chapter 6

Question 1

agarose gel

Answer 1

The medium commonly used for electrophoresis of proteins and nucleic acids. It allows these molecules and an electric current to flow through it, but also acts as a sieve, sorting out the different-sized fragments; shorter DNA fragments migrate through the gel more quickly than longer ones

Question 2

annealing

Answer 2

In PCR, annealing is the process of joining separate strands of DNA together as a result of hydrogen bond pairing; it occurs when the temperature is lowered

Question 3

band on gel

Answer 3

A well-defined line in a lane on a gel; it contains millions of pieces of DNA of the same size

Question 4

biotechnology

Answer 4

The use of living organisms and biological systems and processes for human benefit

Question 5

denature

Answer 5

In PCR, denaturing is changing the molecular structure of a protein or DNA by applying a high temperature; in DNA, the hydrogen bonds break and the two strands separate

Question 6

dna ligase

Answer 6

An enzyme used to catalyse the formation of a bond between two pieces of DNA

Question 7

dna polymerase

Answer 7

A member of a class of enzymes found in all living things, which synthesises new strands of DNA based on a template strand and according to complementary base-pair rules; DNA polymerases are important tools in biotechnology because they are capable of making exact copies of fragments of DNA, enabling efficient and accurate amplification of DNA templates

Question 8

dna profiling

Answer 8

A process that is able to identify natural variations that exist within individual genomes, by using STRs, PCR and gel electrophoresis

Question 9

dna sequencing

Answer 9

The process of establishing the nucleotide sequence of a piece of DNA

Question 10

Ethidium bromide

Answer 10

a chemical that binds to double-stranded DNA and fluoresces pink when exposed to ultraviolet light; used to locate DNA in an agarose gel following electrophoresis

Question 11

Gel electrophoresis

Answer 11

A technique that separates large molecules (either fragments of DNA or proteins) according to their size and charge, for visualisation and identification purposes

Question 12

Gene cloning

Answer 12

The process of using plasmids and bacteria to make numerous identical copies of a gene

Question 13

gene expression

Answer 13

The translating of a gene into a protein by an organism; the phenotype is directly affected by gene expression

Question 14

gene probe

Answer 14

A specific short length of single-stranded DNA that can bind to a particular gene of interest

Question 15

genetic Engerineering

Answer 15

Manipulation of genetic material, including altering DNA in an organism to suppress or enhance a gene’s activity, or combining genetic material from different species

Question 16

genetic mapping

Answer 16

Identifying and recording the relative positions of genes on a chromosome using genetic markers, linkage mapping and physical mapping

Question 17

genetic marker

Answer 17

A nucleotide sequence that is associated with a specific trait; genetic markers may include short DNA sequences, such as STRs, or they may be whole genes

Question 18

Genetically modified organism (GMO)

Answer 18

An organism that has been modified by incorporating into its genome a piece of foreign DNA

Question 19

genome

Answer 19

All of the genetic material contained in an organism or a cell; it includes the chromosomes within the nucleus and the DNA in mitochondria and chloroplasts

Question 20

ladder

Answer 20

A standard collection of DNA fragments of known lengths (molecular size markers) used in gel electrophoresis

Question 21

lane

Answer 21

A corridor through which DNA passes after it leaves a well

Question 22

linkage mapping

Answer 22

Using frequencies of genes that cross over together to determine the relative positions of genes on a chromosome in genetic mapping

identify the relative positions of genetic markers on a chromosome and are based on how frequent the markers are on her to together

Question 23

Molecular size marker

Answer 23

A piece of DNA of known length; a set of molecular size markers are run alongside the samples in a gel to estimate the size of the DNA fragments in the sample (see ladder)

Question 24

Next-generation sequencing (NGS)

Answer 24

An automatic process that finds the order of nucleotides in a strand of DNA. The four nucleotides are labelled with four differently coloured fluorescent dyes. As electrophoresis proceeds, a laser scans across the bottom of the gel, detecting the different dyes and thus the base sequence. A computer can then automatically analyse the information from the gel to read the base sequence

Question 25

Physical mapping

Answer 25

A precise description of a gene’s position on a chromosome; the gene’s position is measured and located by the use of base pairs

Question 26

plasmid

Answer 26

A small circular piece of DNA, found in bacteria that is able to replicate independently of the cell’s chromosomes; engineered plasmids can carry antibiotic-resistance markers

Question 27

Polymerase chain reaction (PCR)

Answer 27

A cyclic method used to rapidly amplify (replicate) relatively small amounts of DNA into extremely large amounts, for further laboratory uses such as gel electrophoresis and DNA profiling

Question 28

primer

Answer 28

A short fragment of single-stranded nucleic acid (DNA or RNA); primers can be made in a laboratory, are about 20 nucleotides long and are usually labelled with an enzyme, or radioactive or fluorescent dye tag; a primer is attracted to a target DNA strand by complementary base pairing and marks where elongation/synthesis should start

Question 29

Recognition site

Answer 29

A specific sequence of DNA at which a restriction enzyme will cut

Question 30

Recombinant DNA technology

Answer 30

Tools and techniques used to transfer a gene from a cell of a member of one species to the genome of a different species

Question 31

Recombinant plasmid

Answer 31

A plasmid with foreign DNA inserted into it

Question 32

Restriction endonuclease (restriction enzyme)

Answer 32

An enzyme that cuts DNA at a specific restriction site

Question 33

Restriction fragment

Answer 33

A short fragment of DNA generated when a restriction enzyme cuts a longer DNA sequence

Question 34

Restriction site

Answer 34

A specific nucleotide sequence, usually 4–8 base pairs long, that is recognised as a cleaving site for a restriction enzyme

Question 35

Short tandem repeat (STR)

Answer 35

A short non-coding region of DNA that is repeated many times in the genome of an organism; it is highly variable between individuals and can be used in DNA profiling; an STR has a repeat sequence of two to five bases

Question 36

Sticky end

Answer 36

The end of a DNA fragment that is created when a restriction enzyme cuts DNA at different positions on each of the two strands

Question 37

Thermal cycler

Answer 37

A machine used in PCR that provides tight control over both the reaction temperature and the duration of each temperature step, ensuring efficient amplification

Question 38

Transformation

Answer 38

The process by which DNA is taken from one organism and inserted into another organism, usually of another species, to obtain a desired characteristic

Question 39

Transgenic organism

Answer 39

An organism that has been modified by incorporating into its genome a piece of foreign DNA; also called a geneticallymodifiedorganism (GMO)

Question 40

Variable nucleotide tandem repeats (VNTRs)

Answer 40

Short non-coding regions of DNA that are repeated many times in the genome of an organism; they are highly variable between individuals and can be used in DNA profiling; VNTRs have a repeat sequence of more than five bases

Question 41

Vector

Answer 41

In medicine, a vector is an agent that transmits pathogens from one host to another; in genetics, it refers to a vehicle used to transfer DNA sequences from one organism to another

Question 42

well

Answer 42

An indentation in a gel used in a gel electrophoresis apparatus. It is made by inserting a comb into the gel as it sets and is placed at the negatively charged end of the apparatus. DNA samples and a standard are pipetted into a row of wells