CP Biology – Genetics Unit
Main Idea: All cells contain DNA wound into chromosomes. DNA is the
instruction book on when and how to make proteins necessary for the cell.
Nucleic Acids and Protein Synthesis (Chapter 10 pp. 185-196)
Objectives:
 Explain the principal function of DNA
DNA stores and transmits hereditary information that controls how and
when cells make proteins
 Describe the monomer structure of nucleic acids
Monomer is a nucleotide with a phosphate group, 5 carbon sugar, and
nitrogen base.
 Describe the structure of DNA including the covalent bonds that connect
nucleotides and the hydrogen bonds that connect bases
DNA is a double helix. If you unfold the helix it looks like a ladder.
Hydrogen bonds connect the nitrogen bases, which are the steps of the
ladder. Phosphates and 5 carbon sugar are bonded covalently to form
the backbone of DNA, or sides of the ladder.
 Explain the complementary base pairing
C pairs with G
A pairs with T (apple tree)
A pairs with U in RNA
 Compare and contrast the structure of DNA and RNA
DNA - Deoxyribonucleic Acid
RNA - Ribonucleic Acid
Sugar - deoxyribose
Sugar - ribose
Double stranded - double helix
Single stranded
Stays in the nucleus
Travels to cytoplasm
Bases: A, T, C, G
Bases: A, U, C, G
 Summarize the main features of DNA replication
DNA replication is how a cell passes an exact coy of their DNA to the
new cell.
Step 1: DNA unwinds
Step 2: Enzyme Helicase helps strands separate
Step 3: Enzyme DNA Polymerase binds to separed chains and builds
new complementary bases
Final result: exact copy of original DNA with each DNA molecule
created from half old and half new strands
 Explain the structure and functions of each type of RNA
MRNA is messenger RNA and carries the codons from the nucleus to
the ribosomes. It is a long strand of nucleotides.
TRNA is transfer RNA and it carries the anticodon that matches the
codon with its amino acid. It is a long strand of nucleotides curved
around itself in a ‘t’ shape.
 Describe the process of transcription and know the enzyme involved
A section of DNA is made into RNA in transcription. Happens in
nucleus.
Step 1: DNA unwinds
Step 2: Enzyme RNA Polymerase makes RNA strand by pairing
complementary bases to one side of DNA (U replaces T)
Step 3: DNA closes
Step 4: RNA leaves nucleus
 Describe the process of translation
Builds protein from codon on mRNA. Happens on ribosomes.
1.
2.
3.
4.
5.
mRNA attaches to ribosome
ribosome reads codon from mRNA
anticodon on tRNA matches with codon on mRNA
tRNA with correct anticodon binds to ribosome bringing corresponding amino acid
another tRNA with correct anticodon binds to ribosome bringing corresponding
amino acid
6. two amino acids bond together using peptide bond
7. first tRNA leaves
8. ribosome continues reading along mRNA until STOP codon is reached
9. mRNA is released from ribosome
10. protein or polypeptide is formed
 Distinguish between a codon and anticodon and know where each is
found
Codon is triplet of nucleotides corresponding to DNA template. It is on
mRNA.
Anticodon is triplet of nucleotides that correspond to codons from
mRNA. Anticodons are on tRNA.
 Know the structure and composition of proteins
Proteins are polypeptides which are polymers of amino acids. They are
built from amino acids that are bonded by peptide bonds.
 Distinguish between the three types of point mutations (addition, deletion,
substitution) and how they can affect the protein structure
Addition – extra nucleotide added to DNA sequence
Deletion – a nucleotide is removed from DNA sequence
Substitution – one nucleotide replaces another
Mutations may be silent – don’t code for new amino acid.
Mutations may cause new protein to be made