Topic 3B definition

Question 1

Mitosis

Answer 1

the process by which a cell divides to produce two genetically identical daughter cells

Question 2

Asexual reproduction

Answer 2

the production of genetically identical offspring from a single parent or organism.

Question 3

meiosis

Answer 3

a form of cell division in which the chromosome number of the original cell is halved, leading to the formation of the gametes.

Question 4

sexual reproduction

Answer 4

the production of offspring that are genetically different from the parent organism or organisms by the fusing of two sex cells ( gametes)

Question 5

histones

Answer 5

positively charged proteins involed in the coiling of DNA to form dense chromosomes in cell division

Question 6

nucelosomes

Answer 6

dense clusters of DNA wound around histones

Question 7

cell cycle

Answer 7

a regulated process of three stages ( interphase, mitosis and cytokinesis) in which cells divide into two genetically identical daughter cells.

Question 8

Interphase

Answer 8

the period between active cell division when cells increase their size and mass, replicate their DNA and carry out normal metabolic activities.

Question 9

Cytokinesis

Answer 9

the final stage of the cell cycle before the cell enters interphase again- division of the cytoplasm at the end of mitosis to form two independent, genticialy identical cells.

Question 10

chromatid

Answer 10

one strand of the replicated chromosome pair that is joined to the other chromatid at the centromere.

Question 11

cyclins

Answer 11

small proteins that build up during interphase and are involved in the control of the cell cycle in their attachment to cyclin-dependent kinases

Question 12

cyclin-dependent kinases

Answer 12

enzymes involved in the control of the cell cycle by phosphorylating other proteins, activated by attachment to cyclins

Question 13

prophase

Answer 13

the first stage of active cell division where the chromosomes are coiled up and consist of two daughter chromatids joined by the centromere; the nucleolus breaks down.

Question 14

metphase

Answer 14

the second stage of active cell division where a spindle of overlapping protein microtubles forms and the chromatids line up on the metphase plate

Question 15

anaphase

Answer 15

the third stage of active cell division, where the centromeres split so chromatids become new chromosomes; they are moved to the opposite poles of the cell, centromere first, by contractions of the microtubules of the spindle

Question 16

telophase

Answer 16

the fourth stage of active cell division, where a nuclear memebrane forms around the two sets of chromosomes, the chromosomes unravel and the spindle breaks down.

Question 17

centromere

Answer 17

the region where a pair of chromatids are joined and which attaches to a single strand of the spindle structure at metaphasee

Question 18

metaphase plate (equator)

Answer 18

the region of the spindle in the middle of the cell along which the chromatids line upc

Question 19

clones

Answer 19

genetically identical individuals resulting from asexual reproduction in a single parent

Question 20

mitotix index

Answer 20

the ratio between the number of cells in a tissue sample that are in mitosis and the total number of cells in the sample.

Question 21

diploid

Answer 21

a cell with a nucleus containning two full sets of chromosomes

Question 22

haploid

Answer 22

a cell with a nucleus containing one complete set of chromosomes

Question 23

zygote

Answer 23

the cell formed when two haploid gametes fuse at fertilisation

Question 24

polyploidy

Answer 24

a cell or an organism with more than two sets of chromosomes

Question 25

gonads

Answer 25

the sexual organs in animals

Question 26

ovaries

Answer 26

the female sex organs in both animals and plants; they produce the female gametes called ovules in plants and pva in animalsh

Question 27

What do you call a female plant gamete?

Answer 27

an ovule

Question 28

What do you call a female animal gamete?

Answer 28

an ova

Question 29

anthers

Answer 29

male sex organs in plants that produce the male gametes contained in the pollen

Question 30

ovules

Answer 30

the haploid female gametes in plants

Question 31

testes

Answer 31

the male sex organs in animals that produce the male gametes - sperm

Question 32

spermatozoa (sperm)

Answer 32

the haploid male gametes in animals

Question 33

ova

Answer 33

the haploid female gametes in animals (singular=OVUM)

Question 34

microspores

Answer 34

the result of meiosis in plants tha develop into the spore (pollen) containing the male gametes

Question 35

megaspores

Answer 35

the result of meiosis in plants that develop into the female gametes, ovulesh

Question 36

homologous pairs

Answer 36

matching pairs of chromosomes in an individual which both carry the same genes, although they may have different alleles.

Question 37

crossing over ( recombination)

Answer 37

the process by which large multi-enzyme complexes cut and re-join in parts of the maternal and paternal chromatids at the end of prophase I, introducing genetic varation

Question 38

chiasmata

Answer 38

the points where th chromatids breakn during recombination

Question 39

mutation

Answer 39

a permanent change in the DNA of an organism

Question 40

Independent assortment (random assortment)

Answer 40

the process by which the chromosomes derived from the male and female parent are distributed into the gametes at random.