CHAPTER 1 INTRO TO GENETICS

CRISPR-Cas

• Ability to rewrite DNA sequence
• Why?

1. More efficient
2. More accurate
3. More versatile
4. Easier to use

•  “Seek and destroy” bacteria
• CRISPR (clustered regularly interspersed short palindromic repeats) refers to the part of the bacterial genome that produces RNA molecules.
• CRISPR RNA binds to a matching sequence in the viral DNA
• Cas nuclease- scissors and cuts DNA

Epigenesis

Preformationism- fertilized egg contains a complete miniature adult (homunculus)

Matthias Schleiden and Theodor Schwann- proposed the Cell Theory

Louis Pasteur- disproved spontaneous generation

The Cell Theory- all organisms are composed of basic structural cells which are derived from preexisting cells

Charles Darwin

• 1859- “On the Origin” of Species published by Charles Darwin

• Natural selection- Alfred Russel Wallace

• evolutionary change

• Population growth is aided by environment adaptation of heritable traits for survival

• If reproductively isolated, they become a new species

- The gap in Darwin Theory- lack of understanding of genetic basis of variation and inheritance

- Chromosome Theory of Inheritance- heredity and development were dependent on genetic information in genes contained in chromosomes which were then contributed to each individual by gametes

Gregor Mendel

• An augustinian monk
• Genes- “a pair of factors”
• Members of a gene separate from each other during gamete formation for genetics

The Chromosomal Theory of Inheritance

• Diploid number (2n) 
  • Humans: 46 diploid number
• Mitosis
  • Chromosomes are copied and distributed so each daughter cell receives a diploid set of chromosomes identical to those in the parent cell
• Meiosis
  • Gamete formation
  • Cells produced receive only one chromosome from each chromosome pair
  • haploid
• Sutton and Boveri- formulated the theory
• The Chromosomal Theory of Inheritance- inherited traits are controlled by genes residing on chromosomes transmitted through gametes, maintaining genetic continuity from generation to generation.

Genetic Variation

1. Mutation- heritable changes in the DNA sequence
2. Allele-  alternative forms of a gene
3. Phenotype- observable features
4. Genotype- set of alleles for a given traits

DNA is the carrier of genetic information- Oswald Avery, Colin Macleod, and Maclyn McCarty (discovered through white-eyed Drosophila)

The Structure of DNA and RNA

James Watson and Francis Crick- structure of DNA is a double helix

Nucleotides- subunits (Adenine, Guanine, Thymine, Cytosine)

RNA- single stranded (ribose than deoxyribose)

Gene Expression

1. Transcription

• the nucleotide sequence in one strand of DNA is used to construct a complementary RNA sequence

• mRNA- binds to a ribosome

1. Translation

• Synthesis of proteins
• Codon- triplet of proteins, complementary to DNA
• Proteins- polymers made up of amino acids (20 kinds)
• rTNA- recognize the information encoded in the mRNA codons and carry the proper amino acids for construction of the protein during translation.

Enzymes- form the largest category of proteins.

The central dogma of molecular biology -- that DNA is a template for making RNA, which in turn directs the synthesis of proteins -- explains how genes control phenotype.

Sickle Cell Anemia

• caused by a mutant form of hemoglobin
• 2 mutant copies of the b-globin gene
• Deformed cells are fragile and break easily (lesser red blood cells)
• Sickles-shaped cells block blood flow in capillaries and small blood vessels

Hemoglobin- protein that transports oxygen

DNA Cloning- Dolly

• Restriction enzymes- used to by bacteria to cut and inactivate DNA
• Vectors- DNA fragments 
• Genome- complete haploid DNA content of a specific organism
• Dolly- a finn dorset sheep from the genetic material of an adult mammary cell

Transgenic Organisms- transfer of heritable traits across species

Genomic, Proteomics, and Bioinformatics

• Genomics- study of genomes
• Proteomics- identifies set of protein present in a cell under conditions
• Bioinformatics- created to develop hardware and software for processing nucleotide and protein data

Reverse genetics- sequence is known but function not so

Gene Knockout- render targeted genes nonfunctional

Model Organisms

•  organisms used for study of basic biological processes

1. Caenorhabditis elegans- few hundred cells
2. Arabidopsis thaliana- short life cycle
3. Danio rerio- study vertebrate development, produces rapidly and transparent