Name____________________________________________ Date:________________ Period:____
DNA/RNA Structure Standards
5a. Students know the chemical structure of DNA, RNA, and protein.
1. Students know that all cells contain the molecule DNA which stores and transfers genetic
information.
Prokaryotes store DNA in the _____________
Eukaryotes store DNA in the ____________
2. Students can describe the structure of DNA as a double
stranded molecule consisting of nucleotides. The backbone of
the DNA molecule consists of “sugar phosphate” units while the
“rungs” consist of nitrogen-containing bases. [A, G, C, & T].
3. Students can describe the structure of
RNA as a single-stranded molecule
consisting of the same A, G, and C
nucleotides but with Uracil instead of
Thymine.
4. Students can identify the two different
types of RNA [mRNA and tRNA] and
describe their functions.
We Love DNA (to the tune of “Row,
Row, Row Your Boat”)!
We love DNA
Made of nucleotides.
Sugar, phosphate and a base
Bonded down one side.
Adenine and thymine
Make a lovely pair.
Cytosine without guanine
Would feel very bare.
Nucleic acids are polymers composed of monomers called nucleotides. Each nucleotide consists of three
subunits: a five-carbon pentose sugar, a phosphoric acid group, and one of four nitrogen bases. (For DNA
these nitrogen bases are adenine, guanine, cytosine, or thymine.) DNA and RNA differ in a number of
major ways. A DNA nucleotide contains a deoxyribose sugar, but RNA contains ribose sugar. The nitrogen
bases in RNA are the same as those in DNA except that thymine is replaced by uracil. RNA consists of only
one strand of nucleotides instead of two as in DNA. The DNA molecule consists of two strands twisted
around each other into a double helix resembling a ladder twisted around its long axis. The outside, or
uprights, of the ladder are formed by the two sugar-phosphate backbones. The rungs of the ladder are
composed of pairs of nitrogen bases, one extending from each upright. In DNA these nitrogen bases always
pair so that T pairs with A, and G pairs with C. This pairing is the reason DNA acts as a template for its
own replication. The bonds between the nitrogen bases are hydrogen bonds which are relatively weak
allowing DNA to be separated for replication and transcription. RNA exists in many structural forms, many
of which play different roles in protein synthesis. The mRNA form serves as a template during protein
synthesis, and its codons are recognized by aminoacylated tRNAs. Protein and rRNA make up the structure
of the ribosome.
DNA
vs
RNA
Proteins are polymers composed of amino acid monomers. Different types of proteins function as enzymes,
transport molecules, hormones, structural components of cells, and antibodies that fight infection. Most
cells in an individual organism carry the same set of DNA instructions but do not use the entire DNA set all
the time. Only a small amount of the DNA appropriate to the function of that cell is expressed. Genes are,
therefore, turned on or turned off as needed by the cell (regulated), and the products coded by these genes
are produced only when required.
The base________________ pairs with _____________. The base ___________ Pairs with __________.
This is called complementary base pairs. Thus one strand of the DNA is complementary to the other strand
(opposite/matching). 5’-----3’ 3’-----5’
_____________________
The structure of DNA resembles a twisted ladder.
Which part of the nucleotide is found comprising the “rungs” of the ladder?
Which part of the nucleotide is found comprising the “frame” of the ladder?
The molecule transcribed/coded directly from DNA is represented by number __ and is called
____________________
The ____________________ can leave the _______________ through the ________________and enter the
___________________ because the molecule is _______________________ not _____________________.
Structure 2 is called a _____________ or _________________ because it carries an amino acid and can
help ___________________ the genetic code. because it consists of three nucleotides. The structure 2
recognizes a __________________ because it has a complementary _________________.
Structure 3 is the building blocks of _________________.
Structure 4 is the __________________ which holds the messenger RNA so that translation using the
transfer RNA can occur.
The bond labeled 5, formed between two amino acids, is known as a __________________________
Which of the following units are repeatedly joined together to form a strand of DNA?
1. amino acids
2. fatty acids
3. nucleotides
4. polysaccharides
The weakest bonds in a double-stranded molecule of deoxyribonucleic acid exist between
the____________________________
(1) deoxyribose sugars
(2) phosphate groups
(3) nitrogenous bases (4) 5-carbon sugars
Molecules C, D, and E will combine to form part
of _______________________________
1. DNA
2. RNA
3. a polysaccharide
4. a polypeptide
Structure B represents a molecule of
____________________________________
1. nuclear DNA
2. cytoplasmic DNA
3. ribosomal RNA
4. transfer RNA
How many codons are located on the messenger
RNA molecule in the diagram?
The type of molecule represented at A is
synthesized according to a template found in
1. DNA
2. RNA
3. dipeptides
4. amino acids
The process shown here would occur in the _____________________ of a cell
One similarity between DNA and messenger RNA molecules is that they both contain
1. the same sugar
2. genetic codes based on sequences of bases
3. a nitrogenous base known as uracil
4. double-stranded polymers
Which of the following features of DNA is most important in determining the phenotype of an organism?
1. the direction of the helical twist
2. the number of deoxyribose sugars
3. the sequence of nitrogenous bases
4. the strength of the hydrogen bonds
A portion of one strand of a DNA molecule has the sequence shown : ACCTGAAGG
Assuming there are no mutations in this portion of the DNA, what is the corresponding sequence on the
complementary DNA strand?
1. ACCTGAAGG
2. GTTCAGGAA
3. TGGACTTCC
4. UGGACUUCC