Section 4

DNA and the production of proteins

DNA and the production of proteins

Learning Intention: To understand the structure and function of DNA, genes and chromosomes.

Success Criteria: Be able to identify chromosomes, genes and DNA and describe their functions.

Starter Activity: What do you know?

2 Minutes- with your partner can you write down whatever you know about………

- DNA- Genes- Chromosomes- Nucleus- Mitosis

DNA

• Watch this short clip to introduce DNA and its functions.

• What is DNA?

Inside the Nucleus• The nucleus of a cell

contains structures called chromosomes.(46)

• Chromosomes are composed of strands of DNA.

• They contain genetic information – these are the instructions that make you!

Chromosomes and Genes

• Chromosomes are split up into smaller segments called genes.

• A gene is a section of a chromosome which contains a separate piece of genetic information.

DNA

A single gene made

of DNA

Genes and chromosomes are made of a chemical called DNA. It is a spiral shaped molecule which carries our genetic code.

DNA-Facts• DNA- stands for

Deoxyribonucleic acid.

• A DNA molecule (nucleotide) is composed of a phosphate, deoxyribose sugar and a base.

• We have 3.2 billion base pairs.

• There are about 20,000–25,000 distinct genes.

• DNA helps generate 2 million+ proteins.

DNA and the production of proteins

Learning Intention: To understand the structure and function of DNA, genes and chromosomes.

Success Criteria: Be able to identify chromosomes, genes and DNA and describe their functions.

Structure of DNA

• The DNA molecule is a double stranded helix.

• There are two strands each of which consists of a backbone with bases attached.

• The bases are joined to each other to form the double helix.

Complementary Base pairs• There are 4 bases

called Adenine, Thymine, Cytosine and Guanine.

• They are usually shown by their initial letters A, T, C and G.

• When the bases join, A always pairs with T and C always pairs with G.

Make a model of DNA

• Your teacher will give you resources and demonstrate how to make your own DNA model.

B

Research task

• Many research biologists have contributed to our knowledge of the structure of DNA.

• Choose one of the following and write a report on their contribution to DNA research.

Watson and Crick Rosalind Franklin Maurice Wilkins Erwin Chargaff

DNA Research Report Assessment Criteria

The report must…(only this information = grade C)• be displayed in any way, using no more than two pieces of A4 paper;• describe the structure of DNA; and• list the references of sources of information.The report should…(plus most/all of the above information = grade B)• state what chromosomes and genes are; and• describe the importance of DNA.The report could…(plus most/all of the above information = grade A)• describe how research biologists have contributed to our knowledge of the

structure of DNA.• include information about one of the scientists below, detailing information

about their contribution to DNA research.

Watson and Crick Rosalind Franklin Maurice Wilkins Erwin Chargaff

Use the above criteria to give feedback: give an overall grade, plus overall comments of strengths and areas for improvement.

Discovery

• Note down some facts that could help with you research task.

• Discovery of DNA

What does DNA do?• Our DNA controls everything that happens in our

body.

• It carries instructions which tell our cells to make particular proteins.

• These proteins control our characteristics.

• How? What are proteins used for?

• These proteins help form enzymes, pigments, muscles, bones and hormones.

• These therefore produce our characteristics, height, eye colour, hair colour, hand span etc

The genetic code• The genes on a chromosome are

made up of a sequence of bases.Eg, ATGCTTACGCTG

• This is the genetic code.

• Each different gene has a different genetic code.

• This code is what instructs the cell to make a specific protein.

Eg, hormone, enzyme, pigment

Gene for eye colour

Gene for height

DNA and the production of proteins

Learning Intention: To understand the structure and function of DNA, genes and chromosomes.

Success Criteria: Be able to identify chromosomes, genes and DNA and describe their functions.

DNA and the production of proteins

Learning Intention: Understand the role of DNA in theproduction of proteins.

Success Criteria: 1. Be able to describe the role of DNA

and mRNA in the production of proteins. 2. State the location of protein synthesis. Describe protein synthesis.

Starter activity

1. What does DNA stand for?2. What structures do we find in a nucleus?3. What is a gene?4. What is the function of DNA?5. Explain what we mean by the genetic

code.6. Name two types of protein that our DNA

helps to produce.

Starter

Starter

D

Answers1. Deoxyribonucleic acid2. Chromosomes3. A gene is a section of a chromosome

which contains a separate piece of genetic information

4. DNA codes for the production of proteins, controls our characteristics

5. The genetic code is the sequence of bases contained within a gene

6. enzymes, pigments, muscles, bones and hormones

DNA and Protein

• Watch the following clip before we look at producing proteins

• How DNA makes protein.

DNA to protein• Proteins are made up of

chains of amino acids.

• Three bases in the genetic code will put one particular amino acid into the chain.

• The sequence of the bases determines the sequence of amino acids in the final protein that is made.

• This is protein synthesis.

DNA to protein• Protein synthesis

occurs in ribosomes.

• DNA must stay in the nucleus.

• Therefore, a special molecule called messenger RNA (mRNA) carries a copy of the code from the nucleus to a ribosome.

• The protein can then be made using this genetic copy.

Stage 1 - TranscriptionIn the nucleus, mRNA carries a copy of the genetic code from DNA to the ribosome.

Stage 2 - TranslationFrom the copied code, the correct amino acids are joined together to form a chain.

Stage 3 – Protein ProductionThe chain of amino acids forms a protein

Protein synthesis

m

ribosomes

D

DNA and the production of proteins

Learning Intention: Understand the role of

DNA in the production of proteins.

Success Criteria: 1. Be able to describe the role of DNA

and mRNA in the production of proteins.2. State the location of protein synthesis.Describe protein synthesis.