Questions and Answers
What is the primary role of chromosomes in the body?
What is the structure that helps condense DNA in chromosomes?
How many chromosomes do humans typically have in each cell?
What component of chromosomes is responsible for copying and repairing DNA?
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What unique information do chromosomes carry for each individual?
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What are sister chromatids and why are they important during cell division?
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What is the main role of telomeres in chromosomes?
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What is the function of histones and other proteins associated with chromosomes?
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During cell division, what role do spindle fibers play in relation to chromosomes?
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What structure can DNA be compared to, and what does this indicate about its nature?
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Study Notes
Chromosomes and DNA
- Chromosomes are integral for passing genetic information between generations and are made of DNA, the code of physical characteristics.
- DNA encodes hereditary traits, with its unique sequences impacting features like eye color and disease susceptibility.
- Each species has a specific number of chromosomes: humans have 46, cats have 38, defining their characteristics.
- Chromosomes contain tightly wound DNA strands and histone proteins that organize and protect genetic material.
- Sister chromatids, formed during DNA replication, ensure genetic consistency during cell division.
Functions of Chromosomes
- Chromosomes carry DNA essential for cellular functions, growth, survival, and reproduction.
- Protective proteins cover chromosomes to guard against damage from enzymes and physical forces during cell division.
- Spindle fibers contract at centromeres to ensure precise distribution of DNA to daughter nuclei.
- Proteins regulate gene action by activating or deactivating the genes, influencing cellular behavior and development.
DNA Structure and Function
- DNA has a double-helix structure, resembling a twisted ladder, made up of nucleotides (sugar, phosphate, nitrogen bases).
- Four nitrogenous bases (Adenine, Thymine, Guanine, Cytosine) pair accordingly: A with T and C with G.
- DNA serves as hereditary information, with genes in DNA ranging from 250 to 2 million base pairs, coding for proteins necessary for organismal function.
- Functions of DNA include replication, mutation management, transcription, cellular metabolism, DNA fingerprinting, and gene therapy.
Cell Division: Mitosis and Meiosis
- Prokaryotes divide through binary fission, while eukaryotes undergo mitosis for growth and repair.
- Cell cycle phases include G1 (growth), S (synthesis and DNA replication), G2 (preparation for division), and M (mitosis).
- During interphase, particularly the S phase, DNA is replicated to create sister chromatids, attached at the centromere.
- In metaphase, chromosomes align at the metaphase plate, each centromere connected to spindle fibers.
- Anaphase is characterized by sister chromatids separating and moving to opposite poles of the cell due to spindle fiber tension.
Stages of Mitosis
- Metaphase: Chromosomes line up at the cell's equator, attached to spindle fibers at their centromeres.
- Anaphase: Cohesin proteins are cleaved; sister chromatids are pulled apart, creating individual chromosomes moving towards cell poles.
- Telophase: Formation of daughter nuclei, reappearance of nucleoli, and de-condensation of chromosomes, preparing for the final stages of cell division.
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Description
This quiz focuses on the structure of chromosomes during the interphase, specifically the S phase where DNA replicates. It covers the formation of sister chromatids and their essential role in cell division. Test your understanding of these fundamental genetics concepts.
