ap bio unit 6 (genetics)

what types of bonds are between complementary base pairs?

hydrogen bonds

which direction is the sugar-phosphate backbone built in?

5’ → 3’ (reverse!!!)

purines

GA; are double-ringed

pyrimidines

CUT; single ring

base pairing rules

A-T, G-C, A-U (rna)

histone

dna coils around these proteins to form chromosomes

plasmid

a dna circle in proks that replicates independently of the main chromosome. usually carries cool traits like virus protection

helicase

unwinds DNA from histone, creating replication fork

primase

starts an RNA primer for lagging strand replication (and very beginning of leading strand)

topisomerase

untangles DNA at replication fork

dna polymerase III

adds nucleotides

dna polymerase I

replaces rna w/ dna

dna ligase

joins dna fragments (lagging strand)

single-stranded binding proteins

keeps replication fork from closing

telomere

a repetitive nucleotide sequence that caps each chromosome, replacing the gap in replicated DNA where the RNA primer was

telomerase

lengthens the telomere; very active in cancer cells

dna transcription

dna → rna; uses dna template strand to make mRNA for protein production

transcription initiation

rna poly binds to recognition sites in the promoter region (TATA box) of dna and unwinds it, can be turned off by a repressor

transcription elongation

nucleotides are built from a template strand (3’ → 5’) in a 5’ → 3’ direction using base pairing rules

rna polymerase

makes mRNA in transcription elongation

transcription factor

helps rna bind in transcription elongation (to promoter)

transcription termination

rna poly reaches a terminator sequence (NOT STOP CODON) and detaches from dna

rna processing

1. addition of 5’ cap (G) and poly a tail

2. introns are removed

spliceosome

cuts out introns and glues exons together

codon chart

has mrna not trna

stop codon

does not code to an amino acid

chaperonin

folds protein

trna

carries an amino acid and brings it to a ribosome during protein synthesis

translation initiation

ribosome gets together with mrna and trna (because of start codon)

translation elongation

polypeptide chain is built with each codon

translation termination

stop codon reached and mrna and protein chain are released

rna translation

rna → amino (viruses can use ribosomes as a factory for their own evil rna)

substitution

one nucleotide is replaced by another one

mutations

ARE RANDOM

deletion

one or more nucleotides are removed (if not a multiple of three, this is a frameshift)

insertion

one or more nucleotides are added (often frame shift)

frameshift

cooked mutations

nonsense mutation

codon no longer codes to an amino

missense mutation

codon goes to wrong amino

silent mutation

same amino is made even with mutation

transduction

dna is moved from one bacteria to another by a virus

conjugation

dna is transferred between bacterial cells

transformation (IMPORTANT)

the transfer and incorporation of foreign dna into a host genome, allows you to genetically engineer traits

transposition

chunks of dna jump from one place to another within the genome

vector

usually a plasmid, an organism that readily picks up foreign dna

regulator

expresses a repressor protein that attaches to operator, switching off the promoter

operator

the on/off switch of an operon

operon

genetic regulatory system, composed of genes that encode for related proteins, a repressor, a promoter, and an operator

inducible operon

the operon is off until turned on (e.g. lactase, which metabolizes lactose, only turns on if there is lactose present)

epigenetics

genes can be turned off for long periods of time due to hereditary and environmental factors (e.g. methylation, which causes genes to wrap more tightly around histones, turning them off)