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Questions and Answers
Cell differentiation is the process of stem cells becoming less specialized.
Cell differentiation is the process of stem cells becoming less specialized.
False (B)
Signaling molecules activate receptors and cause changes in proteins that control gene expression during cell differentiation.
Signaling molecules activate receptors and cause changes in proteins that control gene expression during cell differentiation.
True (A)
Transcription factors are proteins that prevent changes in gene expression.
Transcription factors are proteins that prevent changes in gene expression.
False (B)
Genes are the basic unit of inheritance, composed of RNA.
Genes are the basic unit of inheritance, composed of RNA.
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Nucleotides are composed of a phosphate group, a sugar, and a nitrogenous base.
Nucleotides are composed of a phosphate group, a sugar, and a nitrogenous base.
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In prokaryotic cells, genes are present on chromosomes encased within a nucleus.
In prokaryotic cells, genes are present on chromosomes encased within a nucleus.
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Human cells typically contain 48 chromosomes, organized into 24 pairs.
Human cells typically contain 48 chromosomes, organized into 24 pairs.
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Telocentric chromosomes have their centromere located at the end of the chromosome.
Telocentric chromosomes have their centromere located at the end of the chromosome.
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Gametes produced through meiosis are genetically identical to each other.
Gametes produced through meiosis are genetically identical to each other.
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Mitosis results in the formation of four diploid daughter cells.
Mitosis results in the formation of four diploid daughter cells.
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The exchange of alleles between homologous chromosomes, known as crossing-over, occurs during prophase II of meiosis.
The exchange of alleles between homologous chromosomes, known as crossing-over, occurs during prophase II of meiosis.
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DNA replication occurs before both meiosis I and meiosis II.
DNA replication occurs before both meiosis I and meiosis II.
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Meiosis involves two successive cell divisions, resulting in a reduction in chromosome number.
Meiosis involves two successive cell divisions, resulting in a reduction in chromosome number.
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The purpose of meiosis is to produce diploid cells for growth and repair within an organism.
The purpose of meiosis is to produce diploid cells for growth and repair within an organism.
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Interphase, the phase preceding meiosis, is the shortest phase in a cell's life cycle.
Interphase, the phase preceding meiosis, is the shortest phase in a cell's life cycle.
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Study Notes
Cell Differentiation
- Cell differentiation is the specialization of stem cells.
- It creates diversity in life and within our bodies.
- Specialized cells form unique structures for specific functions.
- Signaling molecules (e.g., signal transduction molecules) activate receptors, changing protein function controlling gene expression.
- Transcription factors are proteins that cause changes in gene expression.
- Differentiation starts around 3 weeks after fertilization through cytoplasmic localization and cytoplasmic induction (external signals).
Genes and DNA
- Genes are the basic units of inheritance, made of DNA.
- DNA is composed of nucleotides (adenine, thymine, cytosine, guanine).
- DNA has a phosphate group, a sugar, and a nucleotide.
- Genes reside in the nucleus of eukaryotic cells (wrapped around histones).
- In prokaryotes, genes are on chromosomes in the cytoplasm.
- Gene expression to proteins is influenced by enhancers and promoters (extrinsic factors).
- Alleles are different versions of genes inherited as pairs.
Chromosomes
- Chromosomes are DNA wrapped around histones (nucleosomes).
- Nucleosomes condense into chromatin.
- Humans have 46 chromosomes (22 pairs autosomal, 1 pair sex).
- Chromosomes are made of sister chromatids connected by a centromere.
- Types of chromosomes: metacentric, submetacentric, acrocentric, telocentric.
- Karyotypes show chromosomes and can identify sex and genetic anomalies.
Meiosis
- Meiosis is a two-part cell division process that produces four gametes (sperm or egg).
- It differs from mitosis (one division, two identical diploid cells).
- Meiosis I:
- Diploid parent cell with homologous chromosome pairs (tetrads).
- Crossing over occurs exchanging alleles.
- Homologous chromosomes separate.
- Two haploid daughter cells are produced.
- Meiosis II: Further division of the two daughter cells produces four genetically unique haploid (half the DNA) gametes.
- DNA replication does not happen before Meiosis II.
- Meiosis produces genetically unique gametes, crucial for offspring variations and evolution.
- The process begins with interphase where DNA replicates and the cell grows.
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Description
This quiz covers the processes of cell differentiation and the fundamental concepts of genes and DNA. It explores how stem cells specialize into various cell types and the role of genetic materials in inheritance and gene expression. Ideal for students studying biology and genetics.
