DNA structure test

Question 1

What is the full name of DNA?

Answer 1

Deoxyribonucleic acid

Question 2

What are the 4 nitrogenous bases

Answer 2

Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

Question 3

What is meant by the term antiparallel?

Answer 3

strands are opposite

Question 4

mRNA

Answer 4

• Messenger RNA
• Carries genetic information from the DNA in the nucleus to the ribosome in the cytoplasm to make proteins

Question 5

tRNA

Answer 5

• Transfer RNA
• Each tRNA transfers a different amino acid to the ribosome during protein synthesis

Question 6

rRNA

Answer 6

• Ribosomal RNA
• Helps form large and small subunits of ribosomes

Question 7

What are start codons and stop codons?

Answer 7

• Start codons- Protein translation is initiated
• Stop codons- Termination of the translation site

Question 8

Components of a nucleotide

Answer 8

Deoxyribosugar, phosphate, and Nitrogenous bases.

Question 9

Hydrogen bonding - which base pairs are held with 3 H bonds vs. 2 H bonds?
5’ to 3’ and 3’ to 5’

Answer 9

Purines are held with 2 bonds
Pyrimidines are held with 3 bonds

Question 10

Complementary base pairing - which ones pair together and why?

Answer 10

Adenine matches with thinine
Guanine matches with cytosine

Question 11

Topoisomerase

Answer 11

• Works in a position just ahead of the helicase
• Untwists the DNA and holds it steady so that helicase can move down the replication bubble

Question 12

What makes DNA twist? - hydrophobic vs. hydrophilic

Answer 12

Alternating deoxyribose and phosphate molecules

Question 13

Helicase

Disrupts by

Answer 13

• Unzips the double helix by disrupting hydrogen bonding between nitrogenous bases
• Creates two single strands with free nitrogenous bases that can be used as a template for free nitrogenous bases to be added
• Moves in both directions from the origin of replication

Question 14

Single Stranded Binding

Answer 14

• Holds the single strand still and stable
• Prevents the two strands from rejoining so that additional proteins may do their jobs of adding new nitrogenous bases

Question 15

Primase (Primer)

Answer 15

• Attaches a short complementary RNA strand to the DNA template - this is a start code, which is a primer that allows the next protein to begin working
• Works only in the 5’ to 3’ direction
• 1 primase is needed for the leading strand (continuous replication)
• Multiple primase is needed for the lagging strand (fragmented synthesis)

Question 16

DNA Polymerase III

Identifies opposite of DNA

Answer 16

• Identifies the RNA primer and attaches to the strand at that location
• Continuously moves in the 5’ to 3’ direction adding free nucleotides from the environment within the nucleus to the template strand
• Releases from the template when two replication forks meet

Question 17

DNA Polymerase I

Answer 17

• Fills in the gaps between Okazaki fragments by adding the correct nucleotides (ones with complementary nitrogenous bases)

Question 18

Okazaki fragments

Answer 18

There are gaps between the fragments of new DNA that must be filled in as replication continues down the lagging strand

Question 19

Ligase

Answer 19

• This joins the fragments into one continuous complementary strand of DNA by synthesizing phosphodiester bonds

Question 20

Nuclease

* ______Bonds
* Helps with….

Answer 20

• Phosphodiester bonds
• play crucial roles in various DNA repair processes, which involve DNA replication, base excision repair,

Question 21

CODons

Answer 21

Codes for a specific amino acid

Question 22

AnTicodons

Answer 22

Found in tRNA and pairs with codon on a strand of mRNA during translation

Question 23

Location of transcription

Answer 23

Nucleus of human cells

Question 24

What is a complementary mRNA gene sequence

Answer 24

A,C,G,U

Question 25

IniTiation (Translation step 1)

Answer 25

* Transcription factors (helper proteins) bind to a promoter region somewhere on the DNA double helix * In humans, our promoter region (TATA box)

Question 26

Elongation (Translation step 2)

Answer 26

The mRNA strand is synthesized * RNA Polymerase III attaches to the double helix * It untwists the double helix to create a transcription bubble * It moves down the template strand in the 3’-->5’ direction , adding complementary RNA nucleotides to the growing mRNA in the 5’-->3’ direction and securing the RNA sugar-phosphate backbone

Question 27

Termination (Translation step 3)

Answer 27

* RNA Polymerase III adds complementary RNA nucleotides to the DNA template until a stop code is reached * termination code is called polyadenylation (a string of A’s) - it tells the polymerase to stop transcribing and the enzyme releases the DNA double helix and the new mRNA strand

Question 28

Termination code

Answer 28

polyadenylation (a string of A’s)

Question 29

Promoter region

Answer 29

TATA box

Question 30

Replication bubble

Answer 30

* Two replication forks are formed at the replication bubble * DNA replication occurs in both directions.

Question 31

Replication fork

Answer 31

A Y-shaped region where the parent DNA splits into two strands

Question 32

What sugar is in RNA? How is the sugar different from DNA?

Answer 32

RNA- Ribose DNA- Deoxy, No ribose

Question 33

Purines vs. pyrimidines

Answer 33

Purines: adenine and guanine Pyrimidines: cytosine and thymine

Question 34

Hydrogen bonding - which base pairs are held with 3 H bonds vs. 2 H bonds?

Answer 34

Purines: Adenine and guanine form 2 bonds Pyrimidines: Cytosine and thymine form 3 bonds

Question 35

5’ to 3’ and 3’ to 5’

Answer 35

Count the amount of sugars starting with oxygen and going clockwise

Question 36

What is the job of DNA? And where is DNA stored?

Answer 36

To store and transmit genetic info. It is stored in the nucleus

Question 37

Leading strand

Answer 37

* Runs from 5' to 3' direction in the replication fork * Can be replicated continuously

Question 38

Lagging strand

Answer 38

* The strand opens in 3' to 5' direction toward the replication fork * Replication is fragmented

Question 39

Transcription

Answer 39

the process of building a complementary RNA copy of a DNA strand

Question 40

Translation

Answer 40

is the process of building a protein based on the sequence of the RNA copy