Protein Synthesis And Cellular Control

Question 1

Describe the function of DNA triplet codes

Answer 1

Each DNA triplet codes for an amino acid or tells the cell when to start or stop the production of a protein

Question 2

What is the genetic code

Answer 2

It’s a sequence of bases that codes for amino acids

Question 3

Name the molecule responsible for carrying the genetic code from the nucleus to cytoplasm

Answer 3

mRNA

Question 4

Name the molecule responsible for carrying the amino acids used to make proteins to the ribosomes

Answer 4

tRNA

Question 5

What is RNA polymerase ? Describe its role in protein synthesis

Answer 5

RNA polymerase is an enzyme that attaches to the DNA double helix, and it lines up free RNA nucleotides alongside the template strand. It then moves along the DNA strand, assembling a complementary mRNA sequence from free RNA nucleotides

Question 6

Describe the function of a ribosome

Answer 6

It joins together amino acids to make proteins following the sequence of codons carried by the mRNA

Question 7

Explain how tRNA molecules pair up with mRNA

Answer 7

A tRNA molecule with an anticodon that’s complementary to the first codon on the mRNA attaches itself to the mRNA by complementary base pairing. A second tRNA molecule attaches itself to the next codon on the mRNA in the same way

Question 8

How is protein synthesis controlled at the genetic level

Answer 8

By starting or stopping transcription

Question 9

Describe the function of structural genes

Answer 9

Code for useful proteins

Question 10

Describe the function of control elements

Answer 10

Include promoter and an operator

Question 11

State the two types of transcription factor and explain how they work

Answer 11

Activators - Start transcription

Represses - stop transcription

Question 12

Describe how the lac operon controls protein production in E Coli

Answer 12

When lactose is not present, it binds to the operator and blocks transcription of lacZ, lacY, lacA. No mRNA is produced so no proteins are made.
When lactose is present, binds to lac repressor, changing the lac repressor’ shape so it can’t bind to the operator. RNA polymerase can now bind to the promoter and begin transcription

Question 13

Describe the way in which molecules like hormones can control protein activation

Answer 13

Molecules like hormones can bind to cell membranes. This triggers the production of cyclic AMP (cAMP) within the cell. cAMP then activates proteins in the cell by changing their 3D structure

Question 14

What body plan

Answer 14

The general structure of an organism

Question 15

Name the genes that control the development of a body plan

Answer 15

Homeotic Genes

Question 16

Explain why development of body plans is similar in animals, plants and fungi

Answer 16

Because it’s controlled by similar homeotic genes in each type of organism

Question 17

What is a mutation

Answer 17

A change in DNA base sequence

Question 18

Give three ways a mutation may have a neutral effect

Answer 18

• If mutation changes the base but the triplet still codes for the same amino acid
• If an amino acid is coded for but it is chemically similar to original so the function is like the original
• If mutated triplet codes for an amino acid not involved with proteins function