DNA

Question 1

What are the two types of nucleic acids?

Answer 1

DNA and RNA

Question 2

What is a deoxyribose nucleotide?

Answer 2

DNA. Which consist of a phosphate, nitrogen base and a 5 carbon sugar

Question 3

What is a ribose nucleotide?

Answer 3

RNA. It’s the same as DNA but it has an extra OH on the 2nd sugars carbon.

Question 4

Nitrogen bases:
C and T
A and G

Answer 4

C and T are pyrimidines= single bonds
A and G are purines= double bonds
* base pairing is C///G
* complementary is A//T

Question 5

What is DNA?

Answer 5

• Double helix that is formed from 2-anti-parrallel strands
• OH bonds link nitrogen bases
• Phosphodiester bonds join nucleotides through condensation rxn’s

Question 6

What is RNA?

Answer 6

Single strand nucleotides
The 3 types are:
tRNA- (transfer RNA) carries amino acids
rRNA- found in ribosomes of the cytoplasm
mRNA- (messenger RNA) carries messages from DNA to ribosomes

Question 7

Differences between RNA and DNA

Answer 7

• DNA has thymine while RNA has uracil
• DNA is double stranded while RNA is single stranded
• DNA contains deoxyribose while RNA contains ribose

Question 8

Nucleoside vs nucleotide

Answer 8

Nucleoside- Nitrogen base + sugar

Nucleotide- Nitrogen base + sugar + phosphate

Question 9

DNA REPLICATION: Step 1

Answer 9

-HELICASE unzips the double helix by breaking the OH bonds between the base pairs and GYRASE relieves the tension during the unzipping process

Question 10

DNA REPLICATION: Step 2

Answer 10

-DNA POLYMERASE 3 starts attaching nucleotides together and SSB prevent the strands from rejoining

Question 11

DNA REPLICATION: Step 4a

Answer 11

• PRIMASE adds RNA primer

- DNA POLYMERASE proof reads and fixes new strand

Question 12

DNA REPLICATION: Step 4b

Answer 12

• LAGGING STRAND is synthesized
• DNA POLYMERASE 3 adds deoxyribonucleotides from primer to primer forming okazaki fragments
• DNA LIGASE joins fragments by creating phosphodister bonds

Question 13

DNA REPLICATION: Step 5

Answer 13

2 new semi conservative strands are produced

Question 14

Discovery of DNA (the scientists)

Answer 14

Griffith- Bacterial transformation
Chargraff- The base pair rule
Avery- DNA= hereditary material of viruses
Hammerling- Hereditary info is stored in the nucleus
Wilkins + Franklin- Shape of DNA is helix
Watson + Crick- Shape of DNA is double helix
Meselson + Stahl- Theory of semi- conservative replication

Question 15

What makes up a chromosome?

Answer 15

DNA + protein

Question 16

Thymine, adanine, cytosine and guanine %

Answer 16

T and A = 30% (60%)
C and G = 20% (40%)
———-
100%

Question 17

Transcription

Answer 17

RNA POLYMERASE splits the 2 halves of the DNA strands then uses 1 half as a template to copy or “transcribe” the other half.
RNA = uracil instead of thymine

EXAMPLE
Template DNA-TTACG
Complementary DNA- AATGC
Messenger RNA- AAUCG

Question 18

Translation

Answer 18

Transfer RNA (tRNA) anticodons that match messenger RNA codons. Each tRNA can hold an amino acid. The amino acids are then joined together to form a polypeptide

EXAMPLE
Anticodon- AUG (mRNA)
Codon- UAC

Question 19

Gene control in prokaryotes- Lac operon

Answer 19

Lactose operon (lac operon) is the stretch of DNA that can be turned on or off to regulate production of lactose degrading enzymes

Question 20

The operon has 3 important regions which are:

Answer 20

1. The promoter/ TATA sequence (binding site of RNA polymerase) to begin transcription
2. Operator (binding site for repressor protein)
3. Cluster of 3 genes:
   LacZ- codes for B-GS
   LacY- codes for B- GSP
   LacA- codes for B- GST

Question 21

MUTATIONS: Deletion

Answer 21

Base is lost

• identical mutation= neutral
• different mutation= harmful

Question 22

MUTATIONS: Insertion

Answer 22

Base is added

Question 23

MUTATIONS: Substitution

Answer 23

3 types:
Missense- Amino acid is switched
Silent- no change
Nonsense- Changes amino sequence to a STOP

Question 24

What are restriction enzymes?

Answer 24

“Molecular scissors”. These are enzymes that cut double strands into fragments or specific sequences

Question 25

What is methylase?

Answer 25

Adds a methyl group and alters chemical composition.

Question 26

What is the difference between sticky and blunt ends?

Answer 26

-Sticky ends: fragment end of a DNA molecule with short single strands that overhang. Blunt ends: fragment ends of a DNA molecule that is perfectly base paired.

Question 27

BIOTECHNOLOGY: PCR

Answer 27

``` Components Polymerase Chain Reaction required: DNA template DNA polymerase enzyme Primers Nucleotides Rxn bufffer ```

Question 28

BIOTECHNOLOGY: RFLP

Answer 28

Everyone has different amounts of the genetic sequences called VNTRs or Variable Number Tandem Repeats. These VNTRs make different sized RFLP's

Question 29

BIOTECHNOLOGY: DNA fingerprinting

Answer 29

- After DNA is isolated it is amplified with PCR. - The DNA is treated with restriction enzymes (DNA is cut a specific sequences) resulting in different sized fragments - These fragments are called RFLP's - The DNA fragments can be observed when an experiment called Gel Electrophoresis is done

Question 30

BIOTECHNOLOGY: Gel electrophoresis

Answer 30

Here, DNA frags are separated out of the gel using a nylon membrane The nylon membrane is treated causing the OH bonds in the DNA to separate the strands The single stranded DNA is cross linked to the nylon membrane * Everyone has a different pattern of bands which make up ur DNA finger print

Question 31

What are the 5 components of electrophoresis?

Answer 31

``` Driving force Sample (DNA, RNA, protein) The support (agarose etc) Buffer Detecting system (stain) ```

Question 32

What is a plasmid?

Answer 32

Double stranded DNA molecules that lacks a protein coat and naturally exists in the cytoplasm in bacteria

Question 33

Plasmid cloning

Answer 33

The multiple cloning site is the region in the plasmid that has been engineered to have recognition sites of a number of endonucleases