Explorations: An Open Invitation to Biological Anthropology - Chapter 3

allele

a non-identical DNA sequence found in the same gene location on a homologous chromosome, or gene copy, that codes for the same trait but produces a different phenotype

amino acids

organic molecules that are the building blocks of protein; all 20 of these each have their own unique chemical property; these are also chained together to form proteins

ancient (aDNA)

DNA that is isolated from organic remains often dating from hundreds to thousands of years ago; typically degraded (i.e., damaged) due to exposure to the elements such as heat, acidity, and humidity

aneuploid

a cell with an unexpected amount of chromosomes; the loss or gain of chromosomes can occur during mitotic or meiotic division

antibodies

immune-related proteins that can detect and bind to foreign substances in the blood such as pathogens

apoptosis

a series of molecular steps that is activated leading to cell death; can be activated when a cell fails checkpoints during the cell cycle; however, cancer cells have the ability to avoid this process

autosomal

refers to a pattern of inheritance where an allele is located on an autosome

base pairs

chemical bonding between nucleotides, like adenine (A) and thymine (T) or cytosine (C) and guanine (G) in DNA; or (A) and uracil (U) in RNA

carbohydrate

molecules composed of carbon and hydrogen atoms that can be broken down to supply energy

carrier

an individual who has a heterozygous genotype that is typically associated with a disease

cell cycle

a cycle the cell undergoes with checkpoints between phases to ensure that DNA replication and cell division occur properly

cell surface antigen

a protein that is found on a red blood cell's surface

centromere

a structural feature that is defined as the "center" of a chromosome and which creates two different arm lengths; term also refers to the region of attachment for microtubules during mitosis and meiosis

chromatin

DNA wrapped around histone complexes; during cell division, this material becomes a condensed chromosome

chromosome

DNA molecule that is wrapped around protein complexes, including histones

codominance

the effects of both alleles in a genotype can be seen in the phenotype

codons

a sequence that comprises three DNA nucleotides that together code for a protein

complex diseases

a category of diseases that are polygenic and are also influenced by environment and lifestyle factors

cytoplasm

the "jelly-like" matrix inside of the cell that contains many organelles and other cellular molecules

deleterious

a mutation that increases an organism's susceptibility to disease

deoxyribonucleic acid (DNA)

a molecule that carries the heredity information passed down from parents to offspring; can be described as a "double helix" shape; it includes two chains of nucleotides held together by hydrogen bonds with a sugar-phosphate backbone

diploid

refers to an organism or cell with two sets of chromosomes

DNA methylation

methyl groups bind DNA, which modifies the transcriptional activity of a gene by turning it "on" or "off"

DNA polymerase

enzyme that adds nucleotides to existing nucleic acid strands during DNA replication; these enzymes can be distinguished by their processivity (e.g., DNA replication)

DNA replication

cellular process in which DNA is copied and doubled

DNA sequence

the order of nucleotide bases; a DNA sequence can be short, long, or representative of entire chromosomes or organismal genomes

dominant

refers to an allele for which one copy is sufficient to be visible in the phenotype

elongation

the assembly of new DNA from template strands with the help of DNA polymerases

enzymes

proteins responsible for catalyzing (accelerating) various biochemical reactions in cells

epigenetic profile

the methylation pattern throughout a genome - that is, when genes (and other genomic sites) are methylated and unmethylated

epigenetics

changes in gene expression that do not result in a change of the underlying DNA sequence; these changes typically involve DNA methylation and histone modifications; these changes are reversible and can also be inherited by the next generation

euchromatin

loosely coiled chromosomes found within the nucleus that is accessible for regulatory processing of DNA

eukaryote

single-celled or multi-celled organism characterized by a distinct nucleus, with each organelle surrounded by its own membrane

exon

protein-coding segment of a gene

gametes

haploid cells referred to as an egg and sperm that will fuse together during sexual reproduction to form a diploid organism

gene

segment of DNA that contains protein-coding information and various regulatory (e.g., promoting) and noncoding (e.g., introns) regions

genetic recombination

a cellular process that occurs during meiosis in which homologous chromosomes pair up and sister chromatids on different chromosomes physically swap genetic information

genome

all the genetic information of an organism

genotype

the combination of two alleles that code for or are associated with the same gene

genotyping

a molecular procedure that is performed to test for the presence of certain alleles or to discover new ones

haploid

cell or organism with one set of chromosomes (n=23)

helicase

a protein that breaks the hydrogen bonds that hold double-stranded DNA together

heterozygous

genotype that consists of two different alleles

histones

protein that DNA wraps around to assist with DNA organization within the nucleus

homologous chromosomes

a matching pair of chromosomes wherein one chromosome is maternally inherited and the other is paternally inherited

homozygous

genotype that consists of two identical alleles

incomplete dominance

heterozygous genotype that produces a phenotype that is a blend of both alleles

initiation

the recruitment of proteins to separate DNA strands and begin DNA replication

interphase

preparatory period of the cell cycle when increased metabolic demand allows for DNA replication and doubling of the cell prior to cell division

introns

segment of DNA that does not code for proteins

karyotyping

the microscopic procedure where the number of chromosomes in a cell is determined

lagging strand

DNA template strand that is opposite to the leading strand; therefore, DNA replication proceeds discontinuously, generating Okazaki fragments

leading strand

DNA template strand in which replication proceeds continuously

lipids

fatty acid molecules that serve various purposes in the cell, including energy storage, cell signaling, and structure

meiosis

the process that gametes undergo to divide; the end of this process results in four haploid daughter cells

Mendelian genetics

a classification given to phenotypic traits that are controlled by a single gene

messenger RNA (mRNA)

RNA molecule that is transcribed from DNA; its tri-nucleotide codons are "read" by a ribosome to build a protein

microarray technology

a genotyping procedure that utilizes a microarray chip, which is a collection of thousands of short nucleotide sequences attached to a solid surface that can probe genomic DNA

microbiome

the collective genomes of the community of microorganisms that humans have living inside of their body

mitochondrial DNA (mtDNA)

circular DNA segment found in mitochondria that is inherited maternally

mitochondrion

specialized cellular organelle that is the site for energy production; it also has its own genome (mtDNA)

mitosis

the process that somatic cells undergo to divide; the end of this process results in two diploid daughter cells

mutation

a nucleotide sequence variation from the template DNA strand that can occur during replication; these can also happen during recombination

next-generation sequencing

a genotyping technology that involves producing millions of nucleotide sequences (from a single DNA sample) that are then read with a sequencing machine; it can be used for analyzing entire genomes or specific regions and requires extensive program-based applications

nuclear envelope

a double-layered membrane that encircles the nucleus

nucleic acid

a complex structure (like DNA or RNA) that carries genetic information about a living organism

nucleotide

the basic structural component of nucleic acids, which includes DNA (A, T, C, and G) and RNA (A, U, C, and G)

nucleus

double-membrane cellular organelle that helps protect DNA and regulation of nuclear activities

Okazaki fragments

short DNA strands derived from DNA replication on the lagging strand; they were discovered by Reiji and Tsuneko Okazaki in the 1960s

organelle

a structure within a cell that performs specialized tasks that are essential for the cell; there are different types of organelles with their own function

pathogenic

a genetic mutation (i.e., allele) that has a harmful phenotypic disease-causing effect

penetrance

the proportion of how often the possession of an allele results in an unexpected phenotype; some alleles have more of this quality than others

phenotype

the physical appearance of a given trait

phospholipid bilayer

two layers of lipids that form a barrier due to the properties of a hydrophilic (water-loving) head and a hydrophobic (water-repelling) tail

polygenic trait

a phenotype that is controlled by two or more genes

polymerase chain reaction (PCR)

a molecular biology procedure that can make copies of genomic DNA segments; a small amount of DNA is used as a starting template and is then used to make millions of copies

primer

a small sequence of nucleotides that bind DNA to start the process of DNA replication or PCR

prokaryote

a single-celled organism characterized by lack of a nucleus and membrane-enclosed organelles

promoter

the region of a gene that initiates transcription; transcription factors can bind and DNA methylation may occur at one of these sites, which can modify the transcriptional activities of a gene

protein

chain of amino acids that fold into a three-dimensional structure that allow a cell to function in a variety of ways

protein synthesis

a multi-step process by which amino acids are strung together by RNA machinery read from a DNA template

recessive

refers to an allele whose effect is not normally seen unless two copies are present in an individual's genotype

ribonucleic acid (RNA)

single-stranded nucleic acid molecule; there are different versions of these found within cells and they perform a variety of functions, such as cell signaling and involvement in protein synthesis

ribosomal RNA (rRNA)

a ribosome-bound molecule that is used to correctly assemble amino acids into proteins

ribosome

an organelle in the cell found in the cytoplasm or endoplasmic reticulum; responsible for reading mRNA and protein assemblage

RNA polymerase

an enzyme that catalyzes the process of making RNA from a DNA template

Sanger-sequencing

a process that involves the usage of fluorescently labeled nucleotides to visualize DNA (PCR fragments) at the nucleotide level

semi-conservative replication

DNA replication in which new DNA is replicated from an existing DNA template strand

sequencing

a molecular laboratory procedure that produces the order of nucleotide bases (i.e., sequences)

sister chromatids

during DNA replication, these are produced on the chromosome; in cell division, these are pulled apart so that two cells can be formed; in meiosis these are also the sites of genetic recombination

somatic cells

diploid cells that comprise body tissues and undergo mitosis for maintenance and repair of tissues

splicing

the process by which mature mRNAs are produced; introns are removed and exons are joined together

sugar phosphate backbone

a biochemical structural component of DNA; consists of deoxyribose sugars and phosphate molecules

telomere

a compound structure located at the ends of chromosomes to help protect the chromosomes from degradation after every round of cell division

termination

the halt of DNA replication activity that occurs when a DNA sequence "stop" codon is encountered

tissue

a cluster of cells that are morphologically similar and perform the same task

transcription

the process by which DNA nucleotides (within a gene) are copied, which results in a messenger RNA molecule

transcription factors

proteins that bind to regulatory regions of genes (e.g., promoter) and increase or decrease the amount of transcriptional activity of a gene, including turning them "on" or "off"

transfer RNA (tRNA)

RNA molecule involved translation; transfers amino acids from the cell's cytoplasm to a ribosome

translation

the process by which messenger RNA codons are read and amino acids are "chained together" to form proteins