Chapter 1: Introduction to Genetics

Genetics

A branch of biology concerned with the study of heredity and variation.

Theory of epigenesis by William Harvey

Organisms develop from the fertilized egg through a succession of developmental events, transforming the egg into an adult.

Theory of preformationism

Organisms develop from the fertilized egg, which contains a complete miniature adult (homunculus).

Cell theory by Schleiden and Schwann

All organisms are composed of basic structural units called cells, which are derived from preexisting cells.

Spontaneous generation

The creation of living organisms from nonliving components, disproved by Louis Pasteur.

Charles Darwin

He published 'The Origin of Species,' presenting ideas on evolutionary theory and natural selection.

Gregor Mendel's

His quantitative data from pea plants showed that traits are passed from parents to offspring in predictable ways.

What is the diploid number of chromosomes in humans?

46 chromosomes.

What are the two forms of cell division in eukaryotic cells?

Mitosis and meiosis.

Mitosis

Chromosomes are copied and distributed so that each daughter cell receives a diploid set of chromosomes identical to the parental cell.

Meiosis

Gamete formation involves a reduction in chromosome number, resulting in haploid cells that receive only half the number of chromosomes.

Chromosome theory of inheritance

Inherited traits are controlled by genes residing on chromosomes, which are faithfully transmitted through gametes.

Alleles

Alternate forms of a gene

Mutations

Any heritable trait in the DNA sequence, which serves as the source of genetic variation.

Genotype

Set of alleles for given trait

Phenotype

Expression of genotype produces observable features

What did Darwin lack in his theory of natural selection?

An understanding of the mechanisms involved in inheritance.

Drosophila melanogaster (fruit fly)

Model animal which contributed to genetics development

Structure of DNA

A long ladder-like macromolecule that twists to form a double helix.

Nitrogenous bases found in DNA

Adenine, Guanine, Thymine, and Cytosine.

Adenine pairs with

Thymine (or Uracil in RNA)

Guanine pairs with

Cytosine

RNA

single-stranded, contains ribose sugar instead of deoxyribose, and has uracil (U) instead of thymine (T).

Transcription

The process where a DNA strand is used to construct a complementary RNA sequence.

messenger RNA (mRNA)

RNA that moves to the cytoplasm after transcription and binds to ribosomes.

Translation

The synthesis of proteins directed by the information encoded in mRNA.

Codons

Nucleotide triplets in mRNA that specify the insertion of specific amino acids into proteins.

Transfer RNA (tRNA)

recognizes mRNA codons and carries the proper amino acid for protein assembly.

Proteins makeup

A combination of 20 different amino acids.

largest category of proteins

Enzymes

How do mutations affect phenotype?

They can modify, alter, or eliminate a protein's function, resulting in an altered phenotype.

What is an example of a condition caused by a mutation?

Sickle-cell anemia.

causes of sickle-cell anemia

A mutant form of hemoglobin due to a mutation in the gene encoding β-globin

sickle-cell anemia effect

Red blood cells become sickle-shaped, deformed, fragile, and break easily.

Who is affected by sickle-cell anemia?

Individuals with two mutant copies of β-globin.

Recombinant DNA Technology

technology that allows for manipulation of genetic material

What discovery began recombinant DNA technology?

The discovery of restriction endonucleases (REs)

Restriction endonuclease (RE)

cut and inactivate invading viral DNA at specific sites

DNA Vectors

A DNA molecule used as a vehicle to carry genetic material into host cells

How do vectors function in recombinant DNA technology?

Vectors are carrier DNA molecules that allow for the creation of recombinant DNA molecules.

What is the significance of recombinant DNA molecules in research?

They can be transferred to bacterial cells for reproduction, leading to thousands of copies (clones).

What is a transgenic organism?

An organism that has been genetically modified to include genes for traits such as herbicide resistance and nutritional enhancement.

Dolly the sheep

The first cloned sheep, created by transferring the nucleus of an adult cell into an egg with the nucleus removed.

Genomics

studies structure, function, and evolution of genes and genomes

Proteomics

The identification of the set of proteins present in cells under specific conditions and the study of their functions and interactions.

Bioinformatics

The development of hardware and software for processing nucleotide and protein data.

Model Organisms

Organisms used in genetic studies that are easy to grow, have short life cycles, and produce many offspring.