-
alleles
Alternative versions of a gene.
-
base (of DNA)
- One of the nitrogen–containing side–chain molecules attached to a sugar
- molecule in the sugar–phosphate backbone of DNA and RNA.
-
base pair
Two nucleotides on complementary strands of DNA that form a pair, linked by hydrogen bonds
-
chromosome
- A linear or circular strand of DNA on which are found specific sequences
- of base pairs; the human genome consists of two copies of each of 23
- unique chromosomes, one from the mother and one from the father
-
code
In genetics, the base sequence of a gene,
-
deoxyribonucleic acid (DNA)
- One of the two types of nucleic acid, DNA carries information about the
- production of particular proteins in the sequences of its nucleotide
- bases,
-
gene
- The basic unit of heredity; a sequence of DNA nucleotides on a
- chromosome that carries the information necessary for making a
- functional product, usually a protein or an RNA molecule.
-
genome
The full set of DNA present in an individual organism
-
genotype
The genes that an organism carries for a particular trait; also, collectively, an organism�s genetic composition.
-
intron
A non–coding region of DNA,
-
messenger RNA (mRNA)
- The ribonucleic acid that �reads� the sequence for a gene in DNA and
- then moves from the nucleus to the cytoplasm, where the next stage of
- protein synthesis will take place,
-
nucleotide
A molecule containing a phosphate group, a sugar molecule, and a nitrogen containing molecule
-
phenotype
The manifested structure, function, and behaviors of an individual; the expression of the genotype of an organism. [
-
trait
Any characteristic or feature of an organism, such as red petal color in a flower,
-
transcription
The process by which a gene�s base sequence is copied to mRNA,
-
translation
The process by which mRNA, which encodes a gene�s base sequence, directs the production of a protein,
-
transfer RNA
RNA molecules in the cytoplasm that link specific triplet base sequences on mRNA to specific amino acids,
-
chromosomal aberration
- A type of mutation characterized by a change in the overall organization
- of genes on a chromosome, such as the deletion of a section of DNA;
-
mutation
An alteration in the base–pair sequence of an individualâ��s DNA
-
point mutation
A mutation in which one base pair in DNA is replaced with another or a base pair is either inserted or deleted,
-
promoter site
A part of a DNA molecule that indicates where the sequence of base pairs that makes up a gene begins,
-
codons
Three–base sequences in mRNA that link with complementary tRNA molecules, which are attached to amino acids
-
ribosomal subunits
- The two structural parts of a ribosome, which function together to
- translate mRNA to build a chain of amino acids that will make up a
- protein,
-
restriction enzymes
Enzymes that recognize and bind to different specific sequences of four to eight bases in DNA and cut the DNA at that point
-
DNA probe
- A short sequence of radioactively tagged single–stranded DNA that
- contains part of the sequence of the gene of interest, used to locate
- that gene in a gene library
-
gene therapy
A therapy designed to treat or cure a disease by insertion of a functional gene to replace a defective version of that gene,
-
plasmid
A circular DNA molecule found outside the chromosome in bacteria,
-
stem cells
Undifferentiated cells that have the ability to develop into any type of cell in the body
-
VNTRs
- Regions of repeating sequences of bases in DNA that vary in the number
- of times the sequence repeats from individual to individual and, in a
- given individual, between homologues
-
genetic engineering
The manipulation of an organism�s genetic material by adding, deleting, or transplanting genes from one organism to another,
-
cloning
The production of genetically identical cells, organisms, or DNA molecules,
-
polymerase chain reaction
A laboratory technique in which a fragment of DNA can be duplicated repeatedly.
-
Human Genome Project
A project to decode the three billion base pairs in the human genome and to identify all genes present in it,
-
clone
A genetically identical DNA fragment, cell, or organism produced by a single cell or organism.
-
transgenic organism
An organism that contains DNA from another species,
-
hybridization
- The process of joining two complementary strands of DNA from different
- sources; hybridization occurs when a DNA probe is used to match with a
- complementary sequence in a gene library.
-
clone library
A collection of cloned DNA fragments; also known as a gene library,
-
biotechnology
The modification of organisms, cells, and their molecules to achieve practical benefits.
-
recombinant DNA technology
Technology that depends on the combination of two or more sources of DNA into a product;
-
phylogenetic tree
A grouping of organisms in a hierarchical system that reflects the evolutionary history and relatedness of the organisms.
-
histones
Proteins around which the long, linear strands of DNA are wrapped
-
sexual reproduction
A type of reproduction in which offspring are produced by the fusion of gametes from two distinct sexes,
-
daughter cells
Cells produced by the division of a parent cell,
-
centromere
After replication, the region of contact between sister chromatids, which occurs near the center of the two chromosome strands.
-
mitotic phase
- The phase of the cell cycle during which first the genetic material and
- nucleus, and then the rest of the cellular contents, divide,
-
reproductive cells
Haploid cells from two individuals that, as sperm and egg, will combine at fertilization to produce offspring
-
telomere
A non–coding, highly repetitive section of DNA at the tip of every eukaryotic chromosome that shortens with every cell division
-
cell cycle
In a cell, the alternation of activities related to cell division and those related to growth and metabolism,
-
somatic cells
The (usually diploid) cells of the body of an organism (in contrast to the haploid reproductive cells).
-
binary fission
- A type of asexual reproduction in which the parent cell divides into two
- genetically identical daughter cells; bacteria and other prokaryotes
- reproduce by binary fission
-
complementary base
A base on a strand of double–stranded DNA that is a pairing partner to a base on the other strand
-
complementarity
- The characteristic of double–stranded DNA that the base on one strand
- always has the same pairing partner, or complementary base, on the other
- strand,
-
asexual reproduction
- A type of reproduction common in prokaryotes, in which the identical
- daughter cells inherit their DNA from a single parent cell,
-
replication
The process by which DNA duplicates itself in both prokaryotes and eukaryotes in preparation for cell division,
-
cytokinesis
- In the cell cycle, the stage following mitosis in which cytoplasm and
- organelles duplicate and are divided into approximately equal parts and
- the cell separates into two daughter cells; in meiosis, two diploid
- daughter cells are formed in cytokinesis following telophase I and four
- haploid daughter cells are formed in cytokinesis following telophase II.
-
mitosis
- The division of a nucleus into two genetically identical nuclei, along
- with cytokinesis, leads to the formation of two identical daughter
- cells.
-
interphase
- In the cell cycle, the phase during which the cell grows and functions;
- during this phase, replication of DNA occurs in preparation for cell
- division.
-
parent cells
Cells that divide to form daughter cells, which are genetically identical to the parent cell,
-
apoptosis
- Programmed cell death, which takes place particularly in parts of the
- body where the cells are likely to accumulate significant genetic damage
- over time and are therefore at high risk of becoming cancerous.
-
anaphase
- The third phase of mitosis, in which the sister chromatids are pulled
- apart by the spindle fibers, with a full set of chromosomes going to
- opposite sides of the cell
-
chromatid
One of the two strands of a replicated chromosome, so called because it readily takes a stain.
-
cancer
Unrestrained cell growth and division.
-
prophase
- The first phase of mitosis, in which the nuclear membrane breaks down,
- sister chromatids condense, and the spindle forms
-
sister chromatids
The two identical strands of a replicated chromosome,
-
metaphase
- The second phase of mitosis, in which the sister chromatids line up at
- the center of the cell; in meiosis, the homologues line up at the center
- of the cell in metaphase I and the sister chromatids line up in
- metaphase II.
-
telophase
- The fourth and last phase of mitosis, in which the chromosomes begin to
- uncoil and the nuclear membrane is reassembled around them;
-
spindle fibers
- Fibers that extend from one pole of a cell to the other, which pull the
- sister chromatids apart in the anaphase stage of mitosis or the anaphase
- II stage of meiosis,
-
spindle
- A part of the cytoskeleton of a cell, formed in prophase (in mitosis) or
- in prophase I (in meiosis), from which extend fibers that organize and
- separate the sister chromatids,
-
crossing over
- The exchange of some genetic material from the father with some from the
- mother that occurs in the prophase I stage of meiosis, producing a
- mixture of paternal and maternal genetic material on each chromatid,
-
karyotype
A visual display of an individual�s full set of chromosomes.
-
homologous pair
The maternal and paternal copies of a chromosome.
-
gonads
The ovaries and testes in sexually reproducing animals.
-
diploid
Describes cells that have two copies of each chromosome
-
nondisjunction
The unequal distribution of chromosomes during cell division
-
X and Y chromosomes
The human sex chromosomes.
-
hermaphrodite
An organism that produces both male and female gametes
-
placenta
- The
- organ formed during pregnancy (and expelled at birth) that allows the
- transfer of gases, nutrients, and waste products between mother and
- fetus
-
haploid
Describes cells that have a single copy of each chromosome
-
fertilization
The fusion of two reproductive cells,
-
meiosis
- In sexually reproducing organisms, a process of nuclear division in the
- gonads that, along with cytokinesis, produces reproductive cells that
- have half as much genetic material as the parent cell, and that all
- differ from each other genetically.
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