Chapter 13: Meiosis And Sexual Life Cycles

Question 1

Heredity

Answer 1

The transmission of traits from one generation to the next

Question 2

Variation

Answer 2

Differences between members of the same species

Question 3

Genetics

Answer 3

The scientific study of heredity and hereditary variation

Question 4

Genes

Answer 4

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA

Question 5

Gamete

Answer 5

A haploid reproductive cell, cul as an egg or sperm, that is formed by meiosis or is the descendant of cells formed by meiosis. Gametes unite during sexual reproduction to produce a diploid zygote

Question 6

Locus

Answer 6

A specific place along the length of a chromosome where a given gene is located

Question 7

Asexual reproduction

Answer 7

The generation of offspring from a single parent that occurs without the fusion of gametes. In most case, the offspring are genetically identical to the parent

Question 8

Clone

Answer 8

A group of sexually identical individuals or cells

Question 9

Sexual Reproduction

Answer 9

Reproduction arising from the fusion of two gametes

Question 10

Life cycle

Answer 10

The generation to generation sequence of stages in the reproductive history of an organism.

Question 11

Karyotype

Answer 11

A display of the chromosomes of the same length, centromere position, and staining pattern that possesses genes for the same characters at corresponding loci. One homologous chromosome is inherited from the father and the other from the mother

Question 12

Sex chromosome

Answer 12

A chromosome responsible for determining the sex of an individual

Question 13

Autosome

Answer 13

A chromosome that is not directly involved in determining sex; not a sex chromosome

Question 14

Diploid cell

Answer 14

A cell containing two sets of chromosomes, one inherited from each parent.

Question 15

Haploid cell

Answer 15

A cell containing only one set of chromosomes

Question 16

Fertilization

Answer 16

The union of haploid gametes during fertilization

Question 17

Alternation of generations

Answer 17

A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte, characteristic of plants and some algae

Question 18

Stages of Meiosis

Answer 18

Interphase - pairs of homologous chromosomes are duplicated which leads to a diploid cell with duplicated chromosomes

Meiosis I - Homologous chromosomes are separated, which leads to haploid cells with duplicated chromosomes

Meiosis II - Sister chromatids are separated which lead to haploid cells with unduplicated chromosomes.

Question 19

Synaptonemal Complex

Answer 19

A zipper-like structure composed of proteins, which connects a chromosome to its homologous tightly along their lengths during part of prophase I 1 of meiosis

Question 20

Synapsis

Answer 20

The pairing and physical connection of one duplicated chromosomes to its homolog during prophase I of meiosis

Question 21

Meiosis vs Mitosis

Answer 21

DNA replication - During interphase before mitosis and meiosis I but not Meiosis II

Number of divisions - mitosis has 1 and meiosis has 2

Synapsis of homologous chromosomes occurs during prophase I along with crossing over between non sister chromatids

Number of daughter cells - mitosis 2 genetically identical daughter cells with the same number of chromosomes.
Meiosis 4 haploid cells that are genetically different.

Question 22

Explain the alternation of fertilization and meiosis

Answer 22

Normal human cells are diploid, they have 46 chromosomes made up of two sets of 23 chromosomes. 22 pairs of homologous that are autosomes and one pair of sex chromosomes. During fertilization, and egg and sperm unite forming a diploid single celled zygote, which develops into a multicellular organism by mitosis.

Question 23

Independent assortment of chromosomes

Answer 23

The random orientation of pairs of homologous chromosomes at the metaphase of meiosis I. Each pair may orient with its maternal or paternal homolog closer to a certain pole.

Since each pair of homologous chromosomes are positioned independently of each other at metaphase I, the first meiosis division results in each pair sorting its maternal and paternal homolog into daughter cells independently of each other pair.

Question 24

Crossing over

Answer 24

Occurs at Chiasma during prophase I of meiosis

Recombinant chromosome - a chromosome created when crossing over combines DNA from two parents into a single chromosome

Question 25

Random Fertilization

Answer 25

the random nature of fertilization adds to the genetic variation that arises from meiosis.