Science (Bio)

Definitions and key terms

DNA

The polymer that stores organisms genetic information and the instructions for making proteins.

Genes

A section of DNA that stores organisms’ genetic information.

Chromosome

A long coiled structure that is made of DNA and proteins that carries many genes.

Genome

A complete set of DNA inside an organism.

Mendel’s Contribution

They showed that traits are inherited through genes of which they come in dominant and recessive forms.

Chargaffs contribution

They worked out the Adenine pairs with Thymine and Cytosine pairs with Guanine.

Franklin contribution

They took the first diffraction of DNA’s double helix shape.

Watson and Crick’s contribution

They created the first model of DNA’s double helix using Franklins diffraction.

Nucleotides

They are essentially the building blocks of DNA, they consist of deoxyribose sugar, phosphate group and a nitrogenous base.

base pairings importance

They ensure accuracy when copying DNA during cell division.

genetic technologies

Designed to alter, configure or change an organisms’ DNA to change the functionality of the organism.

Genetic Technologies Examples

Selective Breeding, GM Crops, CRISPR-Cas 9

Alleles

A different version of a gene. E.g. Round seeds and wrinkled seeds.

homozygous organism

That has inherited two copies of the same allele. Essentially they are pure bred. E.g. RR.

heterozygous organism

Organism that has inherited two different copies of the allele. E.g. round seeds and wrinkled seeds.

genotype

Essentially the combination of the two letters which show the allele it carries.

phenotype

The observable trait in the organism. E.g. Round seeds.

mitosis

The process of making two identical daughter cells from one parent cell.

stages of mitosis

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

5. Cytokinesis

Natural Selection

The environment selecting which traits in an organism are favorable and whether or not they are allowed to be passed down to the next generation.

Variation

Difference in traits within a population

Reproductive isolation

Mechanism that prevents different species from interbreeding

Physical Isolation

Geographical, natural phenomena

Meiosis

A type of cell division that produces four genetically unique daughter cells each with half the genetic material of the original parent. It is essential for the opposite of a*exual reproduction.

haploid

A cell that has one set of chromosomes

Diploid

A cell has two sets of chromosomes

crossing over in Meiosis

Exchange of genetic material between homologous chromosomes, it happens in prophase 1

Independent Assortment

The random separation of homologous chromosomes during meiosis creating different gametes.

Asexual Reproduction

A form of reproduction that involves a single parent organism, resulting in offspring that are genetically identical to the parent.

Sexual Reproduction

A form of reproduction that involves the combination of genetic material from two parent organisms, leading to genetically diverse offspring.