Podcast
Questions and Answers
What type of bond connects adenine to thymine in a DNA molecule?
What type of bond connects adenine to thymine in a DNA molecule?
- Two hydrogen bonds (correct)
- Three hydrogen bonds
- Phosphodiester bond
- Ionic bond
Which of the following best describes the sugar-phosphate backbone of a DNA molecule?
Which of the following best describes the sugar-phosphate backbone of a DNA molecule?
- Located on the interior of the DNA double helix.
- Composed of alternating adenine and thymine molecules.
- Consists of nitrogenous bases.
- Composed of alternating sugar and phosphate groups. (correct)
What is the correct definition of an allele?
What is the correct definition of an allele?
- The process by which DNA is replicated.
- A variant form of a gene at a particular locus. (correct)
- A segment of DNA that codes for a specific protein.
- The complete set of chromosomes in an organism.
Which of the following describes the relationship between DNA strands in a double helix?
Which of the following describes the relationship between DNA strands in a double helix?
How do histones contribute to DNA packaging in eukaryotic cells?
How do histones contribute to DNA packaging in eukaryotic cells?
Given a single strand of DNA with the sequence 5'-TCGAGGATT-3', what would be the sequence of the complementary strand?
Given a single strand of DNA with the sequence 5'-TCGAGGATT-3', what would be the sequence of the complementary strand?
What distinguishes a nucleotide from a nucleoside?
What distinguishes a nucleotide from a nucleoside?
During which phase of the cell cycle does chromatin condense into chromosomes?
During which phase of the cell cycle does chromatin condense into chromosomes?
If a somatic cell in an organism has 24 chromosomes, how many chromosomes would be present in its gametes?
If a somatic cell in an organism has 24 chromosomes, how many chromosomes would be present in its gametes?
What is the primary function of DNA?
What is the primary function of DNA?
Which component of a nucleotide provides the genetic code?
Which component of a nucleotide provides the genetic code?
How does the difference in hydrogen bonds between A-T and G-C base pairs contribute to DNA stability?
How does the difference in hydrogen bonds between A-T and G-C base pairs contribute to DNA stability?
What is the role of the 2' carbon in deoxyribose within the DNA structure?
What is the role of the 2' carbon in deoxyribose within the DNA structure?
What implications arise from the antiparallel arrangement of DNA strands during replication?
What implications arise from the antiparallel arrangement of DNA strands during replication?
Consider a hypothetical organism with a genome consisting of a single, circular chromosome. If this chromosome contains 6 million base pairs, approximately how many nucleosomes would be required to package the entire chromosome, assuming that each nucleosome packages about 200 base pairs of DNA?
Consider a hypothetical organism with a genome consisting of a single, circular chromosome. If this chromosome contains 6 million base pairs, approximately how many nucleosomes would be required to package the entire chromosome, assuming that each nucleosome packages about 200 base pairs of DNA?
A researcher is studying a newly discovered virus with a genome composed of single-stranded DNA. They find that 28% of the viral genome consists of adenine bases. What percentage of the viral genome is composed of guanine bases?
A researcher is studying a newly discovered virus with a genome composed of single-stranded DNA. They find that 28% of the viral genome consists of adenine bases. What percentage of the viral genome is composed of guanine bases?
A geneticist is studying a population of butterflies where wing color is determined by a single gene with two alleles: 'B' for blue wings and 'b' for brown wings. Blue is dominant. They observe that 84% of the butterfly population has blue wings. Assuming the population is in the Hardy-Weinberg equilibrium, what is the approximate frequency of the 'b' allele in the population?
A geneticist is studying a population of butterflies where wing color is determined by a single gene with two alleles: 'B' for blue wings and 'b' for brown wings. Blue is dominant. They observe that 84% of the butterfly population has blue wings. Assuming the population is in the Hardy-Weinberg equilibrium, what is the approximate frequency of the 'b' allele in the population?
In a particular species of plant, the amount of adenine (A) is found to be 30% of the total bases in its DNA. Assuming the DNA composition follows Chargaff's rules, what percentage of the total bases would be guanine (G)?
In a particular species of plant, the amount of adenine (A) is found to be 30% of the total bases in its DNA. Assuming the DNA composition follows Chargaff's rules, what percentage of the total bases would be guanine (G)?
Which of the following statements accurately describes the organization of genetic material within a cell?
Which of the following statements accurately describes the organization of genetic material within a cell?
A scientist discovers a new life form that has a unique nucleic acid structure. Instead of the typical four bases (A, T, G, C), it has five: A, B, C, D, and E. The scientist observes that A always pairs with D, and B always pairs with E. If the life form's nucleic acid contains 20% A, what percentage of C would be expected?
A scientist discovers a new life form that has a unique nucleic acid structure. Instead of the typical four bases (A, T, G, C), it has five: A, B, C, D, and E. The scientist observes that A always pairs with D, and B always pairs with E. If the life form's nucleic acid contains 20% A, what percentage of C would be expected?
Flashcards
What is DNA?
What is DNA?
Molecule that carries genetic information, arranged in a double helix structure.
What is the sugar-phosphate backbone?
What is the sugar-phosphate backbone?
Alternating sugar molecules and phosphate groups that form the structural support of a DNA strand.
What is deoxyribose?
What is deoxyribose?
The sugar molecule present in DNA, lacking an oxygen atom at the 2' carbon.
What are nitrogenous bases?
What are nitrogenous bases?
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What are nucleotides?
What are nucleotides?
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What are 5' and 3' ends?
What are 5' and 3' ends?
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What does antiparallel mean in DNA?
What does antiparallel mean in DNA?
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What are genes?
What are genes?
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What are alleles?
What are alleles?
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What are histones?
What are histones?
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What is a nucleosome?
What is a nucleosome?
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What is chromatin?
What is chromatin?
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What is a chromosome?
What is a chromosome?
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What is a genome?
What is a genome?
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What is the role of gonosomes?
What is the role of gonosomes?
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What is an autosome?
What is an autosome?
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Study Notes
DNA Structure and Function
- DNA carries genetic information and is crucial for understanding life biologically.
- It has a double helix structure similar to a twisted ladder.
- The exterior of DNA contains a sugar-phosphate backbone composed of alternating sugar molecules and phosphate groups.
- The sugar in DNA is deoxyribose, lacking an oxygen at the 2' carbon.
- Nitrogenous bases inside of DNA include adenine (A), thymine (T), guanine (G), and cytosine (C).
- Bases are complementary: adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C).
- Adenine and thymine are connected via two hydrogen bonds.
- Guanine and cytosine are connected via three hydrogen bonds.
- Nucleotides are DNA's building blocks, each consisting of a sugar molecule, a phosphate group, and a base.
- Nucleotides link to form a nucleotide chain; a pair of chains combine to make a single DNA strand.
- DNA strands have directionality, featuring a 5' end (phosphate group) and a 3' end (sugar molecule).
- Two DNA strands run antiparallel, meaning they orient in opposite directions.
Genes and Alleles
- Genes are sections of DNA that carry specific trait information such as hair color or enzymes.
- Alleles are variations of a particular gene.
- Individuals inherit DNA from both parents, so they have two copies of each gene.
- Genes inherited from parents may contain different information.
Chromosomes and Genomes
- DNA is packaged with proteins called histones due to its large size.
- DNA wraps around histones creating a DNA-histone complex called a nucleosome.
- Nucleosomes link to form chromatin or chromatin fibers.
- Chromatin is the active, normal state of DNA.
- During cell division, chromatin condenses into the familiar X-shaped metaphase chromosome.
- Chromosomes carry genetic information on a cellular level.
- A genome is the complete set of chromosomes.
- Humans typically have 46 chromosomes, or 23 pairs; this is called a double chromosome set.
- Sex chromosomes (gonosomes) determine biological sex: women have two X chromosomes, while men have one X and one Y chromosome
- The other chromosomes are called autosomes.
- Sperm and egg cells have a single set of 23 chromosomes.
Summary of Genetic Concepts
- DNA is a double helix with antiparallel strands composed of nucleotides.
- A gene is a DNA segment carrying specific information, while an allele is a gene variant.
- DNA is wound around proteins to form chromosomes.
- Humans have a double set of chromosomes, totaling 46.
- Gonosomes determine the biological sex.
- All chromosomes together form the genome.
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