Nucleic Acids
Large complex molecules that store and transmit genetic information.
Elements in nucleic acids:
Function of nucleic acids:
Two kinds of nucleic acids:
DNA =
RNA =
The subunit of nucleic acids (monomer) is called a nucleotide.
Structure of a Nucleotide:
Nucleotides are made of 3 parts:
phosphate group
a five carbon sugar (deoxyribose or ribose)
a nitrogenous base (A, T, G, C) or (A, U, G, C)
What do the letters A, T, C, G and U stand for? Which are in DNA? Which are in RNA?
Compare RNA to DNA
Quiz yourself: Refer to the diagram
below to answer the questions.
1. What kind of nucleic
acid is this?
2. Circle a nucleotide
and label the parts.
3. How many
nucleotides are
represented?
4. Circle a base pair.
5. What is the base
pairing rule?
How nucleotides bond to form DNA: (draw a DNA molecule)
How nucleotides bond to form RNA: (draw an RNA molecule)
(on a separate sheet of paper)
DNA Replication
1. DNA uncoils and the two strands unzip.
The hydrogen bonds between the base
pairs break and the two strands of the
DNA separate.
2. Free nucleotides move in and bind with
the parent DNA strands (the DNA
template). Complementary bases bind to
the open bases on the template strands.
3. The free nucleotides in the new strands
bind together. The copied DNA re-coils.
The two DNA molecules are identical.
The structure of the DNA molecule (two
complementary strands that can separate
between the base pairs) ensures that the
DNA is copied efficiently (quickly and
correctly).
Protein Synthesis: The process by which proteins are made. Proteins are chains of amino acids
(peptides) that are bonded together by peptide bonds and then folded into a specific shape. If there is
a mistake in the amino acid sequence of a protein, the protein may be misshapen and will not
function properly. This leads to disorders such as diabetes, sickle cell anemia, color blindness,
hemophilia, PKU, lactose intolerance, cystic fibrosis, or albinism, to name a few.
Which organelles are involved in protein synthesis? Explain how each organelle is involved in
the process.
Where is the code for a trait located in the cell? On what kind of molecule?
How does the genetic code for protein synthesis get to the ribosome, where proteins are
assembled?
RNA – Ribonucleic Acid: Name three kinds of RNA and describe their structure and function.
What are codons? What are anti-codons?
Describe the process of transcription –
Where does the mRNA go after transcription?
Describe the process of translation -
Steps of Protein Synthesis:
DNA uncoils and enzymes break hydrogen bonds between base pairs
Transcription takes place in the nucleus
DNA serves as the template for mRNA
mRNA is created by making a complementary strand to the DNA (gene)
mRNA leaves the nucleus and goes to the cytoplasm
mRNA binds to a ribosome
tRNA binds to specific amino acids in the cytoplasm
tRNA carries amino acids to the site of protein synthesis (the ribosome)
Translation occurs at the ribosome
Codons on mRNA are “read” by ribosome
tRNA tranports the amino acid to the ribosome.
Anti-codons on tRNA bind with codons on mRNA.
Ribosome bonds one amino acid to the previous amino acid (peptide bonds form)
Ribosome moves down the mRNA strand and process repeats.
tRNA breaks away from the complex and picks up new amino acids.
The process continues down the mRNA strand until the ribosome encounters a STOP codon.
Modern Genetics Vocabulary List
Watson & Crick
Double Helix
Nucleic Acid –DNA & RNA
Nucleotide
DNA (structure & function)
RNA (3 types, structure &
function)
Nitrogenous bases
4 in DNA
4 in RNA
Base Pair
Base Sequence
Template
Complementary base/strand
DNA replication
Protein synthesis
Transcription
Translation
Codon
Anticodon
Ribosome
Protein
Amino acid sequence
Mutations
Deletion, Insertion, Translocation
Chromosomal abnormalities