mitosis, stem cells

Question 1

DNA needs to be condensed to be manipulated. DNA condensation is firstly caused by multiple rounds of folding and coiling then the chromosomes are condensed by what protein?

Answer 1

condensin
> dimer with a Y shape
> causes looping of DNA

Question 2

At what phase of meiosis is there replicated pairs of chromatids that move towards poles of the cell?

Answer 2

anaphase 1

> PAIRS so its 1 not 2

Question 3

Which of the following description is true about the protein involved in mitosis?
A Lamins polymerise and assist to reform nuclear envelope in anaphase.
B Condensins hold two sister chromatids together during M phase until they are ultimately seperated.
C Tubulins attach to the plus end of the microtubules to form spindle during G2 phase.
D Kinesin-4 and kinesin-10 help move chromesomes to the poles of the microtubules.
E Dyneins attach kinetochore spindles to the plasma membrane

Answer 3

OPTION D Kinesin-4 and kinesin-10 help move chromesomes to the poles of the microtubules.
A: Incorrect. Nuclear envelope is reformed during telophase.
B: Incorrect. This is the function of cohesins.
C: Incorrect. Spindles are formed during prophase.
D: Correct.
E: Incorrect. Astral spindles are attached to the plasma membrane.

Question 4

Where do spindles bind to chromesomes? 
A outer layer of the kinetochore
B inner layer of the kinetochore
C checkpoint layer of the kinetochore
D centromere
E centrosome

Answer 4

A: Incorrect. Outer layer of the kinetochore provides the structural support for kinetochore.
B: Incorrect. Inner layer of the kinetochore binds with the (DNA)chromosome (at centromere).
C: Correct.
D: Incorrect. Centromere is a highly-condensed region on chromosomes that interacts with kinetochore.
E: Incorrect. Centrosome is an organelle. It sends out microtubules and form spindles.

Question 5

Potency refers to the ability of cells to differentiate. Which term best describes cells that can differentiate into a few cell types and haven’t terminally differentiated yet?

Answer 5

oligopotent

Question 6

There are 4 different types of precursors that can be used in tissue engineering as scaffolds. What is the name of the precursors that use tissue banks of epithelial cells (keratinocytes) to replace skin on patients with burns?
A autologous
B heterologous
C xenogenic
D stem

Answer 6

OPTION B
Heterologous/ allogeneic as you ise a different tissue to repair

autologous can be used for replacing musculoskeletal tissues (cartilage repair.)
xenogenic can be used to take human umbilical cord cells to cure mouse cornea blindness.

Question 7

There are 3 types of germ layers and they can each be used to treat different disorders. Which type can be used to treat metabolic disorders, hepatitis B and C?
A endoderm cells
B mesoderm cells
C ectoderm cells

Answer 7

endoderm (the INSIDE)

Question 8

Which of the following cells is mostly likely to have the highest differentiation potency?

A haemopoietic progenitors	
B somatic stem cells from bone marrow	
C osteoblast	
D root apical meristem cells	
E induced pluropotent stem cells

Answer 8

root apical meristems as alsmost all plant tissue is totipotent!

Question 9

There are 3 main therapies for cancer. Which type of therapy blocks cell signalling or communication and interferes with genetic control?
A radiotherapy
B pharmecuticals
C chemotherapy

Answer 9

OPTION B pharmeceuticals

radiotherapy = x-rays have a greater effect on fast dividing tissue (hair loss)
chemotherapy = chemicals to inhibit/ damge fast cells

Question 10

what is the role of interpolar microtuble?
A attatch to kinetochore of chromosome and help to pull chromatids apart in anaphase
B attatch to each other givng spindles rigidity
C anchor to poles of cells and come out of the centrosome

Answer 10

OPTION B

affix to other microtubules in the spindle to form a rigid structure to the spindle

Question 11

At what stage of Mitosis does the chromosomes align at the equator?

Answer 11

metaphase (protometapahse they start to)

Question 12

In mitosis, what number of kinesin(s) moves chromosomes to poles of microtubules?
A 4
B 5
C 10
D 14

Answer 12

kinesin 4 and 10.
Kinesin 4, 10 moves chromosomes to poles of microtubules
Dynein attaches astral microtubules to the plasma membrane.
Kinesin 14 tightens the spindle, Kinesin 5 expands the spindle (by walking in oppostie direction)

Question 13

which cell precursor orignates from a different (non-human) tissue? (tissue engineering)
A autologous
B heterologous
C xenogenic
D stem
E ectoderm
F endoderm

Answer 13

OPTION C
xenogenic cells from a different organism
> e.g. mouse to make human tissue

autologous = same type of tissue
heterologous = using different type tissue

Question 14

centrosome facta

Answer 14

2 centrioles in a centrosome

they are 90° to each other and move to opposite ends of cell as spindle grows

Question 15

why do the spindles attatch to the kinetochore instead of DNA?

Answer 15

DNA has low affinity for spindles. kinetochore is protein blob bluetack
> inner kinetochore attachted to DNA, has + charge
> outer kinetochere is structural
> checkpoint holds spindle in place

Question 16

what is the dna/ploidy at the end of mitosis?what is it for meiosis?
1C/1N
1C/2N
2C/2N
4C/2N
4C/4M

Answer 16

2C/2N - diploid
1C/1N - haploid

c is the amount of DNA in the cell (2c would be two copies of each chromosome).
n is the ploidy of the cell (2n means it is diploid).

Question 17

What is a function of P53?
Initiate apoptosis 
Initiate cell proliferation 
Act as a signalling molecule
Act as a transcription factor

Answer 17

OPTION A

P53 is a tumour suppressing gene therefore initiates apoptosis and regulates the cell cycle

Question 18

What enzyme separates sister chromatids?
Cohesin 
Separase 
Kinase
Dehydrogenase 
Isomerase

Answer 18

mitiotic spindle contracts and and chromatids move to poles aduring anaphase

microtubble depolymerises at both +/- ends
seperase removes cohesin and cyclin degrades cohesin