Lesson 6 Definitions

Question 1

chromatin

Answer 1

the cell’s collection of DNA, together with associated proteins

Question 2

histone

Answer 2

any of a group of basic proteins found in chromatin

Question 3

nucleosomes

Answer 3

basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundamental subunit of chromatin.

Question 4

kinetochore

Answer 4

a complex of proteins associated with the centromere of a chromosome during cell division, to which the microtubules of the spindle attach

Question 5

centromere

Answer 5

the region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division

Question 6

mitosis

Answer 6

interphase → prophase → metaphase → anaphase → telophase → cytokinesis

Question 7

meiosis

Answer 7

the process by which haploid cells form from diploid cells

Question 8

binary fission

Answer 8

performed by all bacteria and some eukaryotes (protozoans)

Question 9

budding

Answer 9

formation of a new organism by the protrusion of part of another organism

Question 10

karyotype

Answer 10

preperation of chromosomes in mitosis

Question 11

nondisjunction

Answer 11

crossing over: occurs during prophase I of meiosis, involves the swapping of genetic info on homologous chromosomes

Question 12

crossing over

Answer 12

occurs during prophase I of meiosis, involves the swapping of genetic info on homologous chromosomes

Question 13

gametogenesis

Answer 13

in female animals, results in one egg and three polar bodies, only the egg produces a viable offspring

Question 14

trisomy

Answer 14

causes Down’s syndrome

Question 15

karyotype

Answer 15

preparation of chromosomes in mitosis

Question 16

spindle

Answer 16

cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells (composed of proteins)

Question 17

sister chromatid

Answer 17

the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be ‘one-half’ of the duplicated chromosome. A pair of sister chromatids is called a dyad

Question 18

daughter chromosome

Answer 18

a chromosome that results from the separation of sister chromatids during cell division. Daughter chromosomes originate from a single stranded chromosome that replicates during the synthesis phase (S phase) of the cell cycle

Question 19

nondisjunction

Answer 19

failure of chromosome pairs to separate properly, usually during meiosis

Question 20

polar body

Answer 20

each of the small cells which bud off from an oocyte at the two meiotic divisions and do not develop into ova.

Question 21

homologous

Answer 21

in the same place

Question 22

chromosomes

Answer 22

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes

Question 23

monosomy

Answer 23

the state of having a single copy of a chromosome pair instead of the usual two copies found in diploid cells

Question 24

trisomy

Answer 24

extra chromosome copy, causes Down’s syndrome

Question 25

heredity

Answer 25

the passing on of physical or mental characteristics genetically from one generation to another