POL sections 7.4, 7.5

Question 0

Overall functions of meiosis

Answer 0

To reduce the chromosome number from diploid to haploid; To ensure that each of the haploid products has a complete set of chromosomes; to generate genetic diversity among the products (gametes)

Question 1

Meiosis

Answer 1

two nuclear divisions; one DNA replication; haploid cells genetically different from each other; consists of two nuclear divisions, meiosis I and meiosis II

Question 2

Meiosis I

Answer 2

Homologous chromosomes come together and line up; Homologous chromosome pairs separate; preceded by DNA replication; at the end, two nuclei form each with half of the original number of chromosomes composed of two sister chromatids

Question 3

Meiosis II

Answer 3

Not preceded by DNA replication; Sister chromatids are separated; produces four genetically different haploid cells

Question 4

Shuffling of genetic material

Answer 4

Crossing over and independent assortment

Question 5

Crossing over

Answer 5

Homologous chromosomes pair by synapsis; four chromatids form a tetras or bivalent; chromatin continues to coil and compact as chromosomes condense; genetic material exchanged between non-sister chromatids

Question 6

Synapsis

Answer 6

Homologous chromosomes pair by adhering along their lengths in this process that lasts from prophase I to end of metaphase I to form a tetras/bivalent

Question 7

Chiasmata

Answer 7

X-shaped attachment points of the two homologous chromosomes; genetic material is exchanged between non-sister chromatids

Question 8

Recombinant chromatids

Answer 8

Contain genetic material from different homologs

Question 9

Independent assortment

Answer 9

Phenomenon regarding which member of a homologous pair goes to which daughter cell at anaphase I

Question 10

Nondisjunction

Answer 10

Failure of homologous chromosome pair or chromatids to separate

Question 11

Aneuploidy

Answer 11

Condition of having an abnormal number of chromosomes

Question 12

Trisomy

Answer 12

Condition of having one extra chromosome

Question 13

Monosomy

Answer 13

Condition of missing one chromosome

Question 14

Most common form of aneuploidy in humans

Answer 14

Trisomy 16 (3 copies of chromosome 16)

Question 15

Down syndrome

Answer 15

Trisomy 21; allows for survival but such people have intellectual disabilities but can otherwise lead long and productive lives

Question 16

Polyploidy

Answer 16

Triploid, tetrapods, or higher order; caused by extra round of DNA replication preceding meiosis or no spindle formed in meiosis II; leads to reproductive isolation and speciation

Question 17

Ploidy

Answer 17

Number of chromosomes in the nucleus

Question 18

Translocation

Answer 18

Chromatids from non-homologous chromosome pairs break and rejoin; quite common in mitotic cells; may be carried on the gametes that result from meiosis and be passed on to offspring at fertilization

Question 19

Necrosis

Answer 19

Occurs when cells are damaged by mechanical means or toxins, or are starved of oxygen or nutrients; cells swell up and burst leading to inflammation

Question 20

Apoptosis

Answer 20

Genetically programmed series of events that result in cell death

Question 21

Two types of cell death

Answer 21

Necrosis and apoptosis

Question 22

Reasons for apoptosis

Answer 22

1. The cell is no longer needed by the organism

2. The longer cells live, the more prone they are to genetic damage that could lead to cancer

Question 23

Events of apoptosis

Answer 23

Cell becomes detached from its neighbors; hydrolyzes its DNA into small fragments, forms blebs that break up into cell fragments

Question 24

Hypersensitive response

Answer 24

Apoptosis used by plant cells in an important defense mechanisms; plant cells digest their own cell contents in the vacuole and then release the digested components into the vascular system

Question 25

Signal transduction pathways that lead to apoptosis

Answer 25

1. Signals from inside (Age of cell or recognition of damaged DNA) or outside the cell (receptors that activate signal transduction pathways
2. Activation of class of enzymes called caspases in animals or a functionally similar class of enzymes in plants
3. Hydrolyzes target proteins in a cascade of events
4. Cell dies as caspases hydrolyze proteins of the nuclear envelope, nucleosomes, and cell membrane