CHAPTER 11

Question 1

What are mutations?

Answer 1

Heritable changes in DNA that can be passed to future generations

Question 2

What is difference between mutations in somatic cells vs germ cells?

Answer 2

In somatic cells, they’re passed on by cell division to daughter cells and not transmitted to future generations. In germ cells, they’re passed onto future generations.

Question 3

What are mutation rates affected by?

Answer 3

Gene Zoe, presence of specific nucleotide repeats, spontaneous or environmentally induced chemical changes

Question 4

What is mutation rate?

Answer 4

The number of mutated alleles per gene in each generations

Question 5

What leads to a spontaneous mutation?

Answer 5

Results from errors in normal cellular processes such as DNA replication. It can also be causes by natural changes in the molecular structure of bases in DNA

Question 6

What causes induced mutations?

Answer 6

Caused by mutagens, such as radiation and chemicals, that affect DNA and cellular processes

Question 7

How can small chemical changes in bases cause spontaneous mutations?

Answer 7

Tautomeric shifts: small atomic shifts that change the structure of nucleotide bases

Question 8

How is radiation a source of mutation?

Answer 8

Ionization and free radicals can both cause DNA mutations

Question 9

What are base analogs ?

Answer 9

Mutagenic chemicals that resemble nucleotides and are incorporated into DNA or RNA during synthesis

Question 10

How can bases in DNA be modified by chemical mutagens?

Answer 10

Nitrous acid changes cytosine to uracil

Question 11

What is nucleotide substitution ?

Answer 11

Replacement of one or more nucleotide in DNA molecule with other nucleotides

Question 12

What is a silent mutation

Answer 12

Nucleotide substitution that does not change the amino acid

Question 13

What is Missense mutation

Answer 13

Single amino acid substitution

Question 14

What is Nonsense substitution

Answer 14

Changes an amino acid to a termination codon

Question 15

What’s a silent mutation?

Answer 15

DNA: TTC —> TTT
mRNA: AAG —> AAA

Question 16

What is a nonsense mutation?

Answer 16

DNA: TTC —> ATC
mRNA: AAG —> UAG

Question 17

What is a missense mutation?

Answer 17

DNA: TTC —> TGC
mRNA: AAG —> ACG

Question 18

What is a frame shift mutation?

Answer 18

Frameshift mutations alter the reading frame, changing the amino acids in the protein

Question 19

How does proofreading during DNA replication works?

Answer 19

Sometimes can add incorrect nucleotides. Synthesizes new strands and proofreads. Will correct mistake if identified.

Question 20

In addition to DNA polymerase, what is another check?

Answer 20

Repair enzymes. It recognizes distortions caused by the insertion of the wrong base during DNA replication.

Question 21

what causes sickle cell anemia?

Answer 21

a specific single nucleotide substitution

Question 22

what causes cystic fibrosis?

Answer 22

associated with many different mutations in a single gene. over 1900 mutations have been identified in this single gene. therefore it has a wide range of symptoms

Question 23

what is epigenetic?

Answer 23

chemical modifications to DNA and alters gene expression (increase or decrease) but doesn’t change DNA sequence

Question 24

How does his tone modification work?

Answer 24

DNA winds around a histone complex to form a nucleosome. Promoters that are wound tightly in a nucleosome are unavailable for RNA polymerase and not expressed

Question 25

epigenetic modification

Answer 25

specific to cell type and can help control human development.