Genetics - 10SCI (now 11SCI because why would i make another set)

omfl get me out of here

What are gametes?

Gametes are haploid sex cells that are produced in the sex organs (gonads) of an organism. They contain half the original number of chromosomes.

Adaptations

Traits/phenotypes which allow an organism to better survive in its environment.

Amino acids

Amino acids are the building blocks of proteins.

What is a chromosome?

A thread-like structure that is a very long molecule of tightly coiled DNA that contains a specific set of instructions for each individual organism. It is found in a cell’s nucleus.

What are the base pairs that are always together?

A and T, C and G

What are the full names of the bases A, T, C and G?

Adenine, Thymine, Cytosine and Guanine.

What is an allele?

A different version of the same gene, e.g. an allele for blue eyes or an allele for brown eyes.

What is a gene?

Genes are segments of DNA that give your cells instructions for specific traits or body functions, e.g. a gene for eye colour.

Ancestor

An organism (or species) from which other organisms (or species) have evolved.

What is a nucleotide?

A three-part unit made of a nitrogen compound, a sugar and a phosphate.

What substances make up a nucleotide?

Phosphate (circle), Sugar (pentagon) and Base (A,T,C, or G)

What is a homozygous pair of alleles?

If the alleles for a characteristic in a homologous pair are the same. (e.g. TT or tt)

What is a heterozygous pair of alleles?

If the alleles for a characteristic in a homologous pair are different. (e.g. Tt)

What is a dominant allele?

An allele that is always expressed even if there is only one copy present.

What is a recessive allele?

An allele that is only expressed in an organism’s phenotype if there are no dominant alleles present.

What is a phenotype?

All the observable traits of an organism.

What is a genotype?

A genotype shows the alleles of an individual represented by letters. e.g. TT, tt, Tt.

Antiparallel

The two strands of a DNA molecule run in opposite directions.

Asexual Reproduction

Requires only one parents and produces genetically identical offspring. The process is easier, faster and less energy-consuming for organisms, but can spread disease and negatively impact populations faster due to shared weaknesses.

What is sexual reproduction?

When a male and female’s haploid gametes fuse to form a genetically unique zygote and therefore produce offspring with diploid cells. This type of reproduction requires two parents and is more time-consuming, but contributes to genetic variation which strengthens a population.

Crossing Over

A process that takes occurs during meiosis where homologous pairs of chromosomes exchange genetic material between non-sister chromatids. This produces gametes with a unique combination of alleles that are genetically different from the chromosomes from the parents.

DNA (Deoxyribonucleic Acid)

The foundational double-helix structured molecule that holds the genetic instructions for the development, growth, and function of almost all living organisms.

DNA sequencing

The process of finding out the exact order of bases on a length of DNA.

Evolution

Gradual change in the genetic code of organisms over a long period of time which may result in the formation of new species.

Fertilisation

A process that occurs during sexual reproduction where a random egg and a random sperm fuse randomly. Through the gametes fusing together, the genes from the two parents combine, leading to the formation of a genetically unique zygote.

Genome

All the DNA in a single cell of an organism.

Genetic Code

The bases of a gene are read in sets of three and each triplet codes for an amino acid, which in turn, are joined to make a protein.

Gene Marker

A short segment of DNA that can be used to follow inheritance of a trait (especially if not visible) or determine relatedness of different organisms.

Genetic variation

All individual organisms in a population or species that have different combinations and types of alleles. This consequently enables a species to undergo the process of natural selection to be able to have a better chance of surviving negative environmental impacts.

Genotypic Ratio

The predicted ratio of inheritance of alleles from the mating of two individuals.

Homologous pairs of chromosomes

Two chromosomes in a cell with the same genes which are paired together. One chromosome is inherited from each parent.

Independent Segregation

A process that occurs during meiosis where homologous pairs of chromosomes align randomly at the equator of the cell. This results in each gamete receiving a unique combination of maternal and paternal chromosomes.

Karyotype

A picture of all the chromosomes in a cell, ordered from largest to smallest in homologous pairs.

Meiosis

A type of cell division that occurs within the gonads (sex organs) of an organism which produces four genetically unique haploid gametes.

Mutation

A permanent change in the base sequence of an organism’s DNA which results in the creation of new alleles; which therefore produces new/altered proteins and new phenotypic traits. This can occur within somatic and gametic cells.

Offspring

The resulting individuals of reproduction.

Pedigree Chart

A branching tree diagram that tracks alleles/traits being passed through a family.

Mutagen

A physical or chemical agent like radiation, ultraviolet rays or certain chemicals that can increase the rate of mutation in an organism.