Cell Cycle, Microscopes, Cell Fractionation

Question 1

what’s are the three key stages

Answer 1

interphase
nuclear division - mitosis or meiosis
cytokinesis

Question 2

what’s cytokinesis

Answer 2

when the cell cytoplasm splits

Question 3

what’s the phases in interphase

Answer 3

G1
S
G2

Question 4

what happens in G1

Answer 4

growth- all the organelles in the cell doubles

Question 5

what happens in S phase

Answer 5

when dna replicates

Question 6

what happens in G2

Answer 6

growth prep for mitosis
G2 checkpoint

Question 7

what’s the order of the stages in mitosis

Answer 7

prophase
metaphase
anaphase
telophase

Question 8

what happens in prophase

Answer 8

chromosomes condense and become visible
centrioles separate to opposite side of cells
nucleolus disappears

Question 9

what are centrioles responsible for

Answer 9

creating spindle fibres which are released from both poles

Question 10

what happens in metaphase

Answer 10

chromosomes line up along the equator of cell
the spindle fibre realised from poles now attach to the centromere and chromatid

Question 11

what is the centromere

Answer 11

circular pinch point in the middle of chromosomes which holds the two chromatids together

Question 12

what is the chromatid

Answer 12

one half of a duplicated chromosome

Question 13

what happens in anaphase

Answer 13

spindle fibres retract causing the centromere to divide in two individual sister chromatids and pulled to opposite poles
this stage requires atp

Question 14

what happens in telophase

Answer 14

spindle fibres disintegrate and nuclear membrane starts to reform, nucleoli reappear, chromosomes unwind into chromatin
cytokinesis occurs

Question 15

how do u calculate mitosis index

Answer 15

no. of cells in mitosis/ total no. of cells. x 100

Question 16

define magnification

Answer 16

how many times larger the image is compared to the actual object

Question 17

define resolution

Answer 17

the minimum distant between two objects in which they can still be viewed as separate

Question 18

state the features of TEM

Answer 18

thin stained specimen needed
place in vacuum
some parts absorb electron and appear dark
2D

Question 19

state the feature of SEM

Answer 19

not thin sample needed
electrons beamed on the surface
3D

Question 20

state disadvantages of TEM

Answer 20

only used on thin specimen
only used on non- living specimen

Question 21

state disadvantages of SEM

Answer 21

lower resolution than TEM
only used on non- living specimen

Question 22

what are artefacts

Answer 22

observation of something that is not part of the cell or specimen
usually made during preparation of specimen

Question 23

what is cell fractionation

Answer 23

process in which different parts and organelles of a cell are separated so they can be studied- 3 steps

Question 24

whats the first step of cell fractionation

Answer 24

homogenisation
grind cell in a blender
- must be ice cold
- must be isotonic ( same water potential)
- add buffer

Question 25

whats the 2nd step of cell fractionation

Answer 25

filtration
homogenised cell solution is filtered to separate large cell or tissue debris

Question 26

whats the last step of cell fractionation

Answer 26

ultracentrifugation
- tube of homogenate is placed in a centrifuge and spun at low speed
- produces pellet ( removed) and supernatant- spun at higher speed
-highest to lightest organelle

Question 27

what order does organelles separate

Answer 27

nuclei
chloroplast
mitochondria
lysosome
ER
ribosome