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5.4: Genes, DNA,
and Proteins
7.1.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
Section 4: Genes, DNA,
and Proteins
What forms the genetic code?
How does a cell produce proteins?
How can mutations affect an
organism?