b5.3

Question 1

1. What structure does DNA have?

Answer 1

-a double helix structure

Question 2

2. What are both strands of the DNA molecule are made up of?

Answer 2

-four different bases which always pair up in the same way (in a nucleotide)

Question 3

2. What is each strand of DNA made of?

Answer 3

-nucleotides

which are small units that contains small molecules called bases

Question 4

2. What is a nucleotide?

Answer 4

-a small unit that contains small molecules called bases

Question 5

2. What are the different bases in DNA?

Answer 5

• adenine (A)
• cytosine (C)
• guanine (G)
• thymine (T)

Question 6

2. What are the pairs of bases that make up strands of DNA molecules?

Answer 6

• A with T (stick letters)

- C with G (circle letters)

Question 7

3. What is the order of bases in a gene?

Answer 7

-the genetic code for the production of a protein

Question 8

4. What does the order of bases in a gene do?

Answer 8

-tells the cell what order to put the amino acids in to produce a particular protein

Question 9

4. What contains genetic code?

Answer 9

-DNA molecules

Question 10

4. What is a gene?

Answer 10

-a section of DNA that contains the instructions for one particular protein

Question 11

4. How many bases code for an amino acid?

Answer 11

• 3

- triplet code

Question 12

5. Where is the genetic code found in plant and animal cells?

Answer 12

-in the nucleus

Question 13

5. Where are proteins produced?

Answer 13

-in the cell cytoplasm

Question 14

5. How are proteins made?

Answer 14

-in the cell cytoplasm by organelles called ribosomes

Question 15

6. Where is DNA found?

Answer 15

• DNA is found in the cell nucleus

- it can’t leave because it is big

Question 16

6. How is information (genetic code) received by the ribosomes in the cytoplasm?

Answer 16

-a copy of DNA is made using a molecule called messenger RNA (mRNA)

Question 17

6. What is messenger RNA?

Answer 17

-similar to DNA but shorter and only a single strand, so can get out of the nucleus to carry genetic code to the ribosomes in the cell cytoplasm

Question 18

6. How is messenger RNA made and what does it do?

Answer 18

• two DNA strands unzip
• molecule of mRNA made using strand of DNA as template, base pairing makes sure it matches
• mRNA moves out of nucleus and joins with ribosome in cytoplasm
• ribosome sticks amino acids in a chain to make a protein, following order of bases in mRNA

Question 19

7. What genes do body cells in an organism contain?

Answer 19

-all body cells in an organism contain the same genes, but many genes in a particular cell are not active (switched off) because the cell only produces the specific proteins it needs

Question 20

8. What is the difference genetically between specialised cells and embryonic stem cells?

Answer 20

• in specialised cells only the genes needed for the cell can be switched on
• in embryonic stem cells any gene can be switched on during development to produce any type of specialised cell

Question 21

9. What do adult stem cells and embryonic stem cells have the potential to do?

Answer 21

-produce cells needed to replace damaged tissues

Question 22

10. What are the ethical issues when using embryonic stem cells?

Answer 22

• when you take the embryonic stem cells, you destroy an embryo
• if believe life begins at conception = murder

Question 23

10. What is embryonic stem cell work subject to?

Answer 23

-Government regulation

Question 24

11. What can mammalian cloning make possible?

Answer 24

-can make stem cells

Question 25

11. How are stem cells made by cloning?

Answer 25

- the nucleus from an adult body cell is transferred to an empty unfertilised egg cell - under right conditions, inactive genes in the nucleus of the body cell can be reactivated, forming an embryo - embryonic stem cells can then be extracted from embryo, which can from any time of specialised cell

Question 26

12. What are the different types of stem cells?

Answer 26

- Embryonic stem cells | - Adult stem cells

Question 27

12. What can embryonic stem cells develop into?

Answer 27

-can develop into any type of cell

Question 28

12. What is a stem cell?

Answer 28

an unspecialised cell

Question 29

12. How do we obtain adult stem cells?

Answer 29

-by safely removing them from the adult patient. E.g. by extracting bone marrow (no embryo destroyed)

Question 30

12. How can stem cells be used? Why?

Answer 30

they offer the potential to treat some illnesses as they are unspecialised

Question 31

12. What illnesses can adult stem cells be used to treat? How?

Answer 31

-Blood diseases like sickle cell anaemia-bone marrow transplants. Adult stem cells in the bone marrow can turn into new blood cells to replace old faulty ones.

Question 32

12. What illnesses can embryonic stem cells be used to treat? How?

Answer 32

-Could be used to replace faulty cells in sick people Heart muscle cells- heart disease Insulin producing cells- diabetes Nerve cells- spinal injuries (paralysed)

Question 33

12. When do cells become specialised?

Answer 33

-during the early development of the organism (8 cell stage)

Question 34

12. What can adult stem cells develop into?

Answer 34

-can develop into many, but not all, types of cell