Gen Bio Unit 5 Vocab

evolution

A change in allele frequencies over time. These genetic shifts can be driven by natural selection, genetic drift, gene flow, and mutation. Natural selection is when organisms better adapted to their environment are more likely to pass on their successive genes to future generations. Genetic drift is when the frequency of genes change randomly due to chance. A mutation is an alteration to DNA that can create genetic variation.

Finches

A natural laboratory that studied ___ evolution and eliminated human inference and isolated the species. Which allowed the scientists to track individual ___ populations and observe natural selection. Scientists observed that during droughts ___ with larger, deeper survived and reproduced more.

environmental influences on phenotypes

Phenotypes are the physical traits that are influenced by gene expression. When a genotype produces multiple phenotypes based on the organism’s environment this is called phenotypic plasticity. Key environment factors that can influence phenotypes are temperature, diet, soil, and epigenetics. (e.g., some ectothermic organisms have the sex of their offspring determined by temperature.)

genetic variation

The different DNA sequences among individuals in a population. It creates the foundation of biodiversity by driving traits like physical appearance and disease susceptibility.

Hardy-Weinberg Principle

______________ states that allele and genotype frequencies in a population will stay constant and avoid evolutionary forces. If the conditions are met then the population reaches equilibrium through no mutations, gene flow, random mating, no natural selection, and a large population is needed.

bottleneck effect

Random reduction in population size that could be caused by natural disasters, disease, or human activities. The surviving generation has much lower genetic diversity and will have a skewed representation of traits compared to the original population. In addition, the decreased diversity leaves the surviving population susceptible to disease, environmental changes, and inbreeding.

gene flow

the transfer of genes from one population to another population through the movement of individuals, seeds, or pollens. A continuous exchange of genes occurs and the receiving populations’ genes are altered which can be a driver for evolution. which impacts population through increased genetic variation, counteracts genetic drift, promotes speciation, facilitates genetic rescue, and risk of hybridization.

evolving forces

The mechanism that drives genetic and phenotypic changes within a population over time. Which can include mutation, genetic drift, gene flow, and natural selection. They may act independently to alter allele frequencies that shape the species and they adapt to their environment.

Darwin’s theory of evolution

A belief that all life evolves through a process of natural selection. Organisms with advantageous traits to their environment are more likely to survive, reproduce, and pass down the advantageous traits.

Culver's work

Dr. Gloria’s molecular research on ribosome genesis where she mostly focused on the assembly of ribosomal machinery that is essential to the growth of all living cells. Gloria's contributions led to the mapping of ribosomes in bacteria, how bacteria can be controlled by selective inhibition, and changed the world’s perception of ribonucleoprotein construction.

Hutton and Lyell’s work

Pioneers of Uniformitarianism who helped improve our understanding of modern geology. One established that the earth is shaped by observable slow processes like erosion and uplift rather than sudden catastrophic events. The other expanded on the ideas by providing Charles Darwin the framework to come up with the Theory of Evolution.

artificial selection

Where humans control reproduction of plants and animals to promote or eliminate specific traits. Humans perform this by identifying desirable traits and breeding two organisms that have these traits, so the successive generations will increase the frequency of those specific alleles.

descent with modification

The foundational principle that species evolve and change over generations as traits are passed down to offspring. This idea explains how all living things are connected to common ancestry and how they accumulated gradual genetic differences over time.

Malthus’s work

Created an essay on the Principle of Population in which he argued that unchecked population growth increases geometrically while food supplies increase arithmetically. He warned that this problem will create famine, disease, and war unless moral restraint is created.

convergent evolution

The independent evolution of similar features in unrelated/ distantly related species. Can occur when organisms face similar environmental hardships that cause them to adapt by developing matching physical traits, behaviors, or body shapes (analogous structures). (e.g., bats, birds, and pterosaurs all independently adapted to the skies by evolving wings, lightweight bones, and high metabolisms.

vestigial organs

Anatomical features/ behaviors that have lost most or all of their original ancestral function through evolution. These structures no longer serve their primary function, but they retain minor functions and persist due to not hindering survival. (e.g.,Arrector pili that creates goosebumps for harrier ancestors would make them look more intimidating or trap heat, for humans today these benefits don’t occur.)

homologous structures

_____ _____ are body parts in different species that share a common evolutionary origin, but may have different functions. (e.g.,Pentadactyl limb, which is a bone structure that humans, bats, and whales have, but use for different purposes like humans for grasping, bats for flying, and whales for swimming.)

analogous structures

_____ _____ are features that have similar functions, but evolved independently in unrelated species. (e.g., Birds and insects with their wings that are both used for flying, but birds’ wings are made of bone and skin, while insects’ wings are made of extension of the exoskeleton.)

bacterial transformation

Bacterial process where bacteria take up free foreign genetic material (typically plasmids) from their environment and incorporate into their genome to replicate it. This mechanism is the backbone of molecular cloning, genetic engineering, and producing recombinant proteins such as insulin for humans.

Hershey and Chase

Famous blender experiment that proved DNA not protein is genetic material. Conducted by Alfred and Martha who were skeptical of DNA carrying genetic information and tested this by using bacteriophage where they found DNA alone was responsible for programming bacteria to create new viruses.

Avery, McCarty & Macleod

A 1944 study that proved DNA, rather than protein, is the hereditary material responsible for genetic transformation in cells. The scientists tested this by extracting cell components from S-strain bacteria and introducing them to R-strain bacteria and they tried to  determine what causes R-strain to turn into lethal S-strain. They learned that DNA is responsible for genetic transformation when they introduced protease which destroys proteins and bacterial transformation still occurred, but when they introduced DNase that destroys DNA and the transformation process stopped.

Chargaff

Discovered that natural DNA in the number of guanine units equals the number of cytosine units and the number of adenine units equal the number of thymine units.

antiparallel strands in DNA

Run along each other but in opposite directions. One strand runs 5’ to 3’ direction, while the complementary partner runs 3’ to 5’ direction. This orientation is important for complimentary base pairing and allows the double helix to maintain a stable, uniform width.

DNA polymerase III

The primary subunit enzyme complex responsible for synthesizing chromosomal DNA in prokaryotes. Works at the replication fork, extends RNA primers and reads template strands to produce a new, complimentary DNA strand.

 5’ —> 3’

The directional synthesis and reading of nucleic acid strands. Enzymes like DNA and RNA polymerase read templates in the 3’ to 5’ direction to build new strands in the 5’ to 3’ direction.

DNA replication

Biological process of duplicating a cell genome prior to division. Operates in three main stages: initiation, elongation, and termination. In initiation, protein targets sites, recruits complex enzymes to pry apart DNA’s hydrogen bonds. In elongation, DNA polymerase begins to work and needs a “kick-starter” provided by enzyme primase which adds a short segment of complementary RNA called primer. In termination, the DNA is fully copied, the replication process concludes with clean up and proofreading phase.

Telomeres

Protective, repetitive DNA sequences located at the end of chromosomes. They prevent chromosomes from fraying, tangling, or fusing with one another. Each time cells divide the telomeres shorten and when they become critically short that lets the cell know to stop dividing.

Histones

Basic proteins in eukaryotic cell nuclei that act as spools around DNA to form structural units called nucleosomes. Nucleosomes are positively charged and bind tightly negatively charged DNA which allows meters of genetic material to be packaged into chromosomes for gene expression.

Codons

A three nucleotide sequence for messenger RNA molecules that acts as a fundamental unit of genetic code. Provides instructions to build proteins by specifying which amino acid to add next or by signaling the termination of protein synthesis.

mRNA

The portable genetic blueprint that copies a specific gene’s instructions from DNA in the nucleus and carries them out to cytoplasm. Has a single-stranded linear molecule and its code read in three-letter segments.

tRNA

The supplier and interpreter that reads mRNA codons and delivers corresponding amino acids to the ribosome to build proteins. The structure resembles a cloverleaf with one end having an anticodon and the other end attaching to a specific amino acid.

rRNA

when proteins are built from RNA and occurs in transcription and translation.

RNA polymerase

An important enzyme that drives gene expression by copying DNA sequence into complementary RNA strands during transcription. Then, it unwinds the double helix and builds RNA molecules which are essential building blocks for protein synthesis.

translation

The process decoding genetic instructions from mRNA to build proteins. The steps include initiation, elongation, and termination. Initiation is when the ribosomes attach to mRNA strand near a start codon; elongation is when tRNA carries specific amino acids and pairs it with anticodon to matching mRNA codon, the ribosome link the amino acids together and create a polypeptide chain; termination is when the ribosome reaches a stop codon to release the completed protein to fold into functional shape.

transcription

The process of copying a segment of DNA into a complementary RNA sequence and is the first step of gene expression. Broken into three steps: initiation, elongation, and termination. Initiation is when the enzyme, RNA polymerase binds to a specific region of DNA called promoter and signals the start of the gene and causes the DNA double helix to unzip. Elongation is the RNA polymerase that moves along that moves one strand of DNA in 3’ to 5’ direction and reads the template, it builds a single strand of complementary RNA in 5’ to 3’ direction. Termination is when the polymerase reaches a specific sequence at the end of the gene, transcription stops and the newly formed RNA transcript is released, so the DNA strand zips back together.

ribozymes

Special RNA molecules that act as biological catalysts to accelerate chemical reactions within the cell. They are important for RNA splicing, viral replication, and protein synthesis. They consist of ribonucleic acid where the RNA is single-stranded and can be folded into intricate 3d shapes that create special active sites. Using these sites ribozymes bind to substrates and facilitate chemical changes to cut, join, or modify RNA and DNA.

RNA

A single-stranded nucleic acid made of nucleotide chains containing the bases: adenine, uracil, cytosine, and guanine. It’s essential to gene expression, regulation, and execution of DNA's genetic instructions to build proteins in all cells.

protein synthesis in eukaryotes

 Protein synthesis is when genetic code is translated into proteins through transcription and translation. ___ go through transcription and then translation.

protein synthesis in prokaryotes

Protein synthesis is when genetic code is translated into proteins through transcription and translation. ___ go through these steps simultaneously in cytoplasm.

gene

The functional unit of hereditary made up of specific sequences of DNA where they act as instruction manuals. They tell cells how to make proteins, which builds the body, regulates functions, and determines traits. They work by being represented by the letters: A, T, G, C where the order of the sequence of the letters can dictate specific instructions for cells.

nonsense mutation

A genetic change that alters DNA sequence so that a premature stop codon is created in the mRNA. This causes the cell to abruptly stop protein synthesis and creates truncated (shortened) nonfunctional proteins.