DNA Flashcards
DNA
Long chains of nucleotides
Made of phosphates,sugar,bases
Two chains run antiparallel in opposite directions
5’ sugar has a phosphate
Double helix, t pairs with a c pairs with g
DNA
DNA replication
Makes more dna
Occurs in nucleus
Occurs during a phase of interphase before mitosis and meiosis
DNA replication is semi conservative
One old stand one new strand
many enzymes work together to copy dna
DNA replication
Helicase
Unwinds dna(separates) by breaking hydrogen bonds
Topoisomerase
(Person standing on black lines)
Holds dna so it doesn’t retwist
Primase
Adds rna primer to start replication ,shows dna polymerase where to attach
DNA polymerase
Removes primer and adds can nucleotides in 5 to 3 direction also proofreads to catch errors and mutations
Leading strand
Made continuously, dna polymerase moves toward helicase as strands are separating
Lagging strand
Made in pieces( Okazaki fragments) bc dna polymerase can only add nucleoTides to growing 3’ end
Ligase
Seals together fragments on lagging strand
Uses dna to make mRNA so that the instructions in dna can be brought to the Protien building machinery outside the nucleus, occurs in nucleus of eukaryotic cells
Transcription
RNA
Single stranded, contains U uracil can be inside or outside nucleus
Helicase
Separates 2 strands of dna by breaking hydrogen bonds , uses in transcription
RNA polymerase
Build s mRNA using dna template used in transcription
Gene
Piece of dna that is use to make mRNA in a protiem
Promoter
Start of gene tells rna polymerase where to start
Terminator
End of a gene, tells rna polymerase where to stop
mRNA editing
Modifications to mRNA after transcription, occurs in nucleus, before the mRNA enters cytoplasm
Spliceosome
Cuts out non coding pieces of mRNA called introns
Introns
Non coding pieces of mRNA
Exons
Coding pieces of mRNA
Alternate splicing
Different mRNA pieces are considered introns, so multiple different protiems can be made using same gene
Two types of mRNA editing
Poly tail A: lots of A added, tells cell this is useful mRNA, not to destroy
5’ cap: modified guanine tells cell the mRNA is ready to leave the nucleus to make a Protien
Translation
Uses mRNA to make a Protien
Protiens
Chains of amino acids
Amino acids
Pieces of a Protien
Codon
A set of 3 mRNA bases that codes for an amino acid
Ribosome
translation occurs
tRNA
Transfer amino acid to ribosome
Point mutation
single base incorrect ( substitution)
Frameshift mutation
Bases added or deleted
How does rna polymerase differ from dna polymersse
Rna polymerase can begin adding mRNA nucleotides but dna polymerase requires primate to begin dna synthesis
Each stand of the original double stranded dna molecule serves as a template for newly constructed completary strand
Characteristic of dna replication
When dna is produced from a dna template strand
Transcription
What would happen if ribosome was disrupted
The cell would not be able to make Protiens
Messing up dna sequence would result in
Change in codons a
Causing different amino acids to be placed in the Protien
What happens when a tRNA molecule delivers an amino acid to the ribosome
The amino acid is bonded to another amino acid to create a growing polypeptide
30 nucleotides results in how many amino acids in a protien
10
RNA contains
Uracil
