DNA Quiz Flashcards
What is DNA made of?
Nucleotides
Structure of a Nucleotide (DNA)
Deoxyribose sugar connects to phosphate and a nitrogen base (adenine, guanine, cytosine, or thymine)
Purines
Big base. Adenine and Guanine.
Pyrimidines.
Small base. Cytosine and Thymine (and Uracil).
What bonds exist within DNA? (2)
Weak hydrogen bonds hold together nucleotides. Strong covalent bonds hold together the sugar molecules and phosphate groups (along the backbone of the DNA molecule).
What are the differences between DNA and RNA?
DNA: Nitrogenous bases are A, T, C, and G. Uses deoxyribose sugar. Double helix.
RNA: Nitrogenous bases are A, U (Uracil), C, and G. Uses ribose sugar. Single strand.
Chargaff’s Rule
The amount of A’s equals the amount of T’s. The amount of C’s equals the amount of G’s.
Chromosomes
Tightly coiled strands of DNA
Genes
A piece of DNA that has instructions to code for one protein. A sequence of nucleotides.
Proteins
Long chains of molecules made of individual amino acids
Sizing order of DNA (8)
Base Pair. Nucleotide. Codon. Amino Acid. Gene. Protein. Strand of DNA. Chromosome.
Codon
A sequence of three nucleotides that code for one specific amino acid
Complementary Base Pairs
Adenine with Thymine. Cytosine with Guanine.
Gene to Protein Process
A gene is a piece of DNA that has instructions to code for one protein. Each gene consists of sequences of three base pairs called codons. Each codon codes for a specific amino acid.
The sequence of amino acids then come together to form a protein.
What is DNA used for? (2)
To store genetic information and make proteins
Nucleic Acid
DNA is a nucleic acid. It’s made of nucleotides.
DNA Replication Process
Enzyme Helicase unzips the DNA into two strands. Enzyme DNA Polymerase adds complementary nucleotides to the template strands. It only adds on the free 3’ end of the template strand, meaning DNA forms in the 5’ to 3’ direction only. Two identical DNA molecules are formed, each with an “old” strand and a “new” strand. (Which is why it’s semi-conservative replication)
Which direction does DNA form in?
5’ to 3’
Helicase
Unzips DNA into two strands
Primase
Signals polymerase to start. Like a “key” for a car ignition. Makes short RNA primers, which are short pieces of RNA to help get the DNA polymerase started.
DNA Polymerase (3 functions)
Adds nucleotides to primase. After all nucleotides are added to complement strand, RNA primer is removed and replaced with DNA by DNA Polymerase. It proofreads the strand before the backbone is finished.
DNA Ligase
“Seals” the gaps in the DNA. Connects DNA pieces by making phosphodiester bonds.
Semi-Conservative Replication: Basic Process
Each parent strand is now a template that determines the order of the new bases. Forms a “complementary” strand to original strand. The two new double helixes are each a combination of one “old” strand and one “new” DNA strand.
DNA Structure: Double Helix
The “sides” (backbone) are made of alternating sugar molecules (deoxyribose) and phosphate groups. The “rungs” of the ladder are made if nitrogen bases held together by weak hydrogen bonds.
Antiparallel
The strands of DNA run in opposite (antiparallel) directions). The first strand runs from 5’ to 3’ and the second strand runs from 3’ to 5’.
5’ end and 3’ end.
5’ end: Phosphate
3’ end: Deoxyribose sugar
Leading Strand
New strand made towards the replication fork. Needs one RNA primer made by Primase. The leading strand is made continuously.
Lagging Strand
New strand made away from the replication fork. Replicates discontinuously. Creates fragments of DNA which are joined together by DNA Ligase, Needs many RNA primers made by Primase.
