Chapters 14, 15 + 16 - DNA

Question 1

What is the genetic code?

Answer 1

The way in which information about the sequence of amino acids which make up a protein is coded for by bases on a molecule of mRNA.

Question 2

What is transcription?

Answer 2

The first stage of protein synthesis in which mRNA is produced from the DNA which makes up a particular gene.

Question 3

What is DNA helicase?

Answer 3

The enzyme that acts on a specific region of DNA to break the hydrogen bonds between bases.

Question 4

What is translation?

Answer 4

The second stage of protein synthesis in which the code on the mRNA molecule is used to control the production of a polypeptide chain by a ribosome.

Question 5

What is an anticodon?

Answer 5

The sequence of three bases on a molecule of tRNA which correspond to a particular codon on an mRNA molecule.

Question 6

What does tRNA stand for?

Answer 6

Transfer ribonucleic acid.

Question 7

What does mRNA stand for?

Answer 7

Messenger ribonucleic acid.

Question 8

What does DNA stand for?

Answer 8

Deoxyribonucleic acid.

Question 9

What is discontinuous variation?

Answer 9

Variation in which individuals fall into distinct categories.

Question 10

What is a gene mutation?

Answer 10

A change to one or more bases in the DNA that forms an organism’s genetic material.

Question 11

What is a substitution mutation?

Answer 11

The replacement of one base by another.

Question 12

What is a deletion mutation?

Answer 12

The removal of one base.

Question 13

What is a non-sense mutation?

Answer 13

A type of substitution mutation where the base change results in the formation of one of the three stop codons that mark the end of a polypeptide chain.

Question 14

What is a mis-sense mutation?

Answer 14

A type of substitution mutation where the base change results in a different amino acid being coded for.

Question 15

What is a silent mutation?

Answer 15

A type of substitution mutation in which the substituted base still codes for the same amino acid as before, but with a different codon.

Question 16

What is a mutagen/mutagenic agent?

Answer 16

An environmental factor which increases the rate of mutation.

Question 17

What is a proto oncogene?

Answer 17

A gene that stimulates cell division.

Question 18

What is an oncogene?

Answer 18

A mutated proto oncogene that results in increased cell division leading to the growth of tumours.

Question 19

What is a tumour suppressor gene?

Answer 19

A gene whose function is to help control multiplication of cells. Any mutation may stop it functioning properly - division is not prevented.

Question 20

What is totipotency?

Answer 20

The ability of a single cell to divide and produce all of the differentiated cells in an organism.

Question 21

What are stem cells?

Answer 21

Undifferentiated dividing cells that occur in embryos and in adult animal tissues that require constant replacement.

Question 22

What are transcriptional factors?

Answer 22

Specific molecules that move from the cytoplasm to the nucleus to stimulate transcription to begin.

Question 23

What is siRNA?

Answer 23

Small interfering RNA - small double stranded sections of RNA.

Question 24

What is recombinant?

Answer 24

A cell which contains a different combination of genes or DNA from that found in its parent cell.

Question 25

What is genetically modified?

Answer 25

A term used to describe organisms whose DNA has been altered by the process of genetic engineering.

Question 26

What is reverse transcriptase?

Answer 26

An enzyme, found in retroviruses, that produces a DNA molecule from the corresponding mRNA.

Question 27

What are restriction endonucleases?

Answer 27

One of a group of enzymes that are able to cut DNA molecules at specific points along their lengths, found naturally in many bacteria.

Question 28

What is a vector?

Answer 28

A molecule of DNA that acts as a carrier.

Question 29

What is DNA ligase?

Answer 29

A type of enzyme which is used to join lengths of DNA together.

Question 30

What is RNA polymerase?

Answer 30

An enzyme that joins RNA nucleotides together during transcription.

Question 31

What is the polymerase chain reaction?

Answer 31

A process used by biologists to make large amounts of identical DNA from very small sample.

Question 32

What are primers?

Answer 32

Short sequences of nucleotides.

Question 33

What is a thermocycler?

Answer 33

A computer controlled machine that varies temperatures precisely over period of time.

Question 34

What is cystic fibrosis?

Answer 34

An inherited condition in which affected individuals lack a protein which is responsible for the transport of chloride ions. This results in the production of a viscous mucus.

Question 35

What is gene replacement?

Answer 35

Where the defective gene is replaced with a healthy gene.

Question 36

What is been supplementation?

Answer 36

One or more copies of the healthy gene are added alongside the defective gene.

Question 37

What is germ line gene therapy?

Answer 37

Involves replacing or supplementing the defective gene in the fertilised egg.

Question 38

What is somatic cell gene therapy?

Answer 38

Affects only affected tissues and must be replaced regularly.

Question 39

What is a DNA probe?

Answer 39

A single strand of DNA which is used to identify a particular gene - it has a complementary base sequence and contain radioactive or fluorescent nucleotides.

Question 40

What is gel electrophoresis?

Answer 40

A technique used to separate DNA fragments of different lengths by placing them on agar gel and passing a voltage across them.

Question 41

What is restriction mapping?

Answer 41

Involves cutting DNA with a series of different restriction endonucleases. The fragments produced are then separated by gel electrophoresis. The distance between recognition sites are then determined by the pattern of fragments produced.

Question 42

What is genetic screening?

Answer 42

Testing for the allele that causes a particular inherited condition.

Question 43

What is genetic counselling?

Answer 43

Informing patients who are at risk about the likelihood of and consequences of a child inheriting a genetic disease and discussing the various options that are open to them.

Question 44

What is genetic engineering?

Answer 44

An aspect of biotechnology which involves altering the genetic make up of an organism.

Question 45

What is genetic fingerprinting?

Answer 45

A technique which can be used to distinguish between individuals by looking at similarities and differences in part of their DNA.