Similarities between DNA & RNA: both polymers of nucleotides, both contain bases adenine, guanine, and cytosine, both made in the 5'à 3' direction; nucleotides held together by phosphodiester bonds
Differences: DNA contains the sugar deoxyribose; RNA contains the sugar ribose. DNA contains the base Thymine; RNA contains the base Uracil.
DNA stores hereditary information for making proteins and remains in the nucleus. RNA copies the information, takes it to the ribosomes in the cytoplasm and assembles proteins. DNA is double stranded, double helix shape. RNA is single stranded, with various shapes.
What is the function of DNA?
. DNA stores hereditary information for making proteins and remains in the nucleus.
What is the function of RNA?
. RNA has three forms , each with a different job. mRNA copies the info from the DNA, then moves to the ribosomes (rRNA) in the cytoplasm. The rRNA attaches to the mRNA and manages the synthesis of the protein. tRNA carries the amino acids into the correct place at the ribosome.
In a DNA double helix, a region along one DNA strand has this sequence of nitrogen bases: 5' TAGGCCT 3'. Copy this sequence and write down its complementary strand, indicating the 5' and 3' end of the complementary strand.
Original strand 5' TAGGCCT 3'
Complementary DNA3' ATCCGGA 5'
RNA made from original 3' AUCCGGA 5'
. Suppose a substitution (mutation) occurred in one DNA strand of the double helix in the previous question, resulting in
5' TAAGCCT 3'
3' ATCCGGA 5'
a. Copy these two strands and circle and label the mismatched bases.
b. If the top strand is used by the cell to make a complementary strand, what would that strand be?
5' TAAGCCT 3' The A in the top strand should be matched to a T in the
3' ATCCGGA 5'complementary strand.
The correct complementary strand would be 3' ATTCGGA 5'
Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?
The phosphodiester linkages of the of the polynucleotide backbone would be broken.
Which of the following pairs of base sequences could form a short stretch of the normal DNA helix?
5'ATGC3' with 5'GCAT3'
Remember the pair in antiparallel direction
What structural feature allows DNA to replicate itself?
. Structural features that allow DNA to replicate (copy) itself perfectly are its double helix (two stranded shape) made up of complementary bases. When the two halves are separated, each acts as a template (pattern) to form the new strand alongside. A always pairs with T , and C with G, allowing correct strands to form.
Compare the structure of a fat with the structure of a phospholipid.
A fat is made up of a glycerol molecule bonded to three fatty acids. A phospholipid contains a glycerol bonded to a phosphate group and only two fatty acids. The fat is hydrophobic, however the phospholipid has a hydrophilic , polar head, and a non-polar, hydrophobic tail.
Draw a picture of how phospholipids might surround a drop of oil, as in certain plant cells.
The tails would all be pointing at the drop of oil, surrounding it. The polar head would be facing outwards.
Which of the following statements concerning unsaturated fats is true?
a. They are more common in animals than plants?
b. They have double bonds in the carbon chains of their fatty acids.
c. They generally solidify at room temperature.
d. They contain more H than do saturated fats having the same number of carbon atoms.
e. They have fewer fatty acid molecules per fat molecule.
A. False, more common in plants
C. False, generally liquids at room temp.
What are the three types of biologically important lipids?
. The three types of biologically important lipids are fats, phospholipids, and steroids.
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