Module 11 - Molecular Genetics

Question 1

What is semiconservative replication?

Answer 1

Method of DNA replication where parental strands separate and serve as templates. It produces DNA molecules that have one strand of parental DNA and one strand of new DNA. Occurs during interphase.

Question 2

What is helicase?

Answer 2

An enzyme that unwinds and unzips the parent double helix. breaks the hydrogen bonds between the base pairs leaving single strands of DNA

Question 3

What is topoisomerase?

Answer 3

An enzyme that keeps the double helix from supercoiling as it is being separated and unwound.

Question 4

What is RNA primase?

Answer 4

Adds an RNA primer on the two separated DNA strands to prepare them to be built upon

Question 5

What is DNA polymerase?

Answer 5

Assembles nucleotides along the individual DNA strands, creating a new strand of DNA

Question 6

What is ligase?

Answer 6

An enzyme that “glues” / seals the new strand to the original strand

Question 7

Leading strand vs lagging strand

Answer 7

The two strands from the parental DNA go in two different directions. The one that goes from 5’ to 3’ is the leading strand and the one that goes from 3’ to 5’ is the lagging strand. That is because DNA polymerase can only build on the 3’ end of the strand, so 3’ to 5’ will have to keep going back as the DNA unwinds. But the one that goes from 5’ to 3’ can continuously be built.

Question 8

What are the steps of protein synthesis?

Answer 8

1. Transcription
2. Translation

Question 9

What is mRNA?

Answer 9

Messenger RNA, carries genetic information from DNA in the nucleas to direct protein synthesis in the cytoplasm. Formed complementary to one strand of DNA.

Question 10

What is rRNA?

Answer 10

Ribosome RNA, associates with protein to form the ribosome.

Question 11

What is tRNA?

Answer 11

Transfer RNA, brings amino acids to ribosomes. Smaller segments of RNA nucleotides.

Question 12

What is a codon?

Answer 12

The three base code for amino acids in DNA or RNA

Question 13

What is a peptide bond?

Question 14

What is a guanine cap?

Answer 14

Guanine on the end of mRNA to protect it as it leaves the nucleus.

Question 15

What has to happen before mRNA can leave the nucleus?

Answer 15

Poly-A Tail must be added, Guanine cap must be added, introns must be removed from mRNA.

Question 16

What is a spliceosome?

Answer 16

A large RNA protein complex that removes the introns from pre-RNA

Question 17

What are exons and introns?

Answer 17

Exons are sequences on DNA that end up on the final mRNA product after transcriptions, while introns do not end up on mRNA after transcription.

Question 18

What is RNA?

Answer 18

A nucleic acid like DNA that has uracil instead of thymine and is single stranded.

Question 19

What is transcription?

Answer 19

The process by which mRNA is synthesized from DNA. DNA code is transferred to mRNA. The first step in the central dogma.

Question 20

What are the steps of transcription?

Answer 20

DNA is unzipped, RNA polymerase binds to a specific section where mRNA will be synthesized. As DNA unwinds, RNA polymerase initiates mRNA synthesis and moves along one of the DNA strands in the 3’ to 5’ direction. Eventually, the mRNA is released and the RNA polymerase detaches from the DNA.

Question 21

What is RNA polymerase?

Answer 21

An enzyme that regulates mRNA synthesis during transcription.

Question 22

Template strand vs nontemplate strand

Answer 22

A double helix gets split into two strands during transcription and RNA polymerase attaches to and reads one of them. That one is the template strand, and the unused strand is the nontemplate strand.

Question 23

What happens to pre-mRNA to make it a mature mRNA?

Answer 23

Introns are removed from the pre-mRNA, a protective cap is added to the 5’ end and a poly-A tail is added to the 3’ end.

Question 24

What is a poly-A tail?

Answer 24

A tail of many adenine nucleotides that stabilizes the mRNA, prevents it from degradation in the cytoplasm, and allows it to be exported from the nucleus.

Question 25

What are somatic cells?

Answer 25

Any cell that isn’t a reproductive cell.

Question 26

What is a polygenic trait?

Answer 26

A trait influenced by multiple genes

Question 27

What is a pleiotropic gene?

Answer 27

A gene that influences multiple traits.

Question 28

What is translation?

Answer 28

The process by which the code is read and translated to make a protein. The second part of the central dogma

Question 29

What are the steps to translation?

Answer 29

The 5’ end of mRNA connects to the ribosome. tRNA acts as interpreters of the mRNA sequence. Activated by an enzyme that attaches a specific amino acid to the 3’ end. This creates an anticodon that will match up to one of the mRNA codons, with the corresponding amino acid.