Science: Genes and DNA

Everything

adenine (A)

A nitrogen-rich base that forms a pair with thymine (T).

alleles

Different forms of the same gene located at the same point of homologous chromosomes.

autosomes

All the chromosomes in a cell other than the sex chromosomes.

carcinogen

A mutagen that can lead to cancer.

centromere

The point on a chromosome where the two chromatids are joined together.

chromatid

One of the strands of a chromosome following replication.

chromosomes

Thread-like structures in the nucleus composed of DNA and proteins; contains genetic information in the form of genes.

complementary base pairs

A pair of bases that can join to make the rungs of the DNA ladder—adenine and thymine, guanine and cytosine.

cytosine (C)

A nitrogen-rich base that forms a pair with guanine (G).

deoxyribonucleic acid (DNA)

A double helix made of nucleotides; the molecule that determines the genetic characteristics of most living things.

deoxyribose sugar

One of the parts that make up a nucleotide.

diploid number

The number of chromosomes in body cells; two sets or 2n.

DNA profiling

A pattern of DNA fragments unique to each individual.

dominant trait

The trait that is observed in the outward appearance of a heterozygous individual.

double helix

Shape like that of a twisted rope ladder.

gametes

Sperm and egg cells.

gene

A section of DNA that carries the genetic code for a particular characteristic.

gene splicing

The process used to add a gene into or remove genes from DNA.

gene therapy

The process of replacing a defective gene with a normal gene.

genetically modified

Having the genes changed.

genetics

The study of inherited characteristics called traits.

genome

The complete set of DNA including all the genes of a cell, individual, or species.

genotype

Genetic information carried by an individual.

guanine (G)

A nitrogen-rich base that forms a pair with cytosine (C).

haploid number

The number of chromosomes in gametes; one set or n.

heterozygous

Having two different alleles on homologous chromosomes.

homologous chromosomes

Chromosomes with genes for particular characteristics at the same location.

homozygous

Having two identical alleles on homologous chromosomes.

induced pluripotent stem cells (iPSCs)

Cells that have been made to revert to pluripotent state by the introduction of certain genes.

meiosis

The type of cell division that produces gametes with half the number of chromosomes of the parent cell.

mitosis

The type of cell division that produces two daughter cells identical to the parent cell.

mutagen

An agent that causes a mutation.

mutation

A mistake that happens as DNA is copied, causing a change to the base sequence.

nitrogen-rich base

Part of a nucleotide; the four types are adenine (A), guanine (G), cytosine (C), and thymine (T).

nucleotides

The building blocks of DNA; comprised of deoxyribose sugar, a phosphate group, and a nitrogen-rich base.

pathogen

A disease-causing organism.

pedigree

A diagram used to show patterns of inheritance over generations.

phenotype

Observable characteristics of the individual; the way the genotype is expressed.

phosphate group

One of the parts that make up a nucleotide.

plasmid

A ring of DNA found in bacteria.

pluripotent embryonic stem cells

Stem cells that are capable of becoming any one of the 200 or so different cell types found in the human body.

pure breeding

Where all individuals have the same genetic information for a characteristic generation after generation.

recessive trait

The trait that remains hidden in the heterozygous condition and seen only in the homozygous condition.

recombinant DNA technology

Technology that allows DNA to be recombined with other genes.

replication

The process of making copies of DNA.

sex chromosomes

The chromosomes that determine the sex of an individual; in humans they are the X and Y chromosomes.

sex-linked genes

Genes present on the sex chromosomes.

single nucleotide polymorphism (SNP)

Locations on chromosomes that differ by only one base from one human to another.

thymine (T)

A nitrogen-rich base that forms a pair with adenine (A).

traits

Inherited characteristics.

Watson–Crick model

The double helix structure of the DNA molecule.

zygote

The cell formed by fusion of two gametes, a sperm and an egg.