DNA RNA and protein systensis

Question 1

Describe the structure of DNA

Answer 1

a chain of nucleotides composed of dexoribose sugar, phosphate and an organic base (adenine, guanine, cytosine and thymine)

Question 2

What are purines

Answer 2

Adenine and Guanine - double ring structures

Question 3

What are pyrimidines

Answer 3

Thymine and Cytosine - single ring structures

Question 4

Complementary base pairings

Answer 4

bases that will pair together to hold DNA strands together by hydrogen bonds
*cytosine - guanine
*Adenine - thymine

Question 5

How does the structure of DNA relate to its function

Answer 5

*complementary base pairings - allows the DNA to replicate itself and copy the same information to mRNA
*weak hydrogen bonds - allow the strands to separate
*it’s compact and long - large amounts of coded information and can fit inside the nucleus of the cell

Question 6

Describe the structure of RNA

Answer 6

a single stranded chain of nucleotides made of a ribose sugar, phosphate and a base (Adenine, Uracil, Guanine, Cytosine) held together by phosphodiester bonds

Question 7

what are the 3 types of RNA

Answer 7

*mRNA - moves the genetic information from the inside of the nucleus to the cytoplasm
*tRNA - carries the correct amino acid into the sequence of a polynucletide
*rRNA - part of the ribosome

Question 8

structure of mRNA

Answer 8

short single stranded chain of RNA polynucleotide

Question 9

Structure and function of tRNA

Answer 9

structure - single stranded, cloverleaf shape, contains 2 regions : anticodons, amino acid attachmenr site
Function - the anticodons allow the tRNA to bring the correct amino acids

Question 10

what are genes

Answer 10

a sequance of DNA that codes for the production of specifc proteins

Question 11

What is ment by the DNA code being degenerate

Answer 11

There is more than one code for each amino acid. There are 20 amino acids and 64 possible combinations

Question 12

What is ment by the DNA code being non-overlapping

Answer 12

Each base is present in only 1 codon

Question 13

What is ment by the DNA code being universal

Answer 13

Each codon is the code for the same amino acid in all living organism

Question 14

Where does transcription occur

Answer 14

in the nucleus

Question 15

what does transcription produce

Answer 15

pre - mRNA

Question 16

Describe the process of transcription

Answer 16

1) the hydrogen bonds between the 2 strands are broken causing the 2 strands to seperate and the nucleotide bases to be exposed
2) RNA polymers bind to the template strand at the start of the sequance, the template strand is complemetary to the coding strand
3) complementary RNA nucleotides join to the template strand and RNA polymerase moves along the template joining RNA nucleotides together with phosophodiester bonds 4
4) when the RNA polymerase reaches a STOP codon the pre-mRNA strand is released and the DNA recoils

Question 17

Describe the process of splicing

Answer 17

The removal of introns from pre-mRNA and binding of the exon ends by a spllicosome in order to make mRNA

Question 18

Where does translation occur

Answer 18

at the ribosome in the cytoplasm

Question 19

How many codons can a ribosome hold

Answer 19

2

Question 20

What is the start codon

Answer 20

AUG

Question 21

Describe the process of translation

Answer 21

1) the mRNA binds to the ribosome
2) the tRNA with the complemenatry anticodon to the mRNA codon brings a specific amino acid to the ribosome
3) a second tRNA molecule brings a second amino acid to the ribosome
4) a peptide bond is formed between the 2 amino acids
5) the ribosomes move along 1 codon and the first tRNA molecule is released back into the cytoplasm to bring another amino acid
6) the process contines untill a stop codon is reached and the polypeptide chain is released.