3.4 Genetic Information, Variation and Relationships

Question 1

Eukaryotic DNA

Answer 1

long linear, double helix, has HISTONES and introns

Question 2

Prokaryotic DNA

Answer 2

shorter, circular, no Histons or Introns, all Exitrons

Question 3

Genes and their characteristics

Answer 3

sequences of bases, in fixed position (LOCUS) which code for polypeptide
-triplet bases (codon) code for 1 amino acid
UNIVERSAL: same codon for same amino acid in all organisms
NON-OVERLAPPING discrete, each base read once
DEGENERATE: >1 possible codon for same amino acid

Question 4

Genome

and Proteome

Answer 4

Genome: complete set of genes in cell (including mitochondria and chloroplasts)
Proteome: range of proteins a genome can make

Question 5

Alleles

and Homologous Pair of Chromosomes

Answer 5

different version/code for same gene

same size chromosome, same gene, different alleles

Question 6

mRNA

Answer 6

(messenger)
short, straight (single helix), unstable
variable length
made by transcription in nucleus, act as template for translation

Question 7

tRNA

Answer 7

(transfer)
carries 1 amino acid, creating ANTICODON (complementary to mRNA codon)
single strand, 3 leaf clover shape, held together by H-Bonds, SHORTEST Nucleic Acid

Question 8

Steps of Transcription

Answer 8

happens in nucleus

1) DNA unwound by helicase (H-bonds broken)
2) RNA nucleotides form temporary H-bond to complementary base
3) RNA polymerase joins nucleotides (condensation reaction, phosphodiester bond)
4) reaches STOP-CODON, mRNA/pre mRNA detaches from DNA and leaves nucleus via nucleic pores

Question 9

Post Transcription Process

Answer 9

WHOLE gene is transcribed to pre mRNA, including introns
-introns removed, exons SPLICED together (different splicing combo for different proteins)
(doesn’t happen in prokaryotic, they have no introns)