gene expression unit

3’ to 5’

template, antisense, negative

• is transcribed

5’ to 3’

coding, sense, positive

types of gene mutations

substitution

• dna polymerase makes mistake

• silent, missense, nonsense

frameshift(bigger effect)

• nucleotide gets inserted/deleted because of mutagens

• insertion, deletion

types of chromosomal mutations

deletion

• piece of chromosome removed/lost

duplication

• segment of chromosome is copied

inversion

• chromosome segment breaks off, flips 180 degrees, and reattaches backwards

reciprocal translocation

• two non-homologous chromosomes switch places with each other

editing for mature mRNA

• 5’ cap

• 3’ poly A tail

• introns cut, exons spliced

alternative splicing

• exons kept varies

• changes # of nucleotides—> leads to protein diversity

causes of genetic diversity

fertilization

• mom/dad have different genes

crossing over

• gametes become different than each other

transduction

• virus transfers DNA from one bacteria to another

• bacteria gains new genes

conjugation

• bacteria connect with bridge then DNA plasmid transfers from one bacteria to another

transformation

• put plasmid into bacteria, transforms it

promoter mutated?

nothing expressed

cell specialization

same DNA throughout body, but different activators cell to cell

repressible operon

• anabolic

• TRP

• on by default

inducible operon

• catabolic

• LAC

• off by default

TRP operon

TRP absent

• repressor inactive, operon on

TRP present

• repressor active, operon off

LAC operon

LAC absent

• repressor active, operon off

LAC present

• repressor inactive, operon on

CAP

lactose present, glucose scarce

• CAP on, more mRNA created

lactose present, glucose present

• CAP off

heterochromatin

highly packed, never expressed

acetyl groups

added onto histone tail, loosen DNA, DNA expressed

methyl groups

added on to DNA, condense DNA, DNA silenced

siRNA

blocks specific mRNA from being translated

binds to mRNA and causes it to be destroyed

silences/turns off gene expression

miRNA

• regulates gene expression after transcription

• binds to mRNA and blocks translation OR causes degradation

• one miRNA can target multiple different mRNAs

piRNA

• protects genome in reproductive cells (gametes)

• silences transposons (jumping genes) to prevent mutations

• mostly active in testes/ovaries

wells side of gel electrophoresis

negative

PCR cycle

• Denaturation (~95°C)

  • Heat breaks hydrogen bonds

  • Double helix separates into 2 single strands

• Annealing (~55°C)

  • Cool down

  • Primers bind to target DNA sequences on each strand

• Extension (~72°C)

  • DNA polymerase adds nucleotides

  • Builds new complementary strands

  • DNA doubles each cycle

cDNA

• made from mature mRNA using reverse transcriptase

• only has exons

bonds between dna strands

• hydrogen bonds

• a-t

• g-c

dna replication is

• semiconservative

• original strand serves as templates

nucleotides added to what end

• 3’ end

• dna synthesis happens 5’ to 3’

• why we have leading/continuous strand and lagging/okasaki fragments

deoxyribose vs ribose

deoxyribose

• H on carbon 2’ O(de-oxy= lacks the o in oxygen)

ribose

• has OH on carbon 2’

transcription initiation

RNA polymerase binds to promoter region on DNA

DNA unwinds and separates at transcription start site

Template strand is ready to be read

TRANSCRIPTION - Elongation

RNA polymerase moves along template strand (3' → 5')

Adds RNA nucleotides to growing mRNA (5' → 3')

Uses base pairing rules (A-U, G-C)

TRANSCRIPTION - Termination

RNA polymerase reaches terminator sequence

mRNA is released from DNA

DNA re-winds back into double helix

TRANSLATION - Initiation

mRNA binds to small ribosomal subunit

tRNA with methionine (Met/AUG) binds to start codon

Large ribosomal subunit attaches = ribosome complete

TRANSLATION - Elongation

• Ribosome moves along mRNA codon by codon

• tRNAs bring amino acids to match codons

• Peptide bonds form between amino acids

TRANSLATION - Termination

Ribosome reaches stop codon (UAA, UAG, or UGA)

Release factor protein binds instead of tRNA

Polypeptide is released, ribosome subunits separate

mRNA

Carries genetic info from DNA to ribosome

Contains codons (3-nucleotide sequences)

Template for protein synthesis

tRNA

Brings specific amino acids to ribosome

Has anticodon that matches mRNA codon

"Translator" between nucleotide sequence and amino acid sequence

rRNA

Makes up the ribosome structure (with proteins)

Catalyzes peptide bond formation (ribozyme)

Provides binding sites for mRNA and tRNA