Unit 1 - Gene Expression

Question 1

What are the components of a RNA neucleotide?

Answer 1

1. Phosphate
2. Ribose Sugar
3. Base

Question 2

What are the RNA Bases called?

Answer 2

Cytosine and Guanine

Adenine and Uracil

Question 3

What are the 3 types of RNA

Answer 3

1. mRNA
2. rRNA
   3.tRNA

Question 4

What is the function and location of mRNA?

Answer 4

Function: copies code from DNA and carries it to the ribosomes.​

Location: nucleus/cytoplasm/ribosome.

Question 5

What is the function and location of tRNA?

Answer 5

Function: Binds to specific amino acids and transports them to the ribosome. Has anticodon

Location: cytoplasm/ribosome

Question 6

What is the function and location of rRNA?

Answer 6

Function: Combines with proteins to form the ribosomes​

Location: ribosome.

Question 7

What are the differences between RNA and DNA

Answer 7

1.RNA has Ribose sugar while DNA had deoxyribose sugar
2.RNA has uracil whil DNA has thymine
3.RNA is single stranded while DNA is double stranded

Question 8

What is Transcription and where does it occur?

Answer 8

Transcription is the synthesis of mRNA from a section of DNA

It is the first stage of protein synthesis ​

It takes place in the nucleus.​

Question 9

What is the Process of Transcription

Answer 9

1. RNA polymerase unwinds the DNA double helix (breaking hydrogen bonds) in the 3’ to 5’ direction. ​
2. Free RNA nucleotides bond with complementary bases on DNA (Hydrogen bonding)​
3. Adjacent RNA nucleotides bond (strong chemical bonds between phosphate of one nucleotide and ribose sugar of the next)​
4. This forms a primary mRNA transcript that leaves the neucleus through a neuclear pore

Question 10

Define Introns and Exons

Answer 10

Introns - non-coding regions in the primary transcript

Exons - coding regions

Question 11

How do are introns removed from the primary transcript?

Answer 11

Splicing

Question 12

Describe the structure of tRNA

Answer 12

Hydrogen bonds between its nucleotides cause the tRNA to fold back on itself creating a 3D structure. ​

Each molecule of tRNA has only one particular triplet of bases exposed called an anticodon.

Each anticodon is complementary to an mRNA codon.

Each tRNA molecule carries a specific amino acid at its attachment site.

Question 13

What is the function of a ribosome?

Answer 13

To bring tRNA molecules in contacts with mRNA.

Question 14

What do ribosomes contain?

Answer 14

Ribosomal RNA (rRNA) and enzymes essential for protein synthesis.

Question 15

Describe the process of Translation

Answer 15

1. The ribosome begins translation at a start codon. This is a triplet of bases recognised at the beginning of a code to be translated.
2. As mRNA moves through the ribosome, codons are translated into amino acids
3. The tRNA anticodon bonds to its complementary codon on mRNA assembling amino acids into the correct order.
4. Peptide bonds form between amino acids to form a polypeptide chain.​
5. Eventually, a stop codon on the mRNA is reached and the ribosome releases the polypeptide.

Question 16

What process allows different proteins to be formed from the same amino acids?

Answer 16

Alternative RNA splicing

Question 17

Describe alternative RNA splicing

Answer 17

Some exons are removed to create a new sequence of exons

The order of exons is not changed

Question 18

How are amino acids linked?

Answer 18

Amino acids in a specific order become linked by peptide bonds​

They form polypeptide chains

Question 19

Describe hydrogen bonds in relation to polypeptide chains

Answer 19

Hydrogen bonds can form between the amino acids on a polypeptide chain​

The chain becomes folded or coiled

Question 20

What does the shape of a protein determine

Answer 20

the funcrtion

Question 21

What can Production of phenotype/protein be influenced by?

Answer 21

environmental factors acting inside or outside of the cell