| Aboriginal | This term refers to the Indigenous peoples of a particular place. In Australia, the term “Aboriginal” refers to the Indigenous peoples of the continent, including those who were present at the time of European colonization. |
| Adenine | Adenine is a purine base that is found in DNA and RNA. It is one of the four nucleotide bases, along with cytosine, guanine, and thymine (in DNA) or uracil (in RNA). Adenine pairs with thymine or uracil through hydrogen bonding, forming one of the two base pairs in the DNA double helix. |
| Admixture | Admixture refers to the mixing of different populations or groups, resulting in a genetic blend. Admixture can occur through intermarriage or migration, and can lead to the introduction of new genetic variants into a population. |
| Allele | An allele is a variant form of a gene. Every person has two alleles for each gene, one inherited from each parent. Alleles can be dominant, recessive, or somewhere in between, and they determine an individual’s traits and characteristics. |
| Amplification | Amplification refers to the process of increasing the quantity of a specific DNA fragment through a series of enzymatic reactions. This can be done for a variety of reasons, including for DNA sequencing, DNA cloning, and forensic analysis. |
| Ancestor | An ancestor is a person from whom one is descended. This can include both biological ancestors, as well as cultural and spiritual ancestors. |
| Ancestral Haplotype | An ancestral haplotype is a group of genetic markers that are inherited together and passed down from one generation to the next. Haplotypes can be used to trace ancestry and understand the genetic relationships between different populations. |
| Ancestral Signature | An ancestral signature is a set of genetic markers that are characteristic of a particular population or geographic region. These markers can be used to trace ancestry and understand the genetic history of a population. |
| Ancestral State | The ancestral state of a trait or characteristic refers to the form that the trait or characteristic had in an ancestor. This can be used to understand how a trait or characteristic has evolved over time and how it has changed in different populations. |
| Anthropology | Anthropology is the study of humans and human societies, including their culture, biology, and evolution. It is a broad field that encompasses many different subfields, including cultural anthropology, linguistic anthropology, physical anthropology, and archaeology. |
| Ashkenazi | Ashkenazi refers to Jewish people who have descended from the Jewish communities of Central and Eastern Europe. The term “Ashkenazi” comes from the Hebrew word for Germany, and Ashkenazi Jews are often referred to as “Eastern European Jews.” |
| Autosomal DNA (atDNA) | Autosomal DNA (atDNA) is the DNA that is found in the 22 pairs of chromosomes that are not the sex chromosomes (X and Y). AtDNA is inherited from both parents and is responsible for most of an individual’s physical characteristics, such as eye color, hair color, and facial features. |
| Autosome | An autosome is a chromosome that is not a sex chromosome (X or Y). Humans have 22 pairs of autosomes, for a total of 44 autosomes. Autosomes are responsible for most of an individual’s physical characteristics, such as eye color, hair color, and facial features. |
| Back Mutation | A back mutation is a mutation that reverses the effects of a previous mutation. This can occur when a mutation changes a gene’s function, and then a subsequent mutation restores the gene’s original function. |
| Base | A base is one of the four nucleotide building blocks of DNA and RNA. The bases are adenine, cytosine, guanine, and thymine (in DNA) or uracil (in RNA). The sequence of bases in a DNA molecule carries the genetic information that is used to build and maintain an organism. |
| Base Pair | A base pair is a pair of nucleotide bases that are bonded together through hydrogen bonding. In DNA, the base pairs are adenine-thymine and cytosine-guanine. In RNA, the base pairs are adenine-uracil and cytosine-guanine. The base pairs hold the two strands of the DNA double helix together and provide the template for protein synthesis. |
| Buccal Cell | A buccal cell is a type of epithelial cell that is found in the lining of the mouth. Buccal cells can be collected by gently rubbing a cotton swab or a small scraper against the inside of the cheek. Buccal cells are often used for DNA testing because they are easy to collect and contain a high concentration of DNA. |
| Catalyst | A catalyst is a substance that speeds up a chemical reaction without being consumed by the reaction. Catalysts work by providing a lower energy pathway for the reaction to take place, which makes the reaction happen more quickly. |
| CentiMorgan (cM) | A centiMorgan (cM) is a unit of genetic distance that is used to measure the amount of recombination that has occurred between two markers or genes. One centiMorgan is equivalent to a 1% chance that a marker or gene will be transmitted to an offspring through recombination. |
| Centromere | The centromere is the point on a chromosome where the two chromatids are held together. It is located in the center of the chromosome and is responsible for the proper segregation of the chromosome during cell division. |
| Chromatid | A chromatid is one of the two identical strands of DNA that are held together at the centromere during cell division. Each chromatid is a copy of the original chromosome and contains the same genetic information. |
| Chromosome | Chromosomes are structures found in the nucleus of cells that contain the genetic material (DNA) of an organism. They are made up of DNA and proteins, and they are found in the cells of all living organisms. Humans have 23 pairs of chromosomes, for a total of 46 chromosomes. |
| Clade | A clade is a group of organisms that share a common ancestor and are considered to be more closely related to each other than to other organisms. Clades can be identified based on shared characteristics or by analyzing the evolutionary relationships between different groups of organisms. |
| Codon | A codon is a sequence of three nucleotide bases in DNA or RNA that specifies a particular amino acid. The sequence of codons in a gene determines the sequence of amino acids in the protein that is produced by that gene. |
| Cohanim Modal Haplotype (CMH) | The Cohanim Modal Haplotype (CMH) is a genetic signature that is shared by many male members of the Cohanim, a Jewish priestly caste. The CMH is a specific pattern of genetic markers on the Y chromosome, which is passed down from father to son. |
| Cohen | Cohen (also spelled Kohanim or Kohen) is a Hebrew word meaning “priest.” It is often used as a surname by people of Jewish ancestry, and it is also the name of a Jewish priestly caste, the Cohanim. |
| Complementary Sequences | Complementary sequences are sequences of nucleotides (the building blocks of DNA) that can bind to each other in a specific way. Complementary sequences are made up of pairs of nucleotides, with one nucleotide from each pair being complementary to the other. For example, the nucleotide adenine (A) is complementary to thymine (T), and cytosine (C) is complementary to guanine (G). |
| Consanguinity | Consanguinity refers to a relationship between individuals who are descended from a common ancestor. This can include relationships between siblings, cousins, and other close relatives. |
| Convergence | Convergence refers to the process by which two or more different species evolve similar characteristics over time due to similar selective pressures in their environments. This can happen when two species live in similar environments and face similar challenges, which leads them to evolve similar adaptations in order to survive. |
| Cytosine | Cytosine is a pyrimidine base that is found in DNA and RNA. It is one of the four nucleotide bases, along with adenine, guanine, and thymine (in DNA) or uracil (in RNA). Cytosine pairs with guanine through hydrogen bonding, forming one of the two base pairs in the DNA double helix. |
| Deletion | Deletion refers to the loss or removal of a section of DNA from a chromosome. This can occur due to a mutation, which is a change in the genetic material of an organism. Deletions can have a variety of effects on an organism, depending on the size and location of the deleted section of DNA. |
| Deoxyribonucleic Acid (DNA) | Deoxyribonucleic acid (DNA) is a molecule that contains the genetic instructions used in the development and function of all known living organisms. It is made up of long chains of nucleotides, which are the building blocks of DNA. DNA is found in the nucleus of cells and is passed from parent to offspring during reproduction. |
| Derived State | A derived state is a trait or characteristic that has evolved in a particular group of organisms after they have diverged from a common ancestor. Derived states are often seen as being more advanced or specialized than the ancestral state, as they are thought to have evolved in response to specific selective pressures in the environment. |
| Descendant | A descendant is an individual or group of individuals that are descended from a common ancestor. Descendants can be traced through a family tree or genealogy, and they may share certain genetic characteristics or traits with their ancestors. |
| Diaspora | Diaspora refers to the dispersion or scattering of a group of people from their original homeland. This can happen for a variety of reasons, including war, persecution, or economic opportunities. Diaspora communities often maintain cultural ties to their homeland and may have a shared history and cultural traditions. |
| D-Loop | The D-loop, or displacement loop, is a region of DNA that is found in the mitochondria. It is called the D-loop because it is shaped like a D when it is visualized on an electrophoresis gel. The D-loop is involved in the regulation of DNA replication and transcription in the mitochondria. |
| DNA Replication | DNA replication is the process by which cells produce copies of their genetic material (DNA) in preparation for cell division. It is a vital process that occurs in all living organisms and is essential for the transmission of genetic information from one generation to the next. |
| DNA Segment | A DNA segment is a section or piece of DNA. DNA segments can vary in size, and they may contain one or more genes or other functional elements. DNA segments can be studied to understand the genetic makeup of an organism and to identify genetic variations that may be associated with certain traits or conditions. |
| DNA Sequencing | DNA sequencing is a laboratory technique that is used to determine the order of the nucleotides (the building blocks of DNA) in a specific piece of DNA. It allows researchers to determine the sequence of genes and other functional elements within a DNA molecule, which can provide insights into an organism’s genetic makeup and function. |
| Dominant | A dominant trait is a trait that is expressed in an individual even if they only have one copy of the trait-associated gene. Dominant traits are usually represented by a capital letter (e.g. A) in genetics notation. |
| Double Helix | The double helix is the structure of DNA, which is made up of two strands of nucleotides that are twisted together in a spiral shape. The double helix was first described by James Watson and Francis Crick in the 1950s, and it is the basis for our understanding of genetics and heredity. |
| Earliest Known Ancestor | The earliest known ancestor is the earliest known member of a particular family or group of individuals. This individual may be traced through a family tree or genealogy and may be a distant relative of the current members of the group. |
| Endogamous | Endogamy refers to the practice of marrying within a specific group or community. This can include marriage within a particular ethnic group, religion, or social class. Endogamy may be practiced for cultural or religious reasons, or it may be driven by social or economic factors. |
| Enzyme | An enzyme is a protein that catalyzes (speeds up) chemical reactions in the body. Enzymes are found in all living cells and perform a variety of functions, including digestion, metabolism, and DNA synthesis. |
| Evolution | Evolution is the process by which populations of organisms change over time in response to their environment. Evolution can occur through the process of natural selection, in which individuals with traits that are advantageous for survival and reproduction are more likely to pass those traits on to their offspring. |
| Exact Match | An exact match refers to a situation in which two or more things are identical or exactly the same. In the context of genetics, an exact match may refer to two individuals who have the same genetic makeup, or to two DNA samples that are identical. |
| Exogamy | Exogamy refers to the practice of marrying outside of a specific group or community. This can include marriage outside of a particular ethnic group, religion, or social class. Exogamy may be practiced for cultural or religious reasons, or it may be driven by social or economic factors. |
| Gene | A gene is a unit of genetic information that is found on a chromosome and is passed from parent to offspring. Genes contain the instructions for making proteins and other molecules that are involved in the development and function of an organism. |
| Genealogical Time Frame | A genealogical time frame is a period of time within which a particular family or group of individuals can be traced through a family tree or genealogy. This may include several generations of ancestors and descendants and may span several centuries. |
| Genealogy | Genealogy is the study of family history and ancestry. It involves researching and documenting the relationships between individuals and their ancestors and descendants, and it often includes creating a family tree or pedigree chart. Genealogy can be a hobby or a profession, and it can be used to trace a family’s history and cultural heritage. |
| Genetic Diversity | Genetic diversity refers to the variety of different genes and alleles that are present within a population. High levels of genetic diversity can increase the adaptability of a population and increase its chances of survival. |
| Genetic Drift | Genetic drift is a process by which the frequency of a gene or allele in a population changes by chance. It can occur in small populations due to the random sampling of genes from one generation to the next. |
| Genetics | Genetics is the study of genes, heredity, and the variation of inherited characteristics. It is a branch of biology that deals with the transmission and expression of genetic information and the variation of inherited traits. Genetics is important for understanding the inherited basis of traits and conditions and for developing treatments and therapies for genetic conditions. |
| Genome | The genome is the complete set of genetic material (DNA) of an organism. It includes all of the genes and other functional elements that make up an organism’s DNA, and it is often studied to understand the genetic makeup and function of an organism. |
| Genotype | The genotype is the genetic makeup of an individual, which includes all of the genes and inherited variations that an individual carries. The genotype determines an individual’s inherited characteristics and traits, such as their physical appearance, susceptibility to certain conditions, and certain behaviors. |
| Glacial maximum | A glacial maximum refers to a period of time when ice sheets and glaciers covered the maximum amount of land. During a glacial maximum, the Earth’s climate is typically much colder and drier than it is during other times. Glacial maximums have occurred several times in Earth’s history, and they can have significant impacts on the environment and on the distribution of plant and animal species. |
| Guanine | Guanine is a purine base that is found in DNA and RNA. It is one of the four nucleotide bases, along with adenine, cytosine, and thymine (in DNA) or uracil (in RNA). Guanine pairs with cytosine through hydrogen bonding, forming one of the two base pairs in the DNA double helix. |
| Haplogroup | A haplogroup is a group of people who share a common ancestor and a specific set of genetic markers. Haplogroups can be used to trace ancestry and understand the genetic relationships between different populations. |
| Haplotype | A haplotype is a group of genetic markers that are inherited together and passed down from one generation to the next. Haplotypes can be used to trace ancestry and understand the genetic relationships between different populations. |
| Heredity | Heredity is the process by which characteristics and traits are passed down from parents to their offspring. Heredity occurs through the transmission of genes from one generation to the next, and it plays a role in determining an individual’s inherited characteristics and traits. |
| Heterozygous | An individual is heterozygous for a particular gene or trait if they have two different alleles for that gene or trait. Heterozygous individuals have one dominant allele and one recessive allele and will usually express the dominant trait. |
| Homozygous | An individual is homozygous for a particular gene or trait if they have two identical alleles for that gene or trait. Homozygous individuals will always express the trait associated with the allele they possess. |
| HVR1 – 16001 to 16569 | HVR1 (Hypervariable Region 1) is a section of DNA that is found on the non-coding region of the mitochondria (the energy-producing organelles in cells). HVR1 is a section of DNA that is thought to be particularly prone to mutation, and it is often used in genetic genealogy to trace ancestry and to identify genetic relationships between individuals. The section of HVR1 that is numbered 16001 to 16569 is one of several subregions within HVR1 that are used for genetic analysis. |
| HVR2 – 00001 to 00574 | HVR2 (Hypervariable Region 2) is another section of DNA that is found on the non-coding region of the mitochondria. Like HVR1, HVR2 is a section of DNA that is thought to be particularly prone to mutation and is often used in genetic genealogy to trace ancestry and identify genetic relationships between individuals. The section of HVR2 that is numbered 00001 to 00574 is one of several subregions within HVR2 that are used for genetic analysis. |
| Hypervariable Region (HVR) | A hypervariable region (HVR) is a section of DNA that is characterized by a high degree of variation or mutation. HVRs are often used in genetic genealogy to trace ancestry and to identify genetic relationships between individuals. There are two main HVRs in the human genome |
| Identical By Descent (IBD) | Identical by descent (IBD) refers to a situation in which two or more individuals share the same genetic material that has been inherited from a common ancestor. This means that the individuals have inherited the same genetic material from the same ancestor, and they are considered to be genetically identical. |
| Levite | A Levite is a member of the Levitical priestly caste in Judaism. The Levites are descended from the tribe of Levi and are responsible for performing certain religious duties in the Jewish faith. |
| Lineage | Lineage refers to a family line or ancestry. It can refer to the ancestry of an individual or a group of individuals, and it often includes a record of the individuals’ ancestors and descendants. Lineage can be traced through a family tree or genealogy and may be used to understand a family’s history and cultural heritage. |
| Linkage Disequilibrium | Linkage disequilibrium is the non-random association of alleles at different loci on a chromosome. It occurs when certain combinations of alleles are more common in a population than would be expected by chance. |
| Locus | A locus is the specific location of a gene or other functional element on a chromosome. Each gene has a specific locus on a chromosome, and the locus of a gene can be used to identify and study the gene. |
| Longest Block | The longest block is the longest segment of DNA that two individuals share in common. It is often used in genetic genealogy to identify relationships between individuals and to trace ancestry. The length of the longest block can provide information about how closely related two individuals are and how far back their common ancestry may go. |
| Meiosis | Meiosis is the process of cell division that occurs during the production of reproductive cells (gametes). It is a specialized form of cell division that results in the production of four daughter cells, each of which has half the number of chromosomes as the parent cell. Meiosis is important for ensuring that the genetic information of an organism is passed on to the next generation in a controlled and accurate way. |
| Micro-Allele | A micro-allele is a variation in a gene that occurs at a single nucleotide (the building blocks of DNA) and that is often not detectable by standard genetic testing methods. Micro-alleles are often used in genetic genealogy to trace ancestry and to identify genetic relationships between individuals. |
| Microarray Chip | A microarray chip (also known as a DNA chip or gene chip) is a laboratory tool that is used to study the expression of many genes simultaneously. It consists of a small glass or plastic chip that is coated with DNA probes that can bind to specific genes or genetic sequences. Microarray chips are often used in genetic research and in medical diagnostic testing to study the genetic basis of diseases and to identify genetic markers for conditions or traits. |
| Mitochondria | Mitochondria are small organelles found in the cells of all living organisms. They are responsible for producing energy for the cell, and they contain their own set of genetic material (DNA). Mitochondrial DNA (mtDNA) is passed down from mother to offspring and is used to trace maternal ancestry. |
| Mitochondrial DNA (mtDNA) | Mitochondrial DNA (mtDNA) is the DNA found in the mitochondria, the energy-producing organelles in cells. MtDNA is passed down from mother to offspring, and it is used to trace maternal ancestry. MtDNA is often used in genetic genealogy to trace ancestry and to identify genetic relationships between individuals. |
| Mizrahi | Mizrahi is a term that refers to Jews who are descended from the Jewish communities of the Middle East and North Africa. Mizrahi Jews often have a distinct cultural and linguistic heritage, and they may also have unique genetic characteristics. |
| Modal haplotype | A modal haplotype is a specific pattern of genetic markers that is shared by many members of a particular group or population. Modal haplotypes are often used in genetic genealogy to trace ancestry and to identify genetic relationships between individuals. |
| Mutation | A mutation is a change in the DNA sequence of a gene or chromosome. Mutations can be harmful, neutral, or beneficial, and they can be caused by a variety of factors, including environmental exposure and mistakes during DNA replication. |
| Mutation Rate | The mutation rate is the rate at which mutations occur in the genetic material of an organism. The mutation rate can vary among different organisms and can be influenced by various factors, such as environmental exposures and the presence of certain genetic conditions. |
| Natural Selection | Natural selection is the process by which populations of organisms change over time in response to their environment. It occurs when individuals with traits that are advantageous for survival and reproduction are more likely to pass those traits on to their offspring. |
| No Call | A “no call” result in genetic testing refers to a situation in which a particular genetic variation or allele cannot be accurately determined. This may occur due to a variety of factors, such as a low quality sample or a technical error. |
| Non-Coding DNA | Non-coding DNA is DNA that does not contain the instructions for making proteins or other functional molecules. Non-coding DNA is often referred to as “junk DNA” because it does not have a known function. However, recent research has suggested that non-coding DNA may play a role in regulating the expression of genes and in other cellular processes. |
| Non-Recombining Y (NRY) | The non-recombining Y (NRY) is a section of the Y chromosome that does not exchange genetic material with other chromosomes during meiosis (the process of cell division that occurs during the production of reproductive cells). The NRY is often used in genetic genealogy to trace ancestry and to identify genetic relationships between individuals, as it is passed down from father to son with little variation. |
| Novel Variant | A novel variant is a genetic variation or allele that has not been previously observed or described. Novel variants may be identified through genetic testing or through the study of genetic material, and they may be of interest to researchers because they may be associated with certain traits or |
| Nuclear DNA | Nuclear DNA is the DNA found in the nucleus of a cell. It is organized into chromosomes and contains the instructions for making proteins and other functional molecules. Nuclear DNA is inherited from both parents and plays a role in determining an individual’s inherited characteristics and traits. |
| Nucleic Acids | Nucleic acids are large molecules that are found in all living cells and that play a vital role in the storage and transmission of genetic information. There are two main types of nucleic acids |
| Nucleotide | A nucleotide is the building block of DNA and RNA. It is made up of a sugar molecule, a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine in DNA; adenine, guanine, cytosine, uracil in RNA). Nucleotides are joined together to form long chains, which make up the genetic material of an organism. |
| Nucleus | The nucleus is a structure found in the cells of all living organisms. It is separated from the rest of the cell by a membrane and contains the cell’s genetic material (DNA). The nucleus is the control center of the cell and plays a vital role in the regulation of cell growth and function. |
| Organelle | An organelle is a small, specialized structure found within a cell that performs a specific function. There are many different types of organelles, including the mitochondria (which produce energy for the cell), the ribosomes (which synthesize proteins), and the endoplasmic reticulum (which processes and transports proteins). |
| Outbreed | Outbreeding refers to the practice of breeding or reproducing with individuals who are not closely related. Outbreeding can lead to greater genetic diversity within a population and may reduce the occurrence of inherited genetic conditions. |
| P Arm | The P arm is one of the two arms of a chromosome (the other is the Q arm). The P arm is the shorter of the two arms and is typically labeled with the letter “p.” Each chromosome has a P arm and a Q arm, and the location of a gene or other functional element on a chromosome can be identified by its position on the P or Q arm. |
| Palindrome | A palindrome is a word or sequence of characters that reads the same forwards and backwards. In genetics, a palindrome may refer to a sequence of DNA or RNA that is the same when read in either direction. Palindromes may play a role in the regulation of gene expression and in other cellular processes. |
| Parallel Mutation | Parallel mutation refers to the occurrence of the same mutation in different individuals or populations. Parallel mutations may be the result of a common ancestor or of exposure to the same environmental factors, and they may be used to trace ancestry and to identify genetic relationships between individuals. |
| Phenotype | The phenotype is the observable characteristics of an organism, including its physical traits, behaviors, and other traits. The phenotype is determined by both an individual’s genotype (their genetic makeup) and the influence of the environment. |
| Pherogram | A pherogram is a graphical representation of electrophoresis data that shows the separation of DNA or protein samples based on size, charge, or both. Pherograms are often used in molecular biology and genetics to analyze the structure and function of DNA and proteins. |
| Phylogenetic Tree | A phylogenetic tree is a graphical representation of the evolutionary relationships between different organisms. It is based on the concept of common ancestry and shows how different species are related through time. The tree is constructed using data from molecular sequences or other genetic or morphological characteristics, and the relationships between the organisms are inferred based on statistical analysis. |
| Phylogenetics | Phylogenetics is the study of evolutionary relationships between organisms. It uses methods from molecular biology, genetics, and computational biology to analyze the evolutionary history of different species and understand how they are related. |
| Polymerase | A polymerase is an enzyme that synthesizes a polymer, which is a long chain of repeating units called monomers. Polymerases are important in many biological processes, including DNA replication, RNA synthesis, and protein synthesis. |
| Polymorphism | Polymorphism is the presence of two or more forms of a gene within a population. These forms are called alleles, and they can lead to differences in the traits or characteristics of an organism. Polymorphism is an important source of genetic variation, which is necessary for the process of evolution. |
| Population | A population is a group of individuals of the same species living in the same area. Populations can be studied to understand the genetic makeup and characteristics of the individuals within them, and to understand how these characteristics change over time. |
| Population Bottleneck | A population bottleneck is a sudden decrease in the size of a population, which can lead to a loss of genetic diversity. This can happen due to natural disasters, human activities, or other factors. Population bottlenecks can have significant impacts on the evolutionary potential of a species, as the smaller population may not have the same genetic diversity as the original population. |
| Primer | A primer is a short piece of DNA or RNA that serves as a starting point for DNA synthesis. Primers are used in a variety of molecular biology techniques, including polymerase chain reaction (PCR), DNA sequencing, and gene expression analysis. |
| Protein | Proteins are large, complex molecules made up of chains of amino acids. They play a vital role in many biological processes, including catalyzing chemical reactions, replicating DNA, and repairing tissues. Proteins can be found in all cells and tissues, and they are essential for the structure, function, and regulation of the body’s tissues and organs. |
| Q Arm | The Q arm is one of the two arms of a chromosome, the other being the P arm. The Q arm is the longer of the two arms and is named for the French word “quatorze,” which means “fourteen,” as it was originally identified as the shorter arm of chromosome 14. The location of specific genes on a chromosome is usually described in terms of their position on the Q or P arm. |
| Recessive | A recessive trait is a trait that is only expressed in an individual if they have two copies of the trait-associated gene. Recessive traits are usually represented by a lowercase letter (e.g. a) in genetics notation. |
| Recombination | Recombination is the process by which genetic material from different sources is brought together to create a new combination of traits. This can occur naturally through processes such as sexual reproduction, or it can be artificially induced through techniques such as genetic engineering. |
| Replication | Replication is the process by which an organism’s cells or a virus’s genetic material copies itself in preparation for cell division. This process is necessary for the continuation of life, as it ensures that each new cell or virus produced contains a complete set of genetic instructions. |
| Restricition enzyme | A restriction enzyme is a type of enzyme that cuts DNA at specific sequences called recognition sites. These enzymes are used in molecular biology laboratories to cut and paste DNA fragments together, a process known as restriction digestion. |
| Sephardic | Sephardic refers to the descendants of the Jews who lived in the Iberian Peninsula (Spain and Portugal) before their expulsion in the late 15th century. The term is often used to distinguish these Jews from Ashkenazi Jews, who have roots in central and eastern Europe. |
| Sex chromosomes | Sex chromosomes are chromosomes that determine an individual’s sex. In humans, females have two copies of the X chromosome (XX), while males have one X chromosome and one Y chromosome (XY). |
| Short tandem repeat (STR) | A short tandem repeat (STR) is a type of DNA sequence that consists of a short sequence of nucleotides that is repeated a number of times in a row. STRs are used in forensic genetics and ancestry testing as a way to identify individuals based on their unique pattern of STRs. |
| Sister clade | A sister clade is a group of closely related organisms that share a common ancestor and are considered to be part of the same branch on the tree of life. A subclade is a smaller group within a larger clade. |
| SNP | A SNP, or single nucleotide polymorphism, is a variation in a single nucleotide base in the DNA sequence. SNPs are the most common type of genetic variation, and they can be used to trace ancestry and understand the genetic relationships between different populations. |
| Surname | A surname is a family name passed down from one generation to the next. Surnames are often used to trace ancestry and identify family relationships. |
| Telomeres | Telomeres are structures found at the ends of chromosomes that protect the ends of the chromosomes from damage or from joining with other chromosomes. Telomeres shorten with each cell division, and their length is thought to be related to the aging process. |
| The Human Genome Project | The Human Genome Project was an international research project that was launched in 1990 with the goal of sequencing the entire human genome. The project was completed in 2003, and it provided a wealth of information about the genetic makeup of humans and how genes function. |
| Thymine | Thymine is a pyrimidine base that is found only in DNA. It is one of the four nucleotide bases, along with adenine, cytosine, and guanine. Thymine pairs with adenine through hydrogen bonding, forming one of the two base pairs in the DNA double helix. |
| Trait | A trait is a characteristic or feature of an organism that is determined by its genotype (genetic makeup) and influenced by the environment. Traits can be physical, such as eye color or height, or behavioral, such as personality or social behavior. |
| Transfer RNA (tRNA) | Transfer RNA (tRNA) is a small RNA molecule that plays a critical role in protein synthesis. tRNA molecules bind to specific amino acids and bring them to the ribosomes, where they are incorporated into the growing protein chain. |
| Transition | A transition is a change in the genetic code from one nucleotide to another that involves the substitution of a purine for a purine (A for G or G for A) or a pyrimidine for a pyrimidine (C for T or T for C). |
| Transmission event | A transmission event is the transfer of genetic material from one organism to another, either through reproduction or through the transfer of genetic material between cells or viruses. |
| Transversion | A transversion is a change in the genetic code from one nucleotide to another that involves the substitution of a purine for a pyrimidine (A for C or G for T) or a pyrimidine for a purine (C for A or T for G). |
| Uracil | Uracil is a pyrimidine base that is found only in RNA. It is one of the four nucleotide bases, along with adenine, cytosine, and guanine. Uracil pairs with adenine through hydrogen bonding, forming one of the two base pairs in RNA. |
| X chromosome | The X chromosome is one of the two sex chromosomes in humans. It is inherited from the mother and contains many genes that are important for various bodily functions. |
| X match | An X match is a type of genetic test that compares the X chromosomes of two individuals to see if they are related. This test is often used to determine paternity or to trace ancestry through the maternal line. |
| X-Linked | X-linked traits are traits that are associated with genes that are located on the X chromosome. X-linked traits are usually more common in males because they only have one X chromosome, while females have two X chromosomes and are more likely to have at least one dominant allele that can mask the effects of the recessive allele. |
| Y-Chromosome | The Y chromosome is one of the two sex chromosomes in humans and other mammals. It is found only in males and is responsible for determining male sex and the development of male characteristics. The Y chromosome is much smaller than the X chromosome and contains a relatively small number of genes. |
