Genetic Concepts: Bottleneck vs. Founder Effect

A genetic bottleneck occurs when a population experiences a sudden decrease in size, resulting in a loss of genetic diversity and altered allele frequencies. The founder effect involves a small group of individuals establishing a new population, leading to a different allele frequency composition compared to the original population.

Gene flow, the movement of alleles between populations, can cause allele frequencies to become more similar. Individuals migrating from one population to another introduce new alleles or alter the existing proportions of alleles in the recipient population.

Mutations are the sole source of new genetic variation. They introduce changes in the DNA sequence, leading to new alleles that can be passed down through generations.

<p>Non-viable zygote (A), Protein has new function (B), Protein non-functional (C), Protein has improved function (D), Reduced protein function (E), Neutral effect (most common) (F)</p> Signup and view all the answers

<p>Gene flow is the movement of alleles between populations through interbreeding.</p> Signup and view all the answers

<p>Microevolution refers to changes in the frequencies of alleles within a population over time.</p> Signup and view all the answers

<p>Mutations are the primary source of new alleles.</p> Signup and view all the answers

<p>A population is a group of individuals of the same species that can interbreed and reproduce within a particular geographic area.</p> Signup and view all the answers

<p>The founder effect occurs when a small group of individuals from a larger population establishes a new population in a new location, leading to a different allele frequency composition compared to the original population.</p> Signup and view all the answers

<p>A genetic bottleneck occurs when a population experiences a sudden and dramatic decrease in size, often due to environmental factors or natural disasters. This leads to a loss of genetic diversity and altered allele frequencies.</p> Signup and view all the answers

<p>Mitosis is a process of cell division that results in two identical daughter cells, each containing the same number of chromosomes as the parent cell. Meiosis, on the other hand, is a specialized type of cell division that produces gametes (sex cells), containing half the number of chromosomes as the parent cell.</p> Signup and view all the answers

<p>The first stage of mitosis involves the replication of each chromosome, resulting in two identical sister chromatids attached at the centromere.</p> Signup and view all the answers

<p>During the second stage of mitosis, the sister chromatids separate and move towards opposite poles of the cell.</p> Signup and view all the answers

<p>Humans have 23 pairs of chromosomes, totaling 46 chromosomes in each cell.</p> Signup and view all the answers

<p>Chromosomes are found in pairs in somatic cells because one chromosome of each pair is inherited from the mother and the other from the father.</p> Signup and view all the answers

<p>Homologous chromosomes are pairs of chromosomes that carry the same genes but may have different alleles. Sister chromatids are identical copies of a chromosome, created during DNA replication, and are attached at the centromere.</p> Signup and view all the answers

<p>A nucleotide is the basic building block of nucleic acids, such as DNA and RNA, consisting of a sugar molecule, a phosphate group, and a nitrogenous base.</p> Signup and view all the answers

<p>A somatic cell is any cell in the body that is not a sperm or egg cell.</p> Signup and view all the answers

<p>A ribosome is an intracellular structure responsible for protein synthesis, made up of both RNA and protein.</p> Signup and view all the answers

<p>Proteins have diverse functions, including structural support (e.g., muscle and bone), defense (e.g., antibodies), enzymatic catalysis, and transport of molecules. Proteins are made up of chains of amino acids linked together.</p> Signup and view all the answers

<p>Antibodies bind to foreign elements, such as pathogens, to neutralize them and protect the body from infection.</p> Signup and view all the answers

<p>Enzymes are biological catalysts that speed up chemical reactions within cells and organs.</p> Signup and view all the answers

<p>Messenger molecules, such as hormones, coordinate biological processes between cells and organs.</p> Signup and view all the answers

<p>Transport proteins bind and carry molecules throughout the body, such as hemoglobin, which binds and transports oxygen.</p> Signup and view all the answers

<p>Transcription is the process of copying the genetic code from DNA to RNA, specifically messenger RNA (mRNA). Translation is the process where the mRNA sequence is read by a ribosome, and based on the codons, a specific amino acid is added to the growing polypeptide chain, ultimately forming a protein.</p> Signup and view all the answers

<p>DNA replication begins with the unwinding of the double helix, separating the two strands. Each strand then serves as a template for the synthesis of a new complementary strand through the action of enzymes. The process results in two identical DNA molecules, ensuring that each daughter cell receives a complete copy of the genetic information.</p> Signup and view all the answers

<p>The independent assortment principle states that during gamete formation, alleles for different traits are sorted independently of each other. This means that the inheritance of one trait does not affect the inheritance of another trait.</p> Signup and view all the answers

<p>Allele frequency refers to the proportion of a specific allele compared to the total number of alleles for that gene in a population.</p> Signup and view all the answers

<p>A hypothesis is an educated guess or prediction about the relationship between two variables.</p> Signup and view all the answers

<p>A theory is a well-substantiated explanation of some aspect of the natural world that is supported by a large body of evidence from many different sources and has been repeatedly tested and confirmed through experimentation.</p> Signup and view all the answers

<p>The scientific method involves a systematic approach to investigation, including observation, hypothesis formulation, prediction, experimentation, and analysis.</p> Signup and view all the answers

<p>Natural selection typically acts on individuals, favoring those with traits that enhance survival and reproduction in a particular environment. Selection on a group level can occur but is less common, as it is more difficult to measure the effects of a trait on the overall fitness of a group.</p> Signup and view all the answers

<p>Heterozygous refers to an individual that has two different alleles for a particular gene at a locus. This means that the individual inherits one allele from each parent.</p> Signup and view all the answers

<p>Pleiotropy is a phenomenon where a single gene can affect multiple different phenotypic traits.</p> Signup and view all the answers

<p>A recessive trait is only expressed if the individual inherits two copies of the recessive allele, one from each parent.</p> Signup and view all the answers

<p>Blending inheritance suggests that traits would be blended together in offspring, resulting in a gradual loss of variation across generations. However, this is not what we observe in nature. If blending inheritance were true, then populations would eventually converge to a uniform appearance, with no distinct traits. Instead, we see that traits are passed down in discrete units, and variation can be maintained, even re-emerging across generations.</p> Signup and view all the answers

<p>Pea plants were an excellent model organism for Mendel's experiments due to their short generation time, ease of cultivation, readily observable traits, and ability to self-pollinate. This allowed for controlled crosses and accurate recording of inheritance patterns.</p> Signup and view all the answers

<p>A haploid cell contains a single set of chromosomes, rather than the two sets found in diploid cells.</p> Signup and view all the answers

<p>mRNA functions as a messenger molecule, carrying the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm, where protein synthesis takes place.</p> Signup and view all the answers

<p>Sister chromatids are identical copies of a chromosome, created during DNA replication, and are joined at the centromere.</p> Signup and view all the answers

<p>DNA has a double helix structure, resembling a twisted ladder with two strands of nucleotides wound around each other. The strands are held together by hydrogen bonds between complementary base pairs: adenine (A) with thymine (T) and guanine (G) with cytosine (C).</p> Signup and view all the answers

<p>In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).</p> Signup and view all the answers

<p>Genotype frequency is the proportion of individuals within a population that possess a specific genotype. It is calculated by dividing the number of individuals with that genotype by the total number of individuals in the population.</p> Signup and view all the answers

<p>Mutations are changes in the DNA sequence. Point mutations involve a single base change. Insertion mutations add one or more bases, while deletion mutations remove one or more bases. Inversion mutations flip a segment of DNA. Frameshift mutations, caused by insertions or deletions that are not in multiples of three, alter the reading frame of the genetic code, leading to potentially significant changes in the amino acid sequence and protein function.</p> Signup and view all the answers

<p>Gene flow is limited by factors such as physical barriers (e.g., mountains or oceans) that prevent individuals from moving between populations. Social rules or preferences can also restrict gene flow, such as mating preferences within specific groups.</p> Signup and view all the answers

<p>Gene flow is the movement of alleles between populations, driven by random factors such as migration. Natural selection, on the other hand, is a non-random process where individuals with traits that enhance their chances of survival and reproduction are more likely to pass on their genes, leading to a gradual shift in allele frequencies within a population.</p> Signup and view all the answers

<p>When multiple genes contribute to a trait, known as polygenic inheritance, a wide range of phenotypes can be observed, even if each contributing gene has only a few alleles. The combined effects of multiple genes create a continuous distribution of phenotypes, rather than discrete categories. This is often seen in traits like height or skin color, where we see a gradual variation rather than distinct groups.</p> Signup and view all the answers

<p>Occam's Razor is a principle that suggests the simplest explanation for a phenomenon is usually the correct one, when faced with multiple competing explanations.</p> Signup and view all the answers

<p>Darwin observed that fossils of extinct organisms resembled the living species in the same region, suggesting a connection between past and present life forms. He also noted that plants and animals on different islands of the Galapagos archipelago had distinct variations, with different beak shapes in finches being a striking example. This variation suggested that species were not fixed and might adapt to their environments.</p> Signup and view all the answers

<p>Darwin's three postulates are the struggle for existence, variation, and inheritance of variation. He proposed that organisms compete for resources, that individuals within a population have variations, and that these variations can be passed on to their offspring.</p> Signup and view all the answers

<p>The Grants' long-term study of Galapagos finches provided compelling evidence for Darwin's postulates. They observed variations in beak size among finches, with some having adaptations better suited for specific food sources. During droughts, finches with larger beaks that could crack open seeds were more likely to survive and reproduce, demonstrating the struggle for existence and the advantage of certain variations. Additionally, they documented the inheritance of beak size from parents to offspring, confirming that variation is heritable.</p> Signup and view all the answers

<p>Even though small-beaked finches face challenges during droughts, they are not entirely eliminated. Natural selection favors the most well-adapted individuals in a given environment, but it does not eliminate all other variations. In times of plenty, smaller beaks might present advantages, such as better efficiency in consuming smaller seeds. This variation allows for a greater diversity within the population, providing resilience and flexibility to adapt to changing environmental conditions.</p> Signup and view all the answers

<p>The argument that an eye is too complex to have evolved by chance ignores the principles of gradual evolution. Evolution is a slow, step-by-step process. Each step can be advantageous, even if it is a small improvement over the previous state. For example, even a simple light-sensitive patch of cells can be beneficial, providing a slight advantage in detecting predators or resources. Over time, through selection of advantageous variations, these simple structures become more intricate and complex, forming the intricately designed eyes we see today. The intermediate forms are not useless; they provide adaptive advantages in their respective environments, demonstrating the gradual progression of evolution.</p> Signup and view all the answers

<p>Evolution is a process of small modifications of existing structures, not a process of designing entirely new systems. It works by repurposing existing components and features, building complexity over time through gradual changes. This is analogous to a tinkerer who modifies and reassembles existing components, rather than an engineer who designs and builds new structures from scratch.</p> Signup and view all the answers

<p>An allele is a specific variant of a gene, responsible for determining a specific trait. Each individual carries two alleles for each gene, one inherited from each parent.</p> Signup and view all the answers

<p>A dominant trait is a trait that is expressed even when only one copy of the dominant allele is present. In other words, the dominant allele masks the expression of the recessive allele.</p> Signup and view all the answers

<p>A genotype is the genetic makeup of an individual for a specific trait. It refers to the combination of alleles that an individual possesses for a given gene.</p> Signup and view all the answers

<p>A locus is the specific physical location of a gene or allele on a chromosome.</p> Signup and view all the answers

<p>A monohybrid cross is a type of genetic cross that involves examining the inheritance of a single trait by crossing two individuals that differ in that trait.</p> Signup and view all the answers

<p>Polygenic traits are traits that are influenced by multiple genes working together.</p> Signup and view all the answers

<p>The principle of segregation states that during gamete formation, alleles for a trait separate, so that each gamete receives only one allele from each pair. During fertilization, the pairs reunite to determine the expression of the trait in the offspring.</p> Signup and view all the answers

<p>TT represents a homozygous dominant genotype for a trait, Tt represents a heterozygous genotype, and tt represents a homozygous recessive genotype. The capital letter indicates the dominant allele, while the lowercase letter indicates the recessive allele.</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Amino acids are the building blocks of proteins, essential for various functions in the body. They are linked together in chains to form proteins.</p> Signup and view all the answers

<p>An anticodon is a sequence of three nucleotides located on a transfer RNA (tRNA) molecule. It is complementary to a specific codon on messenger RNA (mRNA), enabling the tRNA to transport the appropriate amino acid to the ribosome during protein synthesis.</p> Signup and view all the answers

<p>Base pairing in DNA involves the formation of hydrogen bonds between complementary nitrogenous bases. Adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).</p> Signup and view all the answers

<p>Crossing over is an exchange of genetic material between homologous chromosomes during meiosis (the process of cell division that produces sex cells). It involves the swapping of segments of DNA, resulting in new combinations of alleles and increased genetic diversity in offspring.</p> Signup and view all the answers

<p>Diploid refers to a cell or organism that has two sets of chromosomes, one set inherited from each parent.</p> Signup and view all the answers

<p>DNA stands for deoxyribonucleic acid. It is the molecule that carries the genetic instructions for the development, function, and growth of all living organisms.</p> Signup and view all the answers