CRISPR and Early Earth Biology Quiz : Biology Unit 4

CRISPR/Cas9 is a gene-editing tool that allows scientists to precisely target and modify specific DNA sequences.

CRISPR/Cas9 acts as a bacterial immune system. Bacteria store fragments of viral DNA in their genome. If the same virus attacks again, the CRISPR system uses guide RNA to direct Cas9 to cut the viral DNA, preventing infection.

Scientists can design guide RNA to target specific DNA sequences. This guide RNA directs Cas9 to cut the DNA at that exact location, allowing for gene deletion, insertion, or repair.

By using guide RNA to target a specific DNA sequence, Cas9 can cut out the unwanted DNA. The cell then naturally repairs the gap using DNA ligase, effectively removing the targeted gene.

Scientists can deliver new DNA sequences along with the guide RNA and Cas9. Once Cas9 cuts the DNA, the new sequence is incorporated into the genome, enabling repair of mutated genes or introduction of new ones.

Experiments conducted in natural settings to validate laboratory findings.

Experiments that introduce or remove selective pressures to observe their effects on allele frequencies and phenotypes.

Studying past events to provide real-world evidence for evolutionary change and its mechanisms.

Evolutionary forces, like mutation, gene flow, genetic drift, and natural selection, do not act in isolation but interact to shape allele frequencies in populations.

Mutations create new alleles, providing the genetic variation that natural selection acts upon.

Gene flow can either counteract or enhance selection by introducing alleles from other populations.

Genetic drift, random changes in allele frequencies, can outweigh selection in small populations, leading to the persistence of harmful alleles or the loss of beneficial ones.

Non-random mating, like inbreeding, can increase homozygosity and expose deleterious alleles to selection.

The movement of cells from one location to another during development to create the correct structure and organization of tissues and organs.

A network of proteins and carbohydrates surrounding cells that provides a scaffold for cell migration and helps guide them to their destinations.

Cells alter their shape to fit into specific structural roles during development, forming tissues and organs with unique architectures.

A process of programmed cell death that removes unnecessary or damaged cells during development, sculpting structures and removing excess cells.

The process of resetting the gene expression of a differentiated cell back to an undifferentiated, stem cell-like state.

A method of nuclear reprogramming where the nucleus of a differentiated cell is transferred into an enucleated oocyte (egg cell without a nucleus). The oocyte's transcription factors reprogram the differentiated nucleus to a stem cell state.

A method of nuclear reprogramming where specific transcription factors associated with stem cell properties are directly introduced into a differentiated cell, reprogramming its gene expression to a pluripotent state.

Cells produced through direct reprogramming that are capable of developing into a wide range of cell types, but unlike totipotent cells, cannot create a complete organism on their own.

The atmosphere of early Earth was extremely hot and contained high levels of carbon dioxide (CO₂).

As Earth cooled, CO₂ reacted with water to form carbonic acid, which broke down rocks. This released calcium and bicarbonate ions that reacted to form calcium carbonate, effectively sequestering CO₂.

Early Earth experienced extreme temperature fluctuations, from 2000°C to -50°C, resulting in periods of glaciation (ice ages) that caused mass extinctions.

The Earth's crust is composed of tectonic plates that slowly shift over time. This movement has caused continents to merge and separate, forming supercontinents like Rodinia, Pangea, Gondwana and Laurasia.

Fossil distributions across currently separated continents provide strong evidence for continental drift.

Early organisms, particularly photosynthetic ones like cyanobacteria, played a significant role in altering Earth's atmosphere by fixing carbon.

The rise of oxygen levels in the atmosphere, caused by photosynthetic organisms, led to the Great Oxygenation Event (~2.5 billion years ago), which ultimately led to the formation of the ozone layer.

Early microbial life contributed to rock weathering and carbon cycling, accelerating the formation of calcium carbonate in oceans.

The blockage or reduction of genetic exchange between populations. This can occur due to physical barriers like mountains or oceans, isolating populations and leading to their independent evolution.

The formation of new species from geographically isolated populations. This happens because of natural selection favoring different traits in each environment and random genetic drift.

The rapid diversification of a single ancestor into many new species, each adapted to a different ecological niche.

The unique role and position of a species within its environment. This includes its habitat, food sources, and interactions with other organisms.

A model of evolution where changes occur slowly and steadily over long periods, with transitional forms appearing in the fossil record.

A model of evolution where long periods of stability are interrupted by short bursts of rapid change, leading to the sudden appearance of new species in the fossil record.

The study of biodiversity and evolutionary relationships between organisms using various data like morphology, genetics, and behavior.

A branching diagram that shows evolutionary relationships between organisms. It depicts their common ancestry, relative divergence times, and shared characteristics.

Gene editing has the potential to revolutionize medicine by curing genetic diseases, creating medically important proteins, and enabling animal models for research.

While promising, gene editing raises ethical concerns, particularly with germline editing, which could alter future generations. Additionally, access and cost are important considerations.

Gene editing has enabled the development of GM crops with traits like herbicide resistance, but this can lead to herbicide-resistant weeds and potential ecological disruptions.

Bt crops contain genes for insecticidal proteins, providing pest resistance. However, the widespread use of Bt maize raises concerns about insect resistance and ecosystem impacts.

Gene editing could be used to eliminate disease-carrying species, but this could disrupt the delicate balance of ecosystems by affecting the food web.

A transgenic animal has had a foreign gene inserted into its genome, introducing a new trait not naturally present in its species.

Editing germline cells (egg or sperm) means alterations will be passed on to future generations, potentially altering human evolution.

Germline editing raises concerns about creating 'designer babies' with specific traits, prompting ethical debates about genetic selection.

Editing the alleles of entire populations could impact genetic diversity and adaptability, affecting a species' ability to evolve in response to environmental changes.

Genomics involves mapping, sequencing, annotating, and analyzing an organism's complete set of DNA, providing insights into its genes and functions.

A genetic map shows the relative positions of genes based on recombination frequency, while a physical map provides precise, absolute positions of genetic markers.

Automated sequencing utilizes dideoxynucleotides to terminate DNA synthesis, creating fragments of different lengths and sequences.

NGS handles large DNA samples efficiently, using reversible chain terminators to sequence fragments multiple times for accuracy.

Genome annotation involves labeling elements within a DNA sequence, like coding and non-coding regions, to understand gene function and genome structure.

Non-coding DNA, despite not coding for proteins, plays crucial roles in gene regulation, structural functions, genomic integrity, and evolutionary processes.

Non-coding DNA sequences within a gene that are removed during RNA processing.

Coding DNA sequences within a gene that are spliced together to form mature messenger RNA (mRNA).

DNA sequences that are very similar to functional genes but have lost their ability to be transcribed or translated.

DNA sequences that can move around within a genome, sometimes causing disruptions or mutations.

A template used to guide the synthesis of a complementary RNA molecule during transcription.