18-Nucleic acid 2

Question 1

• are polymer of nucleotides linked together via a phosphodiester linkage
• 2 types are DNA and RNA

Answer 1

Nucleic acids

Question 2

• long macromolecule made up of dNMPs joined together by phosphodiester bond (3’–5’)
• in eukaryotic cells: located in nucleus / in the mitochondria (shape is linear supercoiled)
• in prokaryotic cells: located in nucleoid (shape is closed circular)

Answer 2

DNA

Question 3

properties of a double helix (duplex):
1- read from ………. end
2-G—_ and A—_
3- are antiparallel where one strand is …… and the opposite is …… connected with Hbonding

Answer 3

1-5’–3’
2- G–C and A–T
3- 5’ to 3’ , 3’ to 5’

Question 4

DNA structure:
1- the deoxyribose and phosphate form the …..
2- the nitrogenous bases within the nucleotides form the …….. and located inside the duplex
3-the helix is ……… from outside due to the presence of negatively charged phosphate groups

Answer 4

1- backbone
2-H-bonding
3-Hydrophilic

Question 5

site of enzymatic recognition and regulation

Answer 5

Major groove

Question 6

1-the two strands are ……. to each other by H bonds
2-between A and T there are … hydrogen bonds
3-between C and G there are … hydrogen bonds

Answer 6

1-complementary
2- two
3- three

Question 7

the base pairing (A with T, G with C) is called …………

-states the number of purines = number of pyrimidines

Answer 7

Chargaff’s rule

Question 8

DNA (in eukaryote) is wrapped around a core of proteins called …….
-contributes to the compact structure of chromosomal DNA

Answer 8

Histones

Question 9

functions of ……. :
1-storage and transfer
2-protein synthesis

Answer 9

DNA

Question 10

a DNA is divided up into functional units called …….

- provide instructions for a protein

Answer 10

Genes

Question 11

the process in which the genetic information flows from DNA to RNA to make a functional protein

Answer 11

central dogma

Question 12

1-…….: the DNA sequence of a gene is copied to make an mRNA molecule
2-……: mRNA sequence is decoded to specify the amino acid sequence of a protein

Answer 12

1- Transcription

2- Translation

Question 13

How does DNA preserve info in genes?

Answer 13

3 nucleotide makes one code

one code makes one amino acid

Question 14

DNA replication begins when the enzyme …….. unwinds the double helix of the DNA by breaking the hydrogen bonds

Answer 14

Helicase

Question 15

………. are short sequences of nucleotides that signal DNA polymerase enzyme to begin the synthesis of the new daughter complementary strand

Answer 15

Primers

Question 16

the enzyme …………. catalyzes the formation of phosphodiester bonds between free complimentary nucleotides

Answer 16

DNA polymerase

Question 17

1- DNA polymerase can synthesize DNA only in the …….. direction
2- the ……… strand is synthesized continuously (3’ to 5’)
3- ……… strand synthesized discontinuously forming ………….(5’ to 3’)

Answer 17

1- 5’ to 3’
2- leading
3- lagging, Okazaki fragments

Question 18

a protein called ………. connects the fragments by catalyzing the formation of phosphodiester bonds

Answer 18

DNA ligase

Question 19

a principle in which the nitrogenous bases of the DNA molecules bond with one another

Answer 19

Base pairing

Question 20

• polymer of nucleotides attached covalently via a phosphodiester linkage
• usually single-stranded
• vary in size (smaller than DNA)
• contains Ribose sugar and contains Uracil
• no specific structure (coils on itself)
• it has the 3’ end and 5’ end
• present in viruses, bacteria, animals

Answer 20

RNA

Question 21

present in the nucleus and transfer to the ribosome
-resulted from the transcription of a copy of one strand of DNA
-carries genetic information that encodes for proteins (template)
in eukaryotes, it has a cap in the 5’ end and a poly (A) tail in the 3’ end.

Answer 21

mRNA

Question 22

small ssRNA (single strand) that possesses the shape of clover leave located in cytoplasm or mitochondria

• it pairs up with mRNA
• it carries amino acids to the ribosome for protein synthesis
• amino acids are attached to the 3’ end

Answer 22

tRNA

Question 23

RNA of the ribosome

• it is a nucleoprotein responsible for protein biosynthesis
• main function is not fully understood

Answer 23

rRNA

Question 24

What’s identical to both RNA and DNA?

Answer 24

the sugar to phosphate linkages