DNA

Question 1

What are the components of a nucleotide?

Answer 1

A nucleotide consists of a negatively charged phosphate group (PO4), a 5-carbon sugar molecule called deoxyribose, and one of four nitrogenous bases.

Question 2

What kind of hydrogen bond does adenine and thymine have?

Answer 2

Double Hydrogen bond

Question 3

What kind of hydrogen bond does Guanine and Cytosine have?

Answer 3

Triple Hydrogen Bond

Question 4

What cells are histones found in, what are they?

Answer 4

Histones are proteins found in eukaryotes that are tightly package DNA into structures called Nucleosomes.

Question 5

What is RNA?

Answer 5

Ribonucleic Acid

Question 6

What are some differences between RNA and DNA?

Answer 6

A: RNA contains the sugar ribose
- is single-stranded
-has uracil instead of thymine.
-DNA contains the sugar deoxyribose
-double-stranded
-thymine instead of uracil.

Question 7

What is the function of mRNA (messenger RNA)?

Answer 7

mRNA carries the genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.

Question 8

What is the function of tRNA (transfer RNA)?

Answer 8

tRNA brings the correct amino acids to the ribosome during protein synthesis, matching its anticodon with the mRNA codon.

Question 9

What is the function of rRNA (ribosomal RNA)?

Answer 9

rRNA forms the core of the ribosome’s structure and catalyzes protein synthesis.

Question 10

What are 3 adjacent nucleotides called in DNA and RNA?

Answer 10

In DNA – a group of 3 adjacent nucleotides is called a triplet.
When transcribed into mRNA – the 3 nucleotides are called a codon.

Question 11

What is in the structure of a gene?

Answer 11

• promoter region - upstream (5’ end) binding site for RNA polymerase
• introns - non-coding regions of DNA
• exons - coding segments of DNA
• terminator sequence - signals end of transcription
• operator – binding site for repressor proteins (inhibit protein synthesis)

Question 12

Whats the difference between eukaryotic and prokaryotic gene structures?

Answer 12

Eukaryotic genes have no operator, prokaryotic genes has no introns

Question 13

What are the stop codons?

Answer 13

UAA
UAG
UGA

Question 14

What is the promoter?

Answer 14

upstream (5’ end) binding site for RNA polymerase, which is an enzyme responsible for transcription.

Question 15

What are Introns?

Answer 15

Only in eukaryotes, introns are regions of non-coding DNA that are later removed.

Question 16

What are exons?

Answer 16

regions of coding DNA, which are transcribed and translated into the final protein.

Question 17

Termination sequence

Answer 17

a sequence of DNA that signals for the end of transcription.

Question 18

Operator

Answer 18

the binding site for repressor proteins, which can then inhibit gene expression. This region is typically only found in prokaryotic genes, as eukaryotes have different regions for regulating gene expression.

Question 19

In the three steps of protein synthesis, name where they happen and what happens.

Answer 19

1. Transcription –occurs in the nucleus, copying of DNA into pre-mRNA

Question 20

Transcription

Answer 20

occurs in the nucleus, copying of DNA into pre-mRNA

Question 21

RNA processing

Answer 21

RNA processing – occurs occurs in the nucleus , modifies pre-mRNA to produce mRNA
3. Translation - occurs on ribosomes in cytoplasm,

Question 22

Translation

Answer 22

occurs on ribosomes in cytoplasm, involves decoding mRNA strand into polypeptide chain (protein)

Question 23

Elongation

Answer 23

• RNA polymerase moves along
  DNA template strand
• Complementary nucleotides are
  brought into place and joined one
  by one to form pre-mRNA chain
  (in the 5’ to 3’ direction)

Question 24

Termination

Answer 24

When RNA polymerase reaches termination sequence, transcription stops
- pre-mRNA is released from template

Question 25

What are the steps in RNA processsing?

Answer 25

1. Splicing: introns are ‘cut’ out and
   remaining exons are spliced together
2. Capping: addition of methyl-guanine
   cap (methyl-G cap) at 5’ end. Cap
   protects mRNA from enzyme attack
3. Adding an A-tail: chain of adenine
   nucleotides (poly-A tail) is added at 3’
   end. Aids stability of mRNA

Question 26

What does alternative splicing state?

Answer 26

Single pre-mRNA strand can produce many different mRNA molecules
depending on arrangement or removal of exons (allows for many different proteins to be created)

Question 27

What happens in translation?

Answer 27

• mRNA molecule binds to the ribosome
• tRNA anticodons complementary to mRNA codons deliver corresponding amino acids to the ribosome
• Adiacent amino acids are joined with peptide bonds via a condensation reaction to form a polypeptide
• Translation ends when a STOP codon is recognised

Question 28

How many genes are on the human genome?

Answer 28

Approximately 21,000 genes make up the human genome.

Question 29

Structual Genes (main part)

Answer 29

• responsible for producing proteins involved in structure and function of cell
• includes enzymes, transport proteins, receptors or peptide hormones

Question 29

Genome

Answer 29

A: The complete set of genetic material (DNA) in an organism, including all of its genes and non-coding sequences.

Question 30

Regulatory Genes (promoter and regulatory gene before the structual part)

Answer 30

• responsible for production of regulatory proteins such as repressor proteins
• activator proteins initiate or increase expression of structural genes
• regulatory genes turn other genes on or off as required