Control of Gene Expression - Mutations and Stem Cells

Question 1

what is a mutation?

Answer 1

any change to 1 or more nucleotide bases or any rearrangement of bases in DNA

Question 2

what are the types of gene mutation?

Answer 2

substitution

deletion

addition

duplication

inversion

translocation

Question 3

what is a substitution mutation?

Answer 3

when a nucleotide is replaced by another of a different base

Question 4

what are the effects of substitution mutation?

Answer 4

stop codon formed - polypeptide production stopped early

codon for different amino acid formed - slightly different structure

formation of different codon but same amino acid - no effect

Question 5

what is deletion mutation?

Answer 5

when a nucleotide is removed from the sequence

Question 6

what are the effects of deletion mutations?

Answer 6

causes a frame shift to the left

most triplets different so polypeptide very different

Question 7

what is addition mutation?

Answer 7

when a nucleotide is inserted into the sequence

Question 8

what are the effects of addition mutation?

Answer 8

frame shift to the right

not as big an effect if 3 are inserted

Question 9

what is duplication mutation?

Answer 9

one or more nucleotides repeated

Question 10

what are the effects of duplication mutation?

Answer 10

causes frame shift to the right

Question 11

what is inversion of bases mutations?

Answer 11

a group of nucleotides becomes seperated from the sequence and rejoins in the same position but inverse order

Question 12

what are the effects of inversion of bases mutations?

Answer 12

only affects one amino acid if 3 are reversed

Question 13

what is translocation mutation?

Answer 13

a group of nucleotides becomes seperated from the sequence and becomes inserted into the DNA of another chromosome

Question 14

what is the effect of translocation mutations?

Answer 14

significant affect on gene expression leading to abnormal phenotype, including development of some cancer

Question 15

what are the causes of mutations?

Answer 15

during DNA mutations

can be increased by mutagenic agents

Question 16

what is a mutagenic agent?

Answer 16

something that increases the risk of mutations

Question 17

what are two mutagenic agent?

Answer 17

high energy ionising radiation

chemicals such as NO₂

Question 18

what are the advantages of mutations?

Answer 18

produces genetic diversity necessary for natural selection

Question 19

what are the disadvantages of mutations?

Answer 19

can produce an organism less well suited to an environment

if occurs in body cells, leads to disruption of normal cellular activities such as cell division which then leads to cancer

Question 20

how do differentiated cells all differ from each other?

Answer 20

they all produce different proteins

Question 21

what are the different ways that stem cells go through mitosis?

Answer 21

1. one daughter cell differentiates, one stays as a stem cell
2. both daughter cells stay as stem cells
3. both daughter cells differentiate

Question 22

what are the types of stem cell?

Answer 22

embryonic

adult

umbilical cord

placental

totipotent

induced pluripotent

Question 23

where are embryonic stem cells found?

Answer 23

blastocyst stage in embryos

Question 24

what are embryonic stem cells used for?

Answer 24

grow cultures of stem cells

Question 25

what types of cell can embryonic stem cells differentiate into?

Answer 25

most types of cell

Question 26

where are adult stem cells found?

Answer 26

tissues around the body, mainly ones that need to regenerate more often

Question 27

what types of cell can adult stem cells differentiate into?

Answer 27

only into specific cells

eg blood stem cells can only differentiate into specialized blood cells

Question 28

what are the properties of umbilical cord stem cells?

Answer 28

similar to adult stem cells

Question 29

what are the properties of placental stem cells?

Answer 29

similar to adult

Question 30

where are totipotent stem cells found?

Answer 30

early embryos - zygotes

Question 31

what types of cell can totipotent stem cells differentiate into?

Answer 31

any cell type, including pluripotent stem cells

Question 32

what are induced pluripotent stem cells?

Answer 32

genetically reprogrammed body cells

Question 33

what are the properties of induced pluripotent stem cells?

Answer 33

behaves like embryonic stem cells

Question 34

what is potency?

Answer 34

measure of how many types of specialized cell a stem cell can make

Question 35

what is a totipotent cell?

Answer 35

a cell that can differentiate into any type of cell

Question 36

what is a pluripotent cell?

Answer 36

a stem cell that can differentiate into almost any type of specialized cell

Question 37

which stem cells are pluripotent?

Answer 37

induced pluripotent

embryonic

Question 38

what is a multipotent cell?

Answer 38

a stem cell that can make multiple types of specialized cell

Question 39

which stem cells are multipotent?

Answer 39

placental stem cells

umbilical cord blood stem cells

adult stem cells

Question 40

how can stem cells be obtained?

Answer 40

from spare embryos created during IVF

theraputic cloning

from bone marrow

from umbilical cord blood

Question 41

how are stem cells obtained from spare embryos in IVF?

Answer 41

at 8 cell stage, cell removed for genetic diagnosis

cell cultured to produce stem clels

Question 42

what is the process of theraputic cloning?

Answer 42

nucleus of ovum removed, replaced with nucleus from patient

cell given small electric shock to start it dividing

once blastocyst stage reached, stem cells removed and should be genetically identical to patient

Question 43

what are some uses of stem cells?

Answer 43

help with diseases caused by faulty cells (parkinsons, diabetes)

can also potentially grow organs identical to patient for transplant