Chapter 2 Genetics | Oxford Science 10 Australian Curriculum

gene

basic unit of genetic material passed on from parents to offspring

DNA (deoxyribonucleic acid)

a molecule that contains all the instructions for every job performed by the cell; this information can be passed from one generation to the next

hydrogen bond

a type of weak chemical bond between two groups of atoms; the bond between two nitrogen bases in the DNA helix

complementary base

a nucleotide base that pairs with its partner nucleotide on the alternative DNA strand; adenine pairs with thymine, cytosine pairs with guanine

chromosome

the form of DNA that is tightly wound around proteins before replication

karyotype

a way of representing a complete set of chromosomes, arranged in pairs, in order of decreasing size

chromatid

one side of the X-shaped chromosome that contains a double helix of DNA

genetic code

the sequence of nucleotides in DNA, inherited from parent organisms

transcription

the process of copying the DNA that makes up a gene to messenger RNA

somatic cells

the body cells except gametes (egg and sperm)

interphase

a phase of cell life where normal functioning occurs

dominant trait

a characteristic that needs only one copy of an allele to appear in the physical appearance of an organism

recessive trait

a characteristic that is only expressed in the phenotype when two identical alleles are inherited

co-dominant

two different alleles that can both appear in the phenotype at the same time; both can appear with a single allele

achondroplasia

a genetic (inherited) disorder of bone growth resulting in abnormally short stature and short limbs

substitution mutation

a form of mutation where one nucleotide is substituted for another; may or may not result in a deformed protein

stem cell

a cell that can produce different types of cells; adult stem cells can produce a limited number of cell types (e.g. skin stem cells), whereas embyronic stem cells can produce many types of cells

nucleotide

a subunit of a nucleic acid

translation

the formation of a protein from RNA; occurs on a ribosome

codon

a group of three nucleotides on mRNA

mitosis

the process of cell division that results in genetically identical daughter cells; allows growth and repair

cytokinesis

the splitting of a replicating cell into two cells

diploid

containing two complete sets of chromosomes

apoptosis

programmed cell death

meiosis

the process that results in the formation of gametes with half the genetic material of the parent cell

haploid

containing one complete set of chromosomes in each cell; an example is gametes

allele

a version of a gene; a person inherits two alleles from each gene, one coming from each parent

homozygous

having two identical alleles for a particular trait

heterozygous

having two different alleles for a particular trait; a carrier for a recessive trait

carrier

a person who has the allele for a recessive trait that does not show in their phenotype

genotype

the combination of alleles for a particular trait

phenotype

the physical characteristics that result from an interaction between the genotype and the environment

Punnett square

a diagram used to predict the outcome of breeding organisms

autosome

a chromosome that does not determine the sex of an organism

sex chromosome

a chromosome that determines the sex of an organism

pedigree

a chart showing the phenotypes for an individual and their ancestors, usually over several generations; also known as a family tree diagram

mutation

a permanent change in the sequence or amount of DNA

mutagen

a chemical or physical agent that causes a change in genetic material such as DNA

frameshift mutation

a type of mutation in which a nucleotide is added or deleted, causing a shift in the reading frame of codons; usually results in a deformed protein

non-disjunction

the failure of one or more chromosomes to separate during meiosis; can result in an abnormal number of chromosomes in the daughter cells

maternal serum screening (MSS)

the genetic testing of fetal DNA found in the mother's blood

newborn screening

the testing of chromosomes in a baby's white blood cells for the presence of a genetic disease

early detection and predictive testing for adults

the testing of chromosomes for the presence of alleles that increase the probability of cancers forming

genetically modified organism (GMO)

an organism that has had its DNA changed in a laboratory

transgenic organism

an organism that has a gene from another organism inserted into its own chromosomes

genetic engineering

the deliberate engineering of change in the DNA of an organism

gene cloning

the production of identical copies of a gene

gene therapy

inserting a new healthy allele into an organism to treat a genetic disease