8 - DNA, Genes and Protein Synthesis

Question 1

gene

Answer 1

section of DNA located at a particular locus on a DNA molecule that contains the coded information for the amino acid sequences of polypeptides and functional RNA

Question 2

degenerate code

Answer 2

most amino acids are coded for by more than one triplet

Question 3

universal code

Answer 3

each triplet codes for the same amino acid in all organisms

Question 4

exons

Answer 4

coding sequences in eukaryotic DNA

Question 5

introns

Answer 5

non-coding sequences in eukaryotic DNA

Question 6

eukaryotic DNA

Answer 6

has histone proteins associated with it

long and linear molecules

Question 7

prokaryotic DNA

Answer 7

not associated with proteins

shorter and circular

Question 8

homologous pair

Answer 8

two chromosomes that carry the same genes, but not necessarily the same alleles of the genes

Question 9

allele

Answer 9

a form of a gene

Question 10

mRNA

Answer 10

messenger RNA, used to transfer sections of DNA from the nucleus to the cytoplasm because it is small enough to fit through nuclear pores
long stranded polynucleotide arranged in a single helix

Question 11

codon

Answer 11

sequence of 3 bases on mRNA that codes for a single amino acid

Question 12

genome

Answer 12

complete set of genes in a cell

Question 13

proteome

Answer 13

full range of proteins produced by the genome

Question 14

tRNA

Answer 14

small, single-stranded polynucleotide consisting of about 80 nucleotides
folded into a clover leaf shape
carries a specific amino acid

Question 15

transcription

Answer 15

1. DNA helicase acts on a specific region of DNA, causing the DNA strands to separate and expose the nucleotide bases in that region
2. one of the DNA strands acts as a template strand and pairs with free complementary RNA nucleotides
3. RNA polymerase moves along the strand and joins the RNA nucleotides together to form a pre-mRNA molecule
4. the DNA strand rejoins behind the RNA polymerase
5. when a stop code is reached, RNA polymerase detaches and a section of pre-mRNA is produced

Question 16

splicing

Answer 16

process of removing introns from pre-mRNA to leave only the coding exons
produces mRNA
occurs in eukaryotic cells

Question 17

translation

Answer 17

1. a ribosome becomes attached to the starting codon at one end of the mRNA molecule
2. the ribosome works along the mRNA bringing together tRNA molecules with complementary anticodons to the mRNA codons
3. the tRNA molecules each have a specific amino acid attached to them
4. the amino acids attached to the tRNA molecules are joined by peptide bonds
5. these form a polypeptide chain