Genetics Flashcards

Nucleotide Structure

• Nucleotides consist of three components: phosphate, deoxyribose sugar, and a nitrogen-containing base.
• The sugar present in nucleotides is deoxyribose.
• Each nucleotide's nitrogen-containing component is referred to as a base.
• Four nitrogen bases identified in DNA are adenine, thymine, guanine, and cytosine.
• Nitrogen bases form the rungs of the DNA ladder structure, while phosphate makes up the sides or backbone.
• The two strands of DNA are arranged in an antiparallel configuration.

Base Pairing Rules

• Adenine pairs with thymine across the strands, while guanine pairs with cytosine.
• The connection consists of two hydrogen bonds between adenine and thymine and three hydrogen bonds between guanine and cytosine.
• The arrangement of bases in DNA features alternating pairs: adenine/thymine followed by guanine/cytosine.

DNA Structure and Replication

• The double helix shape shows a structure resembling interconnected ovals.
• DNA replication involves breaking hydrogen bonds between nucleotides, separating DNA strands, and attaching free nucleotides to exposed bases.
• DNA helicase is an enzyme that breaks apart nucleotides during replication.
• The base-pair rule governs how new nucleotides are added to the strands.

Semi-Conservative Replication

• DNA replication is termed semi-conservative as it involves reusing one original strand to create two new strands, minimizing mutation risks.
• The presence of one original strand during replication lowers the likelihood of errors in the newly synthesized DNA.

Chromosome and Cell Cycle

• Loose DNA within the nucleus is known as chromatin.
• DNA replication occurs during the S phase of the cell cycle, while DNA condenses into chromosomes during the G2 phase.
• The structure that holds sister chromatids together in preparation for cell division is called the centromere.

Genetic Disorders and Mutations

• Gene mutations, which alter nucleotide sequences, can lead to diseases through errors in polypeptide synthesis.
• Tay-Sachs Disease is characterized by a faulty enzyme affecting the nervous system.
• Huntington's Disease leads to gradual deterioration of brain function and coordination starting in midlife.
• Sickle Cell Anemia results in shape-changed cells with reduced oxygen-carrying capacity.
• Phenylketonuria (PKU) is due to a missing enzyme needed to convert phenylalanine to tyrosine.
• Parkinson's Disease is a disorder affecting movement and coordination.
• Albinism arises from an enzymatic deficiency in melanin production.

Recombinant DNA Technology

• Recombinant DNA technology allows for the production of proteins not normally synthesized by specific organisms.
• Bacteria use circular DNA called plasmids in recombinant procedures.
• Restriction enzymes cut desired DNA sections for incorporation into plasmids, facilitated by DNA ligase.
• Bacteria containing recombined plasmids can produce targeted enzymes or hormones.