topic 8 mutations

Question 1

what is a mutation?

Answer 1

change to the base sequence of DNA

Question 2

what is a substituion?

Answer 2

one or more bases are swapped for another

Question 3

what is a deletion?

Answer 3

one or more bases are removed

Question 4

what is an addition?

Answer 4

one or more bases are added

Question 5

what is a duplication?

Answer 5

one or more bases are repeated

Question 6

what is an inversion?

Answer 6

sequence of bases is reverse

Question 7

what is a translocation?

Answer 7

sequence of bases is moved from one location in the genome to another

Question 8

what does the order of DNA bases in a gene determine?

Answer 8

the sequence of amino acids in a particular polypeptide

Question 9

what can a change in the amino acid sequence result in?

Answer 9

a change to the tertiary structure

Question 10

what is a hereditary mutation?

Answer 10

mutation occurs in a gamete so is present in the new foetus

Question 11

what does degenerate mean?

Answer 11

some amino acids are coded for by more than one DNA triplet

Question 12

why do not all mutations affect the order of amino acids?

Answer 12

genetic code is degenerate

Question 13

what is a silent mutation?

Answer 13

where a mutation doesn’t cause a change in the amino acid order

Question 14

what happens in frameshift?

Answer 14

mutation caused by a deletion or insertion sequence that shifts the way the sequence is read

Question 15

what do mutagenic agents do?

Answer 15

increase the rate of mutation

Question 16

what are examples of mutagenic agents?

Answer 16

UV radiation
ionising radiation
some chemicals
some viruses

Question 17

how can mutagenic agents increase the rate of mutation?

Answer 17

acting as a base
altering bases
changing the structure of DNA

Question 18

what are stem cells?

Answer 18

unspecialised cells that can develop into other types of cell and become specialised

Question 19

where are stem cells found?

Answer 19

in the embryo and in some adult tissues

Question 20

what are totipotent cells?

Answer 20

stem cells that can mature into any type of body cell in an organism

Question 21

when are totipotent stem cells present in mammals?

Answer 21

in the first few cell divisions of an embryo

Question 22

what are pluripotent cells?

Answer 22

cells that can specialise to become any cell in the body except the placenta

Question 23

what are the two types of stem cells present in adult mammals?

Answer 23

multipotent and unipotent

Question 24

what is a multipotent stem cell?

Answer 24

cell that can differentiate into a few different types of cell

Question 25

what is a unipotent stem cell?

Answer 25

cell that can only differentiate into one type of cell

Question 26

how do stem cells become specialised?

Answer 26

stem cells all contain the same genes but in development not all are expressed mNRA only transcribed from specific genes the mRNA from these genes is translated into proteins these modify the cell which leads the cell to become specialised

Question 27

what are cardiomyocytes?

Answer 27

heart muscle cells that make up a lot of the tissue in our hearts

Question 28

how can cardiomyocytes be made from unipotent stem cells?

Answer 28

thought that they couldn't replicate by themselves some scientists now think old/damaged cardiomyocytes can be replaced by new cardiomyocytes from a small supply of unipotent stem cells in the heart either slow- some never replaced in a lifetime, or fast- every cardiomyocyte replaced several times

Question 29

what is an example of how stem cells could be used?

Answer 29

bone marrow has stem cells that can become specialised to form any type of blood cell eg) to treat leukaemia (cancer of blood/bone marrow)

Question 30

what are the benefits of using stem cells in medicine?

Answer 30

could save many lives | could improve the quality of life for people

Question 31

what are the three main sources of human stem cells?

Answer 31

adult stem cells embryonic stem cells induced pluripotent stem cells

Question 32

how are adult stem cells obtained?

Answer 32

from the body tissues of an adult obtained in an operation can only specialise into a limited range of cells

Question 33

how are embryonic stem cells obtained?

Answer 33

from embryos in an early stage of development created in a laboratory using IVF once embryos approx 4 to 5 days old, stem cells removed, rest of embryo destroyed can divide an unlimited number of times into all types of body cells

Question 34

how are induced pluripotent stem cells obtained?

Answer 34

created by scientists in the lab reprogramme specialised adult body cells so they become pluripotent express a series of transcription factors that are associated with pluripotent cells- cuase the adult body to express genes associated with pluripotency

Question 35

what are the ethical issues for stem cell use?

Answer 35

destruction of embryos that could become a foetus