8. Genetics

Genetics

The study of genetics and how traits are passed from parent to offspring.

Gregor Johann Mendel

The founder and father of modern genetics. He did experiments with plants by crossbreeding many varieties and tracking inheritance of traits. He used peas and chose 7 recognizable traits. His studies received a hostile reaction, and unfortunately he died before anyone realized the significance of his research.

Genes

Segments of DNA, which contains the instructions for building and functioning of living organisms. The basic units of inheritance.

Alleles

Different versions/variants of a particular gene.

Dominant genes/trait

A trait that is seen when at least one copy of the dominant allele is present in someone’s genotype. It overwhelms recessive traits.

Recessive genes/trait

A trait that is seen only when someone has two copies of the recessive allele in someone’s genotype. It is hidden otherwise.

Law of Segregation

Also known as the first law of mendelian inheritance, Says that each gamete receives either the maternal or paternal allele, but not both.

Did Mendel formulate the gene as the basic unit of inheritance?

Mendel WAS NOT the first to formulate genes as the basic unit of inheritance.

Hugo de Vries, Carl Correns, Erik Tschermak

Three separate European botanists who rediscover the laws of heredity independently.

George Gaylord Simpson

Played a crucial role in shaping our understanding of the processes of evolution. Formulate new Synthetic Theory

Cell membrane

Like a shell of the cell, thin flexible barrier surrounding the cell.

Cytoplasm

The gel-like substance that fills the cell between the nucleus and cell membrane. Has cytosol.

Nucleus

Acts as the control center of the cell and houses DNA. Chromosomes are stored here.

Rosalind Franklin

Found a way to photograph a cell and see the structure of DNA.

James Watson and Francis Crick

They used and obtained Rosalind Franklins X-ray and published a report about the discovery of DNA’s double helix structure.

Chromosomes

The structures that carry genetic information in the form of DNA

Mitochondria

Organelles found in the cells and are the powerhouses of the cell.

Pairs of chromosomes in humans

We have 46 strands and 23 pairs of chromosomes.

23rd pair of chromosomes

The pair of chromosomes that determines our sex. X or Y.

DNA

Our total molecular code found in the nucleus. It has a double helix structure.

Gene

Portion of DNA that directs development of an identifiable trait.

Allele

The specific information for a trait provided by each parent.

Locus (loci)

The location of instructions for genes and alleles. For genes, it's a pair of locations (two loci). For alleles it's a single locus.

Mitosis

Asexual reproduction, one of the two forms of reproduction. It creates identical cells. Creates diploid cells from one parent.

Meiosis

Sexual reproduction, One of the two forms of reproduction, it is specialized creation of new cells. It is a source of/creates continuity and variability. Source of change. Creates haploid cells from both parents.

Haploid cells

Cells that contain a single set of chromosomes. Produced through meiosis which occurs during the formation of gametes (sperms and eggs)

Diploid cells

Cells that contain two sets of chromosomes. Produced through mitosis.

Homozygous gene

A gene that contains a pair of identical alleles, For example, BB or bb. Recessive or dominant traits are expressed.

Heterozygous gene

A gene that contains a pair of two different alleles, For example, Bb or bB. Dominant traits are expressed.

Genotype

The genetic composition of an organism. BB, Bb, bB, bb for example.

Phenotype

The physical appearance of the organism. What you see, may or may not be not reflect the genotype. Blue and brown eyes for example. The dominant allele is expressed unless there is two recessive alleles, then the recessive allele is expressed.

Monogenic

Expressed phenotypically if it’s only found in one location. Albinism for example. Basically only one gene affects this.

Polygenic

Expressed phenotypically if it’s found in more than one location (loci). Eye color and weight for example. Basically multiple genes affect this.

Mutation

The ultimate source of change in gene frequencies. Any random alteration in a gene.