Lesson Five Flashcards
DNA stands for
Deoxyribose nucleic acid
DNA makes up
Chromosomes
Two types of nucleic acids
DNA and RNA (chains of nucleotides)are involved in functioning of chromosomes in protein synthesis
Shape of DNA is referred to as
Double helix
Nucleotides are composed of
Nitrogen bases, phosphoric acid, 5 carbon sugar (Deoxyribose)
Purines
Double ring
T and C
Pyrimidines
Single ring
A and G
Alternating sugar and phosphates make up the
Rungs of the backbone
Adenine bonds to…
Thymine (2 hydrogen bonds)
Guanine always bonds to…
Cytosine (3 hydrogen bonds)
The bases cannot bond any other way because…
2 purines would overlap and 2 pyrimidines would be too short to form the rungs of the ladder.
The double strand is held in place by…
Hydrogen bonds between the bases
As DNA lengthens, it…
Twists into a double helix
Functions of DNA (3)
- Replicates itself so each new cell has complete identical copy
- Controls the activities of a cell by product ing proteins (combinations of proteins determine characteristics of organisim)
- Undergoes occasional mutations (mistakes in replication) which produces variety
Step one in DNA replication
DNA molecule becomes untwisted, by the enzyme helicase breaking up the weak hydrogen bonds between the nitrogenous base pairs
Step two in DNA replication
New complementary nucleotides (always present in nucleus) move into place and pair with exposed strands. The enzyme DNA polymerase assists with the base pairing
Step 3 in DNA replication
The adjacent nucleotides become joined together, the enzyme Ligase glued the alternating sugar phosphate backbone together
Step 4/5
2 complete DNA are now present which are identical to each other. Both strands will wind back to original helical shape
DNA replication is called…
Semi conservative because it has old strand (parent) and new strand (daughter).
Recombinant DNA is…
DNA which has genes from 2 different organisims, often produced in the lab by introducing foreign genes into a bacterial plasmid which makes new combination of DNA
Most common organism to be a vector for recombinant DNA
Plasmids
Steps of producing recombinant DNA
Plasmid is removed from bacteria and has foreign gene inserted. Enzyme breaks plasmid DNA and then new foreign DNA can be attached to plasmid. Ligase then sticks the foreign DNA to the plasmid to make it whole.
Viral DNA can also be used….
As a vector to carry recombinant DNA into a cell. When a virus containing recombinant DNA infects a cell, the viral DNA enters. Then it reproduces more viruses.
Viral vectors allow…
Cloning of a particular gene
Viral vectors also are used to crate
Genomic libraries
Summary of Recombinant DNA
Certain genes can be inserted into bacteria and then these bacteria will produce these genes.
Uses of recombinant DNA
- Generate DNA library, which will catalogue all the base sequences of known genes.
- Identify specific genes
- Produce synthetic copies of genes
- Insert genetic material into chromosomes to make it generically better
Unique characteristics of DNA
Two strands, a+t, c+g
Pentose sugar is deoxyribose (ribose with one less oxygen)
Unique characteristics of RNA
One strand, A+U, C+G,
Pentode sugar is ribose
