Nucleic Acids

Question 1

The Central Dogma: Infomation Transfer

Answer 1

describes the flow of genetic information in cells

Question 2

DNA Replication

Answer 2

DNA is Replicated into DNA

Question 3

Transcription

Answer 3

DNA is transcribed into messenger RNA (mRNA)

Question 4

Translation

Answer 4

RNA is translated into proteins

Question 5

Reverse Transcription

Answer 5

RNA is transcribed into cDNA

Question 6

Nucleotides

have three components, they are?

Answer 6

• Nitrogenous Base: info
• Pentose sugar: structure
• Phosphate Group: structure
• can exist as monomers when no phosphate group attached.
• can have 1-3 phosphates

Question 7

Nitrogenous Base

Answer 7

• purines: adenine or Guanine (contain 2 rings)
• Pyrimidines: thymine, Cytosine (or Uracil (U) in RNA) (contain 1 ring)
• contain carbon, nitrogen, and amino group (NH2)

Question 8

Pentose Sugar

Answer 8

A 5 Carbon sugar ring

• Deoxyribose in DNA
• Ribose in RNA
• determines direction of nuclei acid

Question 9

Polynucleotide Chains

Answer 9

• nucleotides are connected through a phosphodiester bond

- Have a phosphate group at one end (5’ end) and an OH group attached to the sugar

Question 10

naming of Nuleotides

Answer 10

nMP - 1 phosphate
nDP - 2 phosphates
nTP - 3 phosphates
where n is the name of the nucleoside

Question 11

NTPs (such as ATP) carry what?

Answer 11

chemical energy

Question 12

cAMP and cGMP are important regulators of what?

Answer 12

cellular metabolism

Question 13

Polymerisation:

Answer 13

joining nucleic acids together.

Question 14

Nucleic Acids are polymers of ______

Answer 14

nucleotides

Question 15

Nucleotides are link ___

Answer 15

3’ to 5’ by phosphodiester bonds

Question 16

Polynucleic acid has a …

Answer 16

phosphate group at one end (5’ end) and a OH group attched to the sugar (3’ end)

Question 17

Levels of Structure in DNA

Answer 17

1. Primary Structure
2. Secondary Strcuture
3. Tertiary Structure
4. Quaternary Structure

Question 18

Primary Structure

Answer 18

the order of bases on the polynucleotide sequence (specifies genetic code)

Question 19

Secondary Structure:

Answer 19

3D conformation of polynucleotide backbone (complementary bas pairing - denaturation/replication)

Question 20

Tertiary Structure:

Answer 20

Supercoiling

Question 21

Quaternary Structure

Answer 21

Interactions between DNA and proteins

Question 22

H-Bonds Build Connection

Answer 22

• DNA is formed by two complementary antiparallel strands
• Base pairing is very specific and follows Chargaff’s rule
• Base pairing and H-bonds are v important to hold the complimentary strands
• G-C pairing is stronger than A-T

Question 23

Chargaff’s Rule

Answer 23

[pyrimidines] = [purines]
[A] = [T]
[G] = [C]

Question 24

Secondary Structure: the helical beauty

Answer 24

• Nitrogen base (steps in the ladder)-information is protected
• Pentose sugar (handrails)-structure
• Phosphate group (exposed negative side)-structure
• Two strand antiparallel
• Small groove & large groove & complete turn
• Basic connection (via H-Bonds)
  Diameter is about 20 A

Question 25

Tertiary Structrue: DNA Supercoling

Answer 25

- cellular DNA is extremely compacted (the helix is supercoiled) - to save space

Question 26

Quaternary Structure: DNA wrapping up proteins

Answer 26

In eukaryotes DNA is complexed with positively-charged proteins to form chromatin - Histones (positive proteins) - Nucleosome: DNA (negative wrapped around 8 histones (positive) - 150 base pairs are in contact with the proteins - Packaged into chromosomes and safely located inside the nucleus

Question 27

DNA as a Template:

Answer 27

- DNA helix is denatured to allow replication - Each strand of DNA helix acts as a template for new complementary strand - Semiconservative replication (i.e. Each daughter molecule has one old strand & one new strand) Dependent on complementary bas pairing

Question 28

DNA Replication

Answer 28

- Helicase: unwinds the helix to form a replication fork - Primase: synthesises short RNA primers, complementary to the template - DNA polymerase: reads the strand being copied and links complementary nucleotides to form a new strand - Leading strand and lagging strand - Leading strand is synthesised continuously from the template - Lagging strand is synthesised with fragments (Okazaki fragments) - DNA ligase joins Okazaki fragments and seals the gaps in the newly synthesised short strands

Question 29

RNA: the other class of nucleic acids

Answer 29

* look at table

Question 30

DNA Transcription: to get mRNA

Answer 30

- The information encoded in the genes is copied into a RNA molecule: messenger RNA (mRNA) - Obtained by transcription of complementary section of DNA catalysed by RNA polymerase - Occurs in the nucleus - Carries the information specifying a particular protein It varies in length

Question 31

mRNA: messenger between DNA and Proteins

Answer 31

- It serves as genetic template, as DNA cannot leave the nucleolus - The pre-mRNA transcripts contain non-coding RNA (introns) and coding RNA (exons) - Mature mRNA has the coding regions - mRNA moves to the cytoplasm Information encoded by the mRNA is converted into an amino acid sequence

Question 32

Nucelotides Functions:

Answer 32

- energy carries (e.g. ATP) - Chemical messengers (e.g. cGMP) - components of enzyme cofactors (e.g. NAD+)

Question 33

no phosphate group = ?

Answer 33

nucleoside

Question 34

Nucleoside:

Answer 34

The combination of a base and a sugar linked via a glycoside bond

Question 35

Nucleotide:

Answer 35

When a phosphoric acid is esterfied to a suga (-OH) group of a nucleoside

Question 36

Naming Phosphate Groups: Pyrimidine

Answer 36

add -idine e.g. cytidine

Question 37

Naming Phosphate Groups: Purine

Answer 37

add -osine e.g. Adenosine

Question 38

Can necleotides have more than one phosphate group attached to them?

Answer 38

yes up to 3

Question 39

Naming of Nucleotides: 3 phosphates

Answer 39

nTP | where n is the name of the nucleoside

Question 40

Naming of Nucleotides: 2 phosphates

Answer 40

nDT | where n is the name of the nucleoside

Question 41

Naming of Nucleotides: 1 phosphates

Answer 41

nMP | where n is the name of the nucleoside

Question 42

Are Nucleotides acidic or basic?

Answer 42

Acidic because phosphate groups create a negative charge

Question 43

Nucleic acids are

Answer 43

polymers of nucleotides