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Questions and Answers
Eukaryotic chromosomes come in pairs, also known as homologues.
Eukaryotic chromosomes come in pairs, also known as homologues.
True
How many chromosomes do normal humans have?
How many chromosomes do normal humans have?
46
Each chromosome in a pair comes from the same parent.
Each chromosome in a pair comes from the same parent.
False
Autosomes are found in both males and females.
Autosomes are found in both males and females.
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How many pairs of autosomes are present in humans?
How many pairs of autosomes are present in humans?
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Autosomes in a pair are not homologous.
Autosomes in a pair are not homologous.
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Sex chromosomes determine an individual's gender.
Sex chromosomes determine an individual's gender.
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The X and Y chromosomes are homologous.
The X and Y chromosomes are homologous.
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The X chromosome is smaller than the Y chromosome.
The X chromosome is smaller than the Y chromosome.
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The Y chromosome carries a large number of genes.
The Y chromosome carries a large number of genes.
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In humans and mammals, females have XX chromosomes and males have XY chromosomes.
In humans and mammals, females have XX chromosomes and males have XY chromosomes.
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What is a karyotype?
What is a karyotype?
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A karyotype is a complete set of chromosomes from a cell, including their size, number, and shape.
A karyotype is a complete set of chromosomes from a cell, including their size, number, and shape.
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The goal of cell division is to equally partition two or more identical copies of genetic material between two daughter cells.
The goal of cell division is to equally partition two or more identical copies of genetic material between two daughter cells.
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Prokaryotes are comparatively simple, having only one chromosome, which makes dividing chromosomes relatively easy.
Prokaryotes are comparatively simple, having only one chromosome, which makes dividing chromosomes relatively easy.
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Eukaryotes, with their longer DNA and multiple chromosomes, find it easier to sort chromosomes during division than prokaryotes do.
Eukaryotes, with their longer DNA and multiple chromosomes, find it easier to sort chromosomes during division than prokaryotes do.
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Mitosis is a complex process that ensures each daughter cell ends up with the same number and type of chromosomes as the parent cell.
Mitosis is a complex process that ensures each daughter cell ends up with the same number and type of chromosomes as the parent cell.
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Prokaryotic cell division is required for both development and reproduction.
Prokaryotic cell division is required for both development and reproduction.
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In eukaryotic cells, chromosomes are found in the cytoplasm, not the nucleus.
In eukaryotic cells, chromosomes are found in the cytoplasm, not the nucleus.
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Chromosomes are tightly packaged DNA and are only found during cell division.
Chromosomes are tightly packaged DNA and are only found during cell division.
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Chromatin is unwound DNA and is found throughout interphase.
Chromatin is unwound DNA and is found throughout interphase.
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DNA is not used for macromolecule synthesis during chromosome formation.
DNA is not used for macromolecule synthesis during chromosome formation.
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DNA is being used for macromolecule synthesis during interphase, when DNA exists as chromatin.
DNA is being used for macromolecule synthesis during interphase, when DNA exists as chromatin.
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Chromosomes are formed through replication and not by the joining of existing chromatids.
Chromosomes are formed through replication and not by the joining of existing chromatids.
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Sister chromatids are identical copies of DNA.
Sister chromatids are identical copies of DNA.
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Chromosomes are mainly composed of protein.
Chromosomes are mainly composed of protein.
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A gene is a discrete heritable unit that carries traits.
A gene is a discrete heritable unit that carries traits.
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Alleles are different versions of a gene.
Alleles are different versions of a gene.
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Alleles can only differ by one or a few nucleotides.
Alleles can only differ by one or a few nucleotides.
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Different alleles always code for different phenotypes.
Different alleles always code for different phenotypes.
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A chromatid is considered a chromatid as long as it is associated with a sister chromatid at the centromere.
A chromatid is considered a chromatid as long as it is associated with a sister chromatid at the centromere.
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When sister chromatids separate after metaphase, they become two different chromosomes.
When sister chromatids separate after metaphase, they become two different chromosomes.
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The eukaryotic cell cycle includes interphase and mitosis.
The eukaryotic cell cycle includes interphase and mitosis.
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Interphase consists of three stages: G1, S, and G2.
Interphase consists of three stages: G1, S, and G2.
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The mitotic phase includes mitosis and cytokineses.
The mitotic phase includes mitosis and cytokineses.
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Interphase is longer and more complex than mitosis.
Interphase is longer and more complex than mitosis.
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Interphase is responsible for DNA replication, while mitosis is responsible for cell growth.
Interphase is responsible for DNA replication, while mitosis is responsible for cell growth.
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During prophase, the nucleoli disappear, the mitotic spindle forms, and the centrosomes separate.
During prophase, the nucleoli disappear, the mitotic spindle forms, and the centrosomes separate.
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Metaphase involves the alignment of chromosomes at the metaphase plate, with kinetochores attached to microtubules.
Metaphase involves the alignment of chromosomes at the metaphase plate, with kinetochores attached to microtubules.
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Anaphase is the shortest stage of mitosis, where sister chromatids are pulled apart, becoming individual chromosomes.
Anaphase is the shortest stage of mitosis, where sister chromatids are pulled apart, becoming individual chromosomes.
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Telophase is when the nuclear envelope reforms, chromosomes decondense, and cytokinesis begins.
Telophase is when the nuclear envelope reforms, chromosomes decondense, and cytokinesis begins.
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Cytokinesis is the division of the cytoplasm, resulting in two daughter cells.
Cytokinesis is the division of the cytoplasm, resulting in two daughter cells.
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Meiosis I is the first division of meiosis, in which homologous chromosomes are separated from each other.
Meiosis I is the first division of meiosis, in which homologous chromosomes are separated from each other.
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Meiosis II separates sister chromatids, resulting in four haploid daughter cells.
Meiosis II separates sister chromatids, resulting in four haploid daughter cells.
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Crossing over is a process that happens during prophase I of meiosis, making sister chromatids no longer identical.
Crossing over is a process that happens during prophase I of meiosis, making sister chromatids no longer identical.
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During independent assortment, each human can potentially produce over 8.3 million different gametes in meiosis I.
During independent assortment, each human can potentially produce over 8.3 million different gametes in meiosis I.
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A couple can potentially produce over 64 trillion different zygotes during fertilization.
A couple can potentially produce over 64 trillion different zygotes during fertilization.
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Crossing over is a key factor in creating genetic diversity.
Crossing over is a key factor in creating genetic diversity.
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Synapsis is the pairing of homologous chromosomes during prophase I of meiosis.
Synapsis is the pairing of homologous chromosomes during prophase I of meiosis.
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A chiasma is the site where crossing over occurs.
A chiasma is the site where crossing over occurs.
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Recombinant chromosomes are chromosomes that have undergone crossing over, resulting in the exchange of genetic material.
Recombinant chromosomes are chromosomes that have undergone crossing over, resulting in the exchange of genetic material.
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Study Notes
Eukaryote Chromosomes
- Eukaryotic chromosomes come in pairs (homologous).
- Humans have 46 chromosomes in 23 pairs.
- Each pair has one chromosome from the mother and one from the father.
- Autosomes are found in both males and females.
- Humans have 22 pairs of autosomes.
- Autosomes of the same size and structure are called homologues.
- The remaining pair, sex chromosomes (X and Y), determine gender.
- The X chromosome is larger than the Y chromosome and carries more genes.
- The Y chromosome has fewer genes.
- Females are XX and males are XY in humans and other mammals.
Karyotype
- A karyotype is a picture of chromosomes arranged by size and shape.
- Chromosomes are categorized by their centromere position.
- Size, shape, and number of chromosomes are considered in a karyotype.
- Karyotyping often uses white blood cells during metaphase.
Human Sexual Cycle
- The female reproductive system contains ovaries.
- The female life cycle contains only about 400 viable oocytes.
- Males have testes.
- Meiosis results in haploid gametes (sperm and ova).
- Fertilization of the ovum by a sperm results in a zygote.
- The zygote develops through mitotic growth.
- Diploid adults result.
Chromosome Sorting
- Cell division aims to distribute identical genetic material between daughter cells.
- Prokaryotes are simpler, with one chromosome and quick chromosome sorting.
- Eukaryotes, with multiple chromosomes, face a more complex process.
- Mitosis ensures that each daughter cell inherits the identical number and type of chromosomes of the parent cell.
Chromosomes vs. Chromatin
- Chromosomes are tightly packaged DNA found during cell division.
- Chromatin is unwound DNA located throughout interphase for macromolecule synthesis.
Mitosis
- Mitosis is the process of cell division for growth, development, and tissue renewal.
- The stages of mitosis are interphase, prophase, metaphase, anaphase, telophase, and cytokinesis.
- G2 of interphase: DNA continues to replicate in preparation for mitosis.
- Prophase: Chromosomes condense, nuclear envelope breaks down, mitotic spindle forms, centrosomes separate.
- Metaphase: Chromosomes align at the metaphase plate.
- Anaphase: Sister chromatids separate and move to opposite poles.
- Telophase: Chromosomes decondense, nuclear envelopes reform, and the mitotic spindle breaks down.
- Cytokinesis: The cytoplasm divides to create two daughter cells.
Meiosis I
- Meiosis I is the first stage of meiosis.
- It reduces chromosome number to half in a process called reduction in ploidy.
- Homologous chromosomes pair to form tetrads, exchange genetic material (crossing over), then separate.
Meiosis II
- Meiosis II is the second stage of meiosis.
- Sister chromatids separate to produce four haploid daughter cells. This is identical to mitosis but with haploid cells. No DNA replication occurs between meiosis I and meiosis II
Variation via the Sexual Cycle
- Crossing over produces new genetic combinations in gametes.
- Independent assortment mixes chromosomes in gametes from one individual.
- Random fertilization of unique haploid eggs and sperm creates unique diploid zygotes, increasing genetic variation.
Cytokinesis
- Cytokinesis is the division of the cytoplasm to form two separate daughter cells.
- Animals: Cleavage furrow forms and pinches the cell in two.
- Plants: Cell plate forms in the middle of the dividing cell.
Alleles and Loci
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Genes code for traits, and different alleles of a gene result in variations in an observable trait.
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Alleles are variants of a gene.
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Loci are the specific positions of a gene on a chromosome.
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Different alleles may or may not produce different observable traits.
Prophase in detail
- Chromatic condensation
- Nucleoli disappear
- Mitotic spindle forms
- Centrosome separation
Telophase in detail
- "Sisters" at opposite poles
- Nuclear envelope reformation
- Chromosome decondensation
- Cytokinesis already under way
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Description
Explore the fascinating world of eukaryotic chromosomes and karyotyping in this quiz. Learn about chromosome pairs, autosomes, sex chromosomes, and the significance of karyotypes in understanding genetic structure. Test your knowledge on human sexual cycles and reproductive systems.
