The Mitotic Cell Cycle

Question 1

What is a chromosome?

Answer 1

thread-like structures in the nucleus of cells, made of protein and a tightly coiled DNA molecule, the number of chromosomes is characteristic of a species

Question 2

What is DNA?

Answer 2

deoxyribonucleic acid is the molecule of inheritance which contains the genetic code of organisms

Question 3

What is a histone protein?

Answer 3

the basic protein molecule which forms nucleosomes which DNA wraps around to form chromosomes

Question 4

What is a chromatid?

Answer 4

one half of a duplicated chromosome that forms during DNA replication, containing one DNA molecule

Question 5

What is a centromere?

Answer 5

the region holding chromosomes together, contains two kinetochores from which microtubules extend, where the chromatids separate from during cell division

Question 6

What is a telomere?

Answer 6

extra DNA at the ends of the molecule, made of DNA with multiple repeat sequences, which ensures that DNA telomerase copies the important genes and no information is lost

Question 7

What is mitosis?

Answer 7

nuclear division that produced two genetically identical daughter nuclei

Question 8

Why is mitosis important?

Answer 8

growth, cell replacement and tissue repair, asexual reproduction, immune response

Question 9

What are the stages of the cell cycle?

Answer 9

interphase, nuclear division, cytokinesis

Question 10

What is interphase?

Answer 10

G1 (cell grows), S (DNA replication), G2 (preparation for division)

Question 11

What are the stages of mitosis?

Answer 11

prophase, metaphase, anaphase, telophase

Question 12

What is cytokinesis?

Answer 12

cell division by constriction of cell membrane

Question 13

What are stem cells?

Answer 13

an undifferentiated cell that can divide by mitosis an unlimited number of times, and has potency to differentiate into different specialised cells

Question 14

What is a tumour?

Answer 14

an irregular mass of cells cause by uncontrolled mitosis by cancerous cells

Question 15

What happens in prophase?

Answer 15

the first stage of mitosis where the nuclear envelop breaks down, centrosomes move to opposite poles, chromosomes condense, mitotic spindle begins to form

Question 16

What happens in metaphase?

Answer 16

the second stage of mitosis where the chromosomes line up along the equator of the cell

Question 17

What happens in anaphase?

Answer 17

the third stage of mitosis where chromosomes are pulled apart by spindle fibres

Question 18

What happens in telophase?

Answer 18

the fourth stage of mitosis where the nuclear envelope reforms around the separated sets of chromosomes

Question 19

What is euchromatin?

Answer 19

the loosely coiled form of chromatin seen at interphase, where genes are active

Question 20

What is heterochromatin?

Answer 20

the tightly coiled form of chromatin seen at nuclear division, where genes are inactive

Question 21

What is a zygote?

Answer 21

the cell formed when gametes fuse, all cells in multicellular organisms derived from here, diploid

Question 22

What is a gamete?

Answer 22

reproductive cells, contain half chromosomes of diploid cells, haploid

Question 23

What is the structure of a chromosome?

Answer 23

two identical sister chromatids made of a DNA molecule each, telomeres, centromere

Question 24

What is chromatin?

Answer 24

DNA wound around histone protein molecules

Question 25

How does cancer develop?

Answer 25

carcinogens cause mutations - cancerous cell continues to divide - cancer cell not removed by immune system - tumour gets bigger - supplied with lymph and blood vessels - spreads through blood and lymph - metastasis - secondary cancers form