Topic 2 – Cells and Control-Cell Division and Growth

Question 1

what is cell cycle?

Answer 1

series of events that take place in cell involving cell growth, DNA replication and cell division
described as lifecycle of cell

Question 2

state 3 stages of cell cycle

Answer 2

stage 1- interphase
stage 2-mitosis
stage 3- cytokinesis

Question 3

what is interphase?

Answer 3

longest stage of cell cycle that involves cell growth, synthesis of new organelles and DNA replication

Question 4

what does DNA replication involve?

Answer 4

double helix ‘unzips’ exposing 2 strands
DNA bases align next to complementary bases on DNA strand
complementary base pair joins
2 identical DNA molecule formed

Question 5

what is a chromosome

Answer 5

linear DNA molecule tightly coiled around proteins

Question 6

what happens to chromosome during DNA replication?

Answer 6

DNA in arm of each chromosome is replicated.

Question 7

what is mitosis?

Answer 7

form of cell division that produces 2 diploid daughter cells both genetically identical to parent cell.

Question 8

why is mitosis important in organisms?

Answer 8

asexual reproduction
growth
repair of damaged cells
cell replacement

Question 9

state 4 stages of mitosis

Answer 9

prophase
metaphase
anaphase
telophase

Question 10

outline prophase

Answer 10

dna condenses chromosomes become visible

nuclear membrane disappears

Question 11

outline metaphase

Answer 11

chromosomes line up along cell equator

Question 12

outline anaphase

Answer 12

spindle fibres attach to each chromosome
arms of each chromosomes pulled to opposite pole
chromatids seperated.

Question 13

outline telophase

Answer 13

nucleus of cell divides

new membrane forms around each set of chromosomes.

Question 14

what does cytokinesis involve?

Answer 14

division of cell membrane and cytoplasm

2 genetically identical daughter cells produced.

Question 15

a cell divides by mitosis once each 2 minutes. calculate number of identical cells present after 10 minutes?

Answer 15

10/2=5
5 cells divisions have taken place
2^5=32

Question 16

what is cancer?

Answer 16

non communicable disease
uncontrolled cell divison results in formation of a primary tumour
tumour break off and spread to other tissues forming secondary tumours

Question 17

what are percentile charts?

Answer 17

chart used to monitor growth

measurements can be compared to expected values at a certain age

Question 18

what does 95th percentile mean?

Answer 18

95% of measurements will be below value of 95th percentile

Question 19

what can doctors determine from percentile charts?

Answer 19

slower growth then normal
faster growth then normal
abnormal growth

Question 20

describe growth in animals

Answer 20

cell division occurs in all body cells.occurs at slower rate in adults that in younger animals as growth stops and cell divison is only required for replacement and repair.
most cells differentiate at early age stage become specialised. some adult stem cells retain ability to differentiate.

Question 21

describe growth in plants

Answer 21

cell division can occur in meristematic tissue. rate of cell division remains same throughout a plants life.
meristematic stem cells can differentiate into any cell type for as long as they live
cell elongation occurs in all plants. cells expand and enlarge enabling growth

Question 22

what is meant by differentiation?

Answer 22

process which stem cells become specialised.

some genes switch on or off, determine cell type

Question 23

why is cell differentiation important?

Answer 23

enables formation of specialised tissues with specific functions e.g. muscle tissue.

Question 24

what are embryonic stem cells?

Answer 24

stem cells found in very early embryos that are unspecialised and capable of differentiating into any type of cell

Question 25

what is function of embroyonic stem cells?

Answer 25

enable growth and development of tissues in human embryos.

Question 26

what are adult stem cells?

Answer 26

stem cells that can differentiate into limited range of cell types

Question 27

what is primary function of adult stem cells?

Answer 27

replacement of dead cells, e.g. replacement of red blood cells which live only 120 days.

Question 28

where are stem cells found?

Answer 28

meristems

Question 29

where is meristem tissue found?

Answer 29

regions of plant where cells are continuously dividing.

Question 30

what are meristematic stem cells?

Answer 30

stem cells found in meristems that are not specialised, and capable of differentiating into any cell during life of a plant

Question 31

how can stem cells be used in medicine

Answer 31

stem cells collected
stem cells stimulated to differentiate into specific cell types
specialised cell transplanted into patient
used to treat damage or disease

Question 32

where can embryonic stem cells be collected from?

Answer 32

donor stem cells removed from embryos grown

patients own removed from umbilical blood before birth

Question 33

what are benefits of using stem cells in medicine

Answer 33

treat damage or disease
treat diseases that are untreatable
used in scientific research
growing organs for transplant

Question 34

what are risk of stem cell used medicine

Answer 34

transplanted stem cell can cause tumours.
finding suitable stem cell donors is difficult task
stem cells may be rejected by body
potential side effect
long term risks of using stem cells unkown
may become contaminated during preparation

Question 35

what are ethical issues of stem cells?

Answer 35

embryos are destroyed, which is waste of human live.

may lead to reproductive cloning