Unit 5: Study Guide Questions

Question 1

What marcomolecule would DNA and RNA be categorized as?

Answer 1

Nucleic Acids

Question 2

What is the monomer of DNA?

Answer 2

Nucleotide (phosphate group, sugar, and nitrogenous base)

Question 3

The monomers that get bonded to make DNA are put together in a specific way. Which two pieces of the monomer make up the backbone of DNA?

Answer 3

Sugar and phosphates

Question 4

Which part of the monomer of DNA makes up the “rungs” of its twisted ladder shape?

Answer 4

Bases (A, C, G, T)

Question 5

What is the name for the twisted ladder shape of DNA?

Answer 5

Double Helix

Question 6

What is on the left side of a DNA monomer?

Answer 6

Phosphate Group

Question 7

What is in the middle of a DNA monomer?

Answer 7

Sugar

the deoxyribose sugar remember pls

Question 8

What is on the right side of DNA monomer?

Answer 8

nitrogenous base

Question 9

Why would a cell need to perform DNA replication?

Answer 9

If a cell needs to divide, a complete copy of all DNA needs to be made so that when the cell splits, each cell gets a full set of DNA.

Question 10

Where in the cell would DNA replication occur?

Answer 10

Nucleus, that’s where the DNA is.

Question 11

Explain “semi conservative replication”

Answer 11

DNA molecules will each have one old strand and one new.

Question 12

What does the 5’ to 3’ direction mean on a DNA strand?

Answer 12

The carbons on the deoxyribose sugar are numbered clockwise. The last, highest carbon on the sugar is the 5’. The bottom of that same strand will have a 3’ carbon at the very bottom.

Question 13

Are both strands in the same 5’ to 3’ direction?

Answer 13

Nope. They run in opposite directions. Complementary strand will be in the 3’ to 5’ direction.

Question 14

What is the Helicase?

Answer 14

Unzips the DNA molecule by breaking the hydrogen bonds between bases of nucleotides.

Question 15

What is DNA polymerase?

Answer 15

Lays down new nucleotides in the 5’ to 3’ direction only. It starts wherever it sees a primer from primase. It only needs one primer on the leading strand. On the lagging strand, it needs new primers as helicase unzips.

Question 15

What is Primase?

Answer 15

Lays down start signals along the DNA molecule so that DNA polymerase knows where to start working.

Question 16

What is Ligase?

Answer 16

The gluer that bonds newly copied strands to the old one and hooks fragments together one.

Question 17

What is the Leading strand?

Answer 17

The leading strand’s direction allows for the copied strand to be added in the 5’ to 3’ direction. So this strand can smoothy, continously add nucleotides as helicase unzips the molecule.

Question 18

What do both the Helicase and the DNA Polymearse do?

Answer 18

Both helicase and the DNA polymerase work in the same direction on the leading strand side. (5 to 3 direction)

Question 19

What is the lagging strand?

Answer 19

The lagging strand’s direction (3 to 5) makes it so that DNA polymerase has to add nucleotides in the opposite direction of helicase’s unzipping movements. Many added nucleotides are in fragment, discontinuous fashion. So, the polymearse needs LOTS of primers on this side.

Question 20

What is an Okazaki fragment?

Answer 20

These are the fragments of copied DNA that result from discontinuous base pairing on the lagging strand during DNA replication. Ligase hooks them all together before replication is done.

Question 21

Identify 3 differences between RNA and DNA.

Answer 21

RNA is single stranded, DNA is double stranded.

RNA’s nucleotides have the sugar ribose instead of deoxyribose in DNA.

RNA’s nucleotides have the base Uracil instead of Thymine like in DNA.

Question 22

The process is DNA –> RNA –> proteins. Why can’t DNA be directly translated into a protein?

Answer 22

DNA is too big to leave the nucleus so it’s trapped in there. Proteins are assembled out in the cytoplasm of the cell at ribosomes.

Question 23

What is mRNA? What is its function?

Answer 23

Messenger RNA

Copy a gene’s code from DNA and carry it out into the cytoplasm to make a protein.

Question 24

What is rRNA? What is its function?

Answer 24

Ribosomal RNA

Is part of the ribosome complex and helps bond amino acids together to make proteins.

Question 25

What is tRNA? What is its function?

Answer 25

Transfer RNA

Brings amino acids to the ribosome so they can be assembled into proteins. tRNA’s have anticodons that match the codons on mRNA so that amino acids are added in the right order.

Question 26

What is a codon?

Answer 26

A sequence of 3 nucleotide bases that code for an amino acid.

Question 27

What is an anti-codon?

Answer 27

A sequence of 3 nucleotide bases on a tRNA molecule that match (complementary) a codon on mRNA. Anticodons help a tRNA find its right spot in line at the ribosome so that the amino acid it brings gets added to the protein in the right order.

Question 28

Briefly summarize STEP 1 of protein synthesis.

Answer 28

Transcription of DNA occurs in the nucleus. A TINY portion of DNA that codes for a protein (gene) is opened up and that gene is copied into a complementary message in the form of mRNA. mRNA is small enough to slip out of the nucleus and travel out into the cytoplasm to find a ribosome.

Question 29

Briefly summarize STEP 2 of protein synthesis.

Answer 29

Translation occurs in the cytoplasm of the cell at ribosomes. The mRNA message copied from DNA is read through a ribosome. Each codon (3 bases) on mRNA codes for a specific amino acid, which is brought in to the ribosome by tRNA. The ribosome complex (including rRNA) bonds amino acids together to make a protein.