UNIT 3 2B: The Genetic Code and Gene expression

Question 1

Genome

Answer 1

the collection of all of the genes contained with the DNA of an organism

Question 2

Gene expression

Answer 2

Conversion of the code in DNA of a gene into a protein through protein synthesis

Question 3

Transcription

Answer 3

The process through which DNA is converted to messenger RNA and the genetic code in the DNA is copied to the mRNA

Question 4

Enzyme

Answer 4

A type of protein, also referred to as a biological catalyst, that speeds up reactions within an organism by lowering activation energy

Question 5

Promoter

Answer 5

The region of a gene at which RNA polymeraze binds, to initiate transcription

Question 6

Terminator

Answer 6

The region of a gene at which transcription stops and the RNA polymeraze dissociates from the strand.

Question 7

Intron

Answer 7

A region of a gene that contains sequences that do not code for the protein to be expressed.

Question 8

Exon

Answer 8

A region of a gene that contains genetic information that codes for the specific protein to be synthesized

Question 9

Translation

Answer 9

The process through which the information in mRNA is converted into a sequence of amino acids to synthesize a protein

Question 10

Codon

Answer 10

A set of three bases in mRNA that code for a specific amino acid

Question 11

Anticodon

Answer 11

A set of three bases on tRNA that are complementary to codons in mRNA

Question 12

Amino Acid

Answer 12

The monomer that forms polypeptide chains and proteins

Question 13

Universal triplet code

Answer 13

The genetic coding system based on codons with three bases, shared by most organisms.

Question 14

Degenerate

Answer 14

Describes a genetic code in which multiple codons code for the same amino acid; also referred to as redundant

Question 15

Mutation

Answer 15

A permanent change in the nucleotide sequence of a section of DNA

Question 16

Describe the steps involved in transcription

Answer 16

1. RNA polymerase unwinds the two DNA strands and binds to the promoter, initiating transcription
2. The RNA polymerase moves along the DNA template strand, adding free RNA Nucleotides which creates a strand of pre-mRNA(in eukaryotes) that is complementary to the template strand, and contains the nitrogenous base Uracil instead of Thymine

Question 17

Describe the steps involved in RNA processing

Answer 17

1. A 5’ methyl cap is added to help protect the pre-mRNA from being degraded by enzymes when it exits the nucleus
2. A poly A tail is added to the 3’ end. this makes the strand stable and also prevents degradation
3. The introns (non-coding regions) are removed from the pre-mRNA, so that all that is left in the final mRNA is a continuous stretch of exons (coding regions)

Question 18

5 steps in translation

Answer 18

1. mRNA binds to the ribosome
2. tRNA anticodon binds to complementary mRNA codon
3. tRNA delivers specific amino acid to the ribosome
4. Amino acid joins to previous amino acids by peptide bonds
5. Polypeptide chain (primary structure) is formed