5b Genetics - protein synthesis - gene technology

Question 1

What enzyme is used in transcription?

Answer 1

RNA polymerase

Question 2

An enzyme that synthesises new DNA?

Answer 2

DNA polymerase

Question 3

An enzyme that cuts DNA at specific sequences ?

Answer 3

Restriction Endonuclease

Question 4

An enzyme that reseals cut ends of DNA ?

Answer 4

DNA ligase

Question 5

Small circular pieces of DNA found in bacteria - these pieces of DNA have antibiotic resistance genes ??

Answer 5

Plasmids

Question 6

An enzyme found in some viruses with and RNA genome - this enzyme converts mRNA to DNA??

Answer 6

Reverse transcription

Question 7

Oestrogen is a hormone that affects transcription - it forms a complex with a receptor in the cytoplasm of target cells. Explain how an activated oestrogen receptor affects the target cell…..

Answer 7

1. (Receptor/ transcription factor) binds to promoter
2. Stimulates RNA polymerase
3. Transcribes gene / increase transcription

Question 8

Explain how an antibiotic stops protein synthesis in bacteria?? (Picture of antibiotic blocking mRNA strand)

Answer 8

1. (Antibiotic) binds to / blocks mRNA triplet…
2. tRNA triplet cannot pair with the mRNA triplet…
3. Amino acid not added to polypeptide chain….
4. Translation prevented

Question 9

What do transcriptional factors control??

Answer 9

Protein synthesis

Question 10

The steps to transcriptional factors…..

Answer 10

1. Transcriptional factors bind to a promoter sequence (Specific bases on DNA)
2. This removes the repressor molecule out the way
3. This causes transcription to start happening
4. This means RNA polymerase can attach to DNA and make mRNA

Question 11

How many polynucleotide strands does (siRNA) small interfering RNA have??

Answer 11

Si RNA is double stranded

Question 12

How does siRNA affect the expression of a gene??

Answer 12

1. siRNA binds to mRNA
2. siRNA breaks the mRNA into smaller pieces
3. This can stop translation happening
4. The protein is not produced

Question 13

How can siRNA be useful in medicine??

Answer 13

It can be used to treat diseases caused by genetic mutations (e.g. Cancer) as it will stop the incorrect protein being produced

Question 14

In terms of splicing define….
pre-mRNA ?
mRNA ?

Answer 14

Pre-mRNA = after transcription and before splicing

mRNA = after splicing

Question 15

Describe and explain how expression of the target gene is affected by siRNA??

Answer 15

1. No longer able to make specific protein / cannot make whole protein / mRNA can’t be translated
2. Because the mRNA has been cut into pieces

Question 16

What is a gene probe?

Answer 16

Strand of DNA /
Short strand of DNA /
With base sequence that us complementary to part of a target gene/
Radioactivity labeled or fluorescent labelled

Question 17

Give two characteristic features of stem cells ??

Answer 17

1. Will replace themselves/ keep dividing

2. Undifferentiated/ develop into other cells / totipotent/ pluripotent

Question 18

How many different type of codons are there?

Answer 18

64 codons

Question 19

How many types of different amino acids are there?

Answer 19

20

Question 20

What is the definition of a stem cell??

Answer 20

Undifferentiated cells that continue to divide my mitosis

Question 21

Stem cells from animals ??

Answer 21

From embryos, placenta, bone marrow, fertilised egg

Question 22

Stem cells from a plant??

Answer 22

Cambium or meristem

Question 23

Stem cells can be used for??

Answer 23

Growth of specific tissue 
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Repairing damaged tissues
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Repairing spinal injuries 
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Healing damaged brain nerves (Alzheimer's )