Cellular control (from LOs)

Question 1

Define mutation

Answer 1

Change in the DNA.

Question 2

Define chromosome mutation

Answer 2

Gain/ loss of whole/part of chromosome.

Question 3

Define DNA mutation

Answer 3

Change in base sequence.

Question 4

Define mutagens

Answer 4

Increases chance of a mutation occuring

Question 5

Define somatic mutation

Answer 5

Mutation in cell which is not a gamete/ cannot be passed on to offspring.

Question 6

Define allele

Answer 6

Version of a gene.

Question 7

List some examples of mutagens

Answer 7

UV, tar, radiation

Question 8

State when DNA mutations may occur

Answer 8

When DNA replicates

Question 9

Explain the differences between a somatic mutation and a mutation that occurs during meiosis

Answer 9

Somatic mutation not passed onto offspring, mutation occurs during meiosis = gamete has new allele = mutation passed onto offspring.

Question 10

What are the 3 types of mutation?

Answer 10

Point, insertion and deletion.

Question 11

What happens in a point mutation?

Answer 11

1 base replaces another

Question 12

What happens in an insertion mutation?

Answer 12

1 extra nucleotide added

Question 13

What happens in a deletion mutation?

Answer 13

1 nucleotide removed.

Question 14

Explain what is meant by the term “frame shift”

Answer 14

All codons after the mutation are changed

Question 15

State and explain which type of DNA mutation is likely to have the greatest effect on the protein produced.

Answer 15

Insertion/deletion
cause a frame shift
all codons after the mutation changed
so secondary and tertiary structures changed, so shape changed = not function or function differently.

Question 16

Explain why a substitution mutation may not affect the protein produced

Answer 16

Code is degenerate so new codon may still code for the same amino acid.

Question 17

Define gene expression

Answer 17

Whether a gene is switched on or off (i.e. whether a gene is used to produce a protein or not).

Question 18

Define operon

Answer 18

Length of DNA which is made of structural genes and control sites.

Question 19

Define enzyme induction

Answer 19

Switching on the gene to make the enzyme when needed.

Question 20

Define inducer

Answer 20

Molecule which causes the production of the protein/ switches the gene on.

Question 21

Define repressor protein

Answer 21

Molecule which switches the gene off.

Question 22

Define transcription level

Answer 22

This means controling if transcription happens or not.

Question 23

Define transcription factor

Answer 23

Molecule (usually a protein or group of proteins) which binds to the operator region before a gene, making it possible for the RNA polymerase to bind so transcription can occur.

Question 24

Explain why there are large numbers of some proteins but only small numbers of other proteins in a cell

Answer 24

Genes switched on/ off at different levels.

Question 25

Name the 2 enzymes required to metabolise lactose

Answer 25

Lactose permease and beta- galactosidase

Question 26

What is the function of lactose permease?

Answer 26

Transports lactose into the cell.

Question 27

What is the function of beta-galactosidase?

Answer 27

Hydrolyses lactose/ converts to glucose and galactose.

Question 28

Explain why, when supplied with lactose, bacteria cannot initially respire it

Answer 28

Don't have these 2 enzymes

Question 29

State the function of each part of the lac operon

Answer 29

``` P and O are control sites, RNA polymerase needs to bind to P The repressor binds to O, preventing RNA polymerase binding. Z codes for B galactosidase Y codes for lactose permease ```

Question 30

Name the gene which is not part of the operon but whose product helps with the functioning of the operon.

Answer 30

Regulatory gene

Question 31

Describe how the lac operon works when there is no lactose

Answer 31

B galactosidase and lactose permease genes are switched off. Regulator genes expressed Repressor protein synthesised Repressor protein binds to operator region Repressor protein covers part of promotor region RNA polymerase cannot bind to promoter No transcription No B galactosidase and lactose permease

Question 32

Describe how the lac operon works when lactose is present

Answer 32

B galactosidase and lactose permease genes are switched on. Lactose is the inducer Binds to complementary site on repressor protein Repressor protein changes shape Repressor protein cannot bind to operator region RNA polymerase can bind to promoter region B galactosidase and lactose permease genes are transcribed B galactosidase and lactose permease genes are produced.

Question 33

Define post transcription

Answer 33

Events that occur after transcription (after mRNA has been made)

Question 34

Define post translation

Answer 34

Events that occur after translation (after the protein has been made)

Question 35

Define intron

Answer 35

Non-coding DNA (sequence of bases which do not code for amino acids in the protein).

Question 36

Define primary mRNA

Answer 36

mRNA which is produced during transcription.

Question 37

Define mature mRNA

Answer 37

mRNA that is used at the ribosome to make the protein.

Question 38

Outline how primary mRNA is converted to mature mRNA

Answer 38

Introns are removed, by the enzymes

Question 39

Describe how proteins are activated post translation

Answer 39

By cyclic AMP, this changes their tertiary structure, to make shape of protein complementary to shape of molecule it needs to bind to.

Question 40

Define mitosis

Answer 40

Cell division which produces clones

Question 41

Define differentiation

Answer 41

Process cells go through to become specialised

Question 42

Define homeobox gene

Answer 42

Gene which controls development of organism

Question 43

Define polarity

Answer 43

Difference in charge.

Question 44

Define hox cluster

Answer 44

Several homeobox genes located together

Question 45

What is the anterior side of an organism?

Answer 45

Head

Question 46

What is the posterior side of an organism?

Answer 46

Tail

Question 47

What is the dorsal side of an organism?

Answer 47

Top

Question 48

What is the ventral side of an organism?

Answer 48

Bottom

Question 49

What are 3 types of homeobox genes?

Answer 49

Maternal effect gene, homeobox gene and segmentation gene.

Question 50

What is the function of the maternal effect gene?

Answer 50

Determine polarity of the embryo

Question 51

What is the function of the homeobox gene?

Answer 51

Determine identity of each segment

Question 52

What is the function of the segmentation gene?

Answer 52

Determine polarity of each segment

Question 53

Describe the 2 types of homeotic selector genes

Answer 53

Thorax and abdomen selector genes.

Question 54

Describe the effect a mutation in a homeobox selector gene could have.

Answer 54

Body part in the wrong position.

Question 55

State what type of protein homeobox genes code for

Answer 55

Transcription factors

Question 56

Explain how homeobox genes control development

Answer 56

Each homeobox gene codes for one transcription factor, this then switches on/off genes to make that segment.

Question 57

Describe the relationship between order of activation and location and expression of homeobox genes

Answer 57

Activated in the order they are expressed along the organism.