Lec 3. Meiosis & Heredity Flashcards
What is the purpose of mitosis?
For growth and to replace worn out cells.
What is the outcome of mitosis?
2 cells
What is the purpose of meiosis?
To shuffle genetic information and cut the cellular chromosome number in half, from 46 chromosomes to 23 chromosomes
What is the outcome of meiosis?
4 cells
What happens during Prophase II?
Chromosomes recondense
What happens during Metaphase II?
Chromosomes line up
What happens during Anaphase II?
Sister chromatids separate and move to opposite poles
What happens during Telophase II?
Chromosomes arrive at spindle poles.
When does crossing over occur?
Prophase I
What happens during Cytokinesis?
Cytoplasm divides
What happens during Interkinesis?
Nuclear envelope re-forms, no DNA synthesis takes place
How is Genetic variation produced?
Through random distribution of chromosomes in meiosis.
Define crossing over
Exchange of genetic material between homologous chromosomes, resulting in shuffling of genes.
True or False? Crossing over can result in unequal exchange of genetic material.
True. This can produce chromosomes with deleted or duplicated regions.
What is essential for the normal segregation of chromosomes during Meiosis?
Crossing over
True or False? Crossing over and mapping, distance is important.
True
True or False? Crossover is dependent across the centromere.
False. Crossover is INDEPENDENT across the centromere.
Is there cell division during Mitosis?
Yes.
Is there cell division during Meiosis I?
Yes.
Is there cell division during Meiosis II?
Yes.
Is there reduction of chromosome number during Mitosis?
No.
Is there reduction of chromosome number during Meiosis I?
Yes.
Is there reduction of chromosome number during Meiosis II?
No.
Is Genetic variation produced during Mitosis?
No.
Is Genetic variation produced during Meiosis I?
Yes.
Is Genetic variation produced during Meiosis II?
No.
Does crossing over occur during Mitosis?
No.
Does crossing over occur during Meiosis I?
Yes.
Does crossing over occur during Meiosis II?
No.
Does random distribution of maternal and paternal chromosomes occur during Mitosis?
No.
Does random distribution of maternal and paternal chromosomes occur during Meiosis I?
Yes.
Does random distribution of maternal and paternal chromosomes occur during Meiosis II?
No.
What happens in Mitosis during Metaphase?
Individual chromosomes line up
What happens in Meiosis I during Metaphase?
Homologous pairs line up
What happens in Meiosis II during Metaphase?
Individual chromosomes line up
What happens in Mitosis during Anaphase?
Chromatids separate
What happens in Meiosis I during Anaphase?
Homologous chromosomes separate
What happens in Meiosis II during Anaphase?
Chromatids separate
What is cohesion?
A protein complex that holds chromatids together
What is Spermatogenesis?
Male gamete production
What is Oogenesis?
female gamete production
Why is there only one female gamete?
All the organelles are in there
Why are mules sterile?
Chromosomes fail to separate correctly
What are two diseases that result from failed chromosome segregation?
Trisomy 21. Klinefelter
Define Heredity
Passing on of physical or mental characteristics genetically from one generation to another
Define Heritability
Proportion of total variation between individuals in a give population that is due to genetic variation
What causes red hair?
Receptor deficiency on the MC1R gene resulting in pheomelanin, which is the predominate pigment in red hair.
What causes blond hair in 5%-10% of dark-skinned Solomon Islanders?
A point mutation in the TYRP1 gene.
What is not known but thought to be the function of TYRP1?
To stabilize Tyrosinase.
