing embryonic development across different species provide evidence for evolution?
Classify these relationships as competitive, symbiotic or predator-prey:
Coral has algae that lives in its structure, providing food to the coral, while the coral provides protection and nutrients to the algae.
Great White Sharks off the coast of South Africa feed on the Cape Fur Seals in the area.
Many plant species secrete specific chemicals into their leaves and roots to prevent other nearby plants from growing.
Coral: Symbiotic
Shark: Predatory
Plant: Competitive
Name the specific enzymes responsible for (1) unwinding the DNA helix and (2) gluing Okazaki fragments together.
Helicase and DNA Polymerase
What is the role of tRNA?
tRNA (transfer RNA) carries specific amino acids to the ribosome and matches to the mRNA codon to ensure they are placed in the correct order.
Genetic Drift or Natural Selection? A volcanic eruption kills off 90% of an insect population, leaving the remaining population with very different allele frequencies than the original population.
Genetic Drift
If two species have highly similar DNA sequences, what does that tell us about their evolutionary past?
Shared ancestry
Identify the type of symbiosis for each scenario:
A) A tick feeding on a deer
B) A honeybee pollinating a flower while gathering nectar.
C) An orchid growing on a high tree branch to get sunlight, leaving the tree unharmed.
Tick: Parasitism
Bee: Mutualism
Orchid: Commensalism:
Explain why DNA replication has a leading strand and a lagging strand
DNA polymerase can only build new strands in the 5' to 3' direction, so it has to add in chunks on the lagging strand
Describe what happens during a frameshift mutation and why it is usually more damaging than a substitution mutation.
A frameshift mutation occurs when a nucleotide is inserted or deleted, shifting the entire "reading frame" of three-letter codons from that point forward. This changes every single amino acid after the mutation, unlike a substitution which usually only changes one.
Name at least 3 conditions required for a population to be in Hardy-Weinberg equilibrium (no evolution).
1. No mutations; 2. Random mating; 3. No natural selection; 4. Extremely large population size; 5. No gene flow (no immigration/emigration).
Why are bacteria an ideal organism for studying evolution?
Asexual reproduction + quick reproduction rate = new mutations (like antibiotic resistance) can be introduced and will be passed on to offspring in relatively short amount of time, showing evolutionary changes in real time
Calculate the energy available at each level of a trophic pyramid if it has 4 levels (including the starting producer level), and starts with 20,000 kJ of energy.
start (producers): 20,000 kJ
Primary consumers: 2000 kJ
Secondary consumers: 200 kJ
Tertiary consumers: 20 kJ