Genetic Variation 1 Flashcards
What are gametes?
Sex cells with half the number of chromosomes.
What phase does crossing over happen?
Prophase 1
What is a haploid cell?
A cell with n chromosomes (half)
What is a diploid cell?
A cell with 2n chromosomes (whole)
What happens during prophase I?
Pairing of homologous chromosomes, homologous chromosomes condense
What is synapsis?
Binds homologous chromosomes together
What happens during metaphase I?
Chromosome centromeres attach to spindle fibers, homologous chromosomes line up as a pair at the equator
What happens during anaphase I?
Homologous chromosomes separate and move to opposite poles of the cell, 2n to n
What are homologous chromosomes?
Same length,same centromere position, genes for same traits
What happens during telophase I?
Chromosomes reach the cell’s opposite poles, cytokinesis occurs
How many cells result from cytokinesis in meiosis?
4
Why is meiosis important?
Provides variation
When is genetic variation produced?
Crossing over, fertilization
How is asexual reproduction different from sexual reproduction?
The organism inherits all of its chromosomes from one parent and is genetically identical.
Why is sexual reproduction beneficial?
- Rate of good mutations is faster
- Progressive genes multiply faster over times than they do for asexual organisms
What is one simularity between meoisis and mitosis?
They start with a diploid number of cells.
What is the difference between somatic and stem cells?
Somatic: developed, might be used to maintain and repair tissue.
Stem: Have the potential to become any type of cell.
True or false: is meiosis a cycle?
False
What are cyclins?
Proteins that bind to CDKs
What are sister chromatids?
Two halves of a duplicated chromosome
During meiosis, when does the ploidy (number of sets of chromosomes) get reduced from diploid (2n) to haploid (n)?
Once telophase I of meiosis I is complete
The somatic cells of a cat contain 38 chromosomes.
If a cat cell undergoes meiosis, how many chromosomes will be in the resulting cell?
19
What occurs during meiosis II?
Separation of sister chromatids
How many cells does mitosis yield?
2
What are two things that make meiosis and mitosis different?
- mitosis is a cycle, meiosis is not.
- mitosis replaces damaged cells, meiosis produces gametes
What is crossing over?
The exchange of genetic information between homologous chromosomes.
Down syndrome occurs when there’s an extra chromosome at the chromosome 21 pair. How might Down Syndrome occur?
Sister chromatids fail to separate at chromosome 21 during anaphase II in a parent’s gamete.
What is the order of mitosis?
Interphase, Prophase, Metaphase, Anaphase, Telophase
What is the purpose of mitosis?
- replace damaged cells
- separate replicated DNA
What happens when cells divide uncontrollably?
They are at risk of becoming cancerous
