Protein Synthesis

Grade 7 Science

By Mr. Xander Jon C. Siose

WORK PLAN

• Recall of terms

• Code Breaking Activity

• What is Protein Synthesis

• What are the steps of protein

synthesis

• Protein Synthesis Challenge

• Wrap up

• Agreement

What we already know about DNA

• The nucleus of the cell

contains DNA

• Genes are specific sections

of DNA

• DNA – deoxyribonucleic acid

• The DNA molecule is a

double helix (shaped like a

twisted ladder)

• The DNA subunits are:

Phosphate, Sugar, and

Nitrogen base

What we know about the genetic

code

• There are four DNA bases:

Adenine, Thymine, Cytosine,

Guanine

• The DNA bases compliment

each other: A-T & C-G

• Three bases codes for one

amino acid (triplet code)

• A gene is the entire

sequence of bases that

codes for a specific protein

What we know about RNA

• RNA – ribonucleic acid

• RNA has a ribose sugar

instead of deoxyribose

sugar

• RNA has Uracil instead of

Thymine

• RNA is a single strand

What we know about proteins

• Proteins are large molecules made up of

amino acids

• Different combinations of amino acids form

different proteins

• Protein is a component of

enzymes, hormones, and muscles

Code Breaker

• Decode the message hidden in the words

• Clue: CAPITAL

Life Overcomes Nothing Greater Than Itself

Minus Everything. Now Only Seems Extremely

Easy. Jumping Under Something

Terrible, Another Quirkily Useless Idiot Crafted

Knives. Verily It Stayed In There To Hurt

Openly Unique Goat Herders.

Code Breaker

• Answer:

Long time, no see. Just a quick visit, though

Code Breaker

• Use the cipher to figure out the message

Code Breaker

• Answer:

Those who know the enemy as well as they

know themselves will never suffer defeat.

~ Sun Tzu ‘Art of War’

BIG IDEA

Breaking the code

Cells transcribe and translate

codes to make protein

VOCABULARY

• Protein Synthesis

• Transcription

• mRNA

• Translation

• Ribosome

• rRNA

• tRNA

What is protein synthesis?

• Protein synthesis is the

process of making proteins

using the genetic code found

in DNA

• It involves two processes:

• Transcription

• Translation

DNA RNA Protein

Quick Check

• What is protein synthesis?

• What are the processes involved in protein

synthesis?

Transcription

• Uses one strand of DNA as

a pattern or template

• It produces a single-

stranded mRNA molecule

• It happens inside the

nucleus

Steps of Transcription

1. The DNA molecule

opens up along the

gene

2. RNA nucleotides (A, U,

C, G) match up and join

the open DNA strand

3. The complete RNA

strand (mRNA) is

released an moves out

to the cytoplasm

Difference of Translation to

Replication

• Only one strand of DNA is transcribes, so

only one strand of mRNA is produced

• The mRNA is released, it does not stay

attached to the DNA

• Many copied of mRNA can be made from a

single gene in a short period of time

Quick Check

• What are the steps of transcription?

• How is transcription different to replication?

Translation

• Translation is how the cells

relate the code of nucleotide

bases to the language of

amino acids.

• Translation occurs in the

cytoplasm, specifically at

ribosomes

• The ribosomes use mRNA

and tRNA to make proteins

Steps of Translation

1. The mRNA attaches to a

part of the ribosome.

2. tRNA that carries amino

acids will match the

triplet codes of the

mRNA

3. The amino acid chain

becomes longer as more

tRNA matches up with

mRNA

Translation

Steps of Translation in Detail

1. Translation begins when a ribosome attaches to the

beginning of an mRNA molecule

2. A tRNA molecule carrying an amino acid matches up

to a complementary triplet on mRNA on the ribosome

3. The ribosome attaches one amino acid to another as

it moves along the mRNA molecule

4.The tRNA molecules are released after the amino

acids they carry are attached to the growing chain of

amino acids

5. The ribosome completes the translation when it

reaches the end of the mRNA strand and the newly

made protein molecule is released

Quick Check

• Where does translation occur?

• Which RNA does the actual translation of

bases into amino acids?

Summary

• mRNA is transcribed from DNA in the nucleus

• tRNA translates mRNA into amino acids by

matching nucleotide bases codes

• Ribosomes connect the amino acids together

to form protein

• Check this link to see a video summary:

http://www.youtube.com/watch?v=NJxobgkPEAo

Protein Synthesis Challenge

• Copy this DNA sequence:

A – T – G – A – C – G

• Write the base pairs of the complimentary strand of

DNA (replication)

• Write the complimentary mRNA strand to your new

strand (transcription)

• Use the chart to find the correct amino acid s that the

tRNA would attach to the protein chain (translation

Universal Genetic Code

Answers

• Replication

T – A – C – T – G – C

• Transcription (mRNA)

A – U – G – A – C – G

• Translation (amino acids)

Met (Methionine) and Thr (Threonine)

Agreement

• Bring the following materials for the GRASPS

activity next meeting:

• Coloring materials

• Letter-sized papers (white or colored)

• Pencil

• Scrap book materials and/or old colored

magazines

• Scissors

• Glue

Resources

• Lam Peng Kwan, Eric Y K Lam, Biology Matters

GCE O Level, Marshall Cavendish Education

• http://www.slideshare.net/MrsTabor/dna-for-7th-

grade#btnNext- Tan, Angeline (2010). Science

Process Skills.

• http://ims.ode.state.oh.us/ODE/IMS/Lessons/Conte

nt/CSC_LP_S02_BC_L10_I05_01.pdf

• http://www.youtube.com/watch?v=NJxobgkPEAo