All flashcards
Flashcard 1: What is the primary reason eukaryotic DNA is packaged into linear chromosomes instead of one long strand?
Answer: To enable efficient organization, regulation, and accurate segregation. Multiple chromosomes allow independent assortment and organization.
Flashcard 2: Which proteins form the core around which DNA wraps in a nucleosome?
Answer: Histone proteins. These positively charged proteins attract negatively charged DNA.
Flashcard 3: What is the role of histones in chromosome organization?
Answer: They package and help condense DNA into chromatin. This compaction allows DNA to fit within the cell nucleus.
Flashcard 4: What is the difference between chromatin and a chromosome?
Answer: Chromatin is DNA-protein; a chromosome is highly condensed chromatin. Condensation increases during cell division for easier separation.
Flashcard 5: Where are chromosomes located in eukaryotic cells?
Answer: In the nucleus. This membrane-bound organelle contains the genetic material.
Flashcard 6: Which term describes the DNA-protein fiber that makes up chromosomes: chromatin or cytoskeleton?
Answer: Chromatin. The cytoskeleton provides structural support, not genetic material.
Flashcard 7: Identify the correct statement: each chromatid contains one DNA molecule, or each chromatid contains two DNA molecules.
Answer: Each chromatid contains one DNA molecule. Sister chromatids are identical copies of the same DNA molecule.
Flashcard 8: Which structure is directly responsible for attaching chromosomes to spindle microtubules?
Answer: The kinetochore. This protein complex assembles at the centromere during mitosis.
Flashcard 9: What is a chromatid?
Answer: One of two identical copies of a replicated chromosome. Formed after DNA replication but before cell division.
Flashcard 10: What is meant by a haploid cell with respect to chromosome sets?
Answer: It has one set of chromosomes. Contains half the chromosome number of diploid cells.
Flashcard 11: Which structure connects sister chromatids: telomere or centromere?
Answer: Centromere. This structure holds sister chromatids together until separation.
Flashcard 12: What is a chromatid?
Answer: One of two identical copies of a replicated chromosome. Formed after DNA replication but before cell division.
Flashcard 13: What are sister chromatids?
Answer: Identical chromatids joined together after DNA replication. They contain identical genetic information after replication.
Flashcard 14: What is the centromere?
Answer: The chromosome region where sister chromatids are held together. Essential for proper chromosome segregation during mitosis.
Flashcard 15: What is the main purpose of condensing DNA into chromosomes during cell division?
Answer: To prevent tangling and ensure accurate DNA separation. Condensation makes chromosomes easier to move during mitosis.
Flashcard 16: What is meant by a chromosome being "replicated"?
Answer: It consists of two sister chromatids joined at the centromere. DNA replication doubles the chromosome into two identical parts.
Flashcard 17: What is the difference between chromatin and a chromosome?
Answer: Chromatin is DNA-protein; a chromosome is highly condensed chromatin. Condensation increases during cell division for easier separation.
Flashcard 18: Identify the term for DNA that is loosely packed and generally active in transcription.
Answer: Euchromatin. This relaxed form allows gene expression to occur.
Flashcard 19: Identify the term for DNA that is tightly packed and generally less transcriptionally active.
Answer: Heterochromatin. This condensed form typically represses gene expression.
Flashcard 20: Which form is usually more accessible to transcription machinery: euchromatin or heterochromatin?
Answer: Euchromatin. Loose packing allows transcription factors access to DNA.
Flashcard 21: What is the relationship between DNA length and the need for chromosome packaging?
Answer: Long DNA must be compacted to fit in the nucleus and be organized. Human DNA is about 2 meters long but fits in microscopic nuclei.
Flashcard 22: What is meant by "DNA supercoiling" in chromosome organization?
Answer: Additional twisting of DNA to increase compaction. Creates higher-order structures beyond nucleosome organization.
Flashcard 23: What is the simplest correct hierarchy from smallest to largest: DNA, nucleosome, chromatin, chromosome?
Answer: DNA → nucleosome → chromatin → chromosome. Each level represents increasing organization and compaction.
Flashcard 24: What is the kinetochore (basic definition)?
Answer: A protein structure on the centromere that attaches to spindle fibers. Critical for chromosome movement during cell division.
Flashcard 25: Which structure directly results from DNA wrapped around histones: nucleosome or chromatid?
Answer: Nucleosome. DNA wrapping around histones creates this basic unit.
Flashcard 26: Which structure connects sister chromatids: telomere or centromere?
Answer: Centromere. This structure holds sister chromatids together until separation.
Flashcard 27: Which chromosome region is located at the ends: centromere or telomere?
Answer: Telomere. These protective caps prevent chromosome degradation.
Flashcard 28: What is a homologous pair of chromosomes?
Answer: Two chromosomes with the same genes, one from each parent. They carry the same genes but may have different alleles.
Flashcard 29: What is a chromosome in terms of its molecular composition?
Answer: A DNA molecule packaged with associated proteins (mainly histones). This structure allows DNA to fit in the nucleus.
Flashcard 30: What is chromatin?
Answer: The DNA-protein complex that makes up chromosomes in the nucleus. Found in the nucleus, less condensed than chromosomes.