17.1 Flashcards
What are the 3 stages of the cell cycle? (3)
(1) interphase
(2) nuclear division (mitosis or meiosis)
(3) cell division (CYTOKINESIS)
What are the 3 phases of interphase? Describe what happens in each stage. (6)
(1) G1 (first growth) —> (4) proteins are synthesised & new organelles are formed & production of RNA
(2) synthesis (S) —> (5) DNA replicates
(3) G2 (second growth) —> (6) organelles grow & divide & energy stores increase
How long does a typical mammalian cell take to complete a cell cycle? (1)
And how much (%) of the cell cycle is taken up by interphase? (1)
24 hours
90%
Nuclear division can take place either by ________ or _________ (2)
(1) mitosis / meiosis
(2) mitosis / meiosis
Mitosis is the ___________ of the nucleus of a cell that results in each of the ___________ cells having an _________ copy of the DNA of the _________ cell. (4)
(1) division
(2) daughter
(3) exact / identical
(4) parent
What are the 4 things that happen in interphase? (4)
HINT: Mr. POD
(1) Mr = Metabolic reactions (to produce ATP)
(2) P = Protein synthesis (proteins & enzymes are necessary for cell growth)
(3) O = Organelle numbers are increased (to support the enlarged cell)
(4) D = DNA replication (to ensure a second copy is available for mitosis)
What are the 4 stages of mitosis? (4)
HINT: PMAT
(1) prophase
(2) metaphase
(3) anaphase
(4) telophase
What happens during prophase (mitosis - stage 1)? (3)
(1) chromosomes become visible because the DNA supercoils & condenses
(2) nuclear envelope disintegrates
(3) nucleolus disappears
What happens during metaphase (mitosis - stage 2)? (2)
(1) spindles form
(2) the spindles attach to the chromosomes’ centromeres to line them up at the centre of the cell
What happens during anaphase (mitosis - stage 3)? (2)
(1) spindle fibers attached to the chromatids ** contract & shorten**
(2) chromatids are pulled towards the poles
What happens during telophase (mitosis - stage 4)? (4)
(1) chromatids reach the poles and become invisible again as they de-condense or uncoil
(2) nuclear envelope reforms
(3) nucleolus reforms
(4) spindles disintegrate
What is the best way to remember interphase & the 4 stages of mitosis? (5)
HINT: label IPMAT
I - interphase - increase
P - prophase - pair
M - metaphase - middle
A - anaphase - away
T - telophase - two
What are the 3 main reasons why mitosis is important? (3)
(1) growth
(2) differentiation
(3) repair
NOTE: you have to be able to recognise the stages of mitosis from drawings & photographs & explain the events occurring during each stage.
xoxo
NOTE: the replication of DNA takes place during interphase before the nucleus & the cell divides
xoxo
NOTE: in interphase, the stages continue each other’s roles, so G1 & S phases can overlap. So in the exam, if you say that the G1 phase replicates/produces DNA, it CAN be accepted by examiners.
xoxo
In RP 6, which is using root tips to investigate mitosis, the plants are soaked in hydrochloric acid. Why? (2)
(1) it breaks down the material which holds together plant cell walls
(2) this is done to produce a single layer of cells
In RP 6, which is using root tips to investigate mitosis, root tips are used. Why will mitotic cells only be found in root tips? (3)
(1) mitosis in plants is restricted to meristematic tissues
(2) this is present in the growing point of the root
(3) behind the root tip, cells will elongate but will no longer be dividing
