Molecular Genetics

Question 1

What is the function of the RNA?

Answer 1

1. working copy of a gene.
2. It acts as a medium to transfer genetic information from DNA to the protein translational machinery at the ribosomes.

Question 2

What are the types of RNA?

Answer 2

There are different types of RNA, depending on function and location in the cell;

1. For example, messenger RNA (mRNA) is transcribed in the nucleus and is responsible for carrying a complementary genetic sequence of DNA to the ribosome for translation. 2. Transfer RNA (tRNA) is found in the cytoplasm and is responsible for transferring free cytoplasmic amino acids to the growing polypeptide chain being formed at the ribosome.
2. Ribosomal RNA (rRNA) forms ribosomal subunits and functions to catalyze the formation of a polypetide chain from mRNA.

Question 3

Where is the gentic material are found ?

Answer 3

Early experiments showed that cells could not reproduce without a nucleus,

the genetic material was found in the nucleus.

Question 4

What are nucleic acids and what are they made of?

Answer 4

Nucleic acids are biomolecules that are named for their role within the cell nucleus.

A nucleic acid is made up of a chain of nucleotides.

Question 5

what is the nucleotide made of ?

Answer 5

Each nucleotide is made up of three main components:

1. a sugar (carbon ring),
2. a phosphate molecule,
3. a nitrogenous base.

Question 6

What are the variety of biological roles of the nucleic acids?

Answer 6

Nucleic acids have a variety of important biological roles, including

1. storing and
2. transmitting genetic information.

Question 7

What is the DNA and RNA ?

Answer 7

1. Deoxyribonucleic acid (DNA) and it is the main component of genes.
2. Ribonucleic acid (RNA) are nucleic acids and it translates genes to

build proteins.

Question 8

What is the difference between the RNA and the DNA ?

Answer 8

They are similar in structure except for the following differences:

1. RNA is single-stranded, whereas
2. DNA is double-stranded.
3. RNA has the nitrogenous base uracil in place of the thymine found in DNA.
4. RNA has the sugar ribose instead of the deoxyribose found in DNA.

Question 9

The DNA is a double helix, what is the double made of ?

Answer 9

In the DNA double helix,

1. the nitrogen bases of one DNA strand pair
2. with complementary bases of the other strand.

Question 10

The DNA has 2 types of Nitrogen bases what are they?

Answer 10

There are two types of nitrogenous bases:

1. purines (two rings) and The two purine bases are adenine and guanine.
2. pyrimidines (one ring) and The two pyrimidine bases are cytosine and thymine.

Question 11

The nucleotide containing adenine always pairs with ?

Answer 11

The nucleotide containing adenine always pairs with the nucleotide containing thymine.

Question 12

The nucleotide containing guanine always pairs with?

Answer 12

The nucleotide containing guanine always pairs with the nucleotide containing cytosine.

Question 13

The complementary base pairs are held together by ?

Answer 13

hydrogen bonds

Question 14

What are the two reasons that these nucleotides always pair in the same patter?

Answer 14

1. Maintenance of helical diameter—in order to maintain an even width along the length of the helix, a double-ringed purine, such as adenine or guanine, must always join with a single-ringed pyrimidine, such as cytosine or thymine. If there were random pairings occurring between purines and purines, pyrimidines and pyrimidines, or purines and pyrimidines, the helix would be too wide in some places and too narrow in others and would be unable to maintain its shape.
2. Hydrogen bonding between chemical side groups—each base has specific side groups that can only form hydrogen bonds with their respective partners. The side groups of adenine and thymine form two hydrogen bonds between them, and the side groups of cytosine and guanine form three hydrogen bonds between them.

Question 15

What is DNa Replication?

Answer 15

DNA replication is the process by which a cell makes an exact copy of its DNA.

Question 16

What is DNA helicase ?

Answer 16

A DNA helicase (an enzyme) unzips the double helix by breaking the hydrogen bonds between the nitrogen base pairs. Each single DNA strand acts as a template to build a complementary strand.

Question 17

What does DNA polymerase III enzyme do to the DNA?

Answer 17

• A DNA polymerase III enzyme builds a new strand by pairing free nucleotides in the nucleus with the complementary base in the template strand, which results in the formation of two identical DNA molecules with two DNA strands.
• DNA polymerase III, however, cannot directly add the nucleotides to the existing DNA template strand. It must attach them to an RNA primer chain that has been added to the template strand by another enzyme called primase.
• Once the primer chain is in place, DNA polymerase III must add new nucleotides at the end of the template strand by attaching them to the end of the primer chain.

Question 18

The two original DNA template strands are ——-, the two new strands are being built in ——— directions?

Answer 18

• Anti-Parallel
• Opposite

Question 19

Thw new strand always forms in the——–direction?

Answer 19

5’ –3’

Question 20

What is the leaqding strand in the DNA?

Answer 20

One of the new strands is built continuously in the direction, as DNA polymerase III simply starts at the beginning, whereas DNA helicase starts unzipping the DNA, adds new nucleotides at the end, and continues in the direction of the unzipping.

Question 21

What is the lagging strand in the DNA?

Answer 21

It is the other strand has to start in the middle and work in the opposite direction of the

• unzipping,
• adding new nucleotides in short segments

called Okazaki fragments.

This strand is referred to as the lagging strand.

Question 22

Since the leading strand is built ——–,

only a single ———–primer chain must be added to the template.

However, because the lagging strand is built in ———,

———- ———— must be added for each fragment.

Answer 22

• Continously
• RNA
• Segments
• RNA Primers

Question 23

The RNA primer nucleotide segments on the lagging strand template are eventually replaced by —————————————-through the action of DNA —————-, which is another DNA polymerase.

Answer 23

• DNA nucleotides
• Polymerase

Question 24

Once the RNA primer nucleotides are removed, the Okazaki fragments are joined together into one coherent strand by yet another enzyme called ———————–.

Answer 24

DNA ligase.

Question 25

What are the steps in DNA replication ?

Answer 25

The steps in DNA replication are summarized as follows:

1. DNA helicase unzips the double helix.
2. RNA primase adds the RNA primer nucleotides to the DNA template strands.
3. DNA polymerase III adds either free DNA nucleotides to the RNA polymerase chain or segments at the end of the DNA template strand.
4. RNA primer segments on lagging strand templates are replaced with DNA nucleotides by DNA polymerase I.
5. Okazaki fragments with their RNA primers removed are joined together to form a single cohesive DNA strand by DNA primase.

Question 26

What are the functions of the RNA?

Answer 26

In general, RNA functions as a short-term

1. working copy of a gene.
2. It acts as a medium to transfer genetic information from DNA to the protein translational machinery at the ribosomes.

Question 27

There are different types of RNA, depending on function and location in the cell, please list them ?

Answer 27

1. messenger RNA (mRNA) is transcribed in the nucleus and is responsible for carrying a complementary genetic sequence of DNA to the ribosome for translation.
2. Transfer RNA (tRNA) is found in the cytoplasm and is responsible for transferring free cytoplasmic amino acids to the growing polypeptide chain being formed at the ribosome.
3. Ribosomal RNA (rRNA) forms ribosomal subunits and functions to catalyze the formation of a polypetide chain from mRNA.

Question 28

Early experiments showed that cells could not reproduce without a nucleus, so clearly the genetic material was found in the nucleus. However, there are many types of molecules in the nucleus, so scientists were still far from an answer.