Genetics: DNA Structure and Central Dogma

Study Notes

Double helix model: two complementary strands of nucleotides twisted together
Nucleotides composed of:
1. Sugar molecule (deoxyribose)
2. Phosphate group
3. Nitrogenous base (A, C, G, or T)
Hydrogen bonds between nitrogenous bases hold strands together

Process by which genetic information flows from DNA to proteins
Steps:
1. Transcription: DNA -> RNA (messenger RNA, mRNA)
2. Translation: mRNA -> Protein

Sequence of nitrogenous bases (A, C, G, and T) determines amino acid sequence of proteins
Code is degenerate: more than one codon can code for the same amino acid
Codons: sequence of three nucleotides that code for one amino acid

Mendelian Inheritance: Gregor Mendel's laws of inheritance
- Law of Segregation: each pair of alleles separates during gamete formation
- Law of Independent Assortment: alleles for different genes separate independently
Dominant and Recessive Alleles: one allele can mask the effect of another
Incomplete Dominance: one allele does not completely mask the effect of another
Co-dominance: both alleles have an equal effect on the phenotype

Mutations: changes in the DNA sequence
- Point Mutations: single nucleotide change
- Frameshift Mutations: insertion or deletion of nucleotides, changing the reading frame
Genetic Drift: random change in allele frequency in a population
Gene Flow: movement of alleles from one population to another

Recombinant DNA Technology: combining DNA from different sources
Cloning: creating multiple copies of a DNA sequence
Genetic Modification: altering an organism's DNA sequence to introduce new traits

The double helix consists of two intertwined strands of nucleotides.
Each nucleotide includes a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), cytosine (C), guanine (G), or thymine (T).
Complementary strands are held together by hydrogen bonds formed between nitrogenous bases.

Describes the flow of genetic information from DNA to proteins.
Involves two main processes:
- Transcription: The synthesis of messenger RNA (mRNA) from a DNA template.
- Translation: The conversion of mRNA into a protein.

The order of nitrogenous bases in DNA dictates the amino acid sequence of proteins.
The genetic code is degenerate, meaning multiple codons can specify the same amino acid.
Codons are triplet sequences of nucleotides, each corresponding to an individual amino acid.

Mendelian Inheritance includes key principles established by Gregor Mendel:
- Law of Segregation: Alleles from each parent segregate independently during gamete formation.
- Law of Independent Assortment: Alleles of different genes assort independently from one another.
Dominant and Recessive Alleles: A dominant allele can mask the expression of a recessive allele.
Incomplete Dominance: When the phenotype is intermediate between two alleles.
Co-dominance: Both alleles are expressed equally in the phenotype.

Mutations alter DNA sequences and can include:
- Point Mutations: A change in a single nucleotide.
- Frameshift Mutations: Insertion or deletion of nucleotides causing a shift in the reading frame.
Genetic Drift: A non-selective process that causes random fluctuations in allele frequencies within a population.
Gene Flow: The transfer of alleles between populations, increasing genetic variation.

Recombinant DNA Technology: Enables the combination of DNA segments from different sources, creating new genetic combinations.
Cloning: Involves producing identical copies of a specific DNA sequence.
Genetic Modification: The process of altering an organism's DNA to introduce new characteristics or traits.