Unit 1: Normal Differentiation and Abnormal Division

Question 1

what is benign tumour?

Answer 1

usually do not cause serious problems and can be removed by surgery

Question 2

what is a malignant tumour?

Answer 2

cancer - may undergo metastasis - enter the circulation

Question 3

what is the loss of control of cell division and excessive cell growth due to?

Answer 3

mutations in the genes which regulate cell division

Question 4

what are proliferation genes/proto-oncogenes?

Answer 4

The encode proteins that promote cell division only when an external signal is received

Question 5

what are oncogenes?

Answer 5

They are found in many cancers

Question 6

How many alleles does the mutation need to occur in for proliferation genes and why?

Answer 6

Only one of the pair as it is a dominant allele

Question 7

What are Antiproliferation genes?

Answer 7

The code for proteins which restrict cell division at checkpoints.

Question 8

what are anti proliferation genes also known as and why?

Answer 8

tumour suppressing genes because they normally prevent excessive cell division

Question 9

How many alleles does the mutation need to occur in for anti proliferation genes

Answer 9

both copies as it is recessive

Question 10

Drugs that interfere with the cell’s ability to make microtubules have been used in chemotherapy to treat cancer, how would this treatment work and why should it not be used longterm?

Answer 10

spindle fibres are microtubules. during mitosis spindle fibres guide the chromosomes and pull them apart to opposite ends of the cell. if chemotherapy interfered with the cell’s ability to make microtubules then spindle fibres cannot be formed. chromatids cannot be separated into daughter cells. the cycle stops are the M checkpoint and the daughter cells cannot enter the next G1 phase. Cell stop dividing and prevents the tumour formation. Cannot be used for a long time because it is not specific so it interferes with all cell division. Cell division is important in normal cell growth and repair

Question 11

what do we call the process of cells becoming specialised to perform specific functions?

Answer 11

differentiation

Question 12

how is differentiation brought about in cells?

Answer 12

by the switching off of unnecessary genes and leaving essential and cell specific genes switched on

Question 13

what is a division of labour in multicellular organisms?

Answer 13

They have cells that are specialised, have different structures for particular functions

Question 14

What is tissue made up of?

Answer 14

differentiated cells which has the same function

Question 15

what are organs made up of?

Answer 15

tissues grouped together

Question 16

what are meristems?

Answer 16

The growing points of plants that are capable of cell division

Question 17

what does totipotent mean?

Answer 17

they can differentiate into any other type of cell

Question 18

All cells in an organism has the same set of genes except from?

Answer 18

red blood cells and sex cells

Question 19

Why do red blood cells not have genes?

Answer 19

They don’t have a nucleus

Question 20

What are essential genes?

Answer 20

necessary for all cells to survive

Question 21

what are cell specific genes?

Answer 21

necessary for the function of that cell

Question 22

what are unnecessary genes?

Answer 22

those not needed by the cell

Question 23

what cells have the ability to differentiate into any type of cell

Answer 23

embryonic stem cells

Question 24

what is beta galactosidase?

Answer 24

an enzyme that is involved in the breakdown of lactulose into glucose and galactose

Question 25

what is the role of the regulator gene?

Answer 25

codes for the repressor molecule

Question 26

what is the role of the repressor molecule?

Answer 26

binds to the operator gene to switch it off

Question 27

what is the role of the operator gene?

Answer 27

switches on the structural gene

Question 28

what is the role of the structural gene?

Answer 28

codes for the production of the enzyme

Question 29

together the operator gene and the structural gene are called?

Answer 29

operon

Question 30

Describe the steps of jacob monod theory when lactulose is absent

Answer 30

Regulator gene is always on and causes the repressor molecule to be produced.
The repressor molecule binds to and switches off the operator gene.
operator gene is unable to function therefore the structural gene remains switched off.
The enzyme is not produced.

Question 31

Describe the steps of jacob monod theory when lactulose is present

Answer 31

Regulator gene is always on causing the repressor molecule to be produced.
Repressor molecule combines with lactulose.
Repressor-lactulose complex is unable to switch off the operator gene.
Operator gene switches on the structural gene.
The enzyme is produced and breaks down the lactulose.
When all of the lactulose is broken down, the repressor molecule is again free to switch off the operator gene and enzyme production is stopped.

Question 32

In the jacob monod theory, what is the inducer molecule?

Answer 32

lactulose

Question 33

what do genes code for?

Answer 33

the production of proteins

Question 34

why are genes switched on and off when not required?

Answer 34

for conservation of energy and resources