Genomes, Genes and Alleles

Question 1

Gene expression

Answer 1

The process by which functional products, such as proteins, are produced through two stages: Transcription and Translation.

Question 2

Gene regulation

Answer 2

The process by which cells can either turn on or off gene expression.

Question 3

State the function of RNA polymerase

Answer 3

Copies DNA template strand into pre-mRNA via complementary base pairing.

Question 4

Template strand

Answer 4

It is the strand of DNA that is copied into a pre-mRNA transcript during transcription.

Question 5

Genome

Answer 5

All the genetic information (DNA) in an individual or cell.

Question 6

Transcription followed by RNA processing.

Answer 6

Step 1: DNA unwinds and RNA polymerase attaches to the promoter region (+ context).
Step 2: DNA template strand is copied into pre-mRNA via complementary base pairing using RNA polymerase.
Step 3: pre mRNA undergoes RNA processing. Introns are removed, a 5’ methyl G cap and 3’ poly-A tail are added to form mRNA.
Step 4: mRNA from the _________ gene leaves the nucleus and goes to a ribosome.

Question 7

Describe RNA processing

Answer 7

Introns are removed, a 5’ methyl-G cap and a 3’ poly-A tail are added to form mRNA

Question 8

What is the purpose of a 5’ methyl cap and 3’ poly A tail?

Answer 8

5’ Methyl-G cap (which is added to the 5’ end) protects the mRNA from enzyme degradation and allows the ribosome to bind to the mRNA to begin translation. Poly-A tail (added to the 3’ end) also protects the mRNA from enzyme degradation and allows the mRNA to leave the nucleus.

Question 9

Translation

Answer 9

Step 1: Ribosomes read the mRNA code for (context)
Step 2: tRNA brings the correct and specific amino acid to the ribosome.
Step 3: tRNA anticodons are complementary and specific to mRNA codons. Step 4: Amino acids are joined together by peptide bond in a condensation polymerisation reaction to form a (context) polypeptide

Question 10

Ribosome

Answer 10

Translates the mRNA into (context) polypeptide

Question 11

mRNA codons

Answer 11

Groups of three RNA bases that code for specific amino acids or represent “End” of Translation.

Question 12

tRNA anticodon

Answer 12

A group of three RNA bases found in a tRNA. It is complementary to a particular mRNA codon, allowing the tRNA molecule to bind to its complementary mRNA codon in the mRNA molecule.

Question 13

Degenerate code

Answer 13

It refers to the fact that multiple codons can code for the same amino acid

Question 14

Mutation

Answer 14

A change in the genetic code (in the DNA sequence).

Question 15

Point mutations

Answer 15

Mutations that involve a single base change in the DNA sequence.
Examples: Substitution, Insertion, and Deletion.

Question 16

Silent mutation

Answer 16

the mutated codon codes for the same amino acid as the original codon.

Question 17

Missense mutation

Answer 17

the mutated codon codes for a different amino acid than the original codon.

Question 18

Nonsense mutation

Answer 18

the mutated codon becomes a stop codon.

Question 19

Frameshift mutation

Answer 19

A deletion or addition of bases in the DNA sequence that changes the reading frame of the DNA. It often results in multiple changes in the amino acid sequence.

Question 20

Gene

Answer 20

The hereditary unit, which is a section of DNA occupying a specific location on a chromosome. It determines the characteristic of an organism by directing the formation of a protein.

Question 21

Allele

Answer 21

Variation of a gene at a particular gene locus.

Question 22

Genotype

Answer 22

The allele combination of an individual.

Question 23

Homologous chromosomes

Answer 23

Chromosomes that have identical gene loci.

Question 24

Homozygous

Answer 24

having two of the same allele for a gene at a specific gene locus.

Question 25

Heterozygous

Answer 25

having two different alleles for a gene at a specific gene locus.

Question 26

Dominant trait

Answer 26

A trait that is expressed in a heterozygous genotype.

Question 27

Recessive trait

Answer 27

A trait that is only expressed when the genotype is homozygous.

Question 28

Phenotype

Answer 28

The physical, behavioural or physiological characteristics of an organism which are a result of the combination of the genotype and environment.

Question 29

Epigenetic changes

Answer 29

Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.