biology_flashcards_topic8

Question 1

What is a gene mutation?

Answer 1

A change in the base sequence of DNA.

Question 2

What is a mutagenic agent?

Answer 2

A factor that increases the rate of gene mutation (e.g. UV light).

Question 3

How can gene mutation lead to a non-functional protein?

Answer 3

It changes the sequence of amino acids, altering the tertiary structure and affecting function.

Question 4

Name the types of gene mutation.

Answer 4

Substitution, addition, deletion, duplication, inversion, translocation.

Question 5

Why do some gene mutations not affect the protein?

Answer 5

Because of the degenerate nature of the genetic code or if the mutation is in an intron.

Question 6

What is a frameshift?

Answer 6

An insertion or deletion not in multiples of 3, shifting the reading frame.

Question 7

What are stem cells?

Answer 7

Undifferentiated cells capable of dividing and differentiating into specialised cells.

Question 8

Describe totipotent cells.

Answer 8

Can form all cell types, including extra-embryonic (placenta).

Question 9

Describe pluripotent cells.

Answer 9

Can form most cell types, excluding extra-embryonic cells.

Question 10

Describe multipotent cells.

Answer 10

Can differentiate into a limited range of cells, e.g. blood cells.

Question 11

Describe unipotent cells.

Answer 11

Can only differentiate into one cell type, e.g. cardiomyocytes.

Question 12

How can stem cells be used in treating disorders?

Answer 12

Transplanting them to produce healthy cells for damaged tissues.

Question 13

What are transcription factors?

Answer 13

Proteins that regulate gene expression by binding to promoter regions.

Question 14

How does oestrogen affect transcription?

Answer 14

Binds to receptors, forming an active complex that stimulates transcription.

Question 15

What is epigenetics?

Answer 15

Heritable changes in gene expression without altering DNA sequence.

Question 16

What is methylation?

Answer 16

Addition of methyl groups to DNA, usually inhibiting transcription.

Question 17

What is acetylation?

Answer 17

Addition of acetyl groups to histones, usually promoting transcription.

Question 18

What is RNA interference?

Answer 18

siRNA or miRNA bind to mRNA to inhibit translation.

Question 19

What is a tumour suppressor gene?

Answer 19

A gene that slows cell division or causes apoptosis if DNA is damaged.

Question 20

What is an oncogene?

Answer 20

A mutated proto-oncogene that permanently stimulates cell division.

Question 21

What is the difference between benign and malignant tumours?

Answer 21

Benign are localised and slow growing; malignant spread and grow rapidly.

Question 22

What is a genome?

Answer 22

The complete set of genes in an organism.

Question 23

What is a proteome?

Answer 23

The full range of proteins that can be produced by an organism.

Question 24

Why can’t genomes always predict proteomes?

Answer 24

Due to non-coding DNA and regulatory genes.

Question 25

What is recombinant DNA technology?

Answer 25

The transfer of DNA from one organism to another.

Question 26

How are DNA fragments made using restriction enzymes?

Answer 26

They cut DNA at specific sequences, producing sticky ends.

Question 27

What is PCR?

Answer 27

Polymerase Chain Reaction, amplifies DNA fragments in vitro.

Question 28

What is a vector?

Answer 28

A DNA molecule used to transfer genetic material into a cell, e.g. plasmid.

Question 29

What are DNA probes?

Answer 29

Short labelled DNA sequences that bind to complementary DNA.

Question 30

What is gel electrophoresis?

Answer 30

A technique to separate DNA fragments by size.

Question 31

What is genetic fingerprinting?

Answer 31

Analysing VNTRs to compare genetic similarity.

Question 32

What are VNTRs?

Answer 32

Short repeating sequences of DNA that vary between individuals.

Question 33

How can epigenetics cause cancer?

Answer 33

Changes in methylation or acetylation affect gene expression (oncogenes/tumour suppressor genes).

Question 34

What is gene therapy?

Answer 34

Inserting functional alleles into cells to treat genetic disorders.

Question 35

How does RNA interference regulate translation?

Answer 35

siRNA binds to mRNA and prevents translation by degradation or blocking ribosome binding.

Question 36

Why might iPS cells be preferable to embryonic stem cells?

Answer 36

They avoid ethical issues and immune rejection.

Question 37

What is the difference between siRNA and miRNA?

Answer 37

siRNA usually perfectly complementary to mRNA; miRNA often partially complementary.

Question 38

How does transcription factor binding affect transcription?

Answer 38

It either stimulates or inhibits RNA polymerase binding to DNA.

Question 39

What is a promoter region?

Answer 39

A DNA sequence where transcription factors bind to start transcription.

Question 40

What is DNA hybridisation?

Answer 40

Binding of a single-stranded DNA probe to complementary DNA.

Question 41

What is the advantage of using mRNA to produce DNA fragments?

Answer 41

No introns and easier extraction.

Question 42

What is a gene machine?

Answer 42

A device that synthesises DNA fragments from known sequences.

Question 43

What is a marker gene?

Answer 43

A gene inserted into a vector to identify transformed cells.

Question 44

Why is it important to add promoter and terminator regions?

Answer 44

So the gene can be transcribed and terminated properly in the host.

Question 45

What is a RISC?

Answer 45

RNA-induced silencing complex; binds siRNA/miRNA to inhibit translation.

Question 46

How does oestrogen affect breast cancer?

Answer 46

Increases transcription of genes that stimulate cell division.

Question 47

What is a genome project?

Answer 47

A project that sequences all genes in an organism.

Question 48

What is genetic screening?

Answer 48

Testing DNA for specific alleles linked to disorders.

Question 49

What are the ethical concerns of genetic screening?

Answer 49

Risk of discrimination, stress, and ethical implications of testing embryos.

Question 50

What are variable number tandem repeats (VNTRs)?

Answer 50

Repeating DNA sequences at certain loci, vary between individuals.

Question 51

What is meant by 'universal genetic code'?

Answer 51

Same triplet codes specify the same amino acids in all organisms.

Question 52

What is the difference between in vitro and in vivo amplification?

Answer 52

In vitro: PCR. In vivo: transformed host cells (e.g. bacteria).

Question 53

What is a terminator region?

Answer 53

DNA sequence that stops transcription.

Question 54

What is meant by plagioclimax?

Answer 54

A community maintained at an earlier stage by human activity.

Question 55

What is meant by transcription?

Answer 55

The process of making mRNA from DNA.

Question 56

What is the relevance of proteome studies?

Answer 56

Can identify proteins to target in medicine or agriculture.

Question 57

What is a DNA primer?

Answer 57

Short sequence that allows DNA polymerase to start synthesis.

Question 58

Why might PCR stop?

Answer 58

Primers and nucleotides are used up.

Question 59

What is a gene probe label?

Answer 59

Fluorescent or radioactive tags used to detect binding.

Question 60

Why do transformed cells fluoresce?

Answer 60

They contain a fluorescent marker gene.

Question 61

How are transformed cells identified?

Answer 61

By marker genes conferring antibiotic resistance or fluorescence.

Question 62

Why might people oppose GM crops?

Answer 62

Environmental concerns, superweeds, corporate control.

Question 63

How might gene therapy fail?

Answer 63

Short-lived effect, immune response, or cause cancer.

Question 64

What is gene therapy's limitation?

Answer 64

Not heritable; somatic cells are treated but gametes aren't.

Question 65

Why do many diseases need many probes?

Answer 65

They're polygenic, involving multiple genes.

Question 66

What is gel electrophoresis used for?

Answer 66

Separating DNA fragments for analysis.

Question 67

How do shorter DNA fragments behave in electrophoresis?

Answer 67

They travel faster/further than longer ones.

Question 68

What is the risk of superweeds?

Answer 68

Transfer of herbicide resistance to wild plants.

Question 69

Why do some drugs bind to oestrogen receptors in cancer?

Answer 69

To block oestrogen from activating transcription.

Question 70

What is autoradiography?

Answer 70

Exposing X-ray film to detect radioactive probes.