1C Gene Expression

Question 1

What is the phenotype determined by ?

Answer 1

The proteins produced as the result of gene expression.

Question 2

Are all genes in a cell expressed?

Answer 2

No.

Question 3

The regulation of both transcription and translation leads to what?

Answer 3

Gene expression

Question 4

Describe the structure of RNA

Answer 4

Single stranded
Contains uracil instead of Thymine
Contains ribose instead of deoxyribose

Question 5

What is the function if mRNA?

Answer 5

To carry a copy of the genetic code from the nucleus to the ribosome.

Question 6

What forms the ribosome?

Answer 6

rRNA (ribosomal RNA) and proteins

Question 7

Describe the process of transcription

Answer 7

RNA polymerase unwinds and unzips the DNA strand, breaking hydrogen bond between the strands.
Complementary RNA nucleotides align with their complementary DNA nucleotides on one strand.
Hydrogen bonds form between the complementary base pairs.
Strong chemical sugar-phosphate backbone forms.
RNA polymerase joins RNA nucleotides to the frowning strand of the mRNA at the 3’end.
The primary transcript is now formed.

Question 8

Where does transcription take place?

Answer 8

The nucleus.

Question 9

What are promoter sequences?

Answer 9

DNA sequences that define.

Question 10

What are introns?

Answer 10

The non-coding regions of a gene.

Question 11

What are extrons?

Answer 11

The coding regions of a gene.

Question 12

Are introns or expos removed from the primary transcript?

Answer 12

Introns are removed.

Question 13

What is the process or removing the exons called?

Answer 13

Splicing.

Question 14

Explains why it’s important that the non-coding regions are removed from the primary transcript.

Answer 14

To ensure the correct protein is made.

Question 15

Exons are joined together to form what?

Answer 15

The mature transcript.

Question 16

Explain how a different protein can be produced from the same gene?

Answer 16

Different regions of the primary transcript are treated as exons and introns and therefore different mature transcripts are formed from the same primary transcripts.

Question 17

What is the process of producing different mature transcripts from the same primary transcript called?

Answer 17

Alternative splicing.

Question 18

Where does translation take place?

Answer 18

The ribosome.

Question 19

What is the triplet of bases called on a DNA and mRNA strand?

Answer 19

Codon.

Question 20

What is the function of tRNA?

Answer 20

To transfer specific amino acids to the ribosome (To align specific amino acids in the correct sequence in the protein).

Question 21

What two sites does the tRNA have?

Answer 21

An amino acid attachment site and an anticodon.

Question 22

What is the anticodon of the tRNA complementary to?

Answer 22

An mRNA codon.

Question 23

Describe the method of translation.

Answer 23

mRNA joins to the ribosome.
tRNA transfers specific amino acids to the ribosome and aligns the correct amino acids in the sequence by aligning its anticodon with the complementary codon on the mRNA strand.
Hydrogen bonds form between the bases.
Peptide bonds form between adjacent amino acids.
Polypeptide is formed.

Question 24

How is it possible that different proteins are expressed from one gene?

Answer 24

Alternative splicing and post- translational modification.

Question 25

What is post-translational modification?

Answer 25

The process of cutting and combing polypeptide chains OR
By adding phosphate OR
Adding carbohydrate groups of protein.