Genetic Code

Question 1

What are proteins?

Answer 1

• long chains of amino acids (20 different ones) used by cells to perform a variety of functions

Question 2

Protein functions

Answer 2

• cells in digestive system produce proteins called enzymes which help break down food
• cells in glands can produce hormones such as insulin which is needed to maintain normal sugar levels in your blood
• cells can produce protein pigments used to colour your hair, skin, and eyes

Question 3

How is protein produced?

Answer 3

• produced in the cell by translating the DNA code into an amino acid sequence
  *DNA - mRNA - Amino Acid sequence
• Ribosomes and the Rough Endoplasmic Reticulum are protein making sites in the cytoplasm

Question 4

What is genetic code, and what is it used for?

Answer 4

• nucleotide triplet codes of DNA are used to produce the amino acid chain which makes up the protein

ex. DNA sequence: TAC TGA GCC ATT
Amino acid sequence: Met-Thr-Arg-Stop

Question 5

What do Amino acid sequences have in common?

Answer 5

• They all have the same code for start and stop (TAC ATT)
• They all divide into triplets
• All amino acid sequences tell the ribosomes which protein to generate

Question 6

What is a mutation?

Answer 6

• change or damage to the DNA (amino acid sequence) of an organism

Question 7

What is substitution?

Answer 7

• one base (A, G, C, T) is swapped for another
• A different sequence can change how the protein works

Question 8

What is deletion?

Answer 8

• one base (A, G, C, T) is missing
• most likely to have more severe consequences as every triplet after the change is altered

Question 9

What is addition?

Answer 9

• one base (A, G, C, T) is added
• most likely to have more severe consequences as every triplet after the change is altered

Question 10

What is a mutagen?

Answer 10

• anything that causes a mutation (UV lights, x-rays, cigarette smoke, other chemicals, some viruses)

Question 11

What is a positive mutation?

Answer 11

• a change in DNA that causes the production of a new protein, which benefits the organism
  ex. Mc1r gene in pocket mice –> changes colour to black (suitable for environments with dark ground)

Question 12

What is a negative mutation?

Answer 12

• a change in DNA that causes the production of a new protein, which harms the organism
  ex. Mc1r gene in pocket mice –> changes colour to black (harmful for environments with light sand)
  cancer –> often a mutation

Question 13

What is a neutral mutation

Answer 13

• a change in DNA that does not change the protein that is produced
• it does not harm the organism
• The DNA is different, but the protein is still the same
  ex. AGA, AGG –> both Ser