cell cycle

Question 1

what is G1

Answer 1

growth of cytoplasm and cell membrane. protein synthesis, organelles replicated

Question 2

what is G0

Answer 2

many cells stop dividing once they have specialised to their roles

Question 3

what is S phase

Answer 3

DNA replication

Question 4

what is G2

Answer 4

growth and preparation for mitosis

Question 5

what is mitosis the division of

Answer 5

nucleus

Question 6

what is cytokinesis

Answer 6

division of the cytoplasm

Question 7

what makes stem cells different from normal body cells

Answer 7

they are not specific, have no jobs and have the potential to become any cell (differentiate)

Question 8

what is the potency of a stem cell

Answer 8

the ability to turn into other cells

Question 9

where is a totipotent stem cell found

Answer 9

a zygote - fertilised egg cell, and first few cells of the embryo

Question 10

what can totipotent stem cells differentiate into

Answer 10

any cell type, including the ability to make a complete human

Question 11

where is a pluripotent stem cell found

Answer 11

cells from an embryo

Question 12

what can pluripotent stem cell differentiate into

Answer 12

any type of cell, not a whole organism though

Question 13

where is a multipotent stem cell found

Answer 13

cells from the umbilical cord, bone marrow and other adult body tisses

Question 14

what can a multipotent stem cell differentiate into

Answer 14

a few different types of cells, such as different types of bone and blood cells

Question 15

where are chromosomes found in a cell

Answer 15

nucleus

Question 16

what are chromosomes made of

Answer 16

DNA and histomeproteins

Question 17

why are chromosomes important

Answer 17

carry DNA and the genetic code

Question 18

what are the chromosomes in a human nucleus arranged in pairs called

Answer 18

homologous pairs

Question 19

how many homologous pairs of chromosomes are their in a human

Answer 19

23 pairs or 46 single chromosomes

Question 20

what is a diploid cell

Answer 20

contains 2 copies of every chromosome in homologous pairs, one is paternal and the other is maternal

Question 21

what is a haploid cell

Answer 21

contain 1 copy of each chromosome, no homologous pairs and the only haploid cell are the gametes

Question 22

what are the stages of mitosis

Answer 22

interphase
prophase
metaphase
anaphase
telophase + cytokinesis

Question 23

what happens in interphase of mitosis

Answer 23

DNA is duplicated, diploid at this stage

Question 24

what happens in prophase of mitosis

Answer 24

chromosomes become visible, centrioles start to make the spindle, nuclear membrane breaks down

Question 25

what happens in metaphase of mitosis

Answer 25

the chromosomes move to the equator of the cell. each chromatid is attached at the centromere to the spindle fibres made by the centrioles

Question 26

what happens during the anaphase of mitosis

Answer 26

centromeres are pulled apart by the spindle fibres, chromatids are pulled to opposite poles of the cell

Question 27

what happens during telophase of mitosis

Answer 27

the separated chromosomes uncoil, 2 new nuclei start to reform and this stage is followed by cytokinesis

Question 28

how to work out the mitotic index

Answer 28

number of cells in mitosis/total number of cells

Question 29

where does meiosis take place

Answer 29

reproductive organs to produce sex cells known as gametes

Question 30

how many divisions are there is meiosis

Answer 30

2

Question 31

what happens in interphase of meiosis

Answer 31

DNA is replicating and the chromosomes are not visible

Question 32

what happens in prophase 1 of meiosis

Answer 32

the chromosomes become visible, made up of two sister chromatids attached at the centre of the centrome, the homologous pairs line up next to each other mixing the DNA - crossing over, at the end of prophase the chromosomes are shorter and the nuclear membrane disintegrates, spindle fibres are then formed and attach to the centromeres.

Question 33

what happens in metaphase 1 in meiosis

Answer 33

the homologous pairs line up along the equator of the cell, random orientation of the chromosomes occur - line up randomly

Question 34

what happens in anaphase 1 of meiosis

Answer 34

the homologous pairs begin to separate, each chromosome in a pair migrates to opposite poles, chromosomes still consist of two chromatids held together by their centrosomes - disjunction

Question 35

what happens in telophase 1 in meiosis

Answer 35

the chromosomes reaches the opposite poles, a nuclear membrane forms around the chromosomes, each cell is a haploid - half the number of normal chromosomes.

Question 36

what happens in prophase 2 of meiosis

Answer 36

the chromosomes condense and the spindle fibres appear and attach to the centromere, the nuclear membrane breaks down

Question 37

what happens in metaphase 2 of meiosis

Answer 37

the chromosomes line up at the equator

Question 38

what happens in anaphase 2 of meiosis

Answer 38

the centromeres splitting and the chromatids are pulled by the spindle fibres towards the opposite poles

Question 39

what happens in telophase 2 of meiosis

Answer 39

new nuclear membranes reforms, each cell is haploid - half the net result of meiosis is the production of 4 cells from 1 cell each cell only containing one set of chromosomes which is half of original

Question 40

which events in meiosis ensure that siblings end up with different combinations of their parents DNA

Answer 40

prophase 1 - crossing over metaphase 1 - independent assortment of homologous pairs