5.4: Genes, DNA, and Proteins7.1.a Students know cells function similarly in all living organisms.

The Genetic Code• Proteins help to determine the size, shape,

color, and other traits• DNA is made up of 4 nitrogen bases: adenine,

thymine, guanine, cytosine• Gene- a section of DNA which has the

information to code for a protein• Bases are genes in a specific order• Each gene is located at a specific place on the

chromosome• Chromosome contains thousands of genes

The DNA Code• Chromosomes are inside the nucleus, made of

DNA, and contain thousands of genes• The sequence of bases in a gene forms a code

telling what protein to produce

How Cells Make Proteins• Key concept: “During protein synthesis, the

cell uses information from a gene on a chromosome to produce a specific protein.”

• Messenger RNA- copies the coded message from the DNA in the nucleus, and carries the message to the ribosome in the cytoplasm

• RNA is similar to DNA but different• RNA is 1 strand DNA has of 2 strands• RNA has Uracil DNA has Thymine• RNA has a different sugar molecule• Transfer RNA- carries amino acids to the

ribosome and adds them to the growing protein

Mutations

• Mutation- any change in the gene or chromosome, it can be harmful or helpful

• If a mutation happens in the sex cell the mutation might be passed onto an offspring

• If a mutation happens in a body cell, like a skin cell, it will not be passed on

• A mutation is harmful if it reduces the organisms chance for survival and reproduction

• A mutation is helpful if it improves an organism’s chance for survival and reproduction

Mutations• Key Concept: “Mutations can cause a cell to produce an

incorrect protein during protein synthesis. As a result, the organism’s trait, or phenotype, may be different from what it normally would have been.”

• There are different kinds of mutations

What forms the genetic code?How does a cell produce proteins?How can mutations affect an organism?

Section 4: Genes, DNA, and Proteins