Podcast
Questions and Answers
What is the primary difference between sister chromatids and homologous chromosomes?
What is the primary difference between sister chromatids and homologous chromosomes?
- Sister chromatids are found in haploid cells, while homologous chromosomes are found in diploid cells.
- Sister chromatids are products of meiosis I, while homologous chromosomes are products of meiosis II.
- Sister chromatids are identical copies formed during DNA replication, while homologous chromosomes are pairs with the same genes but potentially different alleles. (correct)
- Sister chromatids are genetically distinct, while homologous chromosomes are genetically identical.
During which phase of meiosis does synapsis occur, leading to the formation of a tetrad?
During which phase of meiosis does synapsis occur, leading to the formation of a tetrad?
- Pachytene phase of prophase I of meiosis I (correct)
- Prophase II of meiosis II
- Metaphase I of meiosis I
- Diakinesis phase of prophase I of meiosis I
What is the significance of 'crossing over' during meiosis?
What is the significance of 'crossing over' during meiosis?
- It is necessary for the formation of diploid daughter cells at the end of meiosis I.
- It increases genetic variation by exchanging genetic material between homologous chromosomes. (correct)
- It ensures that sister chromatids separate correctly during meiosis II.
- It prevents mutations from occurring in gametes.
If a mutation occurs in a somatic cell, will it contribute to genetic variation in the species?
If a mutation occurs in a somatic cell, will it contribute to genetic variation in the species?
Which of the following is NOT a primary source of genetic variation?
Which of the following is NOT a primary source of genetic variation?
What are the products of meiosis I?
What are the products of meiosis I?
How many homologous pairs of chromosomes do human somatic cells typically have?
How many homologous pairs of chromosomes do human somatic cells typically have?
What is the relationship between alleles and genes?
What is the relationship between alleles and genes?
Which of the following best describes 'gene flow' as a source of genetic variation?
Which of the following best describes 'gene flow' as a source of genetic variation?
If paternal chromosome 5 and maternal chromosome 5 are homologous pairs, which of the following is NOT a homologous pair to paternal chromosome 5?
If paternal chromosome 5 and maternal chromosome 5 are homologous pairs, which of the following is NOT a homologous pair to paternal chromosome 5?
Which process contributes to genetic variation by introducing new genes into a population?
Which process contributes to genetic variation by introducing new genes into a population?
During meiosis, what mechanism, besides independent assortment, enhances genetic diversity?
During meiosis, what mechanism, besides independent assortment, enhances genetic diversity?
Which type of mutation occurs in cells that are not involved in reproduction?
Which type of mutation occurs in cells that are not involved in reproduction?
What type of mutation affects a large segment of nucleotides within a chromosome?
What type of mutation affects a large segment of nucleotides within a chromosome?
Which of the following is NOT considered a mutagen?
Which of the following is NOT considered a mutagen?
How do mutagens contribute to genetic diversity?
How do mutagens contribute to genetic diversity?
What role do Y-family polymerases play in the context of mutations?
What role do Y-family polymerases play in the context of mutations?
What is the primary source of genetic variation among species?
What is the primary source of genetic variation among species?
Which biological process generates gametes?
Which biological process generates gametes?
What occurs during crossing over in meiosis?
What occurs during crossing over in meiosis?
Flashcards
Sister Chromatids
Sister Chromatids
Two identical halves of a duplicated chromosome.
Homologous Chromosomes
Homologous Chromosomes
Chromosomes that are similar in shape and size and code for the same genes.
Gametogenesis
Gametogenesis
The process of forming gametes (sperm and egg cells) through meiosis.
Meiosis
Meiosis
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Tetrad
Tetrad
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Synapsis
Synapsis
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Chiasma
Chiasma
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Crossing Over
Crossing Over
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Genetic Variation
Genetic Variation
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Germline Mutations
Germline Mutations
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Gene Flow
Gene Flow
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Independent Assortment
Independent Assortment
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Random Fertilization
Random Fertilization
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Somatic Mutations
Somatic Mutations
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Mutagens
Mutagens
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Types of Mutations
Types of Mutations
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Study Notes
Chromosome Structure and Homologous Pairs
- Chromosomes consist of two sister chromatids, identical genetically.
- Homologous chromosomes carry the same genes but differ in variations.
- Humans have 22 pairs of autosomal homologous chromosomes and 1 pair of sex chromosomes (XY).
- Paternal and maternal chromosomes form homologous pairs.
Meiosis and Genetic Recombination
- Meiosis, a two-stage process, produces gametes (sperm/egg).
- Meiosis I and II each have four phases.
- Synapsis in prophase I pairs homologous chromosomes, forming a tetrad.
- Chiasmata are crossing points where homologous chromosomes exchange genetic material (crossing over).
- Crossing over shuffles genetic information between maternal and paternal chromosomes.
- Meiosis produces four haploid gametes.
Genetic Variation
- Genetic variation refers to differences in genetic code within a species or allele frequencies between populations.
- Alleles are different forms of the same gene.
- Sources of genetic variation include germline mutations, gene flow, and sexual reproduction.
- Germline mutations are heritable changes in gametes.
- Gene flow introduces new genes into a population.
- Sexual reproduction creates unique combinations of traits.
- Some variations are simple (dominant/recessive), others are complex.
Meiosis and Fertilization
- Meiosis and fertilization are essential for sexual reproduction.
- Meiosis creates gametes.
- Fertilization merges gametes to form a zygote.
- Meiosis involves reductional (Meiosis I) and equational (Meiosis II) phases.
- Independent assortment and crossing over contribute to genetic variation.
- Random fertilization further increases genetic diversity.
- Genetic variation is crucial for species' survival in changing environments.
DNA Mutations and Evolution
- Mutations are changes in DNA creating variation within a population.
- Mutations lead to unique traits in individuals.
- Mutations drive evolution.
- Mutations can be somatic (non-heritable) or germline (heritable).
- Mutations can affect genes (gene-level) or chromosomes (chromosomal).
- Factors causing mutations include chance and mutagens.
- Types of DNA changes include substitution, insertion, and deletion.
Mutagens
- Mutagens are agents that cause DNA damage.
- Physical mutagens are forms of radiation, damaging DNA with free radicals.
- Chemical mutagens directly damage DNA bases, causing mismatches.
- Biological mutagens include viruses and bacteria, causing DNA damage and potentially cancer.
- Mutagens disrupt DNA repair mechanisms and may replace DNA polymerases with Y-family polymerases, bypassing proofreading/repair.
- While harmful, mutations are a primary source of genetic diversity and evolution.
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