BSC 101 — Unit 2 Exam Study Guide Flashcards

Vocabulary practice flashcards covering biotechnology, genetics, climate change, population ecology, and ecosystem dynamics from the BSC 101 Unit 2 exam study guide.

DNA (Deoxyribonucleic acid)

The molecule that stores genetic information in living organisms, containing instructions for making RNA and proteins.

Nucleotide

The building block of DNA, composed of a deoxyribose sugar, a phosphate group forming part of the backbone, and one of four nitrogenous bases (adenine, thymine, cytosine, or guanine).

Complementary Base Pairing

The specific pairing rule in DNA where adenine ($A$) pairs with thymine ($T$) and cytosine ($C$) pairs with guanine ($G$), ensuring the sequence of one strand determines the sequence of the other.

Histones

Proteins in eukaryotic cells around which DNA wraps to form nucleosomes and package into linear chromosomes within the nucleus.

Nucleoid

The region in a prokaryotic cell where the main circular, double-stranded chromosomal DNA is located without being enclosed by a nuclear membrane.

Plasmid

A small, circular, independent double-stranded DNA molecule found in prokaryotes that can frequently be transmitted from one bacterium to another.

Semiconservative Replication

The mechanism of DNA replication in which each newly formed DNA molecule consists of one original parent template strand and one newly synthesized strand.

DNA Polymerase

An enzyme that builds new DNA strands during replication by adding complementary nucleotides, matching $A$ with $T$ and $C$ with $G$.

DNA Extraction

A laboratory technique used to separate DNA from cells and other cellular components to obtain purified genetic material for testing, sequencing, PCR, or profiling.

Polymerase Chain Reaction (PCR)

A biotechnology technique that amplifies a specific target DNA region into millions to billions of copies through repeating cycles of denaturation ($94\text{--}95^\times\!\text{C}$), annealing ($50\text{--}65^\times\!\text{C}$), and extending ($72^\times\!\text{C}$).

Gel Electrophoresis

A technique that uses an electric field to separate negatively charged DNA fragments by size through a gel matrix, where smaller fragments travel farther toward the positive electrode than larger fragments.

Short Tandem Repeats (STRs)

Highly variable regions of DNA examined during DNA profiling to compare individuals in forensics, paternity testing, and kinship identification.

Protein Denaturation

A process in which a protein loses its functional three-dimensional shape, often due to high temperature or extreme pH, causing it to stop functioning properly.

Levels of Protein Structure

The hierarchy of protein organization: primary (amino acid sequence), secondary (local folding into $\alpha$-helices or $\beta$-pleated sheets), tertiary (overall 3D folding from side-chain interactions), and quaternary (association of multiple polypeptide chains).

Transcription

The step in gene expression where RNA polymerase uses DNA as a template to synthesize RNA (including mRNA) in the nucleus of eukaryotic cells, utilizing uracil ($U$) in place of thymine ($T$).

Translation

The process occurring at ribosomes where mRNA codons are read in groups of three bases and matched by tRNAs delivering amino acids to build a polypeptide chain.

Universal Genetic Code

The nearly identical codon system shared by almost all known life, allowing codons such as $AUG$ to specify methionine and enabling host organisms like bacteria to express foreign human genes.

Recombinant DNA

A DNA molecule formed by combining genetic material from different sources, such as inserting a human gene into a bacterial plasmid vector.

Genetically Modified Organism (GMO)

An organism whose genetic material has been altered using genetic engineering techniques to introduce beneficial traits such as pest resistance, drought tolerance, or pharmaceutical production.

Silent Mutation

A mutation that alters a codon but does not change the amino acid sequence of the resulting protein.

Missense Mutation

A mutation where a nucleotide substitution results in a codon that codes for a different amino acid.

Nonsense Mutation

A mutation that prematurely creates a stop codon in an mRNA sequence, which may shorten the translated protein.

Frameshift Mutation

A genetic mutation caused by the insertion or deletion of a number of nucleotides that is not a multiple of three, altering the reading frame of codons downstream.

Germline Mutation

A mutation occurring in reproductive cells (sperm or egg) that can be passed down to offspring, unlike somatic mutations in body cells.

CRISPR-Cas9

A genome-editing system adapted from bacterial immune defense that uses a guide RNA to direct the Cas9 endonuclease to cut a targeted DNA sequence adjacent to a PAM sequence.

Heterozygote Advantage

A survival advantage observed when individuals with one copy of an allele (such as the sickle cell allele in the beta-globin gene) have higher fitness in a specific environment (e.g., protection against severe malaria) than either homozygote.

Greenhouse Gas

An atmospheric gas—including carbon dioxide ($CO_2$), methane ($CH_4$), nitrous oxide ($N_2O$), and water vapor—that absorbs and re-emits infrared radiation, helping tap heat in Earth’s climate system.

Greenhouse Effect

The natural process wherein solar radiation absorbed by Earth's surface is emitted as infrared radiation and partially trapped and re-emitted by greenhouse gases, keeping the planet warm enough for life.

Keeling Curve

The continuous record of atmospheric $CO_2$ concentrations initiated by Charles David Keeling in 1958 at Mauna Loa, Hawaii, illustrating a long-term upward trend from about $315\,\text{ppm}$ to over $420\,\text{ppm}$ alongside seasonal oscillations. where co2 rises and dalls each year as plants take up co2 during growing seasons and realease during decomposition.

Carbon Cycle

The continuous movement of carbon through reservoirs including the atmosphere, living organisms, oceans, soil, sediments, and fossil fuels.

Carbon Sink

A natural or artificial reservoir—such as growing forests or the ocean—that absorbs more carbon from the atmosphere than it releases over a given period.

Carbon Source

Any process or reservoir, such as fossil fuel combustion or biological respiration, that releases more carbon into the atmosphere than it absorbs over a given period.

Weather vs. Climate

Weather refers to atmospheric conditions over short periods (hours to days), whereas climate refers to long-term atmospheric patterns typically assessed over decades (e.g., $30\text{ years}$).

Climate Mitigation

Measures aimed at reducing greenhouse gas emissions or enhancing carbon sinks to prevent further human-driven global warming.

Population

A group of individuals belonging to the same species that live in the same geographic area at the same time.

EX: a group of frogs in a pond

Community

All the interacting populations of different species that inhabit a common geographic area.

ex: frogs, fish, algae, and insects in the pond

Ecosystem

A biological community of interacting organisms together with their nonliving physical environment, including sunlight, water, nutrients, and temperature.

ex: Frogs, fish, algae, insects, water, sunlight, nutrients, and temperature make up an ecosystem

Population Growth Equation

The formula representing the change in population size over time: $\Delta N = (B + I) - (D + E)$, where $B$ is births (increase population size), $I$ is immigration (individuals enter the population), $D$ is deaths (decrease the population sizea0, and $E$ is emigration (individuals leave the population).

Density-Dependent Factor

An environmental factor—such as resource competition, disease transmission, predation, or parasitism—whose intensity increases as population density rises.

Density-Independent Factor

An environmental factor—such as hurricanes, severe fires, extreme temperature spikes, floods, or droughts—that impacts a population regardless of its density.

Population Distribution Patterns

The spatial arrangement of individuals within a population's range, categorized as uniform (evenly spaced), random (independent locations), or clumped (aggregated in groups).

Carrying Capacity ($K$)

The maximum population size that a particular environment can sustain over time given available resources and environmental conditions.

Logistic Growth

A pattern of population growth that begins exponentially when resources are abundant but levels off into an S-shaped curve as the population approaches carrying capacity ($K$).

Mutualism

An interspecific interaction in which both species benefit ($+/+$), such as bees gathering nectar while pollinating flowers.

Commensalism

A symbiotic relationship in which one species benefits while the other is neither helped nor harmed ($+/0$), such as an epiphyte growing on a tree.

Amensalism

An ecological interaction where one organism is inhibited or harmed while the other experiences no significant effect ($-/0$).

Stamen

The male reproductive organ of a flower consisting of the anther, which produces pollen, and the filament, which supports the anther.

Carpel (Pistil)

The female reproductive structure of a flower consisting of a receptive stigma, a supporting style, and an ovary containing one or more ovules.

Pollination

The transfer of pollen grains from an anther to a stigma via animals, wind, or water prior to fertilization.

Double Fertilization

The angiosperm reproductive process where one sperm fuses with an egg cell to form a diploid zygote ($2n$) and a second sperm fuses with two polar nuclei to form a triploid endosperm ($3n$).

Photosynthesis

The process represented by $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ by which autotrophs convert light energy into chemical energy stored in organic molecules.

Trophic Level

The hierarchical position an organism occupies in a food chain or web based on how it obtains energy, ranging from primary producers to apex consumers and decomposers.

10% Rule (Trophic Efficiency)

An ecological rule of thumb stating that approximately $10\%$ of the energy at one trophic level is transferred to and available for the next level, with the rest dissipated as heat or used for metabolism.

Generalist Species

A species that utilizes a broad range of resources and tolerates varied environmental conditions, such as a raccoon.

Specialist Species

A species that depends on a narrow range of resources and has highly specific habitat or food requirements, such as a giant panda.

Bioaccumulation

The buildup of a chemical or contaminant within the tissues of an individual organism over its lifespan.

Biomagnification

The increasing concentration of persistent, fat-soluble contaminants (such as DDT) in the tissues of organisms at progressively higher trophic levels of a food chain.

Substitution

One base is replaced by another. May chnage an amino acid.

Insertion.

Bases are added. May cause frameshift.

Deletion

Bases are removed. May cause framshift.

Gene therapy

Uses genetic material or gene editing techniques to treat or prevent disease. It includes adding a functional copy of a gene, altering gene activity, editing a disease-causing DNA sequence, modifying a patients cells outside the boy and returning them.

Why harmful alleles presist

AN alleles effect on survival depends on the environment and whether an individual has one or two copies. ex: sckle cell allele and malaria.

Natural greenhouse effect

• occurs naturally

• keeps earth warm enough for life

• depends on natural atmosphereic greenhouse gasses

• maintains earths natural energy balance

Enhanced greenhouse effect

• intensified by human acitivities

• causes additional warming

• driven manly by increasing green houses gases from human activity

• alters earths energy balance and climate

What increases green house gas concentrations

burning fossil fuels, deforestation, and some agricultural and industrial activities.

Atmosheric compenent of the carbon cycle

stores carbon mainly as co2 and methane

photosynthesis component to the carbon cycle

plants and algae take in co2 to make organic molecules

feeding in the carbon cycle

carbon moves between organisms when one eats another

respiration in the carbon cycle

organisms release co2 while breaking down organic molecules

decomposition in the carbon cycle

decomposers break down dead material and releases carbon

ocean exchnage in the carbon cycle

co2 moves between the atmosphere and ocean

fossil fuel combustion in the carbon cucle

releases long-stored carbon into the atmosphere

sedimentation in the carbon cycle

carbon can be stored in sediments and rocks over long periods

RIsks of a warming planet

• extreme heat and drought

• increase heat-related illness

• water shortages

• crop stress

• wildfire risk

• seal level rises

• ecosystem disruption

• can cause coral bleaching

• specie decline

• extreme percipitation and storms

“its snowing so global warming isnt real”

False. Weather is short-term; climate is long-term. Cold weather can still occur in a warming world.

what can we do about climate chnage

• use public transportation

• reduce food waste

• support climate policies

• protect forests and wetlands

• reduce methane leaks from oil, gas, and landfills.

Organism

studying one individual living thing

EX: studying one wolf