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15 Flashcards in this deck.
The human genome encompasses the complete set of genetic instructions found in each cell of a human being. It consists of approximately 3 billion base pairs of DNA, organized into 23 pairs of chromosomes. Each chromosome contains numerous genes, which are specific sequences of DNA that code for proteins responsible for various bodily functions and traits.
Deoxyribonucleic acid (DNA) is the molecule that carries genetic information. It has a double helix structure composed of two strands twisted around each other. Each strand is made up of nucleotides, which include a phosphate group, a sugar molecule (deoxyribose), and one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
The sequence of these bases encodes genetic information. Adenine pairs with thymine, and cytosine pairs with guanine, forming the base pairs that hold the two strands of the DNA helix together through hydrogen bonds.
$$ \text{A} \leftrightarrow \text{T} \\ \text{C} \leftrightarrow \text{G} $$Genes are segments of DNA that determine specific traits by coding for proteins. Each gene exists in different forms called alleles. Alleles can be dominant or recessive, influencing how traits are expressed in an organism. For example, the gene for eye color may have a brown allele (dominant) and a blue allele (recessive).
The combination of alleles inherited from both parents determines an individual's genotype, which in turn influences their phenotype—the observable characteristics.
Genetic information is passed from parents to offspring through processes of heredity. Gregor Mendel's laws of inheritance describe how traits are transmitted via dominant and recessive alleles. The first law, the Law of Segregation, states that each organism carries two alleles for each trait, which segregate during gamete formation, ensuring that offspring receive one allele from each parent.
The second law, the Law of Independent Assortment, states that genes for different traits assort independently of one another during gamete formation, allowing for genetic variation.
DNA replication is the process by which a cell copies its DNA before cell division. Enzymes like DNA polymerase facilitate the unwinding of the double helix and the synthesis of complementary strands, ensuring genetic information is accurately passed on.
Protein synthesis involves two main steps: transcription and translation. During transcription, a segment of DNA is transcribed into messenger RNA (mRNA). The mRNA then travels to the ribosome, where translation occurs—the mRNA is read, and amino acids are assembled into proteins based on the sequence of codons.
$$ \text{DNA} \xrightarrow{\text{Transcription}} \text{mRNA} \xrightarrow{\text{Translation}} \text{Protein} $$Advancements in genomic technologies have revolutionized our understanding of genetics. DNA sequencing techniques, such as Sanger sequencing and next-generation sequencing (NGS), allow for the rapid and accurate determination of DNA sequences. Genome mapping techniques help in locating genes and their functions within the genome.
These technologies have applications in various fields, including medicine (for diagnosing genetic disorders), forensics (for DNA profiling), and evolutionary biology (for studying genetic diversity).
The manipulation and study of genetic information raise significant ethical questions. Issues such as genetic privacy, designer babies, genetic modification, and the potential for genetic discrimination must be carefully considered. It is essential to balance scientific advancement with ethical responsibility to ensure that genetic technologies are used for the benefit of society.
Aspect | DNA | RNA |
Structure | Double helix | Single-stranded |
Sugar Component | Deoxyribose | Ribose |
Nitrogenous Bases | A, T, C, G | A, U, C, G |
Function | Stores genetic information | Transmits genetic information for protein synthesis |
Location | Primarily in the nucleus | Both nucleus and cytoplasm |
• **Use Mnemonics for Base Pairing:** Remember "A-T and C-G" with the phrase "All Tigers and Cats Growl."
• **Create Flashcards for Key Terms:** Terms like genotype, phenotype, alleles, and loci can be effectively memorized using flashcards.
• **Apply Concepts to Real-Life Examples:** Relate genetic principles to real-world scenarios, such as predicting eye color in offspring, to reinforce understanding.
1. Humans share about 99.9% of their DNA with every other human, highlighting the minute genetic differences that account for individual uniqueness.
2. The Human Genome Project, completed in 2003, was an international effort that mapped all the genes in the human genome, paving the way for personalized medicine.
3. Some regions of the human genome are highly repetitive, which can complicate genetic studies but also play roles in regulating gene expression.
1. **Confusing Genotype and Phenotype:** Students often mix up genotype (genetic makeup) with phenotype (observable traits). For example, having the genotype "TT" for eye color results in the phenotype "brown eyes."
2. **Misunderstanding Dominant and Recessive Alleles:** Thinking that a dominant allele is the only allele expressed. In reality, the dominant allele masks the recessive one, but both are present in the genotype.
3. **Overlooking the Role of Environmental Factors:** Assuming traits are solely determined by genetics without considering how the environment can influence phenotype.