Lesson 10: Mutations

Question 1

what are mutations

Answer 1

errors in genes and DNA

Question 2

are mutations only harmful

Answer 2

no they can be neutral, harmful, and even beneficial

Question 3

what are mutations caused by

Answer 3

chemicals, environmental factors, radiation, etc.

Question 4

what triggers mutations to start, what is it caused by and WHAT TYPES OF MUTATIONS ARE THERE

Answer 4

it is mainly random
- spontaneous mutations happen in nature by accident
- induced mutations are a result of exposure to a physical or chemical agent
- for instanvce, UV light, etc.

Question 5

types of mutations- point mutations and chromosome mutations

Answer 5

point mutations: failure by the replicating cell to copy the genetic information accurately

Question 6

what could point mutations be a result of?

Answer 6

• base-pair substitution
• base-pair insertion
• base-pair deletion

Question 7

chromosome mutations

Answer 7

involve a mutation involving an entire chromosome or large part of it

Question 8

example of chromosome mutation and what does it result in

Answer 8

non disjunction is an example of a chromosome mutation that can happen in meiosis- it may result in genetic disorders if it happens in gametogenesis or early in development during mitosis

Question 9

where does most mutations occur?

Answer 9

in parts of DNA that do NOT code for genes

Question 10

do mutations that occur in somatic cells affect future generations

Answer 10

no

Question 11

do mutations that occur in the formation of gametes (sex cells) affect future generations? whats an example

Answer 11

yes
- CFTR cystic fibrosis transmembrane regulatory, which is an allele that causes cystic fibrosis

Question 12

lactose intolerance, what is it

Answer 12

a trait in which an individual is not able to digest lactose which is the common sugar in milk

Question 13

what is lactose intolerance caused by

Answer 13

a deficiency of the enzyme lactase which breaks down lactose

Question 14

what happens if individuals who are lactose intolerant consume lactose

Answer 14

the undigested lactose will be metabolized by the intestinal bacteria which can cause bloating, cramping, and diarrhea

Question 15

how come 75% of human adults are lactose intolerant?

Answer 15

• adults never consumed milk in human history
• when babies are born, they are lactose tolerant as they need to digest their mother’s milk
• when they grow, they may lose their ability to produce the enzyme to digest dairy products

Question 16

how are non lactose intolerant adults able to digest lactose

Answer 16

due to genetic mutations that inherited this gene

Question 17

sickle cell anemia, what is it (base pair… )

Answer 17

a mutation which is caused by a single nitrogenous base substitution- single adenine base is substituted by a thymine

Question 17

what happens to blood cells when someone has sickle cell anemia

Answer 17

it causes red blood cells to not be healthy and lose its round shape- instead, they turn c-shaped and less effective at moving oxygen around the body through blood

Question 18

what parasite/disease allows for having sickle cell to be beneficial? hows that?

Answer 18

Malaria
- when the parasite enters a red blood cell of an individual with SCA, it causes the oxygen levels in the cell to drop and it becomes sickle shaped
- because the infected red blood cell is no longer doing its job, its removed and destroyed by the body along with the parasite (which obviously kills it)
-

Question 19

process of base excision repair

Answer 19

where one enzyme snips out the damaged base and the other enzymes come in to trim around the site and replace the nucleotides

Question 20

how does UV light damage DNA

Answer 20

UV light can cause two nucleotides to stick together, which distorts the DNA’s double helix shape

Question 21

what kind of repair does UV light damage require? what is the process

Answer 21

nucleotide excision repair, when a team of proteins removes a long strand of 24 or so nucleotides, and replaces them with fresh ones

Question 22

high radiation such as gamma rays and x rays severs what of the DNA?

Answer 22

one or both strands of the DNA backbone

Question 23

what repair do we use for double stranded breaks in DNA

Answer 23

homologous recombination or non-homologous end joining

Question 24

describe and explain homologous recombination

Answer 24

it uses an undamaged section of similar DNA as a template- enzymes interlace the damaged and undamaged strands, get them to exchange sequences of nucleotides, and fill in the missing gaps to end up with two complete double stranded segments

Question 25

describe and explain non-homologous end joining

Answer 25

a series of proteins trims off a few nucleotides and then fuses the broken ends back together

Question 26

how is non-homologous end joining inaccurate sometimes?

Answer 26

it can cause genes to get mixed up or moved around a lot