DNA,Genes and Chromosomes

Question 1

Describe the steps of transcription

Answer 1

1.RNA polymerae attaches to the DNA double helix at the start of the gene
2.Hydrogen bonds between DNA bases are broken by DNA helicase
3.One strand acts as a template strand
4.Free floating RNA nucleotides align with exposed bases on the template strand
5.Uracil replaces thymine
6.RNA polymerase joins adjacent nucleotides in a condensation recatioln forming phosphodiester bonds-pre-mRNA
7.pre mRNA undergoes splicing to remove introns
8.mRNA leaves nucleus through the nuclear pore

Question 2

Where does transcription take place

Answer 2

The nucleus

Question 3

What is the position of a gene called

Answer 3

The locust

Question 4

What is a genome

Answer 4

The complete set of genes within a cell

Question 5

What is a proteome

Answer 5

The full range of proteins that a cell can produce

Question 6

what are the features of the genetic code

Answer 6

• degenerate
• non-overlapping
• universal

Question 7

What does degenerate mean

Answer 7

Each amino acid can be coaded for by more that one codon

Question 8

What does non-overlapping mean

Answer 8

Each codon is read in sequence as triplets and separate to the codons before and after it

Question 9

What are 3 bases on mRNA called

Answer 9

codon

Question 10

What does universal mean

Answer 10

the same codon will give you the same genes in all living organisms

Question 11

What are the features of RNA

Answer 11

• single stranded
• ribose sugar
• uracil instead of thymine

Question 12

What are the features of mRNA

Answer 12

• linear
• longer
• has codons

Question 13

What are the features of tRNA

Answer 13

• clover shape(because of H bonds)
• shorter
• has anticodons
• has amino acid attatchment site

Question 14

What are the similarities of mRNA and tRNA

Answer 14

• both contain ribose sugar
• both are single stranded

Question 15

What is an allele

Answer 15

A different version of the same gene

Question 16

What is splicing of pre-mRNA

Answer 16

removing the introns

Question 17

Describe the steps of translation

Answer 17

1.mRNA attatches to the ribosome
2.A tRNA molecule with an an anticodon that is complementary to the first codon on mRNA binds to mRNA
3.The trna molecule carries a specific amino acid
4.A second tRNA molecule with an anticodon complementary to the second codon binds to mRNA
5.Peptide bonds form between the amino acids by using energy from ATP
6.The first tRNA molecule attaches+leaves the ribosome
7.The ribosome moves along the mRNA molecule untill tje stop codon
8.The stop codon

Question 18

What does mRNA do

Answer 18

carries genetic information to the ribosomes

Question 19

What does tRNA do

Answer 19

carries the amino acid to the ribosome to make the polypeptide