4. Genetic information, variation and relationships between organisms

Question 1

how is DNA stored differently in eukaryotes and prokaryotes

Answer 1

Eukaryotic DNA: long, linear tightly coiled into chromosomes

Prokaryotic DNA: short, circular

Question 2

What’s a gene?

Answer 2

sequence of DNA bases that codes for an amino acid sequence of a polypeptide

Question 3

what’s a DNA triplet?

Answer 3

sequence of 3 bases coding for a specific amino acid

Question 4

What are the 3 natures of the genetic code?

Answer 4

Universal
Non-overlapping
Degenerate

Question 5

how is the genetic code universal?

Answer 5

the same specific DNA base triplets (codons) will code for the same amino acids in all organisms.

Question 6

how is the genetic code non-overlapping?

Answer 6

each base can only be used once and only in one triplet

Question 7

how is the genetic code universal?

Answer 7

the same amino acid can be codes by more than one base triplet

Question 8

what is an allele

Answer 8

different version of the same gene

Question 9

what’s a genome?

Answer 9

the complete set of genes in a cell

Question 10

where does transcription occur?

Answer 10

the nucleus

Question 11

what happens at transcription?

Answer 11

production of mRNA from DNA

Question 12

what is the purpose of mRNA

Answer 12

acts as a template for translation in the cytoplasm

Question 13

purpose of tRNA molecule?

Answer 13

attaches to and transports amino acid, in relation its anticodon
two tRNAs bring amino acids together for the formation of peptide bonds

Question 14

what’s the structure of a tRNA molecule?

Answer 14

3 leafed clover shape
held together by hydrogen bonds

Question 15

What is the similarity between the structure of mRNA and tRNA molecules?

Answer 15

they are both polynucleotides

Question 16

what are differences between the structure of mRNA and tRNA molecules?

Answer 16

-mRNA straight / tRNA folds into a clover shape
-mRNA is longer / tRNA is shorter

Question 17

Describe the process of transcription

Answer 17

1) DNA helix is unzipped by DNA helicase, and hydrogen bonds are broken
2) RNA nucleotides line up next to the complementary base pairs, forming temporary hydrogen bonds
3) RNA polymerase joins the adjacent nucleotides together through a condensation reaction forming phosphodiester bonds
4) When RNA polymerase reaches the stop codon, the mRNA detaches
5) mRNA leaves via nuclear pore

Question 18

Describe the process of translation

Answer 18

1) at the ribosome, tRNA anticodons bind to the complementary codon on the mRNA
2) two amino acids joined together via a condensation reaction, forming a peptide bond
3) tRNA detaches (without the amino acid) ribosome moves along the mRNA and detaches when it reaches the stop codon
4) polypeptide chain is released

Question 19

what is the role of ribosomes in translation?

Answer 19

attaches to the mRNA allowing codon-anticodon
complementary base pairing
allows peptide bonds to form between amino acids

Question 20

Exons

Answer 20

Coding regions

Question 21

Introns

Answer 21

Non-coding regions

Question 22

Role of ATP in translation

Answer 22

-Hydrolysis of ATP → ADP + Pi releases energy
-For peptide bond formation between amino acids

Question 23

Role of tRNA in transcription

Answer 23

• Attaches to, and transfers, a specific amino acid in relation to its anti codon
• tRNA complementary base pairs to mRNA anticodon
• 2 tRNAs bring 2 amino acids together for the formation of peptide bonds

Question 24

Role of ribosomes in translation

Answer 24

• Attatches mRNA and houses tRNA allowing codon anticodon complementary base pairing
• allows peptides bonds to form