Science 2023

Please take all of these definitions with a grain of salt. Genetics: 1 to 3

Allele

Alternate forms of a gene. In most humans, we have two alleles of each gene (one inherened from each paren) which occupy the same relative position on homologous chromosomes

Autosomal chromosomes

Chromosomes that are not sex chromosomes

Base pair

Two complementary DNA nucleotide bases (A,T,C,G) that pair together to form a step of the DNA ladder

Chromosomes

A thread like structure made of DNA. We have 46 chromosomes and 23 pairs of chromosomes

Cloning

A process of asexually reproducing genetically identical genes, cells or organisms from a single parent

Co-dominance

An inheritance pattern where both alleles present are expressed

Diploid

Having two sets of chromosomes (2N)

DNA replication

The process where the DNA makes an identical copy of itself in preparation for cell division

Dominant allele

The gene which is expressed over the recessive gene in a heterozygous condition

Gene

a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring. Each gene is a nucleotide sequence on the DNA that codes for a polypedtide

Gene therapy

A new technology where genetic engineering techiques are used in the treatment of a genetic disorder or chronic disease

Genotoype

The genetic make up of cells in an organism

Haploid

Having one set of chromosomes which are unpaired (n). Gamates are haploid

Hereditary

Also called inheritance, its the passing on of traits from the parents to their offspring

Heterozygous

Having two different alleles for a particle gene in a diploid cell

Homologous

Two similar chromosomes, one paternal and one maternal in origin. It is the chromosome pairs that are matching.

Homozygous

Having identical alleles of a particular gene in a diploid cell

Independent assortment

random seperation of pairs of chromosomes during meiosis, giving different traits an equal opportunity of passing into a gamete. (during meiosis 4 different daughter cells are produced)

Karyotype

An organised, visual representation of the profile of an organisms chromosomes organised from biggest to smallest

Mitosis

a form of cell division that occurs during the growth and repair of cells, and also during asexual reproduction, when identical copies of cells need to be made. The parent cell divides into 2 identical daughter cells with diploid (2n) chromosomes

Meiosis

the process by which animals and plants produce gametes (sex cells) for sexual reproduction. The parent cell divides into 4 different daughter cells with haploid (n) chromosomes in each. The daughter cells produced are gametes. The different daughter cells allow for genetic variety

mRNA

It is a messanger made in the nucleus that carries instructions to make proteins.

Mutagen

A permanent change in the genetic information of an organism

Mutation

A permanent change in the genetic information of an organism

Nucleotide

A building block of DNA. This includes sugar, phosphate and nitrogenous base

Nucleotide/nitrogenous bases

Include Thymine, Adenine, Cytosine and Guanine

RNA

ribonucleic acid, a nucleic acid present in all living cells. Its principal role is to act as a messenger carrying instructions from DNA for controlling the synthesis of proteins, although in some viruses RNA rather than DNA carries the genetic information. It is different to DNA as RNA’s sugar ring is made of ribose while DNA’s is made of deoxyribose

Selective breeding

involves selecting parents that have characteristics of interest in the hope that their offspring inherit those desirable characteristics.

Traits

a specific characteristic of an individual. Traits can be determined by genes, environmental factors or by a combination of both. Traits can be qualitative (such as eye color) or quantitative (such as height or blood pressure).

Phenotype

The physical make up of an organism. The geneotype that is expressed.

Polypeptide

A single chain of animo acids joined together by peptide bonds

Proteins

A molecule consisting of one or more polypetide chain bounded together

Recessive allele

A form of a gene that is only expressed in the homozyous condition

tRNA

is a small RNA molecule that plays a key role in protein synthesis. Transfer RNA serves as a link (or adaptor) between the messenger RNA (mRNA) molecule and the growing chain of amino acids that make up a protein.

Variation

Genetic variation is the presence of differences in sequences of genes between individual organisms of a species. It enables natural selection, one of the primary forces driving the evolution of life.