DNA & RNA

Question 1

What are Nucleic Acids & what are the different types?

Answer 1

-Organic molecules that control the synthesis of proteins and transferring of genetic information.

-Deoxyribonucleic Acid (DNA)
-Ribonucleic Acid (RNA)

Question 2

Where is DNA found?

Answer 2

-DNA occurs mainly in the nucleus, where it forms chromosomes - chromosomal DNA

-Small amounts are found in the mitochondria and in the chloroplast(of plants) - Extranuclear DNA

Question 3

Define a chromosome

Answer 3

-a long, thread-like structure composed of DNA wrapped around histones (proteins)

-found in the nucleus of most living cells and carries genetic information.

Question 4

What are homologous chromosomes?

Answer 4

-Two chromosomes of the same size and shape that contain the same genes.

Question 5

What did James Watson and Francis Crick do?

Answer 5

-They formulated the double helix structure of DNA using a 3D model.

-They received the Nobel Prize for the discovery of the structure of DNA.

Question 6

Who was Rosalind Franklin?

Answer 6

-A woman who took a photo of DNA, which showed its helical structure.

Question 7

Discuss the structure of a DNA nucleotide:

Answer 7

-sugar molecule -> deoxyribose
-Phosphate group
-Nitrogenous base ( four types)

Question 8

How are the DNA nitrogenous bases joined?

Answer 8

-the bases are joined by weak hydrogen bonds (easily broken by enzyme action)

-Base Pairs:
Adenine(A) - Thymine(T)
Guanine(G) - Cytosine(C)

Question 9

Which nitrogenous bases are the large purine bases & which are which are the small pyrimidine bases?

Answer 9

-Large purine bases:
- Adenine
- guanine

-Small pyrimidine bases:
- Thymine
- Cytosine

Question 10

What is the role of DNA?

Answer 10

-DNA carries genetic code(genes) for the synthesis of proteins.

Question 11

Define a Gene:

Answer 11

-short segments of DNA that code for a particular trait.

Question 12

What % of DNA in living cells codes for proteins, and what does the other 98% do?

Answer 12

• Only 2% of DNA in living cells codes for proteins.

-98% is non-coding DNA, used in DNA fingerprinting.

Question 13

What does the sequence of nitrogenous bases determine?

Answer 13

• The sequence of nitrogenous bases determines which type of amino acids will combine to form a protein.

Question 14

What is mtDNA?
- where does it occur?
- what does it look like?
- what does it code for?

Answer 14

-mitochondrial DNA
- occurs in the mitochondria
- circular in shape
- The genes of mtDNA code for the enzymes that control cellular respiration.

Question 15

Where does RNA occur?

Answer 15

-RNA occurs in the nucleus, cytoplasm, and parts of the ribosomes.

Question 16

Discuss the structure of RNA:

Answer 16

-Single strand made up of unlimited nucleotides.

Question 17

Discuss the structure of the RNA nucleotide:

Answer 17

-sugar molecule - ribose
-Phosphate group
-Nitrogenous base ( 4 types)

Question 18

How do the RNA nitrogenous bases join?

Answer 18

Adenine(A) - Uracil(U)
Guanine(G) - Cytosine(C)

Question 19

What are the different types of RNA?

Answer 19

-Messenger RNA (mRNA)
-Transfer RNA (tRNA)
-Ribosomal RNA (rRNA)

Question 20

What is mRNA?
- where is it formed & found?
- What is its structure?
- what does it do?

Answer 20

-Messenger RNA

-Formed in the nucleoplasm using DNA as a template.
-Found in the nucleus & cytoplasm of a cell.

-It is a single strand with unlimited nucleotides.

• It carries genetic code from the DNA in the nucleus to ribosomes in the cytoplasm.

Question 21

What is tRNA?
- where is it found?
- what is its structure?
- what does it do?

Answer 21

-Transfer RNA

-Found in the cytoplasm

-Single strand that folds in on itself to form loops.

-Picks up amino acids and takes them to ribosomes.

Question 22

What is rRNA?
- what is its structure
- what does it do?

Answer 22

-Ribosomal RNA

-Single strand that forms part of the ribosome structure.

-Its function is to serve as a location for protein synthesis.

Question 23

What are the three exposed bases of tRNA called?

-Similarly, what are the bases of mRNA called?

Answer 23

tRNA - Anticodon
mRNA - Codon

Question 24

What duplicates during DNA replication?

• when does this happen?

Answer 24

-DNA duplicates to form two identical chromatids.
-The histones duplicate

-This takes place during interphase.

Question 25

What are the steps for DNA Replication?

Answer 25

1. DNA unwinds 2. Helicase breaks weak hydrogen bonds (unzips DNA strand) 3. Free nucleotides build the complementary DNA strand. 4. DNA polymerase joins free nucleotides to their complementary base pair. 5. New strand are formed!!

Question 25

Why is DNA Replication important?

Answer 25

-It's important that the DNA replicates itself before cell division to ensure each daughter cell has identical DNA as the mother cell.

Question 26

What is protein synthesis? - what controls protein synthesis?

Answer 26

-The process in which proteins are manufactured in living cells. -DNA & RNA control the synthesis of proteins.

Question 27

What are proteins made up of? - what provides the code for a specific amino acid?

Answer 27

-Proteins are made up of amino acids -Base triplets provide a code for a particular amino acid. -> Determine the sequence in which amino acids will link during protein synthesis.

Question 28

What are the two steps of protein synthesis?

Answer 28

-Transcription of DNA -Translation of DNA to Proteins -Transcription comes before Translation

Question 29

Describe the process of transcription of DNA:

Answer 29

1. DNA unzips where gene is located 2. RNA polymerase controls the transfer of code from DNA to RNA & causes hydrogen bonds to break. 3. Free-floating nucleotides are used to build a complementary strand. 4. Single mRNA strand is formed. 5. DNA retwists, mRNA leaves nucleus via nuclear pores.

Question 30

Describe the process of Translation of RNA to Proteins:

Answer 30

1. mRNA strand attaches to ribosomes & provides code for amino acids 2. Anticodon determines which amino acid will bind to tRNA 3. tRNA picks up amino acid 4. tRNA places amino acid in sequence 5. Amino acids join together to form a polypeptide chain. 6. Process continues till 50 or more amino acids join.