Deoxyribonucleic Acid
DNA stands for, one of the two types of nucleic acids, The other is RNA,
DNA
store an organism’s genetic information, directs the synthesis of proteins, which in turn control traits, is found in: The cell nucleus, Mitochondria, Chloroplasts (plants only), It is made up of repeating monomers, called nucleotides
Chromatin
un-condensed form of DNA,
Chromosomes
condensed form of DNA
Histones
coil into chromosomes the DNA must wrap around proteins
Nucleotide
repeating subunit of a nucleic acid, made up of three components: A phosphate group, A 5-carbon sugar (in DNA this sugar is deoxyribose), One of four nitrogenous bases: Adenine, Cytosine, Guanine, Thymine
Phosphate Group
chemical structure that consists of one phosphorus and four oxygen atoms
Deoxyribose
A 5-carbon sugar (in DNA this sugar)
Nitrogenous Bases
Adenine, Cytosine, Guanine, Thymine
Double Helix
these nucleotides come together in a repeating pattern, they create a twisted ladder shaped molecule
Rails of DNA Ladder
made up of repeating alternating units of deoxyribose and phosphate groups, held together by covalent bonds
Rungs of DNA ladder
base pairs, two complementary nitrogenous bases held together by hydrogen bonds
Base Pairs Rule
limits which nitrogenous bases can bond: Adenine bonds with thymine, Cytosine bonds with guanine
Adenine and Guanine
Purines
Thymine and Cytosine
Pyrimidines
Chargaff’s rule
DNA from the cell of any organism should have a 1:1 ratio of purine and pyrimidine bases. Or more simply: %A=%T, %G=%C
Genes
Segments of DNA that code for a protein, be short or very long, depending on how many nucleotides are contained in their length, Humans have ~20,000, code for proteins, which control traits
DNA versus RNA
DNA: Codes genetic info, sugar is Deoxyribose, # of strands 2, bases: Adenine, Thymine, Cytosine, Guanine, Nucleus (Mitochondria, Chloroplasts), Interacts with RNA to create proteins
RNA: Codes for proteins, sugar is Ribose, # of strands 1, bases: Adenine, Uracil**, Cytosine, Guanine **Uracil is a pyrimidine, Nucleus, Cytoplasm, Rough ER, 3 types: Messenger RNA, Transfer RNA, Ribosomal RNA
DNA Replication
double-stranded molecule must split apart so that each strand can be copied, There are approximately 3 billion base pairs in the human genome and all of them must be copied before a cell divides
Semiconservative
each new strand contains one parent strand and one new, complementary strand
Replication Bubbles
the sites along a strand of DNA where the two halves have been split apart so each half of the strand can be copied
5’ to 3’ Direction
This means nucleotides can only be added to the 3’ end
DNA Helicase
unwinds and unzips the double helix
DNA Polymerase
adds on nucleotides to the new strand
DNA Ligase
joins fragments of the new strand together
Mutation
any change in the original sequence of base pairs
Point Mutations
a change in a single nucleotide base, There are several types: Substitution, Insertion, and Deletion
Substitution
one letter replaces another in the sequence, Ex: A → G
Insertion
one base is added into the sequence, Ex: a new T is added in the middle of sequence
Deletion
one base is removed from the sequence, Ex: a C is removed
DNA → mRNA → protein
To control traits, proteins are made
Transcription
Happens before translation, first part of protein synthesis, occurs in the nucleus of eukaryotes, in the cytoplasm of prokaryotes
Translation
happens after Transcription, second part of protein synthesis, occurs at a ribosome in the cytoplasm
Messenger RNA
During transcription, DNA is unwound and unzipped, It is used as a template to create a strand, In eukaryotes, this occurs in the nucleus, In prokaryotes, this occurs in the cytoplasm
Codon
three base sequence that codes for a particular amino acid,
Anticodon
tRNA molecules have _________ which is complementary to the codon of the mRNA
mRNA
arrives at the ribosome, it gives the code for a protein, codon by codon
tRNA
molecules will bring the correct amino acid to the ribosome