lecture 2- mutations & transgenics

Question 1

a mutation is a change in ___

Answer 1

genetic composition
(alteration in DNA that causes a change from that of standard, wild-type sequence)

Question 2

what are mutations good for?

Answer 2

determining the function of a gene
- if you remove one part of the machine…what happens?how essential is it? is there redundancy?

Question 3

types of mutations: physical is the ____
name 4 subsets

Answer 3

direct change of the DNA sequence

deletions
substitutions
transpositions
insertions

Question 4

describe the physical mutation of deletions

Answer 4

single bp deletions & multiple bp deletions

Question 5

describe the physical mutation of substitutions

Answer 5

missense- codes for diff amino acid

nonsense- codes for stop codon

silent

Question 6

describe the physical mutation of transpositions

Answer 6

switch things from one place to another
- small & large scale

Question 7

describe the physical mutation of insertions

Answer 7

single bp (point mutation)

duplication

Question 8

types of mutations: non-physical and others
name the 6

Answer 8

silent
frameshift
reversion
neutral
adaptive
conditional

Question 9

describe the non-physical mutation of silent mutations

Answer 9

change in DNA that does not affect the amino acid it codes for

Question 10

describe the non-physical mutation of frameshifts

Answer 10

change in the AA reading frame
- the insertion of deletion of nucleotide bases that are not in multiples of 3’s

The red cat
T her edc at

Question 11

describe the non-physical mutation of reversions

Answer 11

change of a mutation back to the original state

ATCG –> AACG –> ATCG

Question 12

describe the non-physical mutation of neutral

Answer 12

no affect on fitness

Question 13

describe the non-physical mutation of adaptive

Answer 13

positive affect on fitness

Question 14

describe the non-physical mutation of lethals

Answer 14

causes death of the organism

Question 15

name 7 mutation functional classes

Answer 15

1- loss of function
2- gain of function
3- leaky
4- conditional
5- dominant negative
6- homeotic
7- suppressor

Question 16

describe loss of function

Answer 16

often recessive- gene has reduced or complete lack of function (null allele)

Question 17

describe gain of function

Answer 17

often dominant- gene has gained a new or enhanced function

Question 18

describe a leaky function

Answer 18

only a partial loss of function

Question 19

describe a conditional function

Answer 19

the effect is dependent on certain conditions (such as temp sensitive)

Question 20

describe a dominant negative function

Answer 20

a mutant gene product, which adversely affects the wild-type gene product in the same cell (possible by binding to it)

• usually works in an antagonistic manner, often more detrimental than a null allele

Question 21

is a dominant negative function or a loss of function (null allele) more detrimental?

Answer 21

dominant negative

Question 22

describe a homeotic function

Answer 22

one developmental pattern is replaced by another (Drosphilia antenapodia mutant has legs where its antennae should be)

Question 23

describe a suppressor function

Answer 23

causes a reversion in a mutant phenotype due to a mutation at a site other than the original mutation (second site)

Question 24

name 5 causes of mutations

Answer 24

1- chemical- alkylating agents, intercalating agents, base analogs: EMS

2- physical- chromosomal breaks

3- replication/transcriptional reading errors

4- energy/radiation (UV: thymine dimers) (gamma ray, x-ray, fast neuron- deletions, breaks)

5- biological (transposons, transgenics)

Question 25

what are transgenic organisms?

Answer 25

organism that has its genome altered by the addition of DNA

• fish, mice, transgenic plants, crops, tomatoes

Question 26

where are transgenic organisms?

Answer 26

labs and everywhere
90% of soybean, corn, and cotton

~70% of all food in grocery store contains ingredients from GM plants (soybean oil, cottonseed oil, and corn syrup)

Question 27

name a few transgenic crops

Answer 27

apple
potato
corn
soybean
squash

Question 28

name 5 most popular ways transgenics are made

Answer 28

1- marker lines (LacZ, GFP, GUS)
2- overexpression (constitutive driven promoters)
3- antisense and RNAi
4- specific promoter targeting
5- tagged constructs

Question 29

describe overexpression, constitutively driven promoters (method by which transgenics are made)

Answer 29

expression in all tissues and all times
often a viral promoter
(Adeno/Lentiviral or 35S-CMV)

Question 30

describe antisense and RNAi (method by which transgenics are made)

Answer 30

knockout or knockdown expression of specific gene or multiple genes

Question 31

describe specific promoter targeting (method by which transgenics are made)

Answer 31

spatial, temporal, INDUCIBLE (heat shock, EtOH, Cu, steroid)- any promoter that wouldn’t affect normal or general gene expression of your gene of interest

Question 32

described tagged constructs (method by which transgenics are made)

Answer 32

adding a protein or epitope tag (MYC, HA, His, GFP) to make it easier to do specific work with your protein later (antibodies to specifically get at your protein or associated proteins)

Question 33

what are transgenics good for?

Answer 33

determining the function of a gene:
- tracking gene expression (marker lines)
- removing parts (antisense or RNAi)
- miss or constitutive expression (viral promoters 35S)
- inducible expression (ability to turn on and off a gene at will)
- protein identification (forms or complexes) via antibodies