L17: Meiotic Cell Division & Sexual Life Cycle Flashcards
Does meiotic cell division produce genetically identical or genetically unique daughter cells?
- genetically unique daughter cells
During meiosis how do the daughter cells compare to the parent cell in regards to the number of sets of genes/chromosomes?
- they’re only gonna contain one set of chromosomes instead of 2
How many daughter cells are produced? Are they diploid or haploid?
- 4 haploid daughter cells
What do the terms diploid and haploid mean?
- diploid means two set of chromosomes coming from each parent and haploid is only one set
Which role in your body does meiosis serve?
- to produce gametes for reproduction
Which is the only cell type in your body to undergo meiosis?
- ovary and teste germ cells
What do daughter cells of meiosis become?
- gametes, sperm/egg
Can daughter cells of meiosis divide into new cells?
- no because gametes can’t divide
How does meiotic cell division fit into the animal life cycle?
- reproduction and genetic variation
How many chromosomes are found in human diploid cells and haploid cells?
- 46 chromosomes in diploid and 23 in haploid
What is accomplished during meiosis 1?
- segregate homologous pairs into 2 separate daughter cells
What is accomplished during meiosis 2?
- separate chromatids into 4 daughter cells
What is a homologue?
- a pair of chromosomes with similar genetic information but not identical
Do germ cells have homologues?
- yes because they’re diploid
Do gametes have homologues?
- no since they’re haploid
What happens during fertilization?
What does fertilization accomplish?
- A sperm and egg gamete combine to restore diploidy and reform new homologous pairs in a bigger cell now called a zygote
What is the biological significance of sexual reproduction (meiosis + fertilization)?
- Unique offspring are more likely to survive than clones. sex—> population variation —> adaptation to change
What is a homologue? What is a gene locus? What are alleles?
homologue - pair of chromosomes that are similar in genetic information but not identical
gene locus - the location of a gene on a chromosome
alleles - a variant or alternative form of a gene
How many gene loci do human cells have? How many homologues due human cells have?
estimated that humans have between 20,000 and 25,000 genes
23 homologue pairs
How many alleles per gene locus do human diploid cells possess (at least for autosomes)? Different alleles of a gene locus would be expected to express as different __________________ of a trait.
two alleles at each genetic locus, with one allele inherited from each parent
Different alleles of a gene locus would be expected to express as different VARIATIONS of a trait.
What happens in a germ cell dividing by meiosis according to Mendel’s Law of Segregation?
Because the alleles at different gene loci vary on homologous chromosomes, segregating them results in unique cells.
each cell inherits at least one copy of each allele (dominant or recessive)
What happens in a germ cell dividing by meiosis according to Mendel’s Law of Independent Assortment?
chromosomes align or arrange themselves in random possible ways along the metaphase plate and migrate randomly towards each pole.
What happens during allele cross-over? When dos allele cross-over occur? How does allele cross-over impact the genetic diversity of meiotic daughter cells (gametes)?
Allele cross-over may occur: alleles exchanged among synapsed chromosomes during homologue synapsid (meiosis 1)
generates genetic variation
Random homologue orientation prior to segregation is random and independent for each homologue. How does the independent assortment of homologous chromosomes/alleles impact the genetic diversity of meiotic daughter cells (gametes)?
increase in variation
