Lecture Quiz 3

Question 1

What type of rate are constitutive enzymes expressed in ?

Answer 1

FIXED rate

Question 2

What type of proteins are constantly being transcribed and translated into proteins

Answer 2

Constitutive Enzymes

Question 3

What are other enzymes that are expressed ONLY AS NEEDED?

Answer 3

• repressible enzymes

- inducible enzymes

Question 4

What is induction?

Answer 4

INDUCIBLE genes turned ON by INDUCERS

Question 5

Inducers, often substrates are required for what type of pathways?

Answer 5

Catabolic pathways

Question 6

What is repression

Answer 6

REPRESSIBLE genes turned OFF by REPRESSORS

Question 7

Repressors are end products of what type of pathways?

Answer 7

ANABOLIC (biosynthetic) pathways

Question 8

What happens in anabolic pathways?

Answer 8

• when sufficient product is made gene gets turned off

- this regulation often achieved with the OPEERON

Question 9

Give an example of bacteria that can utilize lactose that require a lag time during which lac operon becomes induced

Answer 9

E. coli

Question 10

If medium contains glucose (preferred sugar) and lactose, are lac operon induced?

Answer 10

NO, it is NOT induced. the only time it will be induced is when all glucose is used up

Question 11

So what if glucose and lactose are present, why not metabolize lactose along with glucose?

Answer 11

• genes for glucose metabolism are CONSTITUTIVE
• activating other genes for more pathways requires energy therefore, bacteria CONSERVE energy by USING GLUCOSE FIRST, then any other energy sources

Question 12

What is mutation?

Answer 12

change in the genetic material

Question 13

Can mutations be neutral, beneficial or harmful?

Answer 13

YES

Question 14

What is a mutagen?

Answer 14

agent that causes mutations

Question 15

What are spontaneous mutations?

Answer 15

occur in the absence of a mutagen

Question 16

What is base substitution?

Answer 16

point mutation

Question 17

What is a missense mutation?

Answer 17

• change in one base

- results in change in amino acid

Question 18

What is nonsense mutation?

Answer 18

• results in a nonsense codon

- stop codon-> protein is going to be short

Question 19

What is frameshift mutation?

Answer 19

insertion or deletion of one or more nucleotide pairs

Question 20

What are three types of mutations?

Answer 20

1. missense mutation
2. nonsense mutation
3. frameshift mutation

Question 21

What causes the formation of ions that can react with nucleotides and the deoxyribose-phosphate backbone?

Answer 21

ionizing radiation (X-RAYS and GAMMA RAYS)

Question 22

What repairs mutations?

Answer 22

Nucleotide excision

Question 23

What causes thymine dimers and bump in DNA?

Answer 23

UV radiation

Question 24

What separates thymine dimers?

Answer 24

Light-repair

Question 25

Is there such a thing as a healthy tan?

Answer 25

UV can be good for Vitamin D

Question 26

Should food be irradiated to destroy microbes and increase shelf life

Answer 26

yes

Question 27

Can group of genes be induced or repressed ?

Answer 27

It can be both: induced and repressed