Bio 2016 (Test 1) Flashcards
(45 cards)
What is a chromosome?
structure of DNA in the nucleus
What is a diploid?
a cell containing two complete sets of chromosomes, one from each parent (total = 2N)
What is a haploid?
of a cell having a single set of unpaired chromosomes (total = N)
What is a somalic cell?
any cell of a living organism other than the reproductive cells
What are gametes?
they are sex cells, only used for reproduction of other life forms
What is meiosis? What are three results of meiosis?
- division that creates gametes in which one diploid (2n) produces four haploids (n) that are genetically different
Result 1) it reduces the number of chromosomes by half
Result 2) it creates double the number of cells
Result 3) daughter cells different from parent and each other
What is crossing over?
exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.
What are homologous chromes?
a homologous pair of chromosomes consists of one chromosome from each parent
(from your notes: “one of a pair of chromosomes received from each parent that carries the same genes”)
What is a tetrad?
a formation of homologous chromosomes, totaling 4 sister chromatids; found in prophase and metaphase.
What is an autosome?
1-22. An autosome is a chromosome that is not an allosome (a sex chromosome).
What are sex chromosomes?
x, y. Sex chromosomes are involved with determining the sex of an organism, typically one of two kinds.
What is the difference between meiosis and mitosis?
Meiosis involves two cell divisions. Mitosis involves one cell division.
What happens in interphase?
It is the resting phase between mitotic divisions of a cell. During this phase, the cell copies its DNA in preparation for mitosis.It is the phase of the cell cycle in which a typical cell spends most of its life.
What is meiosis 1? (Say two things about it)
The separation of homologous chromosomes. It is the first division of meiosis.
What is meiosis 2?
The separation of sister chromatids
What occurs during prophase 1? (Name four things that occur)
1) Each chromosome condenses and remains closely associated.
2) Nuclear membrane breaks down.
3) Spindle fibers form.
4) Crossing over between tetrads
What happens during metaphase 1?
Homologous chromosomes align at the equatorial plate in the form of tetrads
What happens during anaphase 1?
Homologous pairs separate with sister chromatids remaining together
What happens during telophase 1/cytokinesis
Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair
What is meiosis II?
It is the second division of meiosis.
What happens during meiosis II?
Gametes form
What happens during prophase 2?
DNA does not replicate
What happens during metaphase 2?
Chromosomes align at the equatorial plate in a single line.
What happens during anaphase 2?
Centromeres divide and sister chromatid migrate separately to each pole
