Unit 3 - Mutations

Question 1

Mutation is…

Answer 1

a permanent change in the nucleotide sequence of a cells DNA

Question 2

Mutation 3 factors

Answer 2

1) typically, neutral or harmful = rarely beneficial
2) allows species to change over time
3) only those who adapt will live

Question 3

Mutation passes onto

Answer 3

daughter cells

Question 4

Multicellular organisms have two types of mutations:

Answer 4

1) somatic
2) germ line

Question 5

Somatic Mutations

Answer 5

passes on during mitosis, but not so subsequent generations
- non heritable
- non germline tissues

Question 6

Germ Line mutation

Answer 6

occur in cells that give rise to gametes, pass to subsequent generations
- present in egg and sperm
- can be inherited

Question 7

Mutations can be (3)

Answer 7

a) spontaneous or induced
b) physical or chemical
c) chromosomal or single gene

Question 8

a) spontaneous

Answer 8

take place naturally as a result of normal mo interactions
ie. DNA replication

Question 9

a) induced

Answer 9

cause by agents outside the cell
ie. mutagens; an environmental agent increased rate of mutations

Question 10

Environmental agents directly alters DAN in a cell can be..

Answer 10

physical = x-rays or UV
chemical = gasoline or cigarette smoke

Question 11

b) physical

Answer 11

• produces highly reactive chemical species called free radicals which can change the base in DNA to unrecognizable forms by DNA polymerase
• can break DNA backbone = chromosomal rearrangment or deletion

Question 12

Ionizing radiations

Answer 12

x-ray
gamma rays
= induced

Question 13

UV radiation

Answer 13

is absorbed by T in DNA causing it to form inter-base covalent bonds with adjacent nucleotides called DIMERS = chaos in DNA replication

Question 14

b) chemical

Answer 14

can enter the cell nucleus and chemically alter the structure of DNA
ie. co2, tobacco smoke
-modify individual nucleotides
-mimicking DNA mol
-insert itself between strands of double helix and alter structure of DNA

Question 15

Nitrous Acid vs Benzpyrene

Answer 15

1) can turn C in DNA into U = induced
2) A component of cigarette smoke, adds a large chemical group to G making it unavailable for bp = induced

Question 16

Small scale mutations

Answer 16

include mutations of an individual bp called point mutation or of a small group of bp

Question 17

substitution

Answer 17

of one base for anotheri

Question 18

insertion

Answer 18

of a single bp

Question 19

deletion

Answer 19

of a single bp

Question 20

inversion

Answer 20

of two adjoining bp

Question 21

effects of small scale mutations; 4 groups

Answer 21

1) missense mutations
2) nonsense mutations
3) silent mutations
4) frameshift mutations

Question 22

substitution mutation ie sickle cell anemia (5)

Answer 22

1) point mutation in hemoglobin
2) = misshapen hemoglobin
3) reduces lifespan by 30y
4) cant transport O2 effectively
5) nucleotide 19 sub from A=U

Question 23

Missense Mutation

Answer 23

occurs when the change of a single base pair or group of bp results in the code of diff aa
- protein sythensized will have a diff sequence and strucure
- may or may not function (protein)

Question 24

Nonsense Mutation

Answer 24

occurs when a change of a single base pair or group of base pairs results in a premature stop codon
= polypeptide chain is cut short most likely unable to function

Question 25

Silent Mutations

Answer 25

occurs when the change in one or more base pairs does not affect the functioning of the gene. (may occur within an intron). gene codes fro same aa.

Question 26

Frameshift Mutations

Answer 26

occurs when one or more nucleotides are inserted into or deleted from a DNA sequence =reading frame of codons to shift in one direction or the other (deleting or inserting 3bp)

Question 27

Large scale Mutations

Answer 27

also called chromosomal mutations - large scale mutations can invlive multiple nucleotides or entire gene -small pieces of a chromosome or chromosomes may be deleted, duplicated, insertion, inverted, or translocated

Question 28

Deletion

Answer 28

a mutation in which a part of a chromosome or sequence of DNA is deleted and bc "missing"

Question 29

Duplication

Answer 29

any duplication of a region of DNA that contains a gene - this duplication can now supply additional material that had the ability to evolve new functions (Marie-tooth disease type 1)

Question 30

Insertion

Answer 30

a type of chromosomal abnormality in which a DNA sequence is inserted into a gene, disrupting the normal structure and function of that gene.

Question 31

Inversion (3) facts

Answer 31

1) reversal of a segment of DNA in chromosome 2) breaking and rejoining 3) effect if break occurs in a gene

Question 32

Translocation

Answer 32

a fragment of DNA moves from one part of the genome to another = fusion protein ie. leukemia

Question 33

Leukemia

Answer 33

- cancer of the blood and bone marrow caused by translocation between chrom 9 and 22. associated to exposure: benzene, x-rays, radiation

Question 34

negative mutation

Answer 34

renders the individual less fit than other membranes of its group and will be seleced against by nature

Question 35

Benefical Mutation

Answer 35

lead to new versions or proteins that help organisms adapt to change. As a result experience greater survival and reproductive success

Question 36

Neutral mutation

Answer 36

changes in DNA sequence that r neither beneficial nor detrimental to the ability of an organism to survive and reproduce

Question 37

impact of mutation can be beneficial under diff circumstances like

Answer 37

1) mutation causes sickle cell anemia and also gives resistance to malaria 2) mutation that causes lactose tolerance in humans allows us to consume milk from cows

Question 38

DNA composition: coding region

Answer 38

5% of genome - 42000 genes

Question 39

DNA composition: noncoding regions

Answer 39

95% of genome - repetitive DNA telomeres centromeres VNTRs (microsatellites)

Question 40

Pseudogens

Answer 40

genes that r no longer expressed in the cell